Intracellular proton-transfer mutants in a CLC Cl-/H+ exchanger.

ABSTRACT: CLC-ec1, a bacterial homologue of the CLC family's transporter subclass, catalyzes transmembrane exchange of Cl(-) and H(+). Mutational analysis based on the known structure reveals several key residues required for coupling H(+) to the stoichiometric countermovement of Cl(-). E148 (Glu(ex)) transfers protons between extracellular water and the protein interior, and E203 (Glu(in)) is thought to function analogously on the intracellular face of the protein. Mutation of either residue eliminates H(+) transport while preserving Cl(-) transport. We tested the role of Glu(in) by examining structural and functional properties of mutants at this position. Certain dissociable side chains (E, D, H, K, R, but not C and Y) retain H(+)/Cl(-) exchanger activity to varying degrees, while other mutations

SUBMITTER: Lim HH 

PROVIDER: S-EPMC2638202 | biostudies-literature | 2009 Feb

REPOSITORIES: biostudies-literature