The ABC transporter MsbA interacts with lipid A and amphipathic drugs at different sites.

ABSTRACT: MsbA is an essential ABC (ATP-binding cassette) transporter involved in lipid A transport across the cytoplasmic membrane of Gram-negative bacteria. The protein has also been linked to efflux of amphipathic drugs. Purified wild-type MsbA was labelled stoichiometrically with the fluorescent probe MIANS [2-(4'-maleimidylanilino)naphthalene-6-sulfonic acid] on C315, which is located within the intracellular domain connecting transmembrane helix 6 and the nucleotide-binding domain. MsbA-MIANS displayed high ATPase activity, and its folding and stability were unchanged. The initial rate of MsbA labelling by MIANS was reduced in the presence of amphipathic drugs, suggesting that binding of these compounds alters the protein conformation. The fluorescence of MsbA-MIANS was saturably quenched by n

SUBMITTER: Siarheyeva A 

PROVIDER: S-EPMC2662489 | biostudies-literature | 2009 Apr

REPOSITORIES: biostudies-literature