Publications

The accurate spatial segregation into distinct phases within cell membranes coordinates vital biochemical processes and functionalities in living organisms. One of nature's strategies to localize reactivity is the formation of dynamic raft domains. Most raft models rely on liquid-ordered L-0 phases in a liquid-disordered L-d phase lacking correlation and remaining static, often necessitating external agents for phase separation. Here, we introduce a synthetic system of bicomponent glycodendrimersomes coassembled from Janus dendrimers and Janus glycodendrimers (JGDs), where lactose-lactose interactions exclusively drive lateral organization. This mechanism results in modulated phases across two length scales, yielding raft-like microdomains featuring nanoarrays at the nanoscale. By varying the density of lactose and molecular architecture of JGDs, the nanoarray type and size, shape, and spacing of the domains were controlled. Our findings offer insight into the potential primordial origins of rudimentary raft domains and highlight the crucial role of glycans within the glycocalyx.

JTD Keywords: Article, Artificial cells, Atomic force microscopy, Bicomponents, Bilayer, Bilayer membrane, Biochemical functionality, Biochemical process, Biological-membranes, Cell component, Cell membrane, Cellular parameters, Chemical interaction, Chemical structure, Chemistry, Cytology, Defined janus glycodendrimers, Dehydration, Dendrimer, Dendrimers, Dilution, Dimer, External agents, Fourier transform, Giant vesicles, Glycan, Glycans, Glycocalyx, Glycodendrimers, Janus dendrimer, Janus glycodendrimer, Lactose, Lateral organization, Lectin, Lipid rafts, Living organisms, Membrane damage, Membrane microdomain, Membrane microdomains, Membrane structure, Metabolism, Modulated phases, Molecule, Monomer, Nanoarrays, Oligosaccharide, Organization, Periodicity, Phase separation, Phase-separation, Phospholipids, Polysaccharide, Polysaccharides, Raft like domain, Relative humidity, Spatial segregation, Structure analysis, Sugars, Synthetic systems, Tetramer, Unclassified drug, Unilamellar vesicles, Water

Here the authors develop a coacervate micromotor that can display autonomous motion as a result of stochastic distribution of propelling units. This stochastic-induced mobility is validated and explained through experiments and theory. Random fluctuations are inherent to all complex molecular systems. Although nature has evolved mechanisms to control stochastic events to achieve the desired biological output, reproducing this in synthetic systems represents a significant challenge. Here we present an artificial platform that enables us to exploit stochasticity to direct motile behavior. We found that enzymes, when confined to the fluidic polymer membrane of a core-shell coacervate, were distributed stochastically in time and space. This resulted in a transient, asymmetric configuration of propulsive units, which imparted motility to such coacervates in presence of substrate. This mechanism was confirmed by stochastic modelling and simulations in silico. Furthermore, we showed that a deeper understanding of the mechanism of stochasticity could be utilized to modulate the motion output. Conceptually, this work represents a leap in design philosophy in the construction of synthetic systems with life-like behaviors.

JTD Keywords: Cell, Cell component, Enzyme, Enzyme activity, Membrane, Philosophy, Polymer, Stochasticity, Substrate

In many physiological situations, BAR proteins reshape membranes with pre-existing curvature (templates), contributing to essential cellular processes. However, the mechanism and the biological implications of this reshaping process remain unclear. Here we show, both experimentally and through modelling, that BAR proteins reshape low curvature membrane templates through a mechanochemical phase transition. This phenomenon depends on initial template shape and involves the co-existence and progressive transition between distinct local states in terms of molecular organization (protein arrangement and density) and membrane shape (template size and spherical versus cylindrical curvature). Further, we demonstrate in cells that this phenomenon enables a mechanotransduction mode, in which cellular stretch leads to the mechanical formation of membrane templates, which are then reshaped into tubules by BAR proteins. Our results demonstrate the interplay between membrane mechanics and BAR protein molecular organization, integrating curvature sensing and generation in a comprehensive framework with implications for cell mechanical responses.

JTD Keywords: aggregation, amphiphysin, domains, vesicles, Article, Cell, Cell component, Curvature, Detection method, Geomembrane, Mechanotransduction, Membrane, Molecular analysis, Phase transition, Physiology, Protein, Self organization