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Lipid‐protein interactions as a determinant of the function and topogenesis of membrane proteins
Author(s) -
Vitrac Heidi,
Bogdanov Mikhail,
Dowhan William
Publication year - 2012
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.26.1_supplement.602.3
Subject(s) - lactose permease , phosphatidylethanolamine , phosphatidylcholine , chemistry , topology (electrical circuits) , phospholipid , lipid bilayer , permease , function (biology) , membrane transport protein , membrane , membrane protein , biochemistry , escherichia coli , biology , microbiology and biotechnology , mathematics , combinatorics , gene
LacY (lactose permease) expressed in Escherichia coli lacking PE (phosphatidylethanolamine) and containing only anionic phospholipids exhibits downhill but not uphill transport and is topologically misassembled. Substitution in vivo of PE by foreign lipids (including phosphatidylcholine (PC)) with no net charge supports native LacY topology and uphill transport. Here, we further investigate the effects of phospholipid head group and fatty acid composition on topology and function of LacY reconstituted into proteoliposomes. Anionic phospholipids alone do not support uphill transport or native topology. Addition of E. coli derived PE or PC supports both uphill transport and native topology. Synthetic PE or PC containing only unsaturated fatty acids supports proper topology but not uphill transport. PE or PC with one saturated fatty acid supports uphill transport. These results show that LacY structure and function are sensitive to both the polar head group and acyl group composition of phospholipids. Our results demonstrate that membrane protein organization and function are determined through direct interactions of the protein with its lipid environment. Supported by NIH grant R37‐GM20478.