Substrate binding tunes conformational flexibility and kinetic stability of an amino acid antiporter.

ABSTRACT: We used single molecule dynamic force spectroscopy to unfold individual serine/threonine antiporters SteT from Bacillus subtilis. The unfolding force patterns revealed interactions and energy barriers that stabilized structural segments of SteT. Substrate binding did not establish strong localized interactions but appeared to be facilitated by the formation of weak interactions with several structural segments. Upon substrate binding, all energy barriers of the antiporter changed thereby describing the transition from brittle mechanical properties of SteT in the unbound state to structurally flexible conformations in the substrate-bound state. The lifetime of the unbound state was much shorter than that of the substrate-bound state. This leads to the conclusion that the unbound state of St

SUBMITTER: Bippes CA 

PROVIDER: S-EPMC2707244 | biostudies-literature | 2009 Jul

REPOSITORIES: biostudies-literature