A model for the structure of subunit a of the Escherichia coli ATP synthase and its role in proton translocation

Most of what is known about the structure and function of subunit a, of the ATP synthase, has come from the construction and isolation of mutations, a nd their analysis in the context of the ATP synthase complex. Three classes of mutants will be considered in this review. (1) Cys substitutions have b een used for structural analysis of subunit a, and its interactions with su bunit c. (2) Functional residues have been identified by extensive mutagene sis. These studies have included the identification of second-site suppress ors within subunit a. (3) Disruptive mutations include deletions at both te rmini, internal deletions, and single amino acid insertions. The results of these studies, in conjunction with information about subunits b and c: can be incorporated into a model for the mechanism of proton translocation in the Escherichia coli ATP synthase. (C) 2000 Elsevier Science B.V. All right s reserved.