Investigation of the sodium-binding sites in the sodium-coupled betaine transporter BetP.

ABSTRACT: Sodium-coupled substrate transport plays a central role in many biological processes. However, despite knowledge of the structures of several sodium-coupled transporters, the location of the sodium-binding site(s) often remains unclear. Several of these structures have the five transmembrane-helix inverted-topology repeat, LeuT-like (FIRL) fold, whose pseudosymmetry has been proposed to facilitate the alternating-access mechanism required for transport. Here, we provide biophysical, biochemical, and computational evidence for the location of the two cation-binding sites in the sodium-coupled betaine symporter BetP. A recent X-ray structure of BetP in a sodium-bound closed state revealed that one of these sites, equivalent to the Na2 site in related transporters, is located between transmem

SUBMITTER: Khafizov K 

PROVIDER: S-EPMC3497817 | biostudies-literature | 2012 Oct

REPOSITORIES: biostudies-literature