Lipid–protein interactions as determinants of membrane protein structure and function

摘要: To determine how the lipid environment affects membrane protein structure and function, strains of Escherichia coli were developed in which normal phospholipid composition can be altered or foreign lipids introduced. The properties LacY (lactose permease) investigated as a function environment. Assembly membranes lacking PE (phosphatidylethanolamine) results misorientation N-terminal six-TM (transmembrane domain) helical bundle with loss energy-dependent uphill transport retention energy-independent downhill transport. Post-assembly introduction nearly native orientation TMs restoration Foreign no net charge substitute for supporting topology, but is dependent on topology proper folding solvent-exposed domain. Increasing positive density cytoplasmically exposed surface counters TM absence neutral lipids, demonstrating that interactions between these domains bilayer are determinants orientation. Therefore organization reorganization determined either during initial assembly post-insertionally through direct environment, topogenic potency opposing charged residues topological signals independent translocon.