PH- and sodium-induced changes in a sodium/proton antiporter.

ABSTRACT: We examined substrate-induced conformational changes in MjNhaP1, an archaeal electroneutral Na(+)/H(+)-antiporter resembling the human antiporter NHE1, by electron crystallography of 2D crystals in a range of physiological pH and Na(+) conditions. In the absence of sodium, changes in pH had no major effect. By contrast, changes in Na(+) concentration caused a marked conformational change that was largely pH-independent. Crystallographically determined, apparent dissociation constants indicated ∼10-fold stronger Na(+) binding at pH 8 than at pH 4, consistent with substrate competition for a common ion-binding site. Projection difference maps indicated helix movements by about 2 Å in the 6-helix bundle region of MjNhaP1 that is thought to contain the ion translocation site. We propose that t

SUBMITTER: Paulino C 

PROVIDER: S-EPMC3900740 | biostudies-literature | 2014 Jan

REPOSITORIES: biostudies-literature