The same periplasmic ExbD residues mediate in vivo interactions between ExbD homodimers and ExbD-TonB heterodimers.

ABSTRACT: The TonB system couples cytoplasmic membrane proton motive force to TonB-gated outer membrane transporters for active transport of nutrients into the periplasm. In Escherichia coli, cytoplasmic membrane proteins ExbB and ExbD promote conformational changes in TonB, which transmits this energy to the transporters. The only known energy-dependent interaction occurs between the periplasmic domains of TonB and ExbD. This study identified sites of in vivo homodimeric interactions within ExbD periplasmic domain residues 92 to 121. ExbD was active as a homodimer (ExbD(2)) but not through all Cys substitution sites, suggesting the existence of conformationally dynamic regions in the ExbD periplasmic domain. A subset of homodimeric interactions could not be modeled on the nuclear magnetic resonance

SUBMITTER: Ollis AA 

PROVIDER: S-EPMC3232860 | biostudies-literature | 2011 Dec

REPOSITORIES: biostudies-literature