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Influence of lipids on membrane assembly and stability of the potassium channel KcsA
Author(s) -
van Dalen Annemieke,
Hegger Sander,
Killian J.Antoinette,
de Kruijff Ben
Publication year - 2002
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(02)03061-2
Subject(s) - kcsa potassium channel , tetramer , chemistry , vesicle , biophysics , membrane , lipid bilayer , phosphatidylcholine , crystallography , ion channel , biochemistry , phospholipid , biology , enzyme , receptor
Recently we observed in an in vitro system that newly synthesized KcsA assembles efficiently into a tetramer in lipid vesicles [van Dalen et al. (2002) FEBS Lett. 511, 51–58]. Here we used this system to get insight into the importance of the lipid composition for KcsA membrane association and tetramerization and we compared this to the lipid dependency of the thermo‐stability of the KcsA tetramer. It was found that a large amount of phosphatidylethanolamine (>40 mol%) and a lower amount of phosphatidylglycerol (∼20–30 mol%) were optimal for efficient KcsA membrane association and tetramerization. Strikingly, vesicles of the abundant and commonly used membrane lipid phosphatidylcholine did not support assembly, further demonstrating the importance of membrane lipid composition for KcsA assembly. The in vitro assembled KcsA tetramer showed similar thermo‐stability in biological and pure lipid membranes, demonstrating that both tetramers are alike. In addition, we show that solubilization of the membrane with detergent reduces the thermo‐stability of the tetramer. The highest KcsA tetramer stability was observed in intact bilayers in the presence of anionic lipids.