Release of Entropic Spring Reveals Conformational Coupling Mechanism in the ABC Transporter BtuCD-F.

ABSTRACT: Substrate translocation by ATP-binding cassette (ABC) transporters involves coupling of ATP binding and hydrolysis in the nucleotide-binding domains (NBDs) to conformational changes in the transmembrane domains. We used molecular dynamics simulations to investigate the atomic-level mechanism of conformational coupling in the ABC transporter BtuCD-F, which imports vitamin B12 across the inner membrane of Escherichia coli. Our simulations show how an engineered disulfide bond across the NBD dimer interface reduces conformational fluctuations and hence configurational entropy. As a result, the disulfide bond is under substantial mechanical stress. Releasing this entropic spring, as is the case in the wild-type transporter, combined with analyzing the pairwise forces between individual residue

SUBMITTER: Prieß M 

PROVIDER: S-EPMC4906252 | biostudies-literature | 2016 Jun

REPOSITORIES: biostudies-literature