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ACS Nano Feb 2023We report the formation, growth, and dynamics of model protocell superstructures on solid surfaces, resembling single cell colonies. These structures, consisting of...
We report the formation, growth, and dynamics of model protocell superstructures on solid surfaces, resembling single cell colonies. These structures, consisting of several layers of lipidic compartments enveloped in a dome-shaped outer lipid bilayer, emerged as a result of spontaneous shape transformation of lipid agglomerates deposited on thin film aluminum surfaces. Collective protocell structures were observed to be mechanically more stable compared to isolated spherical compartments. We show that the model colonies encapsulate DNA and accommodate nonenzymatic, strand displacement DNA reactions. The membrane envelope is able to disassemble and expose individual daughter protocells, which can migrate and attach via nanotethers to distant surface locations, while maintaining their encapsulated contents. Some colonies feature "exocompartments", which spontaneously extend out of the enveloping bilayer, internalize DNA, and merge again with the superstructure. A continuum elastohydrodynamic theory that we developed suggests that a plausible driving force behind subcompartment formation is attractive van der Waals (vdW) interactions between the membrane and surface. The balance between membrane bending and vdW interactions yields a critical length scale of 236 nm, above which the membrane invaginations can form subcompartments. The findings support our hypotheses that in extension of the "lipid world hypothesis", protocells may have existed in the form of colonies, potentially benefiting from the increased mechanical stability provided by a superstructure.
Topics: Artificial Cells; Lipid Bilayers; DNA
PubMed: 36795609
DOI: 10.1021/acsnano.2c08093 -
Emerging Topics in Life Sciences Mar 2023Membrane asymmetry means that the two sides of membrane are structurally, physically and functionally different. Membrane asymmetry is largely related to the lipid...
Membrane asymmetry means that the two sides of membrane are structurally, physically and functionally different. Membrane asymmetry is largely related to the lipid sidedness and particularly to compositional (lipid head and acyl group) and physical (lipid packing order, charge, hydration and H-bonding interactions) differences in the inner and outer leaflets of lipid bilayer. Chemically, structurally and conformationally different non-covalent bound lipid molecules are physically fluid and deformable and enable to interact dynamically to form transient arrangements with asymmetry both perpendicular and parallel to the plane of the lipid bilayer. Although biological membranes are almost universally asymmetric however the asymmetry is not absolute since only drastic difference in the number of lipids per leaflet is found and symmetric arrangements are possible. Asymmetry is thought to direct and influence many core biological functions by altering the membrane's collective biochemical, biophysical and structural properties. Asymmetric transbilayer lipid distribution is found across all lipid classes, cells and near all endomembrane compartments. Why cell membranes are (a)symmetric and adopt almost exclusively highly entropically disfavored asymmetric state?
Topics: Cell Membrane; Lipid Bilayers
PubMed: 36988943
DOI: 10.1042/ETLS20220088 -
Biochimica Et Biophysica Acta.... May 2021Transport proteins are essential for cells in allowing the exchange of substances between cells and their environment across the lipid bilayer forming a tight barrier.... (Review)
Review
Transport proteins are essential for cells in allowing the exchange of substances between cells and their environment across the lipid bilayer forming a tight barrier. Membrane lipids modulate the function of transmembrane proteins such as transporters in two ways: Lipids are tightly and specifically bound to transport proteins and in addition they modulate from the bulk of the lipid bilayer the function of transport proteins. This overview summarizes currently available information at the ultrastructural level on lipids tightly bound to transport proteins and the impact of altered bulk membrane lipid composition. Human diseases leading to altered lipid homeostasis will lead to altered membrane lipid composition, which in turn affect the function of transporter proteins.
Topics: Animals; Biological Transport; Humans; Lipid Bilayers; Membrane Lipids; Membrane Transport Proteins; Protein Binding
PubMed: 33476785
DOI: 10.1016/j.bbadis.2021.166079 -
Proceedings of the National Academy of... Mar 2023Mechanical forces modify the cell membrane potential by opening mechanosensitive ion channels. We report the design and construction of a lipid bilayer tensiometer to...
Mechanical forces modify the cell membrane potential by opening mechanosensitive ion channels. We report the design and construction of a lipid bilayer tensiometer to study channels that respond to lateral membrane tension, [Formula: see text] , in the range 0.2 to 1.4 [Formula: see text] (0.8 to 5.7 [Formula: see text] ). The instrument consists of a black-lipid-membrane bilayer, a custom-built microscope, and a high-resolution manometer. Values of [Formula: see text] are obtained from the determination of the bilayer curvature as a function of applied pressure by means of the Young-Laplace equation. We demonstrate that [Formula: see text] can be determined by calculating the bilayer radius of curvature from fluorescence microscopy imaging or from measurements of the bilayer's electrical capacitance, both yielding similar results. Using electrical capacitance, we show that the mechanosensitive potassium channel TRAAK responds to [Formula: see text] , not curvature. TRAAK channel open probability increases as [Formula: see text] is increased from 0.2 to 1.4 [Formula: see text] but open probability never reaches 0.5. Thus, TRAAK opens over a wide range of [Formula: see text] , but with a tension sensitivity about one-fifth that of the bacterial mechanosensitive channel MscL.
Topics: Ion Channels; Lipid Bilayers; Potassium Channels
PubMed: 36913590
DOI: 10.1073/pnas.2221541120 -
Archives of Biochemistry and Biophysics Aug 2017Membrane proteins present a challenge for structural biology. In this article, we review some of the recent developments that advance the application of NMR to membrane... (Review)
Review
Membrane proteins present a challenge for structural biology. In this article, we review some of the recent developments that advance the application of NMR to membrane proteins, with emphasis on structural studies in detergent-free, lipid bilayer samples that resemble the native environment. NMR spectroscopy is not only ideally suited for structure determination of membrane proteins in hydrated lipid bilayer membranes, but also highly complementary to the other principal techniques based on X-ray and electron diffraction. Recent advances in NMR instrumentation, spectroscopic methods, computational methods, and sample preparations are driving exciting new efforts in membrane protein structural biology.
Topics: Detergents; Humans; Lipid Bilayers; Membrane Proteins; Nanostructures; Nuclear Magnetic Resonance, Biomolecular
PubMed: 28529197
DOI: 10.1016/j.abb.2017.05.011 -
Biochimica Et Biophysica Acta Jul 2016This is a review. Non-electrolytic compounds typically cross cell membranes by passive diffusion. The rate of permeation is dependent on the chemical properties of the... (Review)
Review
This is a review. Non-electrolytic compounds typically cross cell membranes by passive diffusion. The rate of permeation is dependent on the chemical properties of the solute and the composition of the lipid bilayer membrane. Predicting the permeability coefficient of a solute is important in pharmaceutical chemistry and toxicology. Molecular simulation has proven to be a valuable tool for modeling permeation of solutes through a lipid bilayer. In particular, the solubility-diffusion model has allowed for the quantitative calculation of permeability coefficients. The underlying theory and computational methods used to calculate membrane permeability are reviewed. We also discuss applications of these methods to examine the permeability of solutes and the effect of membrane composition on permeability. The application of coarse grain and polarizable models is discussed. This article is part of a Special Issue entitled: Membrane Proteins edited by J.C. Gumbart and Sergei Noskov.
Topics: Cell Membrane; Cell Membrane Permeability; Computer Simulation; Diffusion; Lipid Bilayers; Membrane Fluidity; Models, Chemical; Models, Molecular; Porosity; Solubility; Solutions
PubMed: 26706099
DOI: 10.1016/j.bbamem.2015.12.014 -
Langmuir : the ACS Journal of Surfaces... Aug 2022α-Synuclein (aSyn) is a 140 residue long protein present in presynaptic termini of nerve cells. The protein is associated with Parkinson's disease, in which case it has...
α-Synuclein (aSyn) is a 140 residue long protein present in presynaptic termini of nerve cells. The protein is associated with Parkinson's disease, in which case it has been found to self-assemble into long amyloid fibrils forming intracellular inclusions that are also rich in lipids. Furthermore, its synaptic function is proposed to involve interaction with lipid membranes, and hence, it is of interest to understand aSyn-lipid membrane interactions in detail. In this paper we report on the interaction of aSyn with model membranes in the form of lipid bilayer discs. Using a combination of cryogenic transmission electron microscopy and small-angle neutron scattering, we show that circular discs undergo a significant shape transition after the adsorption of aSyn. When aSyn self-assembles into fibrils, aSyn molecules desorb from the bilayer discs, allowing them to recover to their original shape. Interestingly, the desorption process has an all-or-none character, resulting in a binary coexistence of circular bilayer discs with no adsorbed aSyn and deformed bilayer discs having a maximum amount of adsorbed protein. The observed coexistence is consistent with the recent finding of cooperative aSyn adsorption to anionic lipid bilayers.
Topics: Amyloid; Lipid Bilayers; Neurons; alpha-Synuclein
PubMed: 35952001
DOI: 10.1021/acs.langmuir.2c01368 -
Langmuir : the ACS Journal of Surfaces... Nov 2022The repulsive electrostatic force between a biomolecule and a like-charged surface can be geometrically tailored to create spatial traps for charged molecules in...
The repulsive electrostatic force between a biomolecule and a like-charged surface can be geometrically tailored to create spatial traps for charged molecules in solution. Using a parallel-plate system composed of silicon dioxide surfaces, we recently demonstrated single-molecule trapping and high precision molecular charge measurements in a nanostructured free energy landscape. Here we show that surfaces coated with charged lipid bilayers provide a system with tunable surface properties for molecular electrometry experiments. Working with molecular species whose effective charge and geometry are well-defined, we demonstrate the ability to quantitatively probe the electrical charge density of a supported lipid bilayer. Our findings indicate that the fraction of charged lipids in nanoslit lipid bilayers can be significantly different from that in the precursor lipid mixtures used to generate them. We also explore the temporal stability of bilayer properties in nanofluidic systems. Beyond their relevance in molecular measurement, such experimental systems offer the opportunity to examine lipid bilayer formation and wetting dynamics on nanostructured surfaces.
Topics: Lipid Bilayers; Nanostructures; Silicon Dioxide; Static Electricity; Surface Properties
PubMed: 36326814
DOI: 10.1021/acs.langmuir.2c02203 -
Science Advances Feb 2019Using nanoparticles as substrates for computation enables algorithmic and autonomous controls of their unique and beneficial properties. However, scalable architecture...
Using nanoparticles as substrates for computation enables algorithmic and autonomous controls of their unique and beneficial properties. However, scalable architecture for nanoparticle-based computing systems is lacking. Here, we report a platform for constructing nanoparticle logic gates and circuits at the single-particle level on a supported lipid bilayer. Our "lipid nanotablet" platform, inspired by cellular membranes that are exploited to compartmentalize and control signaling networks, uses a lipid bilayer as a chemical circuit board and nanoparticles as computational units. On a lipid nanotablet, a single-nanoparticle logic gate senses molecules in solution as inputs and triggers particle assembly or disassembly as an output. We demonstrate a set of Boolean logic operations, fan-in/fan-out of logic gates, and a combinational logic circuit such as a multiplexer. We envisage that our approach to modularly implement nanoparticle circuits on a lipid bilayer will create new paradigms and opportunities in molecular computing, nanoparticle circuits, and systems nanoscience.
Topics: Lipid Bilayers; Lipids; Models, Theoretical; Nanoparticles; Nanotechnology
PubMed: 30801008
DOI: 10.1126/sciadv.aau2124 -
Philosophical Transactions of the Royal... May 2018The plasma membrane represents an outstanding example of self-organization in biology. It plays a vital role in protecting the integrity of the cell interior and... (Review)
Review
The plasma membrane represents an outstanding example of self-organization in biology. It plays a vital role in protecting the integrity of the cell interior and regulates meticulously the import and export of diverse substances. Its major building blocks are proteins and lipids, which self-assemble to a fluid lipid bilayer driven mainly by hydrophobic forces. Even if the plasma membrane appears-globally speaking-homogeneous at physiological temperatures, the existence of specialized nano- to micrometre-sized domains of raft-type character within cellular and synthetic membrane systems has been reported. It is hypothesized that these domains are the origin of a plethora of cellular processes, such as signalling or vesicular trafficking. This review intends to highlight the driving forces of lipid self-assembly into a bilayer membrane and the formation of small, transient domains within the plasma membrane. The mechanisms of self-assembly depend on several factors, such as the lipid composition of the membrane and the geometry of lipids. Moreover, the dynamics and organization of glycosphingolipids into nanometre-sized clusters will be discussed, also in the context of multivalent lectins, which cluster several glycosphingolipid receptor molecules and thus create an asymmetric stress between the two membrane leaflets, leading to tubular plasma membrane invaginations.This article is part of the theme issue 'Self-organization in cell biology'.
Topics: Cell Membrane; Glycosphingolipids; Lipid Bilayers; Protein Transport; Signal Transduction
PubMed: 29632269
DOI: 10.1098/rstb.2017.0117