Search Results (784)

A one-pot synthetic methodology that combines an Ugi-Zhu three-component reaction (UZ-3CR) with a cascade sequence (intermolecular aza Diels–Alder cycloaddition/intramolecular N-acylation/decarboxylation/dehydration) using microwave-heating conditions, ytterbium (III) triflate (Yb(OTf)₃) as the catalyst, and chlorobenzene (for the first time in a multi-component reaction (MCR)) as the solvent, was developed to synthesize twelve new fluorinated-pyrrolo[3,4-b]pyridin-5-ones containing a 4-amino-7-chloroquinoline moiety, yielding 50–77% in 95 min per product, with associated atom economies around 88%, also per product. Additionally, by in vitro tests, compounds 19d and 19i were found to effectively stop early SARS-CoV-2 replication, IC₅₀ = 6.74 µM and 5.29 µM, at 0 h and 1 h respectively, while cell viability remained above 90% relative to the control vehicle at 10 µM. Additional computer-based studies revealed that the most active compounds formed strong favorable interactions with important viral proteins (M_pro, NTDα and NTDo) of coronavirus, supporting a two-pronged approach that affects both how the virus infects the cells and how it replicates its genetic material. Finally, quantum chemistry analyses of non-covalent interactions were performed from Density-Functional Theory (DFT) to better understand how the active compounds hit the virus. Full article

Diacylglycerol-O-acyltransferase 1 (DGAT1, EC 2.3.1.20) is a pivotal enzyme in plant triacylglycerol (TAG) biosynthesis. Previous work identified conserved di-arginine (R) motifs (R-R, R-X-R, and R-X-X-R) in its N-terminal cytoplasmic acyl-CoA binding domain. To elucidate their functional significance, we engineered R-rich sequences in the N-termini of Tropaeolum majus and Zea mays DGAT1s. Comparative analysis with their respective non-mutant constructs showed that deleting or substituting R with glycine in the N-terminal region of DGAT1 markedly reduced lipid accumulation in both Camelina sativa seeds and Saccharomyces cerevisiae cells. Immunofluorescence imaging revealed co-localization of non-mutant and R-substituted DGAT1 with lipid droplets (LDs). However, disruption of an N-terminal di-R motif destabilizes DGAT1, alters LD organization, and impairs recombinant oleosin retention on LDs. Further evidence suggests that the di-R motif mediates DGAT1 retrieval from LDs to the endoplasmic reticulum (ER), implicating its role in dynamic LD–ER protein trafficking. These findings establish the conserved di-R motifs as important regulators of DGAT1 function and LD dynamics, offering insights for the engineering of oil content in diverse biological systems. Full article

Phage therapy shows promise as an adjunct to antibiotics for treating Staphylococcus aureus infections. We previously reported a combined flucloxacillin/two-phage cocktail treatment selected for resistance to podovirus phage 66 in a rodent model of methicillin-susceptible S. aureus (MSSA) endocarditis. Here we show that resistant clones harbor mutations in tarS, which encodes a glycosyltransferase essential for β-GlcNAcylation of wall teichoic acid (WTA). This WTA modification has been described in vitro as critical for podoviruses adsorption. Transcriptomics confirmed continued tarS expression in resistant clones, supporting a loss-of-function mechanism. Accordingly, phage 66 binding and killing were restored by WT tarS complementation. In addition, we investigated the counterintuitive innate susceptibility to phage 66 of the tarM + Laus102 strain used in the endocarditis model. We show that it likely results from a significant lower tarM expression, in contrast to the innate resistant strain RN4220. Our findings demonstrate that tarS-mediated WTA β-GlcNAcylation is critical for podovirus infection also in vivo and identify tarM transcriptional defect as a new mechanism of podoviruses susceptibility in S. aureus. Moreover, and since tarS disruption has been previously shown to enhance β-lactam susceptibility, our results support the development of combined podovirus/antibiotic strategies for the management of MRSA infections. Full article

The mechanism by which quorum sensing (QS) enhances stress resistance in enterohemorrhagic Escherichia coli (E. coli) O157:H7 remains unclear. We employed optimized exogenous QS signal N-acyl-homoserinelactones (AHL) (100 μM 3-oxo-C6-AHL, 2 h) in EHEC O157:H7 strain EDL933, which was validated with endogenous yenI-derived AHL, to investigate QS-mediated protection against acid stress. RNA-seq transcriptomics identified key upregulated genes (e.g., rmf). Functional validation using isogenic rmf knockout mutants generated via λ-Red demonstrated abolished stress resistance and pan-stress vulnerability. Mechanistic studies employing qRT-PCR and stress survival assays established Ribosomal Hibernation Factor (RMF) as a non-redundant executor in a SdiA–RMF–RpoS axis, which activates ribosomal dormancy and SOS response to enhance EHEC survival under diverse stresses. For the first time, we define ribosomal hibernation as the core adaptive strategy linking QS to pathogen resilience, providing crucial mechanistic insights for developing EHEC control measures against foodborne threats. Full article

Cholesterol stress profoundly modulates cellular processes, but its underlying mechanisms remain incompletely understood. To investigate cholesterol-responsive networks, we performed integrated transcriptome (RNA-seq) and metabolome (LC-MS) analyses on HeLa cells treated with cholesterol for 6 and 24 h. Through transcriptomic analysis of cholesterol-stressed HeLa cells, we identified stage-specific responses characterized by early-phase stress responses and late-phase immune-metabolic coordination. This revealed 1340 upregulated and 976 downregulated genes after a 6 h cholesterol treatment, including induction and suppression of genes involved in cholesterol efflux and sterol biosynthesis, respectively, transitioning to Nuclear Factor kappa-B (NF-κB) activation and Peroxisome Proliferator-Activated Receptor (PPAR) pathway modulation by 24 h. Co-expression network analysis prioritized functional modules intersecting with differentially expressed genes. We also performed untargeted metabolomics using cells treated with cholesterol for 6 h, which demonstrated extensive remodeling of lipid species. Interestingly, integrated transcriptomic and metabolic analysis uncovered GFPT1-driven Uridine Diphosphate-N-Acetylglucosamine (UDP-GlcNAc) accumulation and increased taurine levels. Validation experiments confirmed GFPT1 upregulation and ANGPTL4 downregulation through RT-qPCR and increased O-GlcNAcylation via Western blot. Importantly, clinical datasets further supported the correlations between GFPT1/ANGPTL4 expression and cholesterol levels in Non-Alcoholic Steatohepatitis (NASH) liver cancer patients. This work establishes a chronological paradigm of cholesterol sensing and identifies GFPT1 and ANGPTL4 as key regulators bridging glycosylation and lipid pathways, providing mechanistic insights into cholesterol-associated metabolic disorders. Full article

Quorum quenching (QQ) is of interest for potential application as a sustainable strategy for bacterial disease control via communication interruption. The QQ enzyme can be used as a good alternative antagonist to combat antibiotic abuse and bacterial resistance. Here, genomic DNA sequencing was performed on N-acyl homoserine lactonase from the deep-sea strain Bacillus velezensis DH82 with Cluster of Orthologous Groups of proteins (COGs) annotation. The homologous sequences with β-lactamase domain-containing protein were predicted to be potential QQ enzymes and were cloned and expressed to study their quorum quenching properties by comparing them with the reported enzyme AiiA_3DHB. The experimental results of enzyme activity analysis and steady-state kinetics, as well as enzyme structure and substrate docking simulations and predictions, all consistently demonstrated that YtnP_DH82 presented superior enzyme structural stability and higher degradation efficiency of N-acyl homoserine lactones than AiiA_DH82 under the effects of pH, and temperature, and performed better on short -chain and 3-O-substituted AHSLs. The findings revealed the structural and biochemical characterization of YtnP_DH82 from the deep sea, which provide the capacity for further application in sustainable aquaculture as an alternative to antibiotics. Full article

Galectin-3 (Gal-3) is a β-galactoside-binding lectin that mediates diverse signaling events in multiple cell types, including immune cells. It is also a prognostic indicator for multiple clinically important disorders, including cardiovascular disease. Gal-3 binds to cell surface glycans to form lattices that modulate surface receptor signaling and internalization. However, the tissue-specific regulation of Gal-3 surface expression remains poorly understood. Here, we review evidence for the involvement of Gal-3 in cell surface signaling, intranuclear events, and intracellular trafficking. Our focus will be on the O-GlcNAc modification as a regulator of Gal-3 biosynthesis, non-canonical secretion, and recycling. We argue that the nutrient-driven cytoplasmic hexosamine biosynthetic pathway (HBP) and endomembrane transport mechanisms generate unique pools of nucleotide sugars. The differing levels of nucleotide sugars in the cytosol, endoplasmic reticulum (ER), and Golgi apparatus generate differential thresholds for the responsiveness of O-GlcNAc cycling, N- and O-linked glycan synthesis/branching, and glycolipid synthesis. By regulating Gal-3 synthesis and non-canonical secretion, O-GlcNAc cycling may serve as a nexus constraining Gal-3 cell surface expression and lattice formation. This homeostatic feedback mechanism would be critical under conditions where extensive glycan synthesis and branching in the endomembrane system and on the cell surface are maintained by elevated hexosamine synthesis. Thus, O-GlcNAc cycling and Gal-3 synergize to regulate Gal-3 secretion and influence cellular signaling. In humans, Gal-3 serves as an early-stage prognostic indicator for heart disease, kidney disease, viral infection, autoimmune disease, and neurodegenerative disorders. Since O-GlcNAc cycling has also been linked to these pathologic states, exploring the interconnections between O-GlcNAc cycling and Gal-3 expression and synthesis is likely to emerge as an exciting area of research. Full article

The recent global coronavirus pandemic highlighted the ever-present threat of respiratory virus outbreaks and the consequent need for ongoing research into antiviral therapy. To this end, structural analogues of the guanidinium-based drug camostat mesylate have been synthesised to probe their potential inhibition of Transmembrane Serine Protease 2 (TMPRSS2), a human protease that is essential for infection by many respiratory viruses, including Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). Our in vitro fluorescence-based protease assays and supporting computational docking studies suggest that C-terminal camostat analogues retain TMPRSS2 inhibition potencies (IC₅₀ = 1–3 nM, BE = −6.6 to −7.0 kcal/mol) that match or exceed that of the parent drug. Analogues 1c and 1d emerge as lead candidates in this regard, thereby validating the rationale behind C-terminal structural modifications and highlighting these derivatives as promising scaffolds for the future development of targeted antiviral therapeutics. Replacement of camostat’s ester functionality with peptide linkages largely preserves non-covalent binding but disrupts in vitro protease inhibition, findings consistent with the parent drug’s known role as an acylating suicide inhibitor. Docking studies confirm that the replacement of aromatic residues with flexible, equivalent-length alkyl chains is detrimental to drug binding. These function and binding data offer new directions for the synthesis of further analogues of camostat and of other guanidinium-based protease inhibitors that have yet to be refined via structure–activity relationship studies. Further investigation will support tailoring this class of drugs for repurposing in antiviral therapy. Full article

The present study investigated the efficacy of edible coatings formulated with gellan gum and lemon peel extract (LPE) in preserving the postharvest quality of cherry tomatoes (Solanum lycopersicum var. cerasiforme). Selected fruits exhibiting uniform ripeness and free from defects were sanitized and coated with solutions containing different HAG/LAG (high- and low-acyl gellan gum) ratios, incorporating 4.0% (w/v) LPE. Physicochemical and physiological parameters, including soluble solids content, weight loss, pH, titratable acidity, oxygen consumption, carbon dioxide and ethylene production, skin redness (a*/b* ratio), and decay incidence, were systematically assessed under storage conditions of 25 °C and 70% relative humidity. HAG-coated fruits showed the lowest weight loss (1.08%), higher soluble solids (7.11 °Brix), and greater firmness (3.11 N/mm²) compared to uncoated controls. Moreover, they exhibited reduced oxygen consumption (0.06 mg·kg⁻¹·h⁻¹), ethylene production (3.10 mg·kg⁻¹·h⁻¹), and decay rate (2%). Redness was better preserved, and decay rates were substantially (p < 0.05) reduced throughout the storage period. These findings highlight the potential of HAG-based edible coatings enriched with LPE as an innovative postharvest technology to extend shelf life, maintain quality attributes, and reduce postharvest losses in cherry tomatoes. Full article

This review presents information obtained over the past 10 years on the methods to control the widespread worldwide phytopathogen Pectobacterium carotovorum subsp. carotovorum (Pcc). This bacterium is among the ten most dangerous phytopathogens; it affects a wide range of cultivated plants: vegetables, ornamental and medicinal crops, both during vegetation and during the storage of fruits. Symptoms of Pcc damage include the wilting of plants, blackening of vessels on leaves, stems and petioles. At the flowering stage, the stem core gradually wilts and, starting from the root, the stem breaks and the plant dies. Pcc is a rod-shaped, non-capsule and endospore-forming facultative anaerobic Gram-negative bacterium with peritrichous flagellation. Pcc synthesizes bacteriocins—carocins. The main virulence factors of Pcc are the synthesis of N-acyl-homoserine lactone (AHL) and plant cell wall-degrading enzymes (PCWDEs) (pectinases, polygalacturonases, cellulases, and proteases). Diagnostic methods for this phytopathogen include polymerase chain reaction (PCR), loop-mediated isothermal amplification (LAMP), multilocus genotyping of strain-specific genes and detection of unique volatile organic compounds (VOCs). The main methods to control this microorganism include the use of various chemicals (acids, phenols, esters, salts, gases), plant extracts (from grasses, shrubs, trees, and algae), antagonistic bacteria (Bacillus, Pseudomonas, Streptomyces, and lactic acid bacteria), viruses (including a mixture of bacteriophages), and nanomaterials based on metals and chitosan. Full article

Sea urchins (Echinoidea) are marine echinoderms commonly consumed as seafood in East Asia. To date, various metabolic components of sea urchins have been analyzed, and their health benefits for humans have also been attracting attention. Lipids are the major biomolecules present in sea urchins. However, the comprehensive lipid profiling of sea urchins is limited. In this study, we aimed to perform the comprehensive lipid profiling of six types of sea urchins using liquid chromatography–mass spectrometry (LC/MS). The application of untargeted lipidomics led to the identification of 281 lipid molecular species in six varieties of fresh sea urchin gonads. Each lipid metabolite was identified based on its retention time and MS/MS fragmentation pattern. The results of the analysis showed the highest abundance of lipid percentage in Kitamurasakiuni (14.3%), followed by Hokuyobafununi (12.4%). In all the analyzed sea urchins, glycerolipids such as triacylglycerols were found to be the most abundant lipid components. Multivariate analysis revealed that Murasakiuni showed a different lipid profile from the other types. Interestingly, the polyunsaturated fatty acid to saturated fatty acid ratios and health-related nutritional indices factors were found to be higher in Hokuyobafununi compared to other varieties. The ω-3 fatty acids, such as docosapentaenoic acid (FA 22:6) and eicosapentaenoic acid (FA 20:5), were also abundant in Hokuyobafununi. Lipids such as ether and N-acyl-type lysophosphatidylethanolamines were detected for the first time in sea urchins. This study highlights the nutritional significance of sea urchins and their potential use in the development of functional foods. Full article

In this study, gold nanoparticles (AuNPs) and AuNPs-graphene oxide (AuNPs@GO) nanostructures were synthesized in aqueous media using an in-situ photochemical method with bis-acyl phosphine oxide (BAPO) photoinitiator as a photoreducing agent in the presence of HAuCl₄. The parameters for synthesis were arranged to obtain stable and reproducible dispersions with desirable chemical and optical properties. Both AuNPs and AuNPs@GO were employed as sensing platforms for the detection of epinephrine in two concentration ranges: micromolar (µM) and nanomolar (nM). Field emission scanning electron microscopy (FE-SEM), Dynamic Light Scattering (DLS), UV-Vis absorption, fluorescence emission, and Fourier Transform Infrared (FT-IR) spectroscopy techniques were used to investigate the morphological, optical, and chemical properties of the nanostructures as well as their sensing ability towards epinephrine. Fluorescence spectroscopy played a crucial role in demonstrating the high sensitivity and effectiveness of these systems, especially in the low concentration (nM) range, confirming their strong potential as fluorescence-based sensors. By constructing calibration curves on best linear subranges, limit of detection (LOD) and limit of quantification (LOQ) were calculated with two different approaches, SE_intercept and S_y/x. Among all the investigated nanostructures, AuNPs@GO exhibited the highest sensitivity towards epinephrine. The efficiency and reproducibility of the in-situ photochemical AuNPs synthesis approach highlight its applicability in small-molecule detection and particularly in analytical and bio-sensing applications. Full article

In the present study, we describe the synthesis of N-(2-((2-(1H-indol-3-yl)ethyl)carbamoyl)phenyl)furan-2-carboxamide via a two-step reaction sequence. Initially, isatoic anhydride was reacted with tryptamine to afford the corresponding intermediate, which was subsequently subjected to acylation using furan-2-carbonyl chloride. The final product was comprehensively characterized by melting point analysis, ¹H and ¹³C NMR, HSQC, IR, and MS spectrometry. The combined spectroscopic and analytical data unequivocally confirm the successful synthesis and structural integrity of the target compound. Full article

Abiotic stress poses a serious challenge in agriculture. Salinity inhibits crop growth and yields by disrupting ionic homeostasis and osmotic balance. One critical mechanism of salt tolerance is the activation of the Salt Overly Sensitive (SOS) signaling pathway. Investigating this pathway in halophytic plants offers valuable insights into the molecular mechanisms underlying salt stress tolerance. This study explores the structure and function of SOS3/CBL4 from the gray mangrove, Avicennia marina (AmSOS3). Sequence analysis revealed that AmSOS3 shares significant similarities with orthologs of SOS3/CBL4, including Arabidopsis thaliana (AtSOS3). All essential functional domains of SOS3, including the four EF-hands, as well as the N-myristoylation and S-acylation motif, were conserved in AmSOS3. Structural modeling, using Modeller, predicted that AmSOS3 forms a homodimer stabilized by a hydrogen bond at the serine 140 position. Functional characterization further demonstrated that AmSOS3 complements the sos3-1 mutation in A. thaliana, thus confirming that AmSOS3 is an ortholog of AtSOS3. Overexpression of AmSOS3 in wild-type A. thaliana enhanced tolerance under salinity stress. The transgenic lines displayed reduced reactive oxygen species (ROS) accumulation and increased ROS-scavenging enzyme activity. These findings indicate that AmSOS3 plays a critical role in improving salt stress tolerance and maintaining cellular homeostasis. Full article

Light is a source of energy for photosynthesis and hence promotes the regulation of multiple physiological and metabolic processes in photoautotrophic organisms. Understanding how brown macrophytes adjust the physical and biochemical properties of photosynthetic membranes in response to high-irradiance environments has received little attention so far. Particularly, it concerns the lipid flexibility of thylakoid membranes. We examined the lipid classes, fatty acid (FA) profiles, chloroplast ultrastructure, and photosynthetic performance of the brown macroalga Undaria pinnatifida after long-term exposure to high light (HL) and moderate light (ML) intensities, at 400 and 270 µmol photons m⁻² s⁻¹, respectively. U. pinnatifida responded to HL with a reduction in the level of thylakoid membrane lipids, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfoquinovosyldiacylglycerol (SQDG), and phosphatidylglycerol (PG), while the character of lipid modulations was specific. The content of storage lipids, triacylglycerols enriched in n-3 polyunsaturated fatty acids (PUFAs), increased under HL. The general response to long-term HL for the studied thylakoid membrane lipids, but not for SQDG, was the remodeling of FA composition towards increasing the percentages of saturated and monounsaturated acyl groups over PUFAs, suggesting a photoprotective strategy against the intensification of lipid peroxidation. In all, we showed that remodeling in photosynthetic membrane lipids accompanied by structural changes in chloroplasts and modulations in photosynthetic performance augmented the ability of U. pinnatifida to counteract high-intensity light, thereby contributing to its survival potential under suboptimal irradiance conditions. Full article