Probing the conformation of the resting state of a bacterial multidrug ABC transporter, BmrA, by a site-directed spin labeling approach.

ABSTRACT: Previously published 3-D structures of a prototypic ATP-binding cassette (ABC) transporter, MsbA, have been recently corrected revealing large rigid-body motions possibly linked to its catalytic cycle. Here, a closely related multidrug bacterial ABC transporter, BmrA, was studied using site-directed spin labeling by focusing on a region connecting the transmembrane domain and the nucleotide-binding domain (NBD). Electron paramagnetic resonance (EPR) spectra of single spin-labeled cysteine mutants suggests that, in the resting state, this sub-domain essentially adopts a partially extended conformation, which is consistent with the crystal structures of MsbA and Sav1866. Interestingly, one of the single point mutants (Q333C) yielded an immobilized EPR spectrum that could arise from a direct

SUBMITTER: Do Cao MA 

PROVIDER: S-EPMC2775218 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature