Transmembrane potential difference (Vm) plays important roles in regulating various biological processes. At the macro level, Vm can be experimentally measured or calculated using the Nernst or Goldman–Hodgkin–Katz equation. However, the atomic details responsible for its generation and impact on protein and lipid dynamics still need to be further elucidated. In this work, we performed a series of all-atom molecular dynamics (MD) simulations of symmetric model membranes of various lipid compositions and cation contents to evaluate the relationship between membrane asymmetry and Vm. Specifically, we studied the impact of the asymmetric distribution of POPS (1-palmitoyl-2-oleoyl-sn-glycero-3-phospho-l-serine), PIP2 (phosphatidylinositol 4,5-bisphosphate), as well as Na+ and K+ on Vm using atomically detailed MD simulations of symmetric model membranes. The results suggest that, for an asymmetric POPC-POPC/POPS bilayer in the presence of NaCl, the presence of the monovalent anionic lipid POPS in the inner leaflet polarizes the membrane (ΔVm < 0). Intriguingly, replacing a third of the POPS lipids by the polyvalent anionic signaling lipid PIP2 counteracts this effect, resulting in a smaller negative membrane potential. We also found that replacing Na+ ions in the inner region by K+ depolarizes the membrane (ΔVm > 0). These divergent effects arise from variations in the strength of cation–lipid interactions and are correlated with changes in lipid chain order and head-group orientation.
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14 September 2020
Research Article|
September 08 2020
Transmembrane potential of physiologically relevant model membranes: Effects of membrane asymmetry
Xubo Lin
;
Xubo Lin
a)
1
Institute of Single Cell Engineering, Beijing Advanced Innovation Center for Biomedical Engineering, Beihang University
, Beijing 100191, China
a)Authors to whom correspondence should be addressed: linxbseu@buaa.edu.cn and alemayehu.g.abebe@uth.tmc.edu
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Alemayehu A. Gorfe
Alemayehu A. Gorfe
a)
2
Department of Integrative Biology and Pharmacology, McGovern Medical School, The University of Texas Health Science Center at Houston
, Houston, Texas 77030, USA
a)Authors to whom correspondence should be addressed: linxbseu@buaa.edu.cn and alemayehu.g.abebe@uth.tmc.edu
Search for other works by this author on:
a)Authors to whom correspondence should be addressed: linxbseu@buaa.edu.cn and alemayehu.g.abebe@uth.tmc.edu
Note: This paper is part of the JCP Special Topic on Classical Molecular Dynamics (MD) Simulations: Codes, Algorithms, Force Fields, and Applications.
J. Chem. Phys. 153, 105103 (2020)
Article history
Received:
June 13 2020
Accepted:
August 18 2020
Citation
Xubo Lin, Alemayehu A. Gorfe; Transmembrane potential of physiologically relevant model membranes: Effects of membrane asymmetry. J. Chem. Phys. 14 September 2020; 153 (10): 105103. https://doi.org/10.1063/5.0018303
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