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Open accessJournal ArticleDOI: 10.1016/J.BPJ.2020.12.035

Clathrin senses membrane curvature

02 Mar 2021-Biophysical Journal (Elsevier BV)-Vol. 120, Iss: 5, pp 818-828
Abstract: The ability of proteins to assemble at sites of high membrane curvature is essential to diverse membrane remodeling processes, including clathrin-mediated endocytosis Multiple adaptor proteins within the clathrin pathway have been shown to sense regions of high membrane curvature, leading to local recruitment of the clathrin coat Because clathrin triskelia do not bind to the membrane directly, it has remained unclear whether the clathrin coat plays an active role in sensing membrane curvature or is passively recruited by adaptor proteins Using a synthetic tag to assemble clathrin directly on membrane surfaces, here we show that clathrin is a strong sensor of membrane curvature, comparable with previously studied adaptor proteins Interestingly, this sensitivity arises from clathrin assembly rather than from the properties of unassembled triskelia, suggesting that triskelia have preferred angles of interaction, as predicted by earlier structural data Furthermore, when clathrin is recruited by adaptors, its curvature sensitivity is amplified by 2- to 10-fold, such that the resulting protein complex is up to 100 times more likely to assemble on a highly curved surface compared with a flatter one This exquisite sensitivity points to a synergistic relationship between the coat and its adaptor proteins, which enables clathrin to pinpoint sites of high membrane curvature, an essential step in ensuring robust membrane traffic More broadly, these findings suggest that protein networks, rather than individual protein domains, are likely the most potent drivers of membrane curvature sensing

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Topics: Clathrin coat (79%), Clathrin (70%), Membrane curvature (65%) ... read more

7 results found

Open accessJournal ArticleDOI: 10.1016/J.DEVCEL.2021.03.017
19 Apr 2021-Developmental Cell
Abstract: Clathrin-mediated endocytosis is the primary pathway for receptor and cargo internalization in eukaryotic cells It is characterized by a polyhedral clathrin lattice that coats budding membranes The mechanism and control of lattice assembly, curvature, and vesicle formation at the plasma membrane has been a matter of long-standing debate Here, we use platinum replica and cryoelectron microscopy and tomography to present a structural framework of the pathway We determine the shape and size parameters common to clathrin-mediated endocytosis We show that clathrin sites maintain a constant surface area during curvature across multiple cell lines Flat clathrin is present in all cells and spontaneously curves into coated pits without additional energy sources or recruited factors Finally, we attribute curvature generation to loosely connected and pentagon-containing flat lattices that can rapidly curve when a flattening force is released Together, these data present a universal mechanistic model of clathrin-mediated endocytosis

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Topics: Clathrin (64%), Endocytosis (55%), Vesicle (52%) ... read more

3 Citations

Journal ArticleDOI: 10.1016/J.BBAGEN.2021.129971
Chandra Has1, S. Das1Institutions (1)
Abstract: Background Membrane-bound intracellular organelles have characteristic shapes attributed to different local membrane curvatures, and these attributes are conserved across species. Over the past decade, it has been confirmed that specific proteins control the large curvatures of the membrane, whereas many others due to their specific structural features can sense the curvatures and bind to the specific geometrical cues. Elucidating the interplay between sensing and induction is indispensable to understand the mechanisms behind various biological processes such as vesicular trafficking and budding. Scope of review We provide an overview of major classes of membrane proteins and the mechanisms of curvature sensing and induction. We then discuss the importance of membrane elastic characteristics to induce the membrane shapes similar to intracellular organelles. Finally, we survey recently available assays developed for studying the curvature sensing and induction by many proteins. Major conclusions Recent theoretical/computational modeling along with experimental studies have uncovered fascinating connections between lipid membrane and protein interactions. However, the phenomena of protein localization and synchronization to generate spatiotemporal dynamics in membrane morphology are yet to be fully understood. General significance The understanding of protein-membrane interactions is essential to shed light on various biological processes. This further enables the technological applications of many natural proteins/peptides in therapeutic treatments. The studies of membrane dynamic shapes help to understand the fundamental functions of membranes, while the medicinal roles of various macromolecules (such as proteins, peptides, etc.) are being increasingly investigated.

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Topics: Membrane protein (58%), Membrane curvature (55%)

1 Citations

Open accessPosted ContentDOI: 10.1101/2021.04.19.440502
20 Apr 2021-bioRxiv
Abstract: Clathrin-coated structures must assemble on cell membranes to perform their primary function of receptor internalization. These structures show marked plasticity and instability, but what conditions are necessary to stabilize against disassembly have not been quantified. Recent in vitro fluorescence experiments have measured kinetics of stable clathrin assembly on membranes as controlled by key adaptor proteins like AP-2. Here, we combine this experimental data with microscopic reaction-diffusion simulations and theory to quantify mechanisms of stable vs unstable clathrin assembly on membranes. Both adaptor binding and dimensional reduction on the 2D surface are necessary to reproduce the cooperative kinetics of assembly. By applying our model to more physiologic-like conditions, where the stoichiometry and volume to area ratio are significantly lower than in vitro, we show that the critical nucleus contains ~25 clathrin, remarkably similar to sizes of abortive structures observed in vivo. Stable nucleation requires a stoichiometry of adaptor to clathrin that exceeds 1:1, meaning that AP-2 on its own has too few copies to nucleate lattices. Increasing adaptor concentration increases lattice sizes and nucleation speeds. For curved clathrin cages, we quantify both the cost of bending the membrane and the stabilization required to nucleate cages in solution. We find the energetics are comparable, suggesting that curving the lattice could offset the bending energy cost. Our model predicts how adaptor density controls stabilization of clathrin-coated structures against spontaneous disassembly, and shows remodeling and disassembly does not require ATPases, which is a critical advance towards predicting control of productive vesicle formation. Significance StatementStochastic self-assembly of clathrin-coated structures on the plasma membrane is essential for transport into cells. We show here that even with abundant clathrin available, robust nucleation and growth into stable structures on membranes is not possible without sufficient adaptor proteins. Our results thus provide quantitative justification for why structures observed to form in vivo can still spontaneously disassemble over many seconds. The ATPases that drive clathrin disassembly after productive vesicle formation are therefore not necessary to control remodeling during growth. With parameterization against in vitro kinetics of assembly on membranes, our reaction-diffusion model provides a powerful and extensible tool for establishing determinants of productive assembly in cells.

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Topics: Clathrin (63%), Signal transducing adaptor protein (52%), Vesicle (51%)

Open accessPosted ContentDOI: 10.1101/2021.07.15.452420
Cail Rc1, Cyna Shirazinejad1, David G. Drubin1Institutions (1)
15 Jul 2021-bioRxiv
Abstract: During clathrin-mediated endocytosis (CME), flat plasma membrane is rapidly remodeled to produce a nanometer-scale spherical vesicle. The mechanisms underlying this shape change are not known, but it has been hypothesized that the clathrin coat stabilizes membrane curvature. Here, we used nanopatterning to produce glass-like substrates with U-shaped features mimicking membrane shapes induced by fibrillar materials such as collagen. These substrates bend the ventral plasma membranes of cells grown on them into shapes characteristic of the energetically-unfavorable U-shaped intermediate stage of CME. This induced plasma membrane curvature recruits the endocytic machinery and promotes productive endocytosis. Curvature-based localization of the endocytic machinery is unaffected by clathrin disruption, and induced curvature partially bypasses clathrin9s role in cargo uptake, supporting the conclusion that clathrin9s essential endocytic function is to stabilize membrane curvature.

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Topics: Membrane curvature (65%), Clathrin coat (64%), Clathrin (60%) ... read more


48 results found

Journal ArticleDOI: 10.1038/NATURE01451
Sean D. Conner1, Sandra L. Schmid1Institutions (1)
06 Mar 2003-Nature
Abstract: The plasma membrane is the interface between cells and their harsh environment. Uptake of nutrients and all communication among cells and between cells and their environment occurs through this interface. 'Endocytosis' encompasses several diverse mechanisms by which cells internalize macromolecules and particles into transport vesicles derived from the plasma membrane. It controls entry into the cell and has a crucial role in development, the immune response, neurotransmission, intercellular communication, signal transduction, and cellular and organismal homeostasis. As the complexity of molecular interactions governing endocytosis are revealed, it has become increasingly clear that it is tightly coordinated and coupled with overall cell physiology and thus, must be viewed in a broader context than simple vesicular trafficking.

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Topics: Endocytosis (57%), Pinocytosis (54%), Cell signaling (51%)

3,489 Citations

Journal ArticleDOI: 10.1038/NRM3151
Harvey T. McMahon1, Emmanuel Boucrot1Institutions (1)
Abstract: Clathrin-mediated endocytosis is the endocytic portal into cells through which cargo is packaged into vesicles with the aid of a clathrin coat. It is fundamental to neurotransmission, signal transduction and the regulation of many plasma membrane activities and is thus essential to higher eukaryotic life. Morphological stages of vesicle formation are mirrored by progression through various protein modules (complexes). The process involves the formation of a putative FCH domain only (FCHO) initiation complex, which matures through adaptor protein 2 (AP2)-dependent cargo selection, and subsequent coat building, dynamin-mediated scission and finally auxilin- and heat shock cognate 70 (HSC70)-dependent uncoating. Some modules can be used in other pathways, and additions or substitutions confer cell specificity and adaptability.

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Topics: Clathrin coat (66%), Clathrin (62%), Synaptic vesicle endocytosis (62%) ... read more

1,734 Citations

Journal ArticleDOI: 10.1126/SCIENCE.1092586
Brian J. Peter1, Helen M. Kent1, Ian G. Mills1, T. Yvonne Vallis1  +3 moreInstitutions (1)
23 Jan 2004-Science
Abstract: The BAR (Bin/amphiphysin/Rvs) domain is the most conserved feature in amphiphysins from yeast to human and is also found in endophilins and nadrins. We solved the structure of the Drosophila amphiphysin BAR domain. It is a crescent-shaped dimer that binds preferentially to highly curved negatively charged membranes. With its N-terminal amphipathic helix and BAR domain (N-BAR), amphiphysin can drive membrane curvature in vitro and in vivo. The structure is similar to that of arfaptin2, which we find also binds and tubulates membranes. From this, we predict that BAR domains are in many protein families, including sorting nexins, centaurins, and oligophrenins. The universal and minimal BAR domain is a dimerization, membrane-binding, and curvature-sensing module.

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Topics: BAR domain (81%), Amphiphysin (69%), Membrane curvature (54%) ... read more

1,550 Citations

Journal ArticleDOI: 10.1038/NATURE01020
Marijn G. J. Ford1, Ian G. Mills1, Brian J. Peter1, Yvonne Vallis1  +3 moreInstitutions (1)
26 Sep 2002-Nature
Abstract: Clathrin-mediated endocytosis involves cargo selection and membrane budding into vesicles with the aid of a protein coat. Formation of invaginated pits on the plasma membrane and subsequent budding of vesicles is an energetically demanding process that involves the cooperation of clathrin with many different proteins. Here we investigate the role of the brain-enriched protein epsin 1 in this process. Epsin is targeted to areas of endocytosis by binding the membrane lipid phosphatidylinositol-4,5-bisphosphate (PtdIns(4,5)P(2)). We show here that epsin 1 directly modifies membrane curvature on binding to PtdIns(4,5)P(2) in conjunction with clathrin polymerization. We have discovered that formation of an amphipathic alpha-helix in epsin is coupled to PtdIns(4,5)P(2) binding. Mutation of residues on the hydrophobic region of this helix abolishes the ability to curve membranes. We propose that this helix is inserted into one leaflet of the lipid bilayer, inducing curvature. On lipid monolayers epsin alone is sufficient to facilitate the formation of clathrin-coated invaginations.

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Topics: ENTH domain (70%), Epsin (69%), Membrane curvature (64%) ... read more

962 Citations

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