SynBio doi: 10.3390/synbio4020009

Authors: Oran Wasserman Kristin K. Durrant Jackson J. Morley Paula E. Oliveira Mallory R. Wootton Brianne E. Bell Ethon D. Van Noy Randolph V. Lewis Justin A. Jones

Solitary bees account for most described bee species worldwide, with many spinning silk fibers to form protective cocoons during development; however, solitary bee silk proteins remain largely unexplored in recombinant systems and biomaterial fabrication. Here, we report the first recombinant expression and biomaterial formation from a solitary bee silk protein. Osmia lignaria silk fibroin 2 (OligF2) was expressed in Escherichia coli BL21(DE3) using an expression and purification scheme adapted from a recombinant hagfish intermediate filament (rHIF) workflow, yielding 0.34 g/L at ~70% purity. The purified OligF2 protein was cast into films at 0.75% and 1% (w/v). Fourier-transform infrared attenuated total reflectance (FTIR-ATR) analysis estimated higher β-sheet content in 0.75% films (50.3%) than in 1% films (42.3%). Mechanical testing yielded elastic moduli of 7.83 ± 2.73 MPa and 6.80 ± 1.89 MPa for the 0.75% and 1% films, respectively. These results establish the first recombinant production and biomaterial formation of a solitary bee silk protein, providing a foundation for exploring this class of recombinant proteins for the development of tunable biomaterials.

SynBio doi: 10.3390/synbio4020008

Authors: Ana Lilia Hernández-Orihuela Lucía Carolina Alzati-Ramírez Agustino Martínez-Antonio

Indole-3-acetic acid (IAA) is the main natural auxin and a key regulator of plant growth. However, most commercial auxins are synthetically produced from non-renewable resources. Here, we present a minimal synthetic biology platform for microbial IAA production that also serves as a teaching model for genetic circuit design and bioprocess development. We developed codon-optimized versions of the iaaM and iaaH genes, which encode tryptophan 2-monooxygenase and indole-3-acetamide hydrolase, and assembled them into a compact expression cassette in Escherichia coli TOP10. Correct expression of both enzymes was confirmed by SDS-PAGE. The engineered strain was cultivated in a low-cost medium made from avocado seed hydrolysate, an agro-industrial waste, supplemented with tryptophan as a precursor. IAA was quantified using the Salkowski colorimetric assay and further validated by HPLC, reaching approximately 303–313 µg/mL at 48 h, with the medium costing approximately fivefold cheaper locally than traditional LB. The supernatants containing biosynthetic IAA induced root formation in 100% of tobacco leaf explants, outperforming the commercial standard at the same concentration and confirming biological activity. Since this workflow follows the Design–Build–Test–Learn (DBTL) cycle, Design (pathway selection and codon optimization), Build (plasmid assembly), Test (protein expression, metabolite quantification, plant bioassays), and Learn (medium and process optimization), it provides a sustainable production method and an accessible educational platform for synthetic biology.

SynBio doi: 10.3390/synbio4020007

Authors: James A. Davis Jaeden B. Tedsen Elizabeth Brown Luis Corona-Elizarraras Gretchen Berg Mario A. Alpuche-Aviles Jeffrey F. Harper

Lipid nanodiscs are synthetic nanoparticles capable of solubilizing lipophilic drugs and have been shown to improve the potency of the antifungal Amphotericin B (AmphB) against various fungal pathogens. In this study, the SpyCatcher–SpyTag covalent labeling system was used to couple AmphB-loaded Apolipoprotein A1 (ApoA1) lipid nanodiscs to the receptor domain of Dectin-1, which binds to β-1,3/1,6 glucans present in many fungal cell walls. Denaturing protein gel electrophoresis demonstrated that ApoA1-SpyTag003 lipid nanodiscs could be covalently labeled with SpyCatcher003-Dectin-1-superfolder GFP (sfGFP). In microtiter growth assays with Saccharomyces cerevisiae, Dectin-1 AmphB nanodiscs displayed an IC50 1.5-fold lower than uncoupled AmphB nanodiscs and 2.8-fold lower than AmphB-only controls. Nanodiscs without AmphB and SpyCatcher003-Dectin-1-sfGFP themselves did not inhibit yeast growth. Fluorescence microscopy showed that SpyCatcher003-Dectin-1-sfGFP binds to yeast cell walls and accumulated at hot spots, matching the budding scar enrichment pattern previously described for other Dectin-1 fusion proteins. Together these results indicate that Dectin-1 fusions can target AmphB-loaded lipid nanodiscs to fungal cell walls and improve drug delivery. The results here establish the use of a modular SpyCatcher–SpyTag coupling system for targeting drug-loaded lipid nanodiscs to different cells or tissues, thereby increasing drug retention at infection sites, increasing drug potency, and reducing harmful side-effects.

SynBio doi: 10.3390/synbio4010006

Authors: Shu-Chiao Chou Yi-Jyun Lai Boonyawee Saengsawang Si-Yu Li

Metabolic engineering presents the possibility of creating novel and practical whole-cell biocatalysts. The practice of metabolic engineering is achieved first by in vitro DNA assembly, followed by the introduction of the newly constructed DNA into industrial microorganisms to create a novel phenotype. Although this approach of in vitro DNA assembly has been studied extensively, generation of unwanted recombinant DNA products remains a possibility. In this study, a recombinant DNA, namely pGRN02, was constructed using the sequence- and ligation- independent cloning. However, this DNA assembly method had a low success rate (5%). Unexpectedly, we identified an un-wanted recombinant DNA product as a major recombinant product (70%). DNA sequencing of this product indicated that it should not have been formed during in vitro DNA assembly, but rather post in vitro assembly. This study aims to report and discuss profound results of the DNA assembly reaction. The standard SLIC design using 20 bp homology arms is theoretically sufficient for correct assembly under typical conditions. However, longer unexpected repeats, such as the 44 bp internal homology observed here, can outcompete the designed junctions and dominate the recombination outcome.

SynBio doi: 10.3390/synbio4010005

Authors: Matthew J. Argyle Dallin M. Chipman Anna Claire Woolley Bradley C. Bundy Dennis Della Corte

Therapeutic proteins face a critical pharmacokinetic challenge: rapid clearance from circulation limits their clinical efficacy. Albumin-binding domains (ABDs) offer an elegant solution by enabling therapeutic proteins to “hitchhike” on serum albumin’s favorable 19-day half-life through FcRn-mediated recycling. Clinical validation through approved therapeutics like ozoralizumab demonstrates the success of this approach, with preclinical studies showing fusion to an ABD extended half-life to 18 days. This review provides an analysis of ABD-fusion protein design, integrating structural biology, computational prediction, and rational engineering principles. We catalog the major classes of albumin-binding modalities, including bacterial three-helix bundle domains, engineered peptides, antibody-derived binders, and alternative scaffolds, comparing their binding properties, size contributions, cross-species reactivity, and production cost. Critical examination of linker architectures reveals that flexible glycine-serine linkers (particularly the widely successful (GGGGS)3 motif) provide optimal balance between domain independence and molecular economy, though linker choice profoundly influences not only spatial separation but also binding affinity, folding, stability, and pharmacokinetics. We evaluate the utility and limitations of the structure prediction tools for ABD-fusion design. We establish practical guidelines for integrating computational screening with experimental validation. This review provides protein engineers and synthetic biologists with a comprehensive framework for rational design of albumin-binding therapeutics, emphasizing the synergistic integration of structural insight, computational prediction, and systematic experimental validation to accelerate development of next-generation long-acting biotherapeutics.

SynBio doi: 10.3390/synbio4010004

Authors: Shi Du Yuxi Zhu

Synthetic RNA has become an essential modality in therapeutic development. Linear mRNA is already clinically validated, which demonstrated that in vitro-transcribed (IVT) RNA can achieve robust protein expression in humans and can be manufactured at a large scale. Circular RNA (circRNA) represents a more recent format characterized by a covalently closed backbone that confers enhanced resistance to exonucleases and supports sustained translation when paired with appropriate regulatory elements. Although both formats are produced through cell-free synthesis, their manufacturing pathways are distinct. Linear mRNA synthesis requires transcription, capping, polyadenylation, and stringent removal of double-stranded RNA contaminants. circRNA production generally proceeds through transcription of a linear precursor followed by enzymatic or ribozyme-mediated circularization, with emerging strategies such as permuted intron-exon designs improving efficiency and reducing extraneous sequence content. This review summarizes the principal methods used to generate linear and circRNA and identifies the technical barriers that must be overcome during the manufacturing process.

SynBio doi: 10.3390/synbio4010003

Authors: Markos Mathioudakis Rafail Andreou Angeliki-Maria Papapanou Artemis-Chrysanthi Savva Asimenia Ioannidou Nefeli-Maria Makri Stefanos Anagnostopoulos Thetis Tsinoglou Ioanna Gerogianni Christos Giannakopoulos Angeliki-Argyri Savvopoulou-Tzakopoulou Panagiota Baka Nicky Efstathiou Soultana Delizisi Michaela Ververi Rigini Papi Konstantina Psatha Michalis Aivaliotis Spyros Gkelis

Wildfires are increasingly frequent and intense due to climate change, resulting in degraded soils with diminished microbial activity, reduced water retention, and low nutrient availability. In many regions, previously restored areas face repeated burning events, which further exhaust soil fertility and limit the potential for natural regeneration. Traditional reforestation approaches such as seed scattering or planting seedlings often fail in these conditions due to extreme aridity, erosion, and lack of biological support. To address this multifaceted problem, this study proposes a living, biodegradable hydrogel that integrates an engineered soil-beneficial microorganism consortium, designed to deliver beneficial compounds and nutrients combined with endemic plant seeds into a single biopolymeric matrix. Acting simultaneously as a biofertilizer, soil conditioner, and reforestation aid, this 3-in-1 system provides a microenvironment that retains moisture, supports microbial diversity restoration, and facilitates plant germination even in nutrient-poor, arid soils. The concept is rooted in circular economy principles, utilizing polysaccharides from food industry by-products for biopolymer formation, thereby ensuring environmental compatibility and minimizing waste. The encapsulated microorganisms, a Bacillus subtilis strain and a Nostoc oryzae strain, are intended to enrich the soil with useful compounds. They are engineered based on synthetic biology principles to incorporate specific genetic modules. The B. subtilis strain is engineered to break down large polyphenolic compounds through laccase overexpression, thus increasing soil bioavailable organic matter. The cyanobacterium strain is modified to enhance its nitrogen-fixing capacity, supplying fixed nitrogen directly to the soil. After fulfilling its function, the matrix naturally decomposes, returning organic matter, while the incorporation of a quorum sensing-based kill-switch system is designed to prevent the environmental escape of the engineered microorganisms. This sustainable approach aims to transform post-wildfire landscapes into self-recovering ecosystems, offering a scalable and eco-friendly alternative to conventional restoration methods while advancing the integration of synthetic biology and environmental engineering for climate resilience.

SynBio doi: 10.3390/synbio4010002

Authors: Bernd H. A. Rehm

The open access journal SynBio [...]

SynBio doi: 10.3390/synbio4010001

Authors: Sopan Ganpatrao Wagh Akshay Milind Patil Ghanshyam Bhaurao Patil Sachin Ashok Bhor Kiran Ramesh Pawar Harshraj Shinde

Agricultural systems face mounting pressures from climate change, as rising temperatures, elevated CO2, and shifting precipitation patterns intensify plant disease outbreaks worldwide. Conventional strategies, such as breeding for resistance, pesticides, and even transgenic approaches, are proving too slow or unsustainable to meet these challenges. Synthetic biology offers a transformative paradigm for reprogramming plant immunity through genetic circuits, RNA-based defences, epigenome engineering, engineered microbiomes, and artificial intelligence (AI). We introduce the concept of synthetic immunity, a unifying framework that extends natural defence layers, PAMP-triggered immunity (PTI), and effector-triggered immunity (ETI). While pests and pathogens continue to undermine global crop productivity, synthetic immunity strategies such as CRISPR-based transcriptional activation, synthetic receptors, and RNA circuit-driven defences offer promising new avenues for enhancing plant resilience. We formalize synthetic immunity as an emerging, integrative concept that unites molecular engineering, regulatory rewiring, epigenetic programming, and microbiome modulation, with AI and computational modelling accelerating their design and climate-smart deployment. This review maps the landscape of synthetic immunity, highlights technological synergies, and outlines a translational roadmap from laboratory design to field application. Responsibly advanced, synthetic immunity represents not only a scientific frontier but also a sustainable foundation for climate-resilient agriculture.

SynBio doi: 10.3390/synbio3040020

Authors: Thomas Sorrell Ethan Ou Fenyong Liu

Nucleic acid-based gene interfering and editing molecules, such as antisense oligonucleotides, ribozymes, small interfering RNAs (siRNAs), and CRISPR-Cas9-associated guide RNAs, are promising gene-targeting agents for therapeutic applications. Cancer’s heterogeneous and diverse nature demands gene-silencing technologies that are both specific and adaptable. RNase P ribozymes, called M1GS RNAs, are engineered constructs that link the catalytic M1 RNA from bacterial RNase P to a programmable guide sequence. This guide sequence directs the M1GS ribozyme to base-pair with a target RNA, inducing it to fold into a structure resembling pre-tRNA. Catalytic activity can be enhanced through in vitro selection strategies. In this review, we will discuss the application of M1GS ribozymes in targeting cancer-associated RNAs, focusing on the BCR-ABL transcript in leukemia, the internal ribosome entry site (IRES) of hepatitis C virus (HCV), and the replication and transcription activator (RTA) of Kaposi’s sarcoma-associated herpesvirus (KSHV). Together, these examples highlight the versatility of M1GS ribozymes across both viral and cellular oncogenic targets, underscoring their potential as a flexible synthetic biology platform for cancer therapy.

SynBio doi: 10.3390/synbio3040019

Authors: Jonas De Saeger

The CRISPR/SpCas9 system has revolutionized biology by enabling precise and programmable genome modification. While substantial effort has focused on engineering the SpCas9 protein and spacer sequences, the single-guide RNA (sgRNA) scaffold is an equally critical determinant of activity. Since the canonical scaffold was introduced in 2012, numerous variants have been developed. Early designs sought to enhance editing efficiency; however, despite the first improved scaffold being reported in 2013, more than 80% of CRISPR plasmids deposited in the Addgene repository still use the original scaffold rather than an efficiency-optimized alternative, which may not provide optimal performance. Subsequent work has also addressed intra-sgRNA interactions that impair folding, as well as inter-sgRNA interactions that destabilize multiplexed arrays, yet these solutions remain largely overlooked. Beyond efficiency, scaffold engineering—and the inclusion of auxiliary RNA elements—has enabled new capabilities, including effector recruitment, conditional regulation, visualization, improved stability, and large-scale multiplexing. The main goal of this review is to (i) provide a structured overview of the diverse SpCas9 sgRNA scaffold variants and auxiliary RNA modifications developed to date, (ii) summarize their functional characteristics and contexts of use, thereby illustrating how scaffold engineering continues to expand the functional scope of CRISPR technologies, and (iii) present a curated sequence resource comprising more than 230 scaffold variants and 80 auxiliary modifications to support experimental design and benchmarking.

SynBio doi: 10.3390/synbio3040018

Authors: Matthew J. Argyle William P. Heaps Corbyn Kubalek Spencer S. Gardiner Bradley C. Bundy Dennis Della Corte

Protein function emerges from dynamic conformational changes, yet structure prediction methods provide only static snapshots. While AlphaFold3 (AF3) predicts protein structures, the potential for extracting dynamic information from its ensemble predictions has remained underexplored. Here, we demonstrate that AF3 structural ensembles contain substantial dynamic information that correlates remarkably well with molecular dynamics simulations (MD). We developed ChronoSort, a novel algorithm that organizes static structure predictions into temporally coherent trajectories by minimizing structural differences between neighboring frames. Through systematic analysis of four diverse protein targets, we show that root-mean-square fluctuations derived from AF3 ensembles can correlate strongly with those from MD (r = 0.53 to 0.84). Principal component analysis reveals that AF3 predictions capture the same collective motion patterns observed in molecular dynamics trajectories, with eigenvector similarities significantly exceeding random distributions. ChronoSort trajectories exhibit structural evolution profiles comparable to MD. These findings suggest that modern AI-based structure prediction tools encode conformational flexibility information that can be systematically extracted without expensive MD. We provide ChronoSort as open-source software to enable broad community adoption. This work offers a novel approach to extracting functional insights from structure prediction tools in minutes, with significant implications for synthetic biology, protein engineering, drug discovery, and structure–function studies.

SynBio doi: 10.3390/synbio3040017

Authors: Abdul Manan Nabila Qayyum Rajath Ramachandran Naila Qayyum Sidra Ilyas

Synthetic biology, an emergent interdisciplinary field integrating principles from biology, engineering, and computer science, endeavors to rationally design and construct novel biological systems or reprogram extant ones to achieve predefined functionalities. The conventional approach relies on an iterative Design-Build-Test-Learn (DBTL) cycle, a process frequently hampered by the intrinsic complexity, non-linear interactions, and vast design space inherent to biological systems. The advent of Artificial Intelligence (AI), and particularly its subfields of Machine Learning (ML) and Deep Learning (DL), is fundamentally reshaping this paradigm by offering robust computational frameworks to navigate these formidable challenges. This review elucidates the strategic integration of AI/ML/DL across the synthetic biology workflow, detailing the specific algorithms and mechanisms that enable rational design, autonomous experimentation, and pathway optimization. Their advanced applications are specifically underscored across critical facets, including de novo rational design, enhanced predictive modeling, intelligent high-throughput data analysis, and AI-driven laboratory automation. Furthermore, pivotal challenges, such as data sparsity, model interpretability, the “black box” problem, computational resource demands, and ethical considerations, have been addressed, while concurrently forecasting future trajectories for this rapidly advancing and convergent domain. The synergistic convergence of these disciplines is demonstrably accelerating biological discovery, facilitating the creation of innovative and scalable biological solutions, and fostering a more predictable and efficient paradigm for biological engineering.

SynBio doi: 10.3390/synbio3040016

Authors: Arabella Essert Kathrin Castiglione

Researchers strive to exploit kinetic potentials of multistep reactions by positioning enzymes in a regulated fashion. Therein, the proliferating cell nuclear antigen (PCNA) from Sulfolobus solfataricus is a promising biomolecular tool due to its extraordinary architecture. PCNA is a circular DNA sliding clamp, which can bind and move along DNA and thus, be applied for the immobilization and transport of biomolecules on versatile DNA scaffolds. Additionally, its heterotrimeric character facilitates the colocalization of enzyme cascades with defined stoichiometry. This study provides insights into the in vitro binding behavior of PCNA and its potential as protein scaffold for DNA functionalization and controlled biocatalysis: (1) PCNA was capable of binding circular DNA and wireframe DNA nanostructures. (2) DNA binding was predominantly mediated by the PCNA1 subunit. (3) PCNA assembly around DNA was compromised when cysteines were introduced at the PCNA–PCNA interfaces to stabilize the ring via disulfide bonds. (4) A two-enzyme cascade, comprising a pseudo-monomeric cytochrome P450 BM3 monooxygenase and a monomeric alcohol dehydrogenase (ADH), was successfully fused to PCNA, retaining catalytic activity. (5) When immobilized on DNA, the cascade performance was not assessable, due to nearly complete loss of ADH activity in proximity to DNA.

SynBio doi: 10.3390/synbio3040015

Authors: Kuntal Kumar Das Ashutosh Kumar Dubey Bikramjit Basu Yogendra Narain Srivastava

While synthetic biology has traditionally focused on creating biological systems often through genetic engineering, emerging technologies, for example, implantable pacemakers with integrated piezo-electric and tribo-electric materials are beginning to enlarge the classical domain into what we call symbiotic synthetic biology. These devices are permanently attached to a body, although non-living or genetically unaltered, and closely mimic biological behavior by harvesting biomechanical energy and providing functions, such as autonomous heart pacing. They form active interfaces with human tissues and operate as hybrid systems, similar to synthetic organs. In this context, the present paper first presents a short summary of previous in vivo studies on piezo-electric composites in relation to their deployment as battery-less pacemakers. This is then followed by a summary of a recent theoretical work using a damped harmonic resonance model, which is being extended to mimic the functioning of such devices. We then extend the theoretical study further to include new solutions and obtain a sum rule for the power output per cycle in such systems. In closing, we present our quantitative understanding to explore the modulation of the quantum vacuum energy (Casimir effect) by periodic body movements to power pacemakers. Taken together, the present work provides the scientific foundation of the next generation bio-integrated intelligent implementation.

SynBio doi: 10.3390/synbio3040014

Authors: Akimichi Yoshino Riko Shimoji Yuma Nishikawa Hideo Nakano Teruyo Ojima-Kato

Polyproline residues are well known to induce ribosomal stalling during translation. Our previous work demonstrated that inserting a short translation-enhancing peptide, Ser-Lys-Ile-Lys (SKIK), immediately upstream of such difficult-to-translate sequences can significantly alleviate ribosomal stalling in Escherichia coli. In this study, we provide a quantitative evaluation of its translational effect by kinetically analyzing the influence of the SKIK peptide on polyproline motifs using a reconstituted E. coli in vitro translation system. Translation rates estimated under reasonable assumptions fitted well to a Hill equation within a Michaelis–Menten-like kinetic framework. We further revealed that repetition of the SKIK tag did not provide any positive effect on translation. Moreover, introduction of the SKIK tag increased the production of polyproline-containing proteins, including human interleukin 11, human G protein signaling modulator 3, and DUF58 domain–containing protein from Streptomyces sp. in E. coli cell-free protein synthesis. These findings not only provide new insight into the fundamental regulation of translation by nascent peptides but also demonstrate the potential of the SKIK peptide as a practical tool for synthetic biology, offering a strategy to improve the production of difficult-to-express proteins.

SynBio doi: 10.3390/synbio3030013

Authors: Natalia Trufanova Oleh Trufanov Oleksandr Petrenko

Metabolic engineering of mesenchymal stem/stromal cells (MSCs) represents a compelling frontier for advanced cellular therapies, enabling the precise tuning of their biological outputs. This feature paper examines the critical role of engineered culture microenvironments, specifically 3D platforms, hypoxic preconditioning, and other priming approaches, which are synthetic biology strategies used to guide and optimize MSC metabolic states for desired functional outcomes. We show that these non-genetic approaches can significantly enhance MSC survival, immunomodulatory capacity, and regenerative potential by shifting their metabolism toward a more glycolytic phenotype. Furthermore, we propose a new paradigm of “designer” MSCs, which are programmed with synthetic circuits to sense and respond to the physiological cues of an injured microenvironment. This approach promises to transform regenerative medicine from an inconsistent field into a precise, predictable, and highly effective therapeutic discipline.

SynBio doi: 10.3390/synbio3030012

Authors: Aniruddha Acharya Kaitlin Hopkins Tatum Simms

Silicon has a striking similarity to carbon and is found in plant cells. However, there is no specific role that has been assigned to silicon in the life cycle of plants. The amount of silicon in plant cells is species specific and can reach levels comparable to macronutrients. Silicon is used extensively in artificial intelligence, nanotechnology, and the digital revolution, and thus can serve as an informational molecule such as nucleic acids. The diverse potential of silicon to bond with different chemical species is analogous to carbon; thus, it can serve as a structural candidate similar to proteins. The discovery of large amounts of silicon on Mars and the moon, along with the recent development of enzyme that can incorporate silicon into organic molecules, has propelled the theory of creating silicon-based life. The bacterial cytochrome has been modified through directed evolution such that it could cleave silicon–carbon bonds in organo-silicon compounds. This consolidates the idea of utilizing silicon in biomolecules. In this article, the potential of silicon-based life forms has been hypothesized, along with the reasoning that autotrophic virus-like particles could be used to investigate such potential. Such investigations in the field of synthetic biology and astrobiology will have corollary benefits for Earth in the areas of medicine, sustainable agriculture, and environmental sustainability.

SynBio doi: 10.3390/synbio3030011

Authors: Karim S. Elnaggar Ola Gamal Nouran Hesham Sama Ayman Nouran Mohamed Ali Moataz Emad M. Elzayat Nourhan Hassan

Stem cells, unspecialized cells with regenerative and differentiation capabilities, hold immense potential in regenerative medicine, exemplified by hematopoietic stem cell transplantation. However, their clinical application faces significant limitations, including their tumorigenic risk due to uncontrolled proliferation and cellular heterogeneity. This review explores how synthetic biology, an interdisciplinary approach combining engineering and biology, offers promising solutions to these challenges. It discusses the concepts, toolkit, and advantages of synthetic biology, focusing on the design and integration of genetic circuits to program stem cell differentiation and engineer safety mechanisms like inducible suicide switches. This review comprehensively examines recent advancements in synthetic biology applications for stem cell engineering, including programmable differentiation circuits, cell reprogramming strategies, and therapeutic cell engineering approaches. We highlight specific examples of genetic circuits that have been successfully implemented in various stem cell types, from embryonic stem cells to induced pluripotent stem cells, demonstrating their potential for clinical translation. Despite these advancements, the integration of synthetic biology with mammalian cells remains complex, necessitating further research, standardized datasets, open access repositories, and interdisciplinary collaborations to build a robust framework for predicting and managing this complexity.

SynBio doi: 10.3390/synbio3030010

Authors: Dallin M. Chipman Anna C. Woolley Davu N. Chau William A. Lance Joseph P. Talley Tyler P. Green Benjamin C. Robbins Bradley C. Bundy

Cell-free protein synthesis (CFPS) has transformed protein production capabilities by eliminating cellular constraints, enabling the rapid expression of difficult-to-produce proteins in an open, customizable environment. As CFPS applications expand from fundamental research to industrial production, therapeutic manufacturing, and point-of-care diagnostics, the diverse array of reactor formats has become increasingly important yet challenging to navigate. This review examines the evolution and characteristics of thirteen major CFPS reactor formats, from traditional batch systems to advanced platforms. The historical development of CFPS reactors from the 1960s to present day is presented. Additionally, for each format, operational principles, advantages, limitations, and notable applications are evaluated. The review concludes with a comparative assessment of reactor performance across critical parameters, including productivity, scalability, technical complexity, environmental stability, and application suitability. To our knowledge this structured analysis is the first to focus predominantly on the various reactor formats of cell-free systems and to provide a guide to assist researchers in choosing the reactor type that best fits their specific applications.

SynBio doi: 10.3390/synbio3030009

Authors: Sharathchandra Kambampati Pankaj K. Verma Madhusudhana R. Janga

Synthetic biology (SynBio) is an emerging interdisciplinary field that applies engineering principles to the design and construction of novel biological systems or the redesign of existing natural systems for new functions. As autotrophs with complex cellular architectures, plants possess inherent capabilities to serve as “living factories” for SynBio applications. Recent advancements in genetic engineering, genome editing, and transformation techniques are improving the precision and programmability of plant systems. Innovations, such as CRISPR systems, prime editing strategies, and in planta and nanoparticle-mediated delivery, are expanding the SynBio toolkit for plants. However, the efficient delivery of genetic constructs remains a barrier due to plant systems’ complexity. To address these limitations, SynBio is increasingly integrating iterative Design–Build–Test–Learn (DBTL) cycles, standardization, modular DNA assembly systems, and plant-optimized toolkits to enable predictable trait engineering. This review explores the technological foundations of plant SynBio, including genome editing and transformation methods, and examines their integration into engineered systems. Applications, such as biofuel production, pharmaceutical biosynthesis, and agricultural innovation, are highlighted, along with their ethical, technical, and regulatory challenges. Ultimately, SynBio could offer a transformative path toward sustainable solutions, provided it continues to align technological advances with public interest and global sustainability goals.

SynBio doi: 10.3390/synbio3020008

Authors: Leandro Luis Lavandosque Flavia Vischi Winck

Polyamines play a pivotal role in regulating the growth and metabolic adaptation of microalgae, yet their integrative regulatory roles remain underexplored. This review advances a comprehensive perspective of microalgae growth, integrating polyamine dynamics, amino acid metabolism, and redox balance. Polyamines (putrescine, spermidine, and spermine) biology in microalgae, particularly Chlamydomonas reinhardtii, is reviewed, exploring their critical function in modulating cell cycle progression, enzymatic activity, and stress responses through nucleic acid stabilization, protein synthesis regulation, and post-translational modifications. This review explores how the exogenous supplementation of polyamines modifies their intracellular dynamics, affecting growth phases and metabolic transitions, highlighting the complex regulation of internal pools of these molecules. Comparative analyses with Chlorella ohadii and Scenedesmus obliquus indicated species-specific responses to polyamine fluctuations, linking putrescine and spermine levels to important tunable metabolic shifts and fast growth phenotypes in phototrophic conditions. The integration of multi-omic approaches and computational modeling has already provided novel insights into polyamine-mediated growth regulation, highlighting their potential in optimizing microalgae biomass production for biotechnological applications. In addition, genomic-based modeling approaches have revealed target genes and cellular compartments as bottlenecks for the enhancement of microalgae growth, including mitochondria and transporters. System-based analyses have evidenced the overlap of the polyamines biosynthetic pathway with amino acids (especially arginine) metabolism and Nitric Oxide (NO) generation. Further association of the H2O2 production with polyamines metabolism reveals novel insights into microalgae growth, combining the role of the H2O2/NO rate regulation with the appropriate balance of the mitochondria and chloroplast functionality. System-level analysis of cell growth metabolism would, therefore, be beneficial to the understanding of the regulatory networks governing this phenotype, fostering metabolic engineering strategies to enhance growth, stress resilience, and lipid accumulation in microalgae. This review consolidates current knowledge and proposes future research directions to unravel the complex interplay of polyamines in microalgal physiology, opening new paths for the optimization of biomass production and biotechnological applications.

SynBio doi: 10.3390/synbio3020007

Authors: Joyhare Barbosa Souza Samir Mansour Moraes Casseb

The SARS-CoV-2 virus, which causes COVID-19, has rapidly evolved, producing highly transmissible variants like Omicron. Non-structural protein 6 (NSP6) is essential for viral replication and immune evasion. This study analyzed the NSP6 protein of the Omicron variant, focusing on conserved motifs, mutations, and residual properties to better understand its structure, function, and potential for immune evasion. Sequences from humans in South America were obtained from GISAID and aligned using Clustal Omega 1.2.4, with mutations identified by a Python 3 algorithm and conserved motifs detected using the MEME tool. Sequence diversity was assessed with Shannon’s entropy, while hydrophilicity, flexibility, accessibility, and antigenicity were analyzed using EMBOSS PEPSTATS and Expasy’s ProtScale tools. Phylogenetic analysis was performed with IQ-TREE software. Analysis of 161 NSP6 protein sequences revealed significant divergence from the reference sequence, with mutations proximal to conserved regions indicating potential functional and structural changes. The analysis also identified distinct hydrophobic and hydrophilic regions, with specific amino acid positions showing high flexibility and antigenicity. Phylogenetic analysis identified three clades with varying degrees of similarity to the reference sequence. This comprehensive study of the NSP6 protein in the Omicron variant provides insights into its role in viral replication and immune evasion, contributing to the development of targeted interventions against COVID-19.

SynBio doi: 10.3390/synbio3010006

Authors: Martina Duca Nadia Malagolini Fabio Dall’Olio

The carbohydrate antigen Sda is expressed on the cells and secretions of the vast majority of Caucasians. The epitope is formed by a terminal GalNAc residue β4-linked to an α3-sialylated galactose. Different carbohydrate chains N- or O-linked to glycoproteins can be terminated by this epitope. The final step of Sda biosynthesis is catalyzed by the GalNAc transferase B4GALNT2. In this review, we discuss the multifaceted aspects of B4GALNT2/Sda in fertility and pregnancy, susceptibility to infectious diseases, cancer, chronic kidney diseases, and Duchenne muscular dystrophy. We show how multiple synthetic biology approaches have been adopted to investigate its role.

SynBio doi: 10.3390/synbio3010005

Authors: Seung O. Yang Joseph P. Talley Gregory H. Nielsen Kristen M. Wilding Bradley C. Bundy

Enzymes play an essential role in many different industries; however, their operating conditions are limited due to the loss of enzyme activity in the presence of proteases and at temperatures significantly above physiological conditions. One way to improve the stability of these enzymes against high temperatures and proteases is to encapsulate them in protective shells or virus-like particles. This work presents a streamlined, three-step, cell-free protein synthesis (CFPS) procedure that enables rapid in vitro enzyme production, targeted encapsulation in protective virus-like particles (VLPs), and facile purification using a 6× His-tag fused to the VLP coat protein. This process is performed in under 12 h and overcomes several limitations of enzyme encapsulation, such as the control of packing density, speed, and complexity of the process. Here, we encapsulate the enzyme Candida antarctica lipase B in the VLP from the bacteriophage Qβ, while in the presence of a linking RNA aptamer. The encapsulated enzymes largely retained their activity in comparison to the free enzymes. Additionally, when subjected to 90 °C temperatures or 5 h incubation with proteases, the encapsulated enzymes maintained their activity, whereas the free enzymes lost their activity. In this work, we also demonstrate control over packing density by achieving packing densities of 4.7 and 6.5 enzymes per VLP based off the concentration of enzyme added to the encapsulation step.

SynBio doi: 10.3390/synbio3010004

Authors: Rajdeep Banerjee

The increasing prevalence of multi-drug-resistant (MDR) bacterial pathogens presents a critical global health threat, highlighting the urgent need for innovative approaches to understanding bacterial pathogenesis and developing effective therapies. This review underscores the potential of synthetic biology in elucidating host–pathogen interactions and facilitating the creation of advanced diagnostic tools and targeted therapies to combat MDR infections. We first explore CRISPR-based strategies that modulate essential gene expression, providing insights into the molecular mechanisms underlying host–pathogen interactions. Next, we discuss engineered microbial synthetic circuits for rapid pathogen detection by identifying molecular signatures involved in interspecies communication and facilitating swift pathogen elimination. Additionally, we explore phage therapy (PT), which leverages bacteriophages to selectively target and eliminate specific bacterial pathogens, presenting a targeted and promising approach to combat MDR infections. Finally, we review the application of organ-on-a-chip (OOAC) technology, which overcomes the limitations of animal models in predicting human immune responses by using microfluidic devices that simulate organ-level physiology and pathophysiology, thereby enabling more accurate disease modeling, drug testing, and the development of personalized medicine. Collectively, these synthetic biology tools provide transformative insights into the molecular mechanisms of host–pathogen interactions, advancing the development of precise diagnostic and therapeutic strategies against MDR infections.

SynBio doi: 10.3390/synbio3010003

Authors: Maria Isabel Nares-Rodriguez Esther Karunakaran

Synechocystis sp. PCC 6803 is a highly promising organism for the production of diverse recombinant compounds, including biofuels. However, conventional genetic engineering in Synechocystis presents challenges due to its highly polyploid genome, which not only results in low product yields but also compromises the reliability of recombinant strains for biomanufacturing applications. The CRISPR/Cas9 system, renowned for its precision, efficiency, and versatility across a wide range of chassis, offers significant potential to address the limitations posed by polyploid genomes. In this study, we developed and optimized an effective sgRNA for the targeted knock-in of nucleotide sequences of varying lengths into the neutral locus slr0168 of polyploid Synechocystis using CRISPR/Cas9. The gene encoding di-geranylgeranylglycerophospholipid reductase from Sulfolobus acidocaldarius and the methyl ketone operon from Solanum habrochaites were chosen as the exemplar nucleotide sequences for incorporation into the chromosome of Synechocystis. Our results demonstrate that the designed sgRNA effectively facilitated both knock-in events and that CRISPR/Cas9 enabled complete mutant segregation in a single round of selection and induction.

SynBio doi: 10.3390/synbio3010002

Authors: Suravi Majumder Koushik Sen Rabimba Karanjai

Atherosclerosis remains a major driver for cardiovascular disease (CVD), despite advancements in traditional risk factor management therapies. Recent evidence emphasizes the crucial role of the gut microbiome in the progression of atherosclerosis and plaque rupture, highlighting a promising therapeutic avenue. This review focuses on the intertwined relationship between the gut microbiome, its metabolites, and atherosclerosis and CVD, also highlighting the potential therapeutic role of probiotics and prebiotics. Given the diverse and unique gut microbiota signatures among individuals, a one-size-fits-all therapeutic approach is unlikely to be effective. Personalized treatment strategies are therefore necessary. Here, we discussed how Artificial Intelligence (AI) can be leveraged to analyze individual gut microbiome profiles from microbiome sequencing, predict treatment response, and optimize therapeutic strategies based on individual patients, which would significantly improve outcomes of the treatment for atherosclerosis patients.

SynBio doi: 10.3390/synbio3010001

Authors: Dimitrios Stefanoudakis

Pancreatic cancer is the result of mutations in crucial genetic markers like KRAS and TP53 that make treatment challenging. This article discusses how CRISPR Cas9 technology can be combined with these markers to create treatments. CRISPR allows for the alteration or repair of these mutations, with the aim of restoring gene function or blocking cancer-causing pathways. For instance, CRISPR has the potential to fix mutations in TP53 or CDKN2A genes and restore SMAD4 signaling or target the KRAS oncogene in the body’s cells. However promising, it may be that CRISPR encounters obstacles like unintentional effects and challenges in effectively delivering it to pancreatic tumor cells. Furthermore, ethical concerns, especially related to the editing of the germline, need consideration. As techniques based on CRISPR advance, there is a chance for them to transform the treatment landscape for cancer by offering personalized therapies. More studies are needed to enhance how treatments are administered accurately and safely through methods and targeted testing for effectiveness.

SynBio doi: 10.3390/synbio2040024

Authors: Farah Aqel Kristin Schneider Denise Hartung Kathrin Schwarz Olga Shatnyeva

Extracellular Vesicles (EVs) are a focus of intense research worldwide, with many groups exploring their potential for both diagnostic and therapeutic applications. Researchers have characterized EVs into various subtypes, modified common surface markers, and developed diverse isolation and purification techniques. Beyond their diagnostic potential, EVs are being engineered as delivery vehicles for various molecules and therapeutics. RNA therapeutics have the potential to be a transformative solution for patients suffering from chronic and genetic disorders and generally targeting undruggable targets. Despite the success of many RNA therapeutics in both in vivo studies and clinical trials, a significant challenge remains in effectively delivering these therapies to the target cells. Many research groups have adopted the use of lipid nanoparticles (LNPs) and other nanocarriers to encapsulate RNA therapeutics, aiming to deliver them as stably as possible to ensure optimal bioavailability and efficacy. While LNPs have proven successful as delivery vehicles, their use is not without drawbacks, such as accumulation within the body. EVs could be a potential solution to many of the problems around LNPs and other nanocarriers.

SynBio doi: 10.3390/synbio2040023

Authors: Ma Huan Guanyu Wang

Bistability is a fundamental phenomenon in nature. In biochemical systems, it creates digital, switch-like outputs from the constituent chemical concentrations and activities, and it is often associated with hysteresis in such systems. Here, we first introduce the regulation of bistable switches at different levels in natural life systems, then explain the current pioneering applications of bistable switches in synthetic biology, and finally introduce some design and tuning methodologies and principles that may be helpful for the future application of bistable switches in synthetic biology.

SynBio doi: 10.3390/synbio2040022

Authors: Jiaqing Li Eileen Bates Dylan S. Perera Andreea M. Palage Valerie C. A. Ward

Carotenoids are a class of highly hydrophobic compounds synthesized by plants in limited quantities. This study explores the potential for increasing the production yield of lycopene, a typical carotenoid compound, through engineered Escherichia coli. Given that lycopene biosynthesis occurs within microbial hosts and it is subsequently stored within lipid membranes, this study focuses on the impact of inducing membrane vesicles on lycopene yield by expressing monoglycosyldiacylglycerol synthase (MGS) or diglucosyldiacylglycerol synthase (DGS) from Acholeplasma laidlawii and inserting the upstream isopentenol utilization pathway (IUP) into the chromosome. The effect of MGS and DGS on lipid production in the cell was quantified. The results show that inserting the IUP into the chromosome increased the specific lycopene yield by 2.1-fold compared to the plasmid-based system when using a PproD constitutive promoter and by 2.0-fold when using the inducible Ptrc promoter. The expression of MGS and DGS resulted in a small increase of 31% and 33% (w/w) lipid content, respectively. When expressed in lycopene producing strains, the lycopene content decreased in the IUP strains but increased in the negative control strain expressing only the native MEP pathway from undetectable levels to 0.34 ± 0.08 mg/g.

SynBio doi: 10.3390/synbio2040021

Authors: Prihardi Kahar

Many useful chemicals have been industrially produced using genetic recombination technology in microorganisms and animal cells [...]

SynBio doi: 10.3390/synbio2040020

Authors: Satoshi Migita

Solid-binding peptides (SBPs) are a powerful tool for surface modification of metallic biomaterials which improve the biocompatibility and functionality of medical devices. This review provides a comprehensive overview of SBP technology for metallic biomaterials. We begin with a focus on phage display technology, the cornerstone method for selecting and developing SBPs. The application of SBPs to major metallic biomaterials, including titanium, stainless steel, and cobalt–chromium alloys, is then extensively discussed with specific examples and outcomes. We also address the advantages of SBPs compared to traditional surface modification methods, such as their high specificity and biocompatibility. Furthermore, this review explores current challenges in the field, such as the integration of computational approaches for rational SBP design. To create multifunctional surfaces, the combination of SBPs with other advanced technologies is also considered. This review aims to provide a thorough understanding of the current state and future potential of SBP technology in enhancing metallic biomaterials for medical application.

SynBio doi: 10.3390/synbio2030019

Authors: Adenike A. Akinsemolu Helen N. Onyeaka

Methane is the second largest contributor to global warming after carbon dioxide. Once it is released into the atmosphere, methane lingers for over 10 years, during which it traps heat, contributes to the formation of ground-level ozone, and affects air quality adversely. Conversely, methane has some benefits that could be harnessed to address its impact on the environment while utilizing it for good. Methane’s significant role in global warming and potential for energy production and other beneficial applications necessitate the adoption of innovative solutions to remediate the gas from the atmosphere and harness some of its benefits. This article explores Methylococcus capsulatus, a methanotrophic bacterium, and its potential for revolutionizing sustainable methane capture and utilization. With its unique metabolic abilities, M. capsulatus efficiently oxidizes methane, making it a promising candidate for biotechnological applications. We review current research in its current and potential applications in methane capture and utilization, emphasizing key characteristics, implementation challenges, benefits, and limitations in methane capture and conversion. We also highlight the importance of interdisciplinary collaborations and technological advancements in synthetic biology to maximize its energy production potential. Our article analyzes M. capsulatus’ role in addressing methane-related environmental concerns and advancing sustainable energy solutions.

SynBio doi: 10.3390/synbio2030018

Authors: Matthew R. Anderson Caitlin M. Padgett Victoria O. Ogbeifun Natasha M. DeVore

Thermal green protein Q66E (TGP-E) has previously shown increased thermal stability compared to thermal green protein (TGP), a thermal stable fluorescent protein produced through consensus and surface protein engineering. In this paper, we describe the protein crystal structure of TGP-E to 2.0 Å. This structure reveals alterations in the hydrogen bond network near the chromophore that may result in the observed increase in thermal stability. We compare the very stable TGP-E protein to the structure of a yellow mutant version of this protein YTP-E E148D. The structure of this mutant protein reveals the rationale for the observed low quantum yield and directions for future protein engineering efforts.

SynBio doi: 10.3390/synbio2030017

Authors: Hiroshi Arakawa

Despite the recent pandemic, the origin of its causative agent, SARS-CoV-2, remains controversial. This study identifies several prototype SARS-CoV-2 variants (proto-variants) that are descendants of the Wuhan variant. A thorough evaluation of the evolutionary histories of the genomes of these proto-variants reveals that most mutations in proto-variants were biased toward mutations that change the amino acid sequence. While these nonsynonymous substitutions (N mutations) were common in SARS-CoV-2 proto-variants, nucleotide changes that do not result in an amino acid change, termed synonymous substitutions (S mutations), dominate the mutations found in other RNA viruses. The N mutation bias in the SARS-CoV2 proto-variants was found in the spike gene as well as several other genes. The analysis of the ratio of N to S mutations in general RNA viruses revealed that the probability that an RNA virus spontaneously evolves a proto-variant is between 1.5 × 10−9 and 2.7 × 10−26 under natural conditions. These results suggest that SARS-CoV-2 variants did not emerge via a canonical route.

SynBio doi: 10.3390/synbio2030016

Authors: Marcella Silva Vieira Rafael Lara Rezende Cabral Luíza Favaratto Laiane Silva Maciel André da Silva Xavier Francisco Murilo Zerbini Patricia M. B. Fernandes

Plant viral diseases constitute a major contributor to agricultural production losses, significantly impacting the economies of exporting countries by more than USD 30 billion annually. Understanding and researching the biology and genomics of viruses is crucial for developing virus-resistant genetically edited or genetically modified plants. Genetic modifications can be targeted to specific regions within genes of target plants which are important or essential for the virus to establish a systemic infection, thus fostering resistance or enabling plants to effectively respond to invading agents while preserving their yield. This review provides an overview of viral incidence and diversity in tropical fruit crops and aims to examine the current state of the knowledge on recent research efforts aimed at reducing or eliminating the damage caused by viral diseases, with emphasis on genetically edited products that have reached the market in recent years.

SynBio doi: 10.3390/synbio2030015

Authors: Valmore Henrique Pereira dos Santos Monielly Vasconcellos Pereira de Souza Maurício Moraes Victor Valéria Belli Riatto Eliane Oliveira Silva

Endophytic microorganisms are promising sources for new biocatalysts as they must deal with their host plants’ chemicals by developing adaptative strategies, such as enzymatic pathways. As part of our efforts in selecting endophytic strains as biocatalysts, this study describes the screening of endophytic fungi isolated from Handroanthus impetiginosus leaves for selective bioreduction of Acetophenone. The bioreductions were monitored by chiral gas chromatography and conducted to the selection of the endophyte Talaromyces sp. H4 as capable of reducing acetophenone to (S)-1-phenylethanol in excellent conversion and enantiomeric excess rates. The influence of seven parameters on the stereoselective bioreduction of acetophenone by Talaromyces sp. H4 was studied: reaction time, inoculum charge, shaking, pH, temperature, substrate concentration, and co-solvent. The optimal conditions were then used to reduce substituted acetophenones and Acetophenone scale-up, which furnished (S)-1-Phenylethanol in 73% yield and 96% ee. The results highlight the endophytic fungus Talaromyces sp. H4 as an excellent biocatalyst for stereoselective reduction of prochiral carbonyls.

SynBio doi: 10.3390/synbio2030014

Authors: Bodil Bjørndal Tra-My Thi Le Elin Strand Lise Madsen Rolf K. Berge

The antidiabetic drug metformin has a wide range of metabolic effects and may also reduce the risk of obesity-related diseases. The aim of the current study was to investigate if metformin could counteract meldonium-induced fatty liver. Four groups of male C57BL/6J mice were fed a low-fat control diet, or low-fat diets supplemented with metformin, meldonium, or metformin and meldonium for three weeks. Meldonium treatment led to 5.2-fold higher hepatic triacylglycerol (TAG) levels compared to control, and metformin lowered the meldonium-induced lipid accumulation insignificantly by 21%. Mice treated with metformin and meldonium demonstrated significantly lower weight gain, visceral adipose tissue weight and plasma levels of TAG compared to meldonium alone. The hepatic mRNA level of carnitine palmitoyl transferase 1 was increased 2-fold with combined meldonium and metformin treatment compared to meldonium treatment (p < 0.001). Increased hepatic expression of genes involved in fatty acid oxidation and lipid transport was observed in the combination group compared to control, and increased gene expression of the mitochondrial uncoupling protein UCP2 was observed compared to the meldonium group. In addition, the product of fatty acid oxidation, acetylcarnitine, increased in plasma in metformin-treated mice. Altogether, metformin treatment influenced hepatic lipid metabolism and lowered plasma TAG in meldonium-induced fatty liver in mice.

SynBio doi: 10.3390/synbio2020013

Authors: Chuchi Chen Valerie C. A. Ward

Recombinant protein expression is a fundamental aspect of both synthetic biology and biotechnology as well as a field unto itself. Microalgae, with their eukaryotic cellular machinery, high lipid content, cost-effective cultivation conditions, safety profile for human consumption, and environmentally friendly attributes, are a promising system for protein expression or metabolic engineering for sustainable chemical production. Amongst the incredible diversity of microalgae species, Chlorella spp. are heavily studied due to their high growth efficiency, potential for low-cost cultivation, and well-characterized scale-up process for large-scale cultivation. This review aims to comprehensively examine the ongoing advancements in the bioengineering of Chlorella spp. for recombinant protein production and its biotechnological applications. This includes genetic elements such as promoters, terminators, reporters and markers, enhancers, and tags successfully used in Chlorella spp.

SynBio doi: 10.3390/synbio2020012

Authors: Maria Athanasiadou Christina Papaefthymiou Angelos Kontarinis Maria Spiliopoulou Dimitrios Koutoulas Marios Konstantopoulos Stamatina Kafetzi Kleomenis Barlos Kostas K. Barlos Natalia Dadivanyan Detlef Beckers Thomas Degen Andrew N. Fitch Irene Margiolaki

Octreotide is the first synthetic peptide hormone, consisting of eight amino acids, that mimics the activity of somatostatin, a natural hormone in the body. During the past decades, advanced instrumentation and crystallographic software have established X-Ray Powder Diffraction (XRPD) as a valuable tool for extracting structural information from biological macromolecules. The latter was demonstrated by the successful structural determination of octreotide at a remarkably high d-spacing resolution (1.87 Å) (PDB code: 6vc1). This study focuses on the response of octreotide to different humidity levels and temperatures, with a particular focus on the stability of the polycrystalline sample. XRPD measurements were accomplished employing an Anton Paar MHC-trans humidity-temperature chamber installed within a laboratory X’Pert Pro diffractometer (Malvern Panalytical). The chamber is employed to control and maintain precise humidity and temperature levels of samples during XRPD data collection. Pawley analysis of the collected data sets revealed that the octreotide polycrystalline sample is remarkably stable, and no structural transitions were observed. The compound retains its orthorhombic symmetry (space group: P212121, a = 18.57744(4) Å, b = 30.17338(6) Å, c = 39.70590(9) Å, d ~ 2.35 Å). However, a characteristic structural evolution in terms of lattice parameters and volume of the unit cell is reported mainly upon controlled relative humidity variation. In addition, an improvement in the signal-to-noise ratio in the XRPD data under a cycle of dehydration/rehydration is reported. These results underline the importance of considering the impact of environmental factors, such as humidity and temperature, in the context of structure-based drug design, thereby contributing to the development of more effective and stable pharmaceutical products.

SynBio doi: 10.3390/synbio2020011

Authors: Wasayf J. Almalki Alison O. Nwokeoji Seetharaman Vaidyanathan

Microalgae have considerable potential as a renewable feedstock for biochemical and bioethanol production that can be employed in processes associated with carbon capture. Large-scale microalgae cultivations are often non-axenic and are often cohabited by bacteria. A better understanding of the influence of cohabiting bacteria on microalgae productivity is required to develop sustainable synthetic co-culture processes at scale. Nutrient limitation is a frequently employed strategy in algal cultivations to accumulate energy reserves, such as lipids and carbohydrates. Here, a non-axenic culture of an estuarine green microalga, Chlorella vulgaris CCAP 211/21A, was studied under nutrient replete and deplete conditions to assess how changes in nutrient supply influenced the cohabiting bacterial population and its association with intracellular carbohydrate accumulations in the alga. Nutrient limitation resulted in a maximum carbohydrate yield of 47%, which was 74% higher than that in nutrient replete conditions. However, the latter condition elicited a 2-fold higher carbohydrate productivity. Three cohabiting bacterial isolates were cultivable from the three culture conditions tested. These isolates were identified using the 16S rRNA gene sequence to belong to Halomonas sp. and Muricauda sp. The composition of the bacterial population varied significantly between the growth conditions and time points. In all cases and at all time points, the dominant species was Halomonas isolates. Nutrient depletion resulted in an apparent loss of Muricauda sp. This finding demonstrates that nutrient supply can be used to control cohabiting bacterial populations in algal cultures, which will enable the development of synthetic co-culture strategies for improving algae productivity.

SynBio doi: 10.3390/synbio2020010

Authors: Derek W. Nelson Alexander Connor Yu Shen Ryan J. Gilbert

Elastin-like polypeptides (ELPs) are popular biomaterials due to their reversible, temperature-dependent phase separation and their tunability, which is achievable by evolving procedures in recombinant technology. In particular, recursive direction ligation by plasmid reconstruction (PRe-RDL) is the predominant cloning technique used to generate ELPs of varying lengths. Pre-RDL provides precise control over the number of (VPGXG)n repeat units in an ELP due to the selection of type IIS restriction enzyme (REs) sites in the reconstructed pET expression plasmid, which is a low-to-medium copy number plasmid. While Pre-RDL can be used to seamlessly repeat essentially any gene sequence and overcome limitations of previous cloning practices, we modified the Pre-RDL technique, where a high copy number plasmid (pBluescript II SK(+)—using a new library of type IIS REs) was used instead of a pET plasmid. The modified technique successfully produced a diblock ELP gene of 240 pentapeptide repeats from 30 pentapeptide “monomers” composed of alanine, tyrosine, and leucine X residues. This study found that the large, GC-rich ELP gene compromised plasmid yields in pBluescript II SK(+) and favored higher plasmid yields in the pET19b expression plasmid. Additionally, the BL21 E. coli strain expression consistently provided a higher transformation efficiency and higher plasmid yield than the high cloning efficiency strain TOP10 E. coli. We hypothesize that the plasmid/high GC gene ratio may play a significant role in these observations, and not the total plasmid size or the total plasmid GC content. While expression of the final gene resulted in a diblock ELP with a phase separation temperature of 34.5 °C, future work will need to investigate RDL techniques in additional plasmids to understand the primary driving factors for improving yields of plasmids with large ELP-encoding genes.

SynBio doi: 10.3390/synbio2020009

Authors: Vamsi Krishna Gali Kang Lan Tee Tuck Seng Wong

Genetic diversity is the foundation of evolutionary resilience, adaptive potential, and the flourishing vitality of living organisms, serving as the cornerstone for robust ecosystems and the continuous evolution of life on Earth. The landscape of directed evolution, a powerful biotechnological tool inspired by natural evolutionary processes, has undergone a transformative shift propelled by innovative strategies for generating genetic diversity. This shift is fuelled by several factors, encompassing the utilization of advanced toolkits like CRISPR-Cas and base editors, the enhanced comprehension of biological mechanisms, cost-effective custom oligo pool synthesis, and the seamless integration of artificial intelligence and automation. This comprehensive review looks into the myriad of methodologies employed for constructing gene libraries, both in vitro and in vivo, categorized into three major classes: random mutagenesis, focused mutagenesis, and DNA recombination. The objectives of this review are threefold: firstly, to present a panoramic overview of recent advances in genetic diversity creation; secondly, to inspire novel ideas for further innovation in genetic diversity generation; and thirdly, to provide a valuable resource for individuals entering the field of directed evolution.

SynBio doi: 10.3390/synbio2020008

Authors: Márcia R. Couto Joana L. Rodrigues Oscar Dias Lígia R. Rodrigues

Chondroitin is a glycosaminoglycan that has gained widespread use in nutraceuticals and pharmaceuticals, mainly for treating osteoarthritis. Traditionally, it has been extracted from animal cartilage but recently, biotechnological processes have emerged as a commercial alternative to avoid the risk of viral or prion contamination and offer a vegan-friendly source. Typically, these methods involve producing the chondroitin backbone using pathogenic bacteria and then modifying it enzymatically through the action of sulfotransferases. Despite the challenges of expressing active sulfotransferases in bacteria, the use of eukaryotic microorganisms is still limited to a few works using Pichia pastoris. To create a safer and efficient biotechnological platform, we constructed a biosynthetic pathway for chondroitin production in S. cerevisiae as a proof-of-concept. Up to 125 mg/L and 200 mg/L of intracellular and extracellular chondroitin were produced, respectively. Furthermore, as genome-scale models are valuable tools for identifying novel targets for metabolic engineering, a stoichiometric model of chondroitin-producing S. cerevisiae was developed and used in optimization algorithms. Our research yielded several novel targets, such as uridine diphosphate (UDP)-N-acetylglucosamine pyrophosphorylase (QRI1), glucosamine-6-phosphate acetyltransferase (GNA1), or N-acetylglucosamine-phosphate mutase (PCM1) overexpression, that might enhance chondroitin production and guide future experimental research to develop more efficient host organisms for the biotechnological production process.

SynBio doi: 10.3390/synbio2020007

Authors: Miguel Angel Bello-González Leidy Patricia Bedoya-Perez Miguel Alberto Pantoja-Zepeda Jose Utrilla

Pseudomonas chlororaphis ATCC 9446 is a non-pathogenic bacterium associated with the rhizosphere. It is commonly used as a biocontrol agent against agricultural pests. This organism can grow on a variety of carbon sources, has a robust secondary metabolism, and produces secondary metabolites with antimicrobial properties. This makes it an alternative host organism for synthetic biology applications. However, as a novel host there is a need for well-characterized molecular tools that allow fine control of gene expression and exploration of its metabolic potential. In this work we developed and characterized expression vectors for P. chlororaphis. We used two different promoters: the exogenously induced lac-IPTG promoter, and LuxR-C6-AHL, which we evaluated for its auto-inducible capacities, as well as using an external addition of C6-AHL. The expression response of these vectors to the inducer concentration was characterized by detecting a reporter fluorescent protein (YFP: yellow fluorescent protein). Furthermore, the violacein production operon was evaluated as a model heterologous pathway. We tested violacein production in shake flasks and a 3 L fermenter, showing that P. chlororaphis possesses a vigorous aromatic amino acid metabolism and was able to produce 1 g/L of violacein in a simple batch reactor experiment with minimal medium using only glucose as the carbon source. We compared the experimental results with the predictions of a modified genome scale model. The presented results show the potential of P. chlororaphis as a novel host organism for synthetic biology applications.

SynBio doi: 10.3390/synbio2010006

Authors: Max A. J. Rivers Andrew N. Lowell

Type II polyketide synthase (PKS) systems are a rich source of structurally diverse polycyclic aromatic compounds with clinically relevant antibiotic and chemotherapeutic properties. The enzymes responsible for synthesizing the polyketide core, known collectively as the minimal cassette, hold potential for applications in synthetic biology. The minimal cassette provides polyketides of different chain lengths, which interact with other enzymes that are responsible for the varied cyclization patterns. Additionally, the type II PKS enzyme clusters offer a wide repertoire of tailoring enzymes for oxidations, glycosylations, cyclizations, and rearrangements. This review begins with the variety of chemical space accessible with type II PKS systems including the recently discovered highly reducing variants that produce polyalkenes instead of the archetypical polyketide motif. The main discussion analyzes the previous approaches with an emphasis on further research that is needed to characterize the minimal cassette enzymes in vitro. Finally, the potential type II PKS systems hold the potential to offer new tools in biocatalysis and synthetic biology, particularly in the production of novel antibiotics and biofuels.

SynBio doi: 10.3390/synbio2010005

Authors: Roman G. Bielski M. Ahsanul Islam

Removal of fixed nitrogen compounds such as ammonium and nitrite from wastewater is of critical importance for balancing the nitrogen cycle and protecting aquatic environments from eutrophication. ANaerobic AMMonium OXidising (ANAMMOX) bacteria have recently been employed for fixed nitrogen removal purposes in wastewater treatment processes. These specialised bacteria convert ammonium and nitrite into nitrogen gas anaerobically, thereby reducing the amount of energy required for aeration in conventional wastewater treatment processes. However, slow growth rates of ANAMMOX remain a major obstacle towards their widespread use in industrial wastewater treatment processes. Thus, a pangenome-scale, constraint-based metabolic model, iRB399, of ANAMMOX bacteria has been developed to design strategies for accelerating their growth. The main metabolic limitation was identified in the energy metabolism of these bacteria, concerning the production of ATP. The extremely low efficiency of the electron transport chain combined with very high growth-associated maintenance energy is likely to be responsible for the slow growth of ANAMMOX. However, different ANAMMOX species were found to conserve energy using a variety of different redox couples, and the modelling simulations revealed their comparative advantages under different growth conditions. iRB399 also identified dispensable catabolic reactions that have demonstrably beneficial effects on enhancing the growth rates of ANAMMOX bacteria. Thus, the pangenome-scale model will not only help identify and overcome metabolic limitations of ANNAMOX bacteria, but also provide a valuable resource for designing efficient ANNAMOX-based wastewater treatment processes.

SynBio doi: 10.3390/synbio2010004

Authors: Tsung-Ming Hu Shih-Hsin Hsu Hsin-Yao Tsai Min-Chih Cheng

The glutamate ionotropic kainate receptors, encoded by the GRIK gene family, are composed of four subunits and function as ligand-activated ion channels. They play a critical role in regulating synaptic transmission and various synaptic receptors’ processes, as well as in the pathophysiology of schizophrenia. However, their functions and mechanisms of action need to be better understood and are worthy of exploration. To further understand the exact role of the kainate receptors in vitro, we generated kainate-receptor-knockout (KO) isogenic SH-SY5Y cell lines using the CRISPR/Cas9-mediated gene editing method. We conducted RNA sequencing (RNA-seq) to determine the differentially expressed genes (DEGs) in the isogenic edited cells and used rhodamine-phalloidin staining to quantitate filamentous actin (F-actin) in differentiated edited cells. The RNA-seq and the Gene Ontology enrichment analysis revealed that the genetic deletion of the GRIK1, GRIK2, and GRIK4 genes disturbed multiple genes involved in numerous signal pathways, including a converging pathway related to the synaptic membrane. An enrichment analysis of gene–disease associations indicated that DEGs in the edited cell lines were associated with several neuropsychiatric disorders, especially schizophrenia. In the morphology study, fluorescent images show that less F-actin was expressed in differentiated SH-SY5Y cells with GRIK1, GRIK2, or GRIK4 deficiency than wild-type cells. Our data indicate that kainate receptor deficiency might disturb synaptic-membrane-associated genes, and elucidating these genes should shed some light on the pathophysiology of schizophrenia. Furthermore, the transcriptomic profiles for kainate receptor deficiency of SH-SY5Y cells contribute to emerging evidence for the novel mechanisms underlying the effect of kainate receptors and the pathophysiology of schizophrenia. In addition, our data suggest that kainate-receptor-mediated F-actin remodeling may be a candidate mechanism underlying schizophrenia.

SynBio doi: 10.3390/synbio2010003

Authors: Mark Hogan Yuhao Song Jimmy Muldoon Patrick Caffrey

A number of antifungal drugs are based on polyene macrolides that cause severe side effects. Most of these compounds contain a single aminodeoxysugar, D-mycosamine. Toxicity can be reduced by increasing the extent of glycosylation. The aromatic heptaene 67-121C and two analogues of the degenerate heptaene nystatin have a second sugar attached to the C4′ hydroxyl of mycosamine. Another nystatin analogue has L-digitoxose as a second sugar attached to C35 on the macrolactone ring. The pentaene selvamicin has 4-O-methyl-L-digitoxose at C27, the equivalent position. To assist the production of new antifungals by synthetic biology, we explore further the utility of three classes of polyene glycosyltransferase: extending glycosyltransferases that form disaccharide-containing polyenes, glycosyltransferases that add the L-digitoxose sugars of nystatin A3 and selvamicin, and mycosaminyltransferases that add the primary aminodeoxysugar. In addition, we combine enzymatic hyperglycosylation with a known chemical method for adding sugars to the C3′ amino group of mycosamine. This was used to convert the disaccharide-containing 67-121C heptaene to forms containing branched trisaccharide or tetrasaccharide chains. These analogues are of interest for testing as anti-Leishmania drugs.

SynBio doi: 10.3390/synbio2010002

Authors: Saad Alrashdi Federica Casolari Kwaku Kyeremeh Hai Deng

Carbazoles are key scaffolds of either antimicrobial/antiviral alkaloid natural products or therapeutics. As such, access to structurally diverse indole-containing carbazoles has attracted considerable attention. In this report, a pilot study is described using biotransformation to provide carbazoles that contain various acyl substituents. The biotransformation system contains the thiamine-diphosphate (ThDP)-dependent enzyme NzsH, the FabH-like 3-ketoacyl-ACP synthase NzsJ, and the aromatase/cyclase NzsI, encoded in the biosynthetic gene cluster (nzs) of the bacterial carbazole alkaloid natural product named neocarazostatin A. The utilization of a range of acyl-SNACs (synthetic acyl-thioester analogues of the native substrate) together with indole-3-pyruvate and pyruvate in the designed biotransformation system allows production of carbazole derivatives. Our results demonstrate that this three-enzyme system displays a considerable substrate profile toward acyl donors for production of carbazoles with different acyl substituents. Finally, two more enzymes were included in the biotransformation system: the tryptophan synthase stand-alone β-subunit variant, PfTrpB, generated from directed evolution in the literature, and a commercially available L-amino acid oxidase (LAAO). The addition of these two enzymes allows the transformation to start with indole building blocks to provide carbazoles with modifications in the indole ring system.

SynBio doi: 10.3390/synbio2010001

Authors: Christian Andrea Lopez-Ayuso Benjamin Aranda-Herrera Dulce Guzman-Rocha Patricia Alejandra Chavez-Granados Rene Garcia-Contreras

Biotechnology and artificial intelligence have sparked a revolution in dentistry, with a focus on restoring natural tissue functions. This transformation has given rise to bioactive materials, inspired by biomimetics, aimed at replicating the processes found in nature. As synthetic biology advances, there is a heightened focus on signaling systems crucial for bio-based diagnostics and therapeutics. Dentistry now harnesses synthetic proteins for tissue regeneration and dental material enhancement. A current research priority is bacterial biofilm inhibition, vital for dental health. Given the role of Streptococcus mutans in dental caries, the development of synthetic antimicrobial peptides targeting this bacterium is underway. The balance of dental enamel between demineralization and remineralization impacts caries formation. Factors such as the presence of hydroxyapatite and salivary peptides influence enamel health. Recent studies have spotlighted salivary protein-inspired peptides for enhanced remineralization. In the realm of bone regeneration, synthetic proteins like bone morphogenetic proteins (BMP) have been spotlighted, earning FDA approval. Research is currently delving into peptides such as cementum protein 1 peptide (CEMP-1-p1) and parathyroid hormone variants like PTH (1-34), underscoring their potential in advancing dental and bone health.

SynBio doi: 10.3390/synbio1030016

Authors: Shikhar Kumar Gupta Foram Joshi Amay Agrawal Sourav Deb Martin Sajfutdinow Dixita Limbachiya David M. Smith Manish K. Gupta

To assist in the speed and accuracy of designing brick-based DNA nanostructures, we introduce a lightweight software suite 3DNA that can be used to generate complex structures. Currently, implementation of this fabrication strategy involves working with generalized, typically commercial CAD software, ad-hoc sequence-generating scripts, and visualization software, which must often be integrated together with an experimental lab setup for handling the hundreds or thousands of constituent DNA sequences. 3DNA encapsulates the solutions to these challenges in one package by providing a customized, easy-to-use molecular canvas and back-end functionality to assist in both visualization and sequence design. The primary motivation behind this software is enabling broader use of the brick-based method for constructing rigid, 3D DNA-based nanostructures, first introduced in 2012. 3DNA is developed to provide a streamlined, real-time workflow for designing and implementing this type of 3D nanostructure by integrating different visualization and design modules. Due to its cross-platform nature, it can be used on the most popular desktop environments, i.e., Windows, Mac OS X, and various flavors of Linux. 3DNA utilizes toolbar-based navigation to create a user-friendly GUI and includes a customized feature to analyze the constituent DNA sequences. Finally, the oligonucleotide sequences themselves can either be created on the fly by a random sequence generator, or selected from a pre-existing set of sequences making up a larger molecular canvas.

SynBio doi: 10.3390/synbio1030015

Authors: Sergii Krysenko

Actinobacteria from the genus Streptomyces feature complex primary and secondary metabolism, developmental cycle, and ability to produce a variety of natural products. These soil bacteria are major producers of antibiotics and other bioactive compounds and have been extensively investigated due to the medical and industrial relevance of Streptomyces-derived secondary metabolites. However, the genetic toolbox for Streptomyces engineering as well as yield optimization strategies for the production of relevant metabolites are limited. On the one hand, the genetic potential of these organisms has not been fully utilized due to many “silent” or poorly expressed biosynthetic gene clusters, whose activation depends on environmental stimuli and nutrient availability. On the other hand, these GC-rich Gram-positive bacteria are difficult to manipulate, and traditional genetic manipulation strategies are time-consuming and have low efficiency. Recent studies of Streptomyces metabolism and genomes provided new insights into possibilities to overcome these challenges. In this review, advances and approaches for Streptomyces manipulations and secondary metabolite production optimization are discussed. Special focus is given to understanding the interplay between primary and secondary metabolism in Streptomyces and the supply of nitrogen-containing compounds into secondary metabolism. Existing strategies to manipulate cellular metabolism in Streptomyces are reviewed.

SynBio doi: 10.3390/synbio1030014

Authors: Joyhare Barbosa Souza Samir Mansour Moraes Casseb

MicroRNAs (miRNAs) are small non-coding RNA molecules that play a fundamental role in the regulation of gene expression in humans. There has been a growing interest in investigating the interactions between human miRNAs and viruses to better understand the underlying mechanisms of the immune response and viral pathogenesis. The Ilheus virus, an arbovirus transmitted by mosquitoes, is known to cause disease in humans, with symptoms ranging from mild fever to severe neurological complications. This scientific article aims to explore the potential role of human miRNAs in their association with the genome of the Ilheus virus. Previous research has indicated that miRNAs can affect viral replication and the host’s immune response, playing a critical role in modulating the virus–host interaction. Here, we will investigate the possible interactions between specific human miRNAs and regions of the Ilheus virus genome, focusing on identifying miRNAs that may impact viral replication or the host’s immune response. A search for potential human miRNAs associated with the viral genome of ILHV was conducted through database searches such as miRBase. For the elucidation of targets regulated by these miRNAs, the TargetScan program was adopted. Functional enrichment analysis, inferring the function of genes regulated by miRNAs, was provided by the DAVID software. To elucidate the secondary structure, tools hosted in the RNAFold repositories were employed. In summary, our research has identified miRNAs linked to crucial sections of the Ilheus virus genome. These miRNAs can potentially regulate genes associated with neurological and immune functions. This highlights the intricate interplay between human miRNAs and the Ilheus virus genome, suggesting a pivotal role for these molecules in the host’s response to viral infections.

SynBio doi: 10.3390/synbio1030013

Authors: Masahito Yamagata

Synthetic biology is a science that uses engineering principles to design and build new biological systems [...]

SynBio doi: 10.3390/synbio1020012

Authors: Fang Ba Yufei Zhang Luyao Wang Wan-Qiu Liu Jian Li

Serine integrases are emerging as one of the most powerful biological tools for biotechnology. Over the past decade, many research papers have been published on the use of serine integrases in synthetic biology. In this review, we aim to systematically summarize the various studies ranging from structure and the catalytic mechanism to genetic design and interdisciplinary applications. First, we introduce the classification, structure, and catalytic model of serine integrases. Second, we present a timeline with milestones that describes the representative achievements. Then, we summarize the applications of serine integrases in genome engineering, genetic design, and DNA assembly. Finally, we discuss the potential of serine integrases for advancing interdisciplinary research. We anticipate that serine integrases will be further expanded as a versatile genetic toolbox for synthetic biology applications.

SynBio doi: 10.3390/synbio1020011

Authors: Georg Voelcker

Even more than 60 years after its introduction into the clinic, cyclophosphamide (CP), which belongs to the group of alkylating cytostatics, is indispensable for the treatment of cancer. This is despite the fact that its exact mechanism of action was unknown until a few years ago, and therefore, all attempts to improve the effectiveness of CP failed. The reason for not knowing the mechanism of action was the uncritical transfer of the chemical processes that lead to the formation of the actual alkylating CP metabolite phosphoreamide mustard (PAM) in vitro to in vivo conditions. In vitro—e.g., in cell culture experiments—PAM is formed by β-elimination of acrolein from the pharmacologically active CP metabolite aldophosphamide (ALD). In vivo, on the other hand, it is formed by enzymatic cleavage of ALD by phosphodiesterases (PDE) with the formation of 3-hydroxypropanal (HPA). The discovery of HPA as a cyclophosphamide metabolite, together with the discovery that HPA is a proapoptotic aldehyde and the discovery that the cell death event in therapy with CP is DNA-alkylation-initiated p53-controlled apoptosis, led to the formulation of a mechanism of action of CP and other oxazaphosphorine cytostatics (OX). This mechanism of action is presented here and is confirmed by newly developed CP-like compounds with lower toxicity and an order of magnitude better effectiveness.

SynBio doi: 10.3390/synbio1020010

Authors: Yuwei Li Justin E. Clarke Alex J. O’Neill Francisco M. Goycoolea James Smith

In bacterial communities, quorum sensing (QS) is a process mediated via chemical signalling that individuals use to coordinate their collective phenotypes. It is closely associated with pathogenic traits such as virulence factor production and antibiotic resistance. In their natural habitats, bacteria live in small niches, forming intricate consortia, where the role of QS is little understood. This work aims to construct a tuneable, trackable, and reconfigurable model bacterial community for studying QS. To this end, three Escherichia coli fluorescent reporter strains were constructed based on the paradigm LuxI/LuxR QS system. The strains recreate the three major aspects of QS response: sensing (S), autoinducer production (P), and regulation (R). We found that the response of the S strain as a function of the N-(3-oxohexanoyl)-L-homoserine lactone (OHHL) concentration did not saturate and exhibited a concentration-dependent response (in the range 10−7 to 10−4 M). The P strain produced OHHL and showed the ability to activate the S response, while the R strain showed the ability to attenuate the response due to the expression of the lactonase AiiA. Monitoring the fluorescent signals of the strains permits tracking the activation and attenuation activities of the LuxI/LuxR QS system. Future studies can now also benefit from this straightforward subcloning strategy to study other QS systems.

SynBio doi: 10.3390/synbio1010009

Authors: Chun-Tse Wang Bor-Sen Chen

Periodontitis, a chronic inflammatory oral condition triggered by bacteria, archaea, viruses, and eukaryotic organisms, is a well-known and widespread disease around the world. While there are effective treatments for periodontitis, there are also several shortcomings associated with its management, including limited treatment options, the risk of recurrence, and the high cost of treatment. Our goal is to develop a more efficient, systematic drug design for periodontitis before clinical trials. We work on systems drug discovery and design for periodontitis treatment via systems biology and deep learning methods. We first applied big database mining to build a candidate genome-wide genetic and epigenetic network (GWGEN), which includes a protein-protein interaction network (PPIN) and a gene regulatory network (GRN) for periodontitis and healthy control. Next, based on the unhealthy and healthy microarray data, we applied system identification and system order detection methods to remove false positives in candidate GWGENs to obtain real GWGENs for periodontitis and healthy control, respectively. After the real GWGENs were obtained, we picked out the core GWGENs based on how significant the proteins and genes were via the principal network projection (PNP) method. Finally, referring to the annotation of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways, we built up the core signaling pathways of periodontitis and healthy control. Consequently, we investigated the pathogenic mechanism of periodontitis by comparing their core signaling pathways. By checking up on the downstream core signaling pathway and the corresponding cellular dysfunctions of periodontitis, we identified the fos proto-oncogene, AP-1 Transcription Factor Subunit (FOS), TSC Complex Subunit 2 (TSC2), Forkhead Box O1 (FOXO1), and nuclear factor kappa-light chain enhancer of activated B cells (NF-κB) as significant biomarkers on which we could find candidate molecular drugs to target. To achieve our ultimate goal of designing a combination of molecular drugs for periodontitis treatment, a deep neural network (DNN)-based drug-target interaction (DTI) model was employed. The model is trained with the existing drug-target interaction databases for the prediction of candidate molecular drugs for significant biomarkers. Finally, we filter out brucine, disulfiram, verapamil, and PK-11195 as potential molecular drugs to be combined as a multiple-molecular drug to target the significant biomarkers based on drug design specifications, i.e., adequate drug regulation ability, high sensitivity, and low toxicity. In conclusion, we investigated the pathogenic mechanism of periodontitis by leveraging systems biology methods and thoroughly developed a therapeutic option for periodontitis treatment via the prediction of a DNN-based DTI model and drug design specifications.

SynBio doi: 10.3390/synbio1010008

Authors: Van Giap Do

Rheumatoid arthritis (RA) is one of the most common autoimmune diseases, affecting 0.5% to 1% of the population. It could ultimately result in joint destruction, functional decline, work disability, and enhanced mortality. Cyclic citrullinated peptide antibodies (CCP Abs) are useful biomarkers for the early detection and diagnosis of RA. In this study, we used plant viral-based expression vectors that produce rapidly large quantities of CCP-specific monoclonal antibodies. Heavy and light chain genes of a CCP monoclonal antibody (CCP mAb) were cloned from the hybridoma cell (12G1) and introduced into two separate plant viral-based expression vectors, TMV and PVX. A cyclic citrullinated peptide monoclonal antibody was produced in Nicotiana benthamiana through an Agrobacterium-mediated transient expression system. The expression of CCP mAb in tobacco plants was confirmed by dot blot, western blot analysis, and enzyme-linked immunosorbent assays (ELISA). It was shown that tobacco plants could accumulate CCP mAbs up to 0.35% of total soluble protein. Accumulated CCP mAb from infiltrated leaves was purified by protein G affinity chromatography. Immunoblot assays and ELISA showed plant-produced CCP mAbs successfully bound to a synthetic CCP peptide antigen. This system provides a fast strategy for the production of pharmaceutical CCP mAbs in tobacco plants.

SynBio doi: 10.3390/synbio1010007

Authors: Fleurdeliz Maglangit Hai Deng

Covering 2009–2022. Phenylnaphthacenoid polyketides have gained significant interest in recent years owing to their potent antibacterial and anticancer activities. Notably, more than 100 members of this class of natural products have been discovered from various Streptomyces species by different research groups including ours over the last 13 years. This review summarizes the current knowledge of the discovery, chemical diversity, and bioactivity of phenylnaphthacenoid polyketides. The current review also highlights the cell factory for phenylnaphthacenoid production: (1) native strains, (2) mutant strains, (3) heterologous expression, and (4) biocatalytic halogenations. Furthermore, current challenges and future opportunities are also presented as a guide for researchers to explore them more purposefully.

SynBio doi: 10.3390/synbio1010006

Authors: Madison M. Mann Toriana N. Vigil Samantha M. Felton William E. Fahy Mason A. Kinkeade Victoria K. Kartseva Mary-Jean C. Rowson Abigail J. Frost Bryan W. Berger

Synthetic biology tools have become increasingly prevalent as we look to nature for biological approaches to complex problems. With an ever-growing global population, issues of food safety and security, as well as addressing pollution and striving for sustainability are of the utmost importance. In this review, we first highlight synthetic biology techniques such as directed evolution as a toolset for protein engineering and show direct applications for food safety and security. Moreover, we offer an introduction to creative approaches for biosensor design and development and spotlight a few innovative examples. Finally, we address biomanufacturing with direct applications, as well as biomanufacturing to improve natural processes.

SynBio doi: 10.3390/synbio1010005

Authors: Masahito Yamagata

Programmable proteins to detect, visualize, modulate, or eliminate proteins of selection in vitro and in vivo are essential to study the targets recognized and the biology that follows. The specificity of programmable proteins can be easily altered by designing their sequences and structures. The flexibility and modularity of these proteins are currently pivotal for synthetic biology and various medical applications. There exist numerous reviews of the concept and application of individual programmable proteins, such as programmable nucleases, single-domain antibodies, and other protein scaffolds. This review proposes an expanded conceptual framework of such programmable proteins based on their programmable principle and target specificity to biomolecules (nucleic acids, proteins, and glycans) and overviews their advantages, limitations, and future directions.

SynBio doi: 10.3390/synbio1010004

Authors: Xiuhong Liang Huibin Zou

Cutinases (EC 3.1.1.74) are widely distributed in fungi, bacteria and plants with diversified structures and properties. Besides acting on the natural substrate cutin, cutinases are the first line of natural biocatalysts to hydrolyze artificial polyesters and toxic xenobiotics such as polyethylene terephthalate (PET), polycaprolactone (PCL), polylactic acid (PLA), polyhydroxybutyl succinate (PBS), phthalate and malathion esters. Moreover, cutinases can act as promising stereoselective catalysts in esterification and transesterification reactions and present better selectivities than lipases. These pioneering studies indicate that the biotechnological application of cutinase as a powerful tool in synthetic biology deserves further investigation, for both degradation and biosynthesis towards a broader range of ester bond-containing substrates. This review summarizes the classifications and properties of cutinases from different sources and insights into the structure–function relationship of different cutinases. It also highlights the uniqueness and advantages of representative cutinases in biodegradation and biosynthesis, and then prospects the future application of natural and engineered cutinases in synthetic biology.

SynBio doi: 10.3390/synbio1010003

Authors: Antônio Luiz Fantinel Rogério Margis Edson Talamini Homero Dewes

Despite the acknowledged relevance of renewable energy sources, biofuel production supported by food-related agriculture has faced severe criticism. One way to minimize the considered negative impacts is the use of sources of non-food biomass or wastes. Synthetic biology (SB) embraces a promising complex of technologies for biofuel production from non-edible and sustainable raw materials. Therefore, it is pertinent to identify the global evolution of investments, concepts, and techniques underlying the field in support of policy formulations for sustainable bioenergy production. We mapped the SB scientific knowledge related to biofuels using software that combines information visualization methods, bibliometrics, and data mining algorithms. The United States and China have been the leading countries in developing SB technologies. The Technical University of Denmark and Tsinghua University are institutions with higher centrality and have played prominent roles besides UC Los Angeles and Delft University Technology. We identified six knowledge clusters under the terms: versatile sugar dehydrogenase, redox balance principle, sesquiterpene production, Saccharomyces cerevisiae, recombinant xylose-fermenting strain, and Clostridium saccharoperbutylacetonicum N1-4. The emerging trends refer to specific microorganisms, processes, and products. Yarrowia lipolytica, Oleaginous yeast, E. coli, Klebsiella pneumoniae, Phaeodactylum tricornutum, and Microalgae are the most prominent microorganisms, mainly from the year 2016 onward. Anaerobic digestion, synthetic promoters, and genetic analysis appear as the most relevant platforms of new processes. Improved biofuels, bioethanol, and N-butanol are at the frontier of the development of SB-derived products. Synthetic biology is a dynamic interdisciplinary field in environmentally friendly bioenergy production pushed by growing social concerns and the emergent bioeconomy.

SynBio doi: 10.3390/synbio1010002

Authors: Joana L. Rodrigues

Acrylic acid (AA) is a chemical with high market value used in industry to produce diapers, paints, adhesives and coatings, among others. AA available worldwide is chemically produced mostly from petroleum derivatives. Due to its economic relevance, there is presently a need for innovative and sustainable ways to synthesize AA. In the past decade, several semi-biological methods have been developed and consist in the bio-based synthesis of 3-hydroxypropionic acid (3-HP) and its chemical conversion to AA. However, more recently, engineered Escherichia coli was demonstrated to be able to convert glucose or glycerol to AA. Several pathways have been developed that use as precursors glycerol, malonyl-CoA or β-alanine. Some of these pathways produce 3-HP as an intermediate. Nevertheless, the heterologous production of AA is still in its early stages compared, for example, to 3-HP production. So far, only up to 237 mg/L of AA have been produced from glucose using β-alanine as a precursor in fed-batch fermentation. In this review, the advances in the production of AA by engineered microbes, as well as the hurdles hindering high-level production, are discussed. In addition, synthetic biology and metabolic engineering approaches to improving the production of AA in industrial settings are presented.

SynBio doi: 10.3390/synbio1010001

Authors: Bernd H. A. Rehm

It is my pleasure to inaugurate the new open access journal, SynBio (ISSN: 2673-9259) [...]