Special Issue "Membranous and Membraneless Interfaces—Origins of Artificial Cellular Complexity"

A special issue of Life (ISSN 2075-1729). This special issue belongs to the section "Synthetic Biology and Systems Biology".

Deadline for manuscript submissions: 31 May 2022 | Viewed by 2166

Special Issue Editors

Prof. Dr. Pasquale Stano
E-Mail Website
Guest Editor
Dipartimento di Scienze e Tecnologie Biologiche e Ambientali (DiSTeBA), Università del Salento Campus Ecotekne, S. P. 6 Lecce-Monteroni, 73100 Lecce, Italy
Interests: origins of life; synthetic biology; artificial life; synthetic cells; drug delivery; bio-chem-ICTs; autopoiesis and cognition
Special Issues, Collections and Topics in MDPI journals
Prof. Dr. Kanta Tsumoto
E-Mail Website
Guest Editor
Division of Chemistry for Materials, Graduate School of Engineering, Mie University, Tsu, Mie 514-8507, Japan
Interests: artificial membranes; liposomes; biological phase separation; membrane proteins; membrane fusion; virus-related materials

Special Issue Information

Dear Colleagues,

Living cell architecture is based on the concept of micro-compartmentation at different hierarchical levels. Cells themselves are self-bounded compartments, limited by a lipid membrane; eukaryotic cells have internal membrane-bound organelles dedicated to specific cellular functions, such as the cell nucleus, mitochondria and chloroplasts, the endoplasmic reticulum, the Golgi apparatus, as well as endosomes, lysosomes, etc. Moreover, membraneless compartments are currently under intense investigation in all types of cells. Compartments imply confinement and chemical gradients, and thus the non-homogeneous distribution of chemical species. Ultimately, compartmentation sustains fundamental processes for life maintenance, regulation, and information processing.

For decades, such complicated colloidal fine structures have attracted scientific attention. In addition to descriptive investigations, a bottom-up (constructive, synthetic) approach has recently emerged, often recognized within the bottom-up branch of Synthetic Biology.

Several biofunctions (in whole or in part) have been reconstituted in vesicles, usually—but not uniquely—made of lipids. Membraneless organelles have been recently featured thanks to experiments on liquid/liquid phase separation (LLPS) occurring in highly crowded solutions. Microdroplets made of hydrophilic polymer systems, similar to the PEG/dextran aqueous two-phase systems (ATPSs), are commonly used for modeling membraneless compartments. Various types of coacervates have shown complex cell-like behavior under several experimental conditions.

This Special Issue aims at collecting the most recent studies on artificial systems based on different types of compartmentalization. The final goal is the understanding of inter-cellular and intra-cellular mechanisms that contribute to the development of cellular complexity, revealing “emergent” properties occurring in cell and protocell systems. Biological meanings of interfaces and compartmentalization, set by not only membranous but also membraneless boundaries, will be discussed by viewing the results of theoretical consideration, wet experiments and plausible hypotheses based on artificial cell systems, such as membrane vesicles (liposomes), microemulsion droplets, and membraneless microdroplets emerging upon the micro-phase separation of the aqueous binary or multi-component (bio)polymer systems. These are considered to emerge as conventional and brand-new microstructures that assume intracellular environments highly crowded with biomacromolecules. The Special Issue also includes research presentations on related experimental/theoretical investigations; thus, let us think deeply about how (proto)cells could emerge as molecular microcompartment systems that developed their own interfaces.

We would like to elicit the submission of articles (full articles, reviews, etc.) related to the broad subject of membrane and membraneless microcompartments, their physico-chemical features, their use as cell or organellae models and, in general, about the peculiar characteristics of compartment architectures. All types of approaches are welcome (experimental, theoretical, conceptual, numerical simulations, etc.).

We look forward to receiving your best contributions and assembling a high-quality Special Issue.

Prof. Dr. Pasquale Stano
Prof. Dr. Kanta Tsumoto
Guest Editors

Manuscript Submission Information

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Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Life is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 1800 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • aqueous two-phase systems
  • artificial cells
  • coacervates
  • colloids
  • compartments
  • droplets
  • liposomes
  • liquid/liquid phase separation
  • membrane
  • membraneless
  • micelles
  • microdomains
  • organellae
  • proteinosomes
  • protocells
  • synthetic biology
  • synthetic cells
  • vesicles

Published Papers (2 papers)

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Research

Article
Evaporation Patterns of Dextran–Poly(Ethylene Glycol) Droplets with Changes in Wettability and Compatibility
Life 2022, 12(3), 373; https://doi.org/10.3390/life12030373 - 04 Mar 2022
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Abstract
The dextran–PEG system is one of the most famous systems exhibiting phase separation. Various phase behaviors, including the evaporation process of the dextran–PEG system, have been studied in order to understand the physicochemical mechanism of intracellular phase separation and the effect of condensation [...] Read more.
The dextran–PEG system is one of the most famous systems exhibiting phase separation. Various phase behaviors, including the evaporation process of the dextran–PEG system, have been studied in order to understand the physicochemical mechanism of intracellular phase separation and the effect of condensation on the origin of life. However, there have been few studies in dilute regime. In this study, we focused on such regimes and analyzed the pattern formation by evaporation. The specificity of this regime is the slow onset of phase separation due to low initial concentration, and the separated phases can have contrasting wettability to the substrate as evaporation progresses. When the polymer concentration is rather low (<5 wt%), the dextran–PEG droplets form a phase-separated pattern, consisting of PEG at the center and dextran ring of multiple strings pulling from the ring. This pattern formation is explained from the difference in wettability and compatibility between dextran and PEG upon condensation. At the initial dilute stage, the dextran-rich phase with higher wettability accumulates at the contact line of the droplet to form a ring pattern, and then forms multiple domains due to density fluctuation. The less wettable PEG phase recedes and pulls the dextran domains, causing them to deform into strings. Further condensation leads to phase separation, and the condensed PEG with improved wettability stops receding and prevents a formed circular pattern. These findings suggest that evaporation patterns of polymer blend droplets can be manipulated through changes in wettability and compatibility between polymers due to condensation, thus providing the basis to explore origins of life that are unique to the process of condensate formation from dilute systems. Full article
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Article
Colocalization Analysis of Lipo-Deoxyribozyme Consisting of DNA and Protic Catalysts in a Vesicle-Based Protocellular Membrane Investigated by Confocal Microscopy
Life 2021, 11(12), 1364; https://doi.org/10.3390/life11121364 - 08 Dec 2021
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Abstract
The linkage between the self-reproduction of compartments and the replication of DNA in a compartment is a crucial requirement for cellular life. In our giant vesicle (GV)-based model protocell, this linkage is achieved through the action of a supramolecular catalyst composed of membrane-intruded [...] Read more.
The linkage between the self-reproduction of compartments and the replication of DNA in a compartment is a crucial requirement for cellular life. In our giant vesicle (GV)-based model protocell, this linkage is achieved through the action of a supramolecular catalyst composed of membrane-intruded DNA and amphiphilic acid catalysts ([email protected]) in a GV membrane. In this study, we examined colocalization analysis for the formation of the supramolecular catalyst using a confocal laser scanning fluorescence microscope with high sensitivity and resolution. Red fluorescence spots emitted from DNA tagged with Texas Red (Texas Red-DNA) were observed in a GV membrane stained with phospholipid tagged with BODIPY (BODIPY-HPC). To our knowledge, this is the first direct observation of DNA embedded in a GV-based model protocellular membrane containing cationic lipids. Colocalization analysis based on a histogram of frequencies of “normalized mean deviation product” revealed that the frequencies of positively correlated [lipophilic catalyst tagged with BODIPY (BODIPY-C) and Texas Red-DNA] were significantly higher than those of [BODIPY-HPC and Texas Red-DNA]. This result demonstrates the spontaneous formation of [email protected] in the GV membrane, which serves as a lipo-deoxyribozyme for producing membrane lipids from its precursor. Full article
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