Membrane remodeling capacity of a vesicle‐inducing glycosyltransferase

Abstract

Intracellular vesicles are abundant in eukaryotic cells but absent in the Gram‐negative bacterium Escherichia coli. However, strong overexpression of a monotopic glycolipid‐synthesizing enzyme, monoglucosyldiacylglycerol synthase from Acholeplasma laidlawii (alMGS), leads to massive formation of vesicles in the cytoplasm of E. coli. More importantly, alMGS provides a model system for the regulation of membrane properties by membrane‐bound enzymes, which is critical for maintaining cellular integrity. Both phenomena depend on how alMGS binds to cell membranes, which is not well understood. Here, we carry out a comprehensive investigation of the membrane binding of alMGS by combining bioinformatics methods with extensive biochemical studies, structural modeling and molecular dynamics simulations. We find that alMGS binds to the membrane in a fairly upright manner, mainly by residues in the N‐terminal domain, and in a way that induces local enrichment of anionic lipids and a local curvature deformation. Furthermore, several alMGS variants resulting from substitution of residues in the membrane anchoring segment are still able to generate vesicles, regardless of enzymatic activity. These results clarify earlier theories about the driving forces for vesicle formation, and shed new light on the membrane binding properties and enzymatic mechanism of alMGS and related monotopic GT‐B fold glycosyltransferases.

Anisotropic Membrane Curvature Sensing by Amphipathic Peptides

“…Simulations of proteins interacting with mixed bilayers can be challenging to converge due to slow lipid diffusion and long-lived protein-lipid interactions [65]. For this reason, we run three independent replicas rather than one long simulation for each peptide, and use them as a simple control of the robustness of our conclusions.…”

Protein Amphipathic Helix Insertion: A Mechanism to Induce Membrane Fission

“…Class II: Passive mechanism, normal topology. Examples: fission mediated, in the absence of nucleoside triphosphate hydrolysis, by Bacillus subtilis FisB (Doan et al, 2013), C-terminal Binding Protein 1 Short form/Brefeldin A ADP-Ribosylation substrate (CtBP1-S/BARS) (Spanò et al, 1999;Weigert et al, 1999;Hidalgo Carcedo et al, 2004;Valente et al, 2005Valente et al, , 2012Liberali et al, 2008;Pagliuso et al, 2016;Zhukovsky et al, 2019b), and by numerous AH-containing proteins, such as endophilins (Rostovtseva et al, 2009;Ambroso et al, 2014;Genet et al, 2019), amphiphysins (Wu and Baumgart, 2014;Snead et al, 2019), epsins (Ford et al, 2002;Boucrot et al, 2012;Brooks et al, 2015), α-synuclein (Nakamura et al, 2011;Braun et al, 2017;Pozo Devoto and Falzone, 2017;Fakhree et al, 2019), GDAP1 (Huber et al, 2016), ankyrin repeats and KH domain-containing protein 1 (ANKHD1) (Kitamata et al, 2019), Saccharomyces cerevisiae Atg18 (Gopaldass et al, 2017), Agrobacterium tumefaciens PmtA (Danne et al, 2017b), EcMurG (van den Brink-van der Laan et al, 2003, Acholeplasma laidlawii MGS (Eriksson et al, 2009;Ariöz et al, 2014;Ge et al, 2014) and DGS (Eriksson et al, 2009).…”

Curvature sensing by cardiolipin in simulated buckled membranes

“…Simulating curvature sensing and deformation in a flat bilayer patch relies on induced local membrane deformations which can be difficult to interpret. 18,23,[44][45][46] Curved membrane surfaces can be generated by simulating spheres 47,48 or cylinders, 49 but require equilibration of lipids and solute in different leaflets and compartments, which is only feasible for strongly coarsegrained membrane models. In this work, we use simulated membrane buckling [50][51][52][53][54][55][56][57][58][59][60] and develop an elastic theory to overcome these difficulties.…”