1
|
Denker L, Dixon AM. The cell edit: Looking at and beyond non-structural proteins to understand membrane rearrangement in coronaviruses. Arch Biochem Biophys 2024; 752:109856. [PMID: 38104958 DOI: 10.1016/j.abb.2023.109856] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 11/24/2023] [Accepted: 12/08/2023] [Indexed: 12/19/2023]
Abstract
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a positive-stranded RNA virus that sits at the centre of the recent global pandemic. As a member of the coronaviridae family of viruses, it shares features such as a very large genome (>30 kb) that is replicated in a purpose-built replication organelle. Biogenesis of the replication organelle requires significant and concerted rearrangement of the endoplasmic reticulum membrane, a job that is carried out by a group of integral membrane non-structural proteins (NSP3, 4 and 6) expressed by the virus along with a host of viral replication enzymes and other factors that support transcription and replication. The primary sites for RNA replication within the replication organelle are double membrane vesicles (DMVs). The small size of DMVs requires generation of high membrane curvature, as well as stabilization of a double-membrane arrangement, but the mechanisms that underlie DMV formation remain elusive. In this review, we discuss recent breakthroughs in our understanding of the molecular basis for membrane rearrangements by coronaviruses. We incorporate established models of NSP3-4 protein-protein interactions to drive double membrane formation, and recent data highlighting the roles of lipid composition and host factor proteins (e.g. reticulons) that influence membrane curvature, to propose a revised model for DMV formation in SARS-CoV-2.
Collapse
Affiliation(s)
- Lea Denker
- Warwick Medical School, Biomedical Sciences, University of Warwick, Coventry, CV4 7AL, UK.
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry, CV4 7SH, UK.
| |
Collapse
|
2
|
Sun H, Yao Z. Conformal order and Poincaré-Klein mapping underlying electrostatics-driven inhomogeneity in tethered membranes. Phys Rev E 2023; 108:025001. [PMID: 37723772 DOI: 10.1103/physreve.108.025001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Accepted: 07/17/2023] [Indexed: 09/20/2023]
Abstract
Understanding the organization of matter under the long-range electrostatic force is a fundamental problem in multiple fields. In this work, based on the electrically charged tethered membrane model, we reveal regular structures underlying the lowest-energy states of inhomogeneously stretched planar lattices by a combination of numerical simulation and analytical geometric analysis. Specifically we show the conformal order characterized by the preserved bond angle in the lattice deformation and reveal the Poincaré-Klein mapping underlying the electrostatics-driven inhomogeneity. The discovery of the Poincaré-Klein mapping, which connects the Poincaré disk and the Klein disk for the hyperbolic plane, implies the connection of long-range electrostatic force and hyperbolic geometry. We also discuss lattices with patterned charges of opposite signs for modulating in-plane inhomogeneity and even creating 3D shapes, which may have a connection to metamaterials design. This work suggests the geometric analysis as a promising approach for elucidating the organization of matter under the long-range force.
Collapse
Affiliation(s)
- Honghui Sun
- School of Physics and Astronomy, and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| | - Zhenwei Yao
- School of Physics and Astronomy, and Institute of Natural Sciences, Shanghai Jiao Tong University, Shanghai 200240, China
| |
Collapse
|
3
|
Kluge C, Pöhnl M, Böckmann RA. Spontaneous local membrane curvature induced by transmembrane proteins. Biophys J 2022; 121:671-683. [PMID: 35122737 PMCID: PMC8943716 DOI: 10.1016/j.bpj.2022.01.029] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2021] [Revised: 01/13/2022] [Accepted: 01/28/2022] [Indexed: 11/26/2022] Open
Abstract
The (local) curvature of cellular membranes acts as a driving force for the targeting of membrane-associated proteins to specific membrane domains, as well as a sorting mechanism for transmembrane proteins, e.g., by accumulation in regions of matching spontaneous curvature. The latter measure was previously experimentally employed to study the curvature induced by the potassium channel KvAP and by aquaporin AQP0. However, the direction of the reported spontaneous curvature levels as well as the molecular driving forces governing the membrane curvature induced by these integral transmembrane proteins could not be addressed experimentally. Here, using both coarse-grained and atomistic molecular dynamics (MD) simulations, we report induced spontaneous curvature values for the homologous potassium channel Kv 1.2/2.1 Chimera (KvChim) and AQP0 embedded in unrestrained lipid bicelles that are in very good agreement with experiment. Importantly, the direction of curvature could be directly assessed from our simulations: KvChim induces a strong positive membrane curvature (≈0.036 nm-1) whereas AQP0 causes a comparably small negative curvature (≈-0.019 nm-1). Analyses of protein-lipid interactions within the bicelle revealed that the potassium channel shapes the surrounding membrane via structural determinants. Differences in shape of the protein-lipid interface of the voltage-gating domains between the extracellular and cytosolic membrane leaflets induce membrane stress and thereby promote a protein-proximal membrane curvature. In contrast, the water pore AQP0 displayed a high structural stability and an only faint effect on the surrounding membrane environment that is connected to its wedge-like shape.
Collapse
Affiliation(s)
- Christoph Kluge
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Matthias Pöhnl
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany
| | - Rainer A. Böckmann
- Computational Biology, Department of Biology, Friedrich-Alexander-Universität Erlangen-Nürnberg (FAU), Erlangen, Germany,National Center for High-Performance Computing Erlangen (NHR@FAU), Erlangen, Germany,Corresponding author
| |
Collapse
|
4
|
Jawaid MZ, Sinclair R, Bulone V, Cox DL, Drakakaki G. A biophysical model for plant cell plate maturation based on the contribution of a spreading force. PLANT PHYSIOLOGY 2022; 188:795-806. [PMID: 34850202 PMCID: PMC8825336 DOI: 10.1093/plphys/kiab552] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/13/2021] [Accepted: 10/27/2021] [Indexed: 06/13/2023]
Abstract
Plant cytokinesis, a fundamental process of plant life, involves de novo formation of a "cell plate" partitioning the cytoplasm of dividing cells. Cell plate formation is directed by orchestrated delivery, fusion of cytokinetic vesicles, and membrane maturation to form a nascent cell wall by timely deposition of polysaccharides. During cell plate maturation, the fragile membrane network transitions to a fenestrated sheet and finally a young cell wall. Here, we approximated cell plate sub-structures with testable shapes and adopted the Helfrich-free energy model for membranes, including a stabilizing and spreading force, to understand the transition from a vesicular network to a fenestrated sheet and mature cell plate. Regular cell plate development in the model was possible, with suitable bending modulus, for a two-dimensional late stage spreading force of 2-6 pN/nm, an osmotic pressure difference of 2-10 kPa, and spontaneous curvature between 0 and 0.04 nm-1. With these conditions, stable membrane conformation sizes and morphologies emerged in concordance with stages of cell plate development. To reach a mature cell plate, our model required the late-stage onset of a spreading/stabilizing force coupled with a concurrent loss of spontaneous curvature. Absence of a spreading/stabilizing force predicts failure of maturation. The proposed model provides a framework to interrogate different players in late cytokinesis and potentially other membrane networks that undergo such transitions. Callose, is a polysaccharide that accumulates transiently during cell plate maturation. Callose-related observations were consistent with the proposed model's concept, suggesting that it is one of the factors involved in establishing the spreading force.
Collapse
Affiliation(s)
- Muhammad Zaki Jawaid
- Department of Physics and Astronomy, University of California, Davis, California, USA
| | - Rosalie Sinclair
- Department of Plant Sciences, University of California, Davis, California, USA
| | - Vincent Bulone
- School of Food, Agriculture and Wine, The University of Adelaide, Waite Campus, Adelaide SA 5064, Australia
- Department of Chemistry, Division of Glycoscience, KTH Royal Institute of Technology, Stockholm, Sweden
| | - Daniel L Cox
- Department of Physics and Astronomy, University of California, Davis, California, USA
| | - Georgia Drakakaki
- Department of Plant Sciences, University of California, Davis, California, USA
| |
Collapse
|
5
|
Amaya C, Cameron CJF, Devarkar SC, Seager SJH, Gerstein MB, Xiong Y, Schlieker C. Nodal modulator (NOMO) is required to sustain endoplasmic reticulum morphology. J Biol Chem 2021; 297:100937. [PMID: 34224731 PMCID: PMC8327139 DOI: 10.1016/j.jbc.2021.100937] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/07/2021] [Revised: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 12/03/2022] Open
Abstract
The endoplasmic reticulum (ER) is a membrane-bound organelle responsible for protein folding, lipid synthesis, and calcium homeostasis. Maintenance of ER structural integrity is crucial for proper function, but much remains to be learned about the molecular players involved. To identify proteins that support the structure of the ER, we performed a proteomic screen and identified nodal modulator (NOMO), a widely conserved type I transmembrane protein of unknown function, with three nearly identical orthologs specified in the human genome. We found that overexpression of NOMO1 imposes a sheet morphology on the ER, whereas depletion of NOMO1 and its orthologs causes a collapse of ER morphology concomitant with the formation of membrane-delineated holes in the ER network positive for the lysosomal marker lysosomal-associated protein 1. In addition, the levels of key players of autophagy including microtubule-associated protein light chain 3 and autophagy cargo receptor p62/sequestosome 1 strongly increase upon NOMO depletion. In vitro reconstitution of NOMO1 revealed a "beads on a string" structure likely representing consecutive immunoglobulin-like domains. Extending NOMO1 by insertion of additional immunoglobulin folds results in a correlative increase in the ER intermembrane distance. Based on these observations and a genetic epistasis analysis including the known ER-shaping proteins Atlastin2 and Climp63, we propose a role for NOMO1 in the functional network of ER-shaping proteins.
Collapse
Affiliation(s)
- Catherine Amaya
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Christopher J F Cameron
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Swapnil C Devarkar
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Sebastian J H Seager
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Mark B Gerstein
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA; Program in Computational Biology and Bioinformatics, Yale University, New Haven, Connecticut, USA; Department of Computer Science, Yale University, New Haven, Connecticut, USA; Department of Statistics and Data Science, Yale University, New Haven, Connecticut, USA
| | - Yong Xiong
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA
| | - Christian Schlieker
- Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, Connecticut, USA; Department of Cell Biology, Yale School of Medicine, New Haven, Connecticut, USA.
| |
Collapse
|
6
|
Brooks RL, Mistry CS, Dixon AM. Curvature sensing amphipathic helix in the C-terminus of RTNLB13 is conserved in all endoplasmic reticulum shaping reticulons in Arabidopsis thaliana. Sci Rep 2021; 11:6326. [PMID: 33737685 PMCID: PMC7973432 DOI: 10.1038/s41598-021-85866-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/05/2021] [Indexed: 11/24/2022] Open
Abstract
The reticulon family of integral membrane proteins are conserved across all eukaryotes and typically localize to the endoplasmic reticulum (ER), where they are involved in generating highly-curved tubules. We recently demonstrated that Reticulon-like protein B13 (RTNLB13) from Arabidopsis thaliana contains a curvature-responsive amphipathic helix (APH) important for the proteins' ability to induce curvature in the ER membrane, but incapable of generating curvature by itself. We suggested it acts as a feedback element, only folding/binding once a sufficient degree of curvature has been achieved, and stabilizes curvature without disrupting the bilayer. However, it remains unclear whether this is unique to RTNLB13 or is conserved across all reticulons-to date, experimental evidence has only been reported for two reticulons. Here we used biophysical methods to characterize a minimal library of putative APH peptides from across the 21 A. thaliana isoforms. We found that reticulons with the closest evolutionary relationship to RTNLB13 contain curvature-sensing APHs in the same location with sequence conservation. Our data reveal that a more distantly-related branch of reticulons developed a ~ 20-residue linker between the transmembrane domain and APH. This may facilitate functional flexibility as previous studies have linked these isoforms not only to ER remodeling but other cellular activities.
Collapse
Affiliation(s)
- Rhiannon L Brooks
- MAS Centre for Doctoral Training, University of Warwick, Coventry, CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Chandni S Mistry
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK.
| |
Collapse
|
7
|
Bonazzi F, Hall CK, Weikl TR. Membrane morphologies induced by mixtures of arc-shaped particles with opposite curvature. SOFT MATTER 2021; 17:268-275. [PMID: 32270169 DOI: 10.1039/c9sm02476j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
Biological membranes are shaped by various proteins that either generate inward or outward membrane curvature. In this article, we investigate the membrane morphologies induced by mixtures of arc-shaped particles with coarse-grained modeling and simulations. The particles bind to the membranes either with their inward, concave side or their outward, convex side and, thus, generate membrane curvature of opposite sign. We find that small fractions of convex-binding particles can stabilize three-way junctions of membrane tubules, as suggested for the protein lunapark in the endoplasmic reticulum of cells. For comparable fractions of concave-binding and convex-binding particles, we observe lines of particles of the same type, and diverse membrane morphologies with grooves and bulges induced by these particle lines. The alignment and segregation of the particles is driven by indirect, membrane-mediated interactions.
Collapse
Affiliation(s)
- Francesco Bonazzi
- Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Am Mühlenberg 1, 14476 Potsdam, Germany.
| | | | | |
Collapse
|
8
|
Brooks RL, Dixon AM. Revealing the mechanism of protein-lipid interactions for a putative membrane curvature sensor in plant endoplasmic reticulum. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2019; 1862:183160. [PMID: 31874147 DOI: 10.1016/j.bbamem.2019.183160] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 11/22/2019] [Accepted: 12/16/2019] [Indexed: 01/05/2023]
Abstract
Membrane curvature sensing via helical protein domains, such as those identified in Amphiphysin and ArfGAP1, have been linked to a diverse range of cellular processes. However, these regions can vary significantly between different protein families and thus remain challenging to identify from sequence alone. Greater insight into the protein-lipid interactions that drive this behavior could lead to production of therapeutics that specifically target highly curved membranes. Here we demonstrate the curvature-dependence of membrane binding for an amphipathic helix (APH) in a plant reticulon, namely RTNLB13 from A. thaliana. We utilize solution-state nuclear magnetic resonance spectroscopy to establish the exact location of the APH and map the residues involved in protein-membrane interactions at atomic resolution. We find that the hydrophobic residues making up the membrane binding site are conserved throughout all A. thaliana reticulons. Our results also provide mechanistic insight that leads us to propose that membrane binding by this APH may act as a feedback element, only forming when ER tubules reach a critical size and adding stabilization to these structures without disrupting the bilayer. A shallow hydrophobic binding interface appears to be a feature shared more broadly across helical curvature sensors and would automatically restrict the penetration depth of these structures into the membrane. We also suggest this APH is highly tuned to the composition of the membrane in which it resides, and that this property may be universal in curvature sensors thus rationalizing the variety of mechanisms reported for these functional elements.
Collapse
Affiliation(s)
- Rhiannon L Brooks
- MAS Centre for Doctoral Training, University of Warwick, Coventry CV4 7AL, UK; Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Ann M Dixon
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK.
| |
Collapse
|
9
|
Lavi I, Goudarzi M, Raz E, Gov NS, Voituriez R, Sens P. Cellular Blebs and Membrane Invaginations Are Coupled through Membrane Tension Buffering. Biophys J 2019; 117:1485-1495. [PMID: 31445681 DOI: 10.1016/j.bpj.2019.08.002] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2018] [Revised: 07/26/2019] [Accepted: 08/01/2019] [Indexed: 01/06/2023] Open
Abstract
Bleb-type cellular protrusions play key roles in a range of biological processes. It was recently found that bleb growth is facilitated by a local supply of membrane from tubular invaginations, but the interplay between the expanding bleb and the membrane tubes remains poorly understood. On the one hand, the membrane area stored in tubes may serve as a reservoir for bleb expansion. On the other hand, the sequestering of excess membrane in stabilized invaginations may effectively increase the cell membrane tension, which suppresses spontaneous protrusions. Here, we investigate this duality through physical modeling and in vivo experiments. In agreement with observations, our model describes the transition into a tube-flattening mode of bleb expansion while also predicting that the blebbing rate is impaired by elevating the concentration of the curved membrane proteins that form the tubes. We show both theoretically and experimentally that the stabilizing effect of tubes could be counterbalanced by the cortical myosin contractility. Our results largely suggest that proteins able to induce membrane tubulation, such as those containing N-BAR domains, can buffer the effective membrane tension-a master regulator of all cell deformations.
Collapse
Affiliation(s)
- Ido Lavi
- Laboratoire Jean Perrin, UMR 8237 CNRS, Sorbonne University, Paris, France.
| | - Mohammad Goudarzi
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Erez Raz
- Institute of Cell Biology, Center for Molecular Biology of Inflammation, University of Münster, Münster, Germany
| | - Nir S Gov
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
| | - Raphael Voituriez
- Laboratoire Jean Perrin, UMR 8237 CNRS, Sorbonne University, Paris, France
| | - Pierre Sens
- Institut Curie, PSL Research University, CNRS, UMR 168, Paris, France
| |
Collapse
|
10
|
Pezeshkian W, König M, Marrink SJ, Ipsen JH. A Multi-Scale Approach to Membrane Remodeling Processes. Front Mol Biosci 2019; 6:59. [PMID: 31396522 PMCID: PMC6664084 DOI: 10.3389/fmolb.2019.00059] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Accepted: 07/08/2019] [Indexed: 12/31/2022] Open
Abstract
We present a multi-scale simulation procedure to describe membrane-related biological processes that span over a wide range of length scales. At macroscopic length-scale, a membrane is described as a flexible thin film modeled by a dynamic triangulated surface with its spatial conformations governed by an elastic energy containing only a few model parameters. An implicit protein model allows us to include complex effects of membrane-protein interactions in the macroscopic description. The gist of this multi-scale approach is a scheme to calibrate the implicit protein model using finer scale simulation techniques e.g., all atom and coarse grain molecular dynamics. We previously used this approach and properly described the formation of membrane tubular invaginations upon binding of B-subunit of Shiga toxin. Here, we provide a perspective of our multi-scale approach, summarizing its main features and sketching possible routes for future development.
Collapse
Affiliation(s)
- Weria Pezeshkian
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Melanie König
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute and Zernike Institute for Advanced Materials, University of Groningen, Groningen, Netherlands
| | - John H Ipsen
- Department of Physics, Chemistry and Pharmacy, Center for Biomembrane Physics (MEMPHYS), University of Southern Denmark, Odense, Denmark
| |
Collapse
|
11
|
Bonazzi F, Weikl TR. Membrane Morphologies Induced by Arc-Shaped Scaffolds Are Determined by Arc Angle and Coverage. Biophys J 2019; 116:1239-1247. [PMID: 30902368 DOI: 10.1016/j.bpj.2019.02.017] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Revised: 01/13/2019] [Accepted: 02/19/2019] [Indexed: 10/27/2022] Open
Abstract
The intricate shapes of biological membranes such as tubules and membrane stacks are induced by proteins. In this article, we systematically investigate the membrane shapes induced by arc-shaped scaffolds such as proteins and protein complexes with coarse-grained modeling and simulations. We find that arc-shaped scaffolds induce membrane tubules at membrane coverages larger than a threshold of ∼40%, irrespective of their arc angle. The membrane morphologies at intermediate coverages below this tubulation threshold, in contrast, strongly depend on the arc angle. Scaffolds with arc angles of about 60°, akin to N-BAR domains, do not change the membrane shape at coverages below the tubulation threshold, whereas scaffolds with arc angles larger than about 120° induce double-membrane stacks at intermediate coverages. The scaffolds stabilize the curved membrane edges that connect the membrane stacks, as suggested for complexes of reticulon proteins. Our results provide general insights on the determinants of membrane shaping by arc-shaped scaffolds.
Collapse
Affiliation(s)
- Francesco Bonazzi
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany
| | - Thomas R Weikl
- Max Planck Institute of Colloids and Interfaces, Department of Theory and Bio-Systems, Potsdam, Germany.
| |
Collapse
|
12
|
Krishna A, Sengupta D. Interplay between Membrane Curvature and Cholesterol: Role of Palmitoylated Caveolin-1. Biophys J 2018; 116:69-78. [PMID: 30579563 DOI: 10.1016/j.bpj.2018.11.3127] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Revised: 10/14/2018] [Accepted: 11/01/2018] [Indexed: 01/07/2023] Open
Abstract
Caveolin-1 (cav-1) is an important player in cell signaling and endocytosis that has been shown to colocalize with cholesterol-rich membrane domains. Experimental studies with varying cav-1 constructs have suggested that it can induce both cholesterol clustering and membrane curvature. Here, we probe the molecular origin of membrane curvature and cholesterol clustering by cav-1 by using coarse-grain molecular dynamics simulations. We have performed a series of simulations of a functionally important cav-1 construct, comprising the membrane-interacting domains and a C-terminal palmitoyl tail. Our results suggest that cav-1 is able to induce cholesterol clustering in the membrane leaflet to which it is bound as well as the opposing leaflet. A positive membrane curvature is observed upon cav-1 binding in cholesterol-containing bilayers. Interestingly, we observe an interplay between cholesterol clustering and membrane curvature such that cav-1 is able to induce higher membrane curvature in cholesterol-rich membranes. The role of the cav-1 palmitoyl tail is less clear and appears to increase the membrane contacts. Further, we address the importance of the secondary structure of cav-1 domains and show that it could play an important role in membrane curvature and cholesterol clustering. Our work is an important step toward a molecular picture of caveolae and vesicular endocytosis.
Collapse
Affiliation(s)
- Anjali Krishna
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India
| | - Durba Sengupta
- CSIR-National Chemical Laboratory, Pune, Maharashtra, India.
| |
Collapse
|
13
|
Allolio C, Haluts A, Harries D. A local instantaneous surface method for extracting membrane elastic moduli from simulation: Comparison with other strategies. Chem Phys 2018. [DOI: 10.1016/j.chemphys.2018.03.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
|
14
|
Nanomaterial interactions with biomembranes: Bridging the gap between soft matter models and biological context. Biointerphases 2018; 13:028501. [DOI: 10.1116/1.5022145] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
|
15
|
Lazutin AA, Vasilevskaya VV, Khokhlov AR. Self-assembly in densely grafted macromolecules with amphiphilic monomer units: diagram of states. SOFT MATTER 2017; 13:8525-8533. [PMID: 29091101 DOI: 10.1039/c7sm01560g] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
By means of computer modelling, the self-organization of dense planar brushes of macromolecules with amphiphilic monomer units was addressed and their state diagram was constructed. The diagram of states includes the following regions: disordered position of monomer units with respect to each other, strands composed of a few polymer chains and lamellae with different domain spacing. The transformation of lamellae structures with different domain spacing occurred within the intermediate region and could proceed through the formation of so-called parking garage structures. The parking garage structure joins the lamellae with large (on the top of the brushes) and small (close to the grafted surface) domain spacing, which appears like a system of inclined locally parallel layers connected with each other by bridges. The parking garage structures were observed for incompatible A and B groups in selective solvents, which result in aggregation of the side B groups and dense packing of amphiphilic macromolecules in the restricted volume of the planar brushes.
Collapse
Affiliation(s)
- A A Lazutin
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova ul., 28, Moscow 119991, Russia.
| | - V V Vasilevskaya
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova ul., 28, Moscow 119991, Russia.
| | - A R Khokhlov
- A. N. Nesmeyanov Institute of Organoelement Compounds RAS, Vavilova ul., 28, Moscow 119991, Russia. and Faculty of Physics, M. V. Lomonosov Moscow State University, Leninskie gory, Moscow 119991, Russia
| |
Collapse
|
16
|
Abstract
Lipid droplets (LDs) are ubiquitous organelles that store neutral lipids for energy or membrane synthesis and act as hubs for metabolic processes. Cells generate LDs de novo, converting cells to emulsions with LDs constituting the dispersed oil phase in the aqueous cytoplasm. Here we review our current view of LD biogenesis. We present a model of LD formation from the ER in distinct steps and highlight the biology of proteins that govern this biophysical process. Areas of incomplete knowledge are identified, as are connections with physiology and diseases linked to alterations in LD biology.
Collapse
Affiliation(s)
- Tobias C Walther
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115; , .,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115.,Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142.,Howard Hughes Medical Institute, Boston, Massachusetts 02115
| | - Jeeyun Chung
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115; , .,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115
| | - Robert V Farese
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, Massachusetts 02115; , .,Department of Cell Biology, Harvard Medical School, Boston, Massachusetts 02115.,Broad Institute of Harvard and MIT, Cambridge, Massachusetts 02142
| |
Collapse
|
17
|
Fedorov EG, Shemesh T. Physical Model for Stabilization and Repair of Trans-endothelial Apertures. Biophys J 2017; 112:388-397. [PMID: 28122224 DOI: 10.1016/j.bpj.2016.11.3207] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 11/16/2016] [Accepted: 11/28/2016] [Indexed: 01/13/2023] Open
Abstract
Bacterial toxins that disrupt the stability of contractile structures in endothelial cells promote the opening of large-scale apertures, thereby breaching the endothelium barrier. These apertures are formed by fusion of the basal and apical membranes into a tunnel that spans the height of the cell. Subsequent to the aperture formation, an active repair process, driven by a stimulated polymerization of actin, results in asymmetrical membrane protrusions and, ultimately, the closure of the aperture. Here, we propose a physics-based model for the generation, stabilization and repair of trans-endothelial apertures. Our model is based on the mechanical interplay between tension in the plasma membrane and stresses that develop within different actin structures at the aperture's periphery. We suggest that accumulation of cytoskeletal fragments around the aperture's rim during the expansion phase results in parallel bundles of actin filaments and myosin motors, generating progressively greater contraction forces that resist further expansion of the aperture. Our results indicate that closure of the tunnel is driven by mechanical stresses that develop within a cross-linked actin gel that forms at localized regions of the aperture periphery. We show that stresses within the gel are due to continuous polymerization of actin filaments against the membrane surfaces of the aperture's edges. Based on our mechanical model, we construct a dynamic simulation of the aperture repair process. Our model fully accounts for the phenomenology of the trans-endothelial aperture formation and stabilization, and recaptures the experimentally observed asymmetry of the intermediate aperture shapes during closure. We make experimentally testable predictions for localization of myosin motors to the tunnel periphery and of adhesion complexes to the edges of apertures undergoing closure, and we estimate the minimal nucleation size of cross-linked actin gel that can lead to a successful repair of the aperture.
Collapse
Affiliation(s)
- Eduard G Fedorov
- Department of Biology, Israel Institute of Technology, Haifa, Israel
| | - Tom Shemesh
- Department of Biology, Israel Institute of Technology, Haifa, Israel.
| |
Collapse
|
18
|
Dan N. Membrane-induced interactions between curvature-generating protein domains: the role of area perturbation. AIMS BIOPHYSICS 2017. [DOI: 10.3934/biophy.2017.1.107] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
|
19
|
Griffing LR, Lin C, Perico C, White RR, Sparkes I. Plant ER geometry and dynamics: biophysical and cytoskeletal control during growth and biotic response. PROTOPLASMA 2017; 254:43-56. [PMID: 26862751 PMCID: PMC5216105 DOI: 10.1007/s00709-016-0945-3] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 01/13/2016] [Indexed: 05/20/2023]
Abstract
The endoplasmic reticulum (ER) is an intricate and dynamic network of membrane tubules and cisternae. In plant cells, the ER 'web' pervades the cortex and endoplasm and is continuous with adjacent cells as it passes through plasmodesmata. It is therefore the largest membranous organelle in plant cells. It performs essential functions including protein and lipid synthesis, and its morphology and movement are linked to cellular function. An emerging trend is that organelles can no longer be seen as discrete membrane-bound compartments, since they can physically interact and 'communicate' with one another. The ER may form a connecting central role in this process. This review tackles our current understanding and quantification of ER dynamics and how these change under a variety of biotic and developmental cues.
Collapse
Affiliation(s)
- Lawrence R Griffing
- Biology Department, Texas A&M University, 3258 TAMU, College Station, TX, 77843, USA
| | - Congping Lin
- Mathematics Research Institute, Harrison Building, University of Exeter, Exeter, EX4 4QF, UK
| | - Chiara Perico
- Biosciences, CLES, Exeter University, Geoffrey Pope Building, Stocker Rd, Exeter, EX4 4QD, UK
| | - Rhiannon R White
- Biosciences, CLES, Exeter University, Geoffrey Pope Building, Stocker Rd, Exeter, EX4 4QD, UK
| | - Imogen Sparkes
- Biosciences, CLES, Exeter University, Geoffrey Pope Building, Stocker Rd, Exeter, EX4 4QD, UK.
| |
Collapse
|
20
|
Singh S, Mittal A. Transmembrane Domain Lengths Serve as Signatures of Organismal Complexity and Viral Transport Mechanisms. Sci Rep 2016; 6:22352. [PMID: 26925972 PMCID: PMC4772119 DOI: 10.1038/srep22352] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/12/2016] [Indexed: 12/24/2022] Open
Abstract
It is known that membrane proteins are important in various secretory pathways, with
a possible role of their transmembrane domains (TMDs) as sorting determinant
factors. One key aspect of TMDs associated with various
“checkposts” (i.e. organelles) of intracellular trafficking
is their length. To explore possible linkages in organisms with varying
“complexity” and differences in TMD lengths of membrane
proteins associated with different organelles (such as Endoplasmic Reticulum, Golgi,
Endosomes, Nucleus, Plasma Membrane), we analyzed ~70000 membrane
protein sequences in over 300 genomes of fungi, plants, non-mammalian vertebrates
and mammals. We report that as we move from simpler to complex organisms, variation
in organellar TMD lengths decreases, especially compared to their respective plasma
membranes, with increasing organismal complexity. This suggests an evolutionary
pressure in modulating length of TMDs of membrane proteins with increasing
complexity of communication between sub-cellular compartments. We also report
functional applications of our findings by discovering remarkable distinctions in
TMD lengths of membrane proteins associated with different intracellular transport
pathways. Finally, we show that TMD lengths extracted from viral proteins can serve
as somewhat weak indicators of viral replication sites in plant cells but very
strong indicators of different entry pathways employed by animal viruses.
Collapse
Affiliation(s)
- Snigdha Singh
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Aditya Mittal
- Kusuma School of Biological Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| |
Collapse
|