Complexity in Lipid Membrane Composition Induces Resilience to Aβ42 Aggregation

AbstractListeria monocytogenes is a food-borne pathogen with the ability to grow at low temperatures down to − 0.4 °C. Maintaining cytoplasmic membrane fluidity by changing the lipid membrane composition is important during growth at low temperatures. In Listeria monocytogenes, the dominant adaptation effect is the fluidization of the membrane by shortening of fatty acid chain length. In some strains, however, an additional response is the increase in menaquinone content during growth at low temperatures. The increase of this neutral lipid leads to fluidization of the membrane and thus represents a mechanism that is complementary to the fatty acid-mediated modification of membrane fluidity. This study demonstrated that the reduction of menaquinone content for Listeria monocytogenes strains resulted in significantly lower resistance to temperature stress and lower growth rates compared to unaffected control cultures after growth at 6 °C. Menaquinone content was reduced by supplementation with aromatic amino acids, which led to a feedback inhibition of the menaquinone synthesis. Menaquinone-reduced Listeria monocytogenes strains showed reduced bacterial cell fitness. This confirmed the adaptive function of menaquinones for growth at low temperatures of this pathogen.

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Abstract P404: Membrane Composition Of Cardiac-derived Extracellular Vesicles Changes With Vesicle Origin And Determines Uptake

Circulation Research ◽

10.1161/res.129.suppl_1.p404 ◽

2021 ◽

Vol 129 (Suppl_1) ◽

Author(s):

Sruti Bheri ◽

Jessica R Hoffman ◽

Hyun-Ji Park ◽

Michael E Davis

Keyword(s):

Extracellular Vesicles ◽

Lipid Membrane ◽

Recipient Cell ◽

Donor Cell ◽

Membrane Lipid ◽

Least Squares Regression ◽

Membrane Composition ◽

Cell Type ◽

Uptake Mechanism ◽

Donor Cell Type

Introduction: Myocardial infarction (MI) is a leading cause of mortality worldwide. The potency of cell-based therapies for MI is increasingly attributed to the release of extracellular vesicles (EVs) which consist of a lipid/protein membrane and encapsulate RNA cargo. Specifically, EVs from ckit+ progenitor cells (CPCs) and mesenchymal stromal cells (MSCs) are shown to be pro-reparative, with clinical trials ongoing. Despite copious research into EV cargo, the role of donor cell type on EV membrane composition and its effects on EV uptake mechanism by recipient cells remain unclear. This is crucial for designing EV-based therapeutics as uptake mechanism dictates the functionality of the cargo. Thus, we hypothesized that (1) EV membrane composition varies by donor cell type and (2) this variation covaries with the mechanism of uptake. Methods: EVs were isolated using differential ultracentrifugation from four cardiac cell types: CPCs, MSCs, cardiac endothelial cells (CECs) and rat cardiac fibroblasts (RCFs) grown in normoxia (18% O 2 ) or hypoxia (1% O 2 ) to mimic ischemic conditions. EVs were characterized for size and concentration. EV lipid membrane profile was assessed through LC/MS/MS. Donor cell’s role on EV uptake mechanism was determined by inhibiting known uptake pathways (clathrin, dynamin, macropinocytosis and caveolae/lipid raft) with small molecules and quantifying CEC/RCF endocytosis of EVs with flow cytometry. Finally, partial least squares regression was used to determine the most important lipids involved in EV uptake mechanism. Results: EVs were successfully isolated and characterized. The EV membrane lipid profiles clustered by donor cell type. Uptake mechanism of EVs varied based on both donor and recipient cell type with dynamin mediated endocytosis being the most common. Further, the uptake mechanism was independent of normoxic/hypoxic conditioning. Finally, supervised learning methods revealed specific lipid classes (sphingolipids and glycerophospholipids) covaried with EV uptake mechanism. Conclusion: This work highlights the importance of the understudied EV membrane and its role in delivering therapeutic cargo. Active donor cell selection for efficient EV uptake will allow for more potent EV-based MI therapies.

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Unsaturated fatty acids augment protein transport via the SecA:SecYEG translocon

10.1101/2021.03.26.437172 ◽

2021 ◽

Author(s):

Michael Kamel ◽

Maryna Löwe ◽

Stephan Schott-Verdugo ◽

Holger Gohlke ◽

Alexej Kedrov

Keyword(s):

Fatty Acids ◽

Protein Transport ◽

Unsaturated Fatty Acids ◽

Lipid Membrane ◽

Cell Envelope ◽

Membrane Surface ◽

Bacterial Cells ◽

Hydrophobic Core ◽

Membrane Composition ◽

Dynamics Simulations

AbstractThe translocon SecYEG forms the primary protein-conducting channel in the cytoplasmic membrane of bacteria, and the associated ATPase SecA provides the energy for the transport of secretory and cell envelope protein precursors. The translocation requires negative charge at the lipid membrane surface, but its dependence on the properties of the membrane hydrophobic core is not known. Here, we demonstrate that SecA:SecYEG-mediated protein transport is immensely stimulated by unsaturated fatty acids (UFAs). Furthermore, UFA-rich tetraoleoyl-cardiolipin, but not bis(palmitoyloleoyl)-cardiolipin, facilitate the translocation via the monomeric translocon. Biophysical analysis and molecular dynamics simulations show that UFAs determine the loosely packed membrane interface, where the N-terminal amphipathic helix of SecA docks. While UFAs do not affect the translocon folding, they promote SecA binding to the membrane, and the effect is enhanced manifold at elevated ionic strength. Tight SecA:lipid interactions convert into the augmented translocation. As bacterial cells actively change their membrane composition in response to their habitat, the modulation of SecA:SecYEG activity via the fatty acids may be crucial for protein secretion over a broad range of environmental conditions.

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Lipid Membrane Composition has A Dramatic Effect on the Dynamics of the GlpG Rhomboid Protease from Escherichia Coli

Biophysical Journal ◽

10.1016/j.bpj.2009.12.1210 ◽

2010 ◽

Vol 98 (3) ◽

pp. 224a

Author(s):

Ana Nicoleta Bondar ◽

Stephen H. White

Keyword(s):

Escherichia Coli ◽

Lipid Membrane ◽

Membrane Composition ◽

Rhomboid Protease ◽

Dramatic Effect

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Electrostatically Driven Spatial Patterns in Lipid Membrane Composition

Physical Review Letters ◽

10.1103/physrevlett.95.048101 ◽

2005 ◽

Vol 95 (4) ◽

Cited By ~ 22

Author(s):

Raghuveer Parthasarathy ◽

Paul A. Cripe ◽

Jay T. Groves

Keyword(s):

Spatial Patterns ◽

Lipid Membrane ◽

Membrane Composition

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Solvent-exposed lipid tail protrusions depend on lipid membrane composition and curvature

Biochimica et Biophysica Acta (BBA) - Biomembranes ◽

10.1016/j.bbamem.2016.01.026 ◽

2016 ◽

Vol 1858 (6) ◽

pp. 1207-1215 ◽

Cited By ~ 14

Author(s):

Mukarram A. Tahir ◽

Reid C. Van Lehn ◽

S.H. Choi ◽

Alfredo Alexander-Katz

Keyword(s):

Lipid Membrane ◽

Membrane Composition

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Variation of lipid membrane composition caused by strong bending

Biochemistry (Moscow) Supplement Series A Membrane and Cell Biology ◽

10.1134/s199074781101003x ◽

2011 ◽

Vol 5 (2) ◽

pp. 205-211 ◽

Cited By ~ 6

Author(s):

P. V. Bashkirov ◽

K. V. Chekashkina ◽

S. A. Akimov ◽

P. I. Kuzmin ◽

V. A. Frolov

Keyword(s):

Lipid Membrane ◽

Membrane Composition

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Rcs phosphorelay activation in cardiolipin-deficient Escherichia coli reduces biofilm formation

10.1101/522219 ◽

2019 ◽

Cited By ~ 1

Author(s):

Julia F. Nepper ◽

Yin C. Lin ◽

Douglas B. Weibel

Keyword(s):

Escherichia Coli ◽

Stress Response ◽

Biofilm Formation ◽

Lipid Membrane ◽

Protein Translocation ◽

Membrane Composition ◽

Anionic Phospholipid ◽

Envelope Stress ◽

Biofilm Development

AbstractBiofilm formation is a complex process that requires a number of transcriptional, proteomic, and physiological changes to enable bacterial survival. The lipid membrane presents a barrier to communication between the machinery within bacteria and the physical and chemical features of their extracellular environment, and yet little is known about how the membrane influences biofilm development. We found that depleting the anionic phospholipid cardiolipin reduces biofilm formation in Escherichia coli cells by as much as 50%. The absence of cardiolipin activates the Rcs envelope stress response, which represses production of flagella, disrupts initial biofilm attachment, and reduces biofilm growth. We demonstrate that a reduction in the concentration of cardiolipin impairs translocation of proteins across the inner membrane, which we hypothesize activates the Rcs pathway through the outer membrane lipoprotein RcsF. Our study demonstrates a molecular connection between the composition of membrane phospholipids and biofilm formation in E. coli and suggests that altering lipid biosynthesis may be a viable approach for altering biofilm formation and possibly other multicellular phenotypes related to bacterial adaptation and survival.ImportanceThere is a growing interest in the role of lipid membrane composition in the physiology and adaptation of bacteria. We demonstrate that a reduction in the anionic phospholipid cardiolipin impairs biofilm formation in Escherichia coli cells. Depleting cardiolipin reduced protein translocation across the inner membrane and activated the Rcs envelope stress response. Consequently, cardiolipin depletion produced cells lacking assembled flagella, which impacted their ability to attach to surfaces and seed the earliest stage in biofilm formation. This study provides empirical evidence for the role of anionic phospholipid homeostasis in protein translocation and its effect on biofilm development, and highlights modulation of the membrane composition as a potential method of altering bacterial phenotypes related to adaptation and survival.

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A non-linear system patterns Rab5 GTPase on the membrane

10.1101/2019.12.17.880203 ◽

2019 ◽

Author(s):

A Cezanne ◽

J Lauer ◽

A Solomatina ◽

IF Sbalzarini ◽

M Zerial

Keyword(s):

Lipid Bilayers ◽

Lipid Membrane ◽

Small Gtpases ◽

Small Gtpase ◽

Nucleotide Exchange ◽

Membrane Composition ◽

Dynamic Interactions ◽

Universal System ◽

Non Linear ◽

Non Linear System

AbstractProteins can self-organize into spatial patterns via non-linear dynamic interactions on cellular membranes. Modelling and simulations have shown that small GTPases can generate patterns by coupling guanine nucleotide exchange factors (GEF) to effector binding, generating a positive feedback of GTPase activation and membrane recruitment. Here, we reconstituted the patterning of the small GTPase Rab5 and its GEF/effector complex Rabex5/Rabaptin5 on supported lipid bilayers as a model system for membrane patterning. We show that there is a “handover” of Rab5 from Rabex5 to Rabaptin5 upon nucleotide exchange. A minimal system consisting of Rab5, RabGDI and a complex of full length Rabex5/Rabaptin5 was necessary to pattern Rab5 into membrane domains. Surprisingly, a lipid membrane composition mimicking that of the early endosome was required for Rab5 patterning. The prevalence of GEF/effector coupling in nature suggests a possible universal system for small GTPase patterning involving both protein and lipid interactions.

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