Binding of anionic lipids to at least three nonannular sites on the potassium channel KcsA is required for channel opening.

ABSTRACT: In addition to the annular or boundary lipids that surround the transmembrane surface of the potassium channel KcsA from Streptomyces lividans, x-ray crystallographic studies have detected one anionic lipid molecule bound at each protein-protein interface in the homotetrameric structure, at sites referred to as nonannular sites. The binding constant for phosphatidylglycerol at the nonannular sites has been determined using fluorescence quenching methods with a mutant of KcsA lacking the normal three lipid-exposed Trp residues. Binding is weak, with a binding constant of 0.42 +/- 0.06 in units of mol fraction, implying that the nonannular sites will only be approximately 70% occupied in bilayers of 100% phosphatidylglycerol. However, the nonannular sites show high selectivity for anionic li

SUBMITTER: Marius P 

PROVIDER: S-EPMC2242745 | biostudies-literature | 2008 Mar

REPOSITORIES: biostudies-literature