Phosphatidylserine inhibits and calcium promotes model membrane fusion.

Journal Article (Journal Article)

PEG-mediated fusion of SUVs composed of dioleoylphosphatidylcholine, dioleoylphosphatidylethanolamine, sphingomyelin, cholesterol, and dioleoylphosphatidylserine was examined to investigate the effects of PS on the fusion mechanism. Lipid mixing, content mixing, and content leakage measurements were carried out with vesicles containing from 0 to 8 mol % PS and similar amounts of phosphatidylglycerol. Fitting these time courses globally to a 3-state (aggregate, intermediate, pore) sequential model established rate constants for each step and probabilities of lipid mixing, content mixing, and leakage in each state. Charged lipids inhibited both the rates of intermediate and pore formation as well as the extents of lipid and contents mixing, although electrostatics were not solely responsible for inhibition. Ca(2+) counteracted this inhibition and increased the extent of fusion in the presence of PS to well beyond that seen in the absence of charged lipids. The effects of both PS and Ca(2+) could be interpreted in terms of a previous proposal for the nature of lipid fluctuations that account for transition states for the two steps of the fusion process examined. The results suggest a more significant role for Ca(2+)-lipid interactions than is acknowledged in current thinking about cell membrane fusion.

Full Text

Duke Authors

Cited Authors

  • Tarafdar, PK; Chakraborty, H; Dennison, SM; Lentz, BR

Published Date

  • November 7, 2012

Published In

Volume / Issue

  • 103 / 9

Start / End Page

  • 1880 - 1889

PubMed ID

  • 23199916

Pubmed Central ID

  • PMC3491704

Electronic International Standard Serial Number (EISSN)

  • 1542-0086

Digital Object Identifier (DOI)

  • 10.1016/j.bpj.2012.09.030

Language

  • eng

Conference Location

  • United States