Molecular modeling of membrane curvature driven by epsin

2012 ◽  
Author(s):  
Ryan Bradley ◽  
Ravi Radhakrishnan
Keyword(s):  
Molecular Modeling ◽  
Membrane Curvature ◽  
Curvature Driven

scholarly journals Membrane curvature and the Tol-Pal complex determine polar localization of the chemoreceptor Tar inE. coli

2017 ◽  
Author(s):  
Terrens N. V. Saaki ◽  
Henrik Strahl ◽  
Leendert W. Hamoen
Keyword(s):  
Cell Division ◽  
Cell Membrane ◽  
Cellular Localization ◽  
Cluster Formation ◽  
Signal Transduction Pathway ◽  
Membrane Curvature ◽  
Deletion Mutants ◽  
E Coli ◽  
Polar Localization ◽  
Curvature Driven

AbstractChemoreceptors are localized at the cell poles ofEscherichia coliand other rod-shaped bacteria. Over the years different mechanisms have been put forward to explain this polar localization; from stochastic clustering, membrane curvature driven localization, interactions with the Tol-Pal complex, to nucleoid exclusion. To evaluate these mechanisms, we monitored the cellular localization of the aspartate chemoreceptor Tar in different deletion mutants. We did not find any indication for either stochastic cluster formation or nucleoid exclusion. However, the presence of a functional Tol-Pal complex appeared to be essential to retain Tar at cell poles. This finding also implies that the curvature of cell poles does not attract chemoreceptor complexes. Interestingly, Tar still accumulated at midcell intoland inpaldeletion mutants. In these mutants, the protein appears to gather at the base of division septa, a region characterised by strong membrane curvature. Chemoreceptors, like Tar, form trimer-of-dimers that bend the cell membrane due to a rigid tripod structure with an estimated curvature of approximately 37 nm. This curvature approaches the curvature of the cell membrane generated during cell division, and localization of chemoreceptor tripods at curved membrane areas is therefore energetically favourable as it lowers membrane tension. Indeed, when we introduced mutations in Tar that abolish the rigid tripod structure, the protein was no longer able to accumulate at midcell or cell poles. These findings favour a model where chemoreceptor localization inE. coliis driven by strong membrane curvature and association with the Tol-Pal complex.ImportanceBacteria have exquisite mechanisms to sense and to adapt to the environment they live in. One such mechanism involves the chemotaxis signal transduction pathway, in which chemoreceptors specifically bind certain attracting or repelling molecules and transduce the signals to the cell. In different rod-shaped bacteria, these chemoreceptors localize specifically to cell poles. Here, we examined the polar localization of the aspartate chemoreceptor Tar inE. coli, and found that membrane curvature at cell division sites and interaction with the Tal-pol protein complex, localize Tar at cell division sites, the future cell poles. This study shows how membrane curvature can guide localization of proteins in a cell.

scholarly journals Synergistic actions of v-SNARE transmembrane domains and membrane-curvature modifying lipids in neurotransmitter release

eLife ◽  
2020 ◽  
Vol 9 ◽  
Author(s):  
Madhurima Dhara ◽  
Maria Mantero Martinez ◽  
Mazen Makke ◽  
Yvonne Schwarz ◽  
Ralf Mohrmann ◽  
...  
Keyword(s):  
Active Role ◽  
Underlying Mechanism ◽  
Membrane Curvature ◽  
Transmembrane Domains ◽  
Snare Complex ◽  
Fusion Pore ◽  
Pore Evolution ◽  
Tightly Coupled ◽  
Membrane Bending ◽  
Curvature Driven

Vesicle fusion is mediated by assembly of SNARE proteins between opposing membranes. While previous work suggested an active role of SNARE transmembrane domains (TMDs) in promoting membrane merger (Dhara et al., 2016), the underlying mechanism remained elusive. Here, we show that naturally-occurring v-SNARE TMD variants differentially regulate fusion pore dynamics in mouse chromaffin cells, indicating TMD flexibility as a mechanistic determinant that facilitates transmitter release from differentially-sized vesicles. Membrane curvature-promoting phospholipids like lysophosphatidylcholine or oleic acid profoundly alter pore expansion and fully rescue the decelerated fusion kinetics of TMD-rigidifying VAMP2 mutants. Thus, v-SNARE TMDs and phospholipids cooperate in supporting membrane curvature at the fusion pore neck. Oppositely, slowing of pore kinetics by the SNARE-regulator complexin-2 withstands the curvature-driven speeding of fusion, indicating that pore evolution is tightly coupled to progressive SNARE complex formation. Collectively, TMD-mediated support of membrane curvature and SNARE force-generated membrane bending promote fusion pore formation and expansion.

scholarly journals The influence of phosphatidylserine localisation and lipid phase on membrane remodelling by the ESCRT-II/ESCRT-III complex

2020 ◽  
Author(s):  
Andrew Booth ◽  
Christopher J. Marklew ◽  
Barbara Ciani ◽  
Paul A. Beales
Keyword(s):  
Lipid Bilayers ◽  
Electrostatic Interactions ◽  
Annexin V ◽  
Membrane Curvature ◽  
Lipid Phase ◽  
Membrane Mechanics ◽  
Anionic Phospholipids ◽  
Escrt Complex ◽  
Phospholipid Distribution ◽  
Curvature Driven

AbstractThe endosomal sorting complex required for transport (ESCRT) organises in supramolecular structures on the surface of lipid bilayers to drive membrane invagination and scission of intraluminal vesicles (ILVs), a process also controlled by membrane mechanics. However, ESCRT association with the membrane is also mediated by electrostatic interactions with anionic phospholipids. Phospholipid distribution within natural biomembranes is inhomogeneous due to, for example, the formation of lipid rafts and curvature-driven lipid sorting. Here, we have used phase-separated giant unilamellar vesicles (GUVs) to investigate the link between phosphatidylserine (PS)-rich lipid domains and ESCRT activity. We employ GUVs composed of phase separating lipid mixtures, where unsaturated DOPS and saturated DPPS lipids are incorporated individually or simultaneously to enhance PS localisation in liquid disordered (Ld) and/or liquid ordered (Lo) domains, respectively. PS partitioning between the coexisting phases is confirmed by a fluorescent Annexin V probe. Ultimately, we find that ILV generation promoted by ESCRTs is significantly enhanced when PS lipids localise within Ld domains. However, the ILVs that form are rich in Lo lipids. We interpret this surprising observation as preferential recruitment of the Lo phase beneath the ESCRT complex due to its increased rigidity, where the Ld phase is favoured in the neck of the resultant buds to facilitate the high membrane curvature in these regions of the membrane during the ILV formation process. Ld domains offer lower resistance to membrane bending, demonstrating a mechanism by which the composition and mechanics of membranes can be coupled to regulate the location and efficiency of ESCRT activity.

scholarly journals Comparing physical mechanisms for membrane curvature-driven sorting of BAR-domain proteins

Soft Matter ◽  
2021 ◽  
Vol 17 (16) ◽  
pp. 4254-4265
Author(s):  
Feng-Ching Tsai ◽  
Mijo Simunovic ◽  
Benoit Sorre ◽  
Aurélie Bertin ◽  
John Manzi ◽  
...  
Keyword(s):  
Theoretical Models ◽  
Membrane Curvature ◽  
Bar Domain ◽  
Curvature Sensing ◽  
Physical Mechanisms ◽  
Electron Microscopy Data ◽  
Bar Domain Proteins ◽  
Microscopy Data ◽  
Curvature Driven ◽  
Review Current

We review current theoretical models for curvature sensing of BAR-domain proteins, test the models on 2 proteins, and present new electron microscopy data on the organization of BAR domains on tubes.

NMR and molecular modeling: application to wine ageing

1998 ◽  
Vol 95 (2) ◽  
pp. 357-365 ◽  
Author(s):  
C. Saucier ◽  
I. Pianet ◽  
M. Laguerre ◽  
Y. Glories
Keyword(s):  
Molecular Modeling ◽  
Wine Ageing
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