Environmental study of subunit i, a F(o) component of the yeast ATP synthase

Biochemistry. 2000 Apr 11;39(14):4199-205. doi: 10.1021/bi992438l.

Abstract

The topology of subunit i, a component of the yeast F(o)F(1)-ATP synthase, was determined by the use of cysteine-substituted mutants. The N(in)-C(out) orientation of this intrinsic subunit was confirmed by chemical modification of unique cysteine residues with 4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid. Near-neighbor relationships between subunit i and subunits 6, f, g, and d were demonstrated by cross-link formation following sulfhydryl oxidation or reaction with homobifunctional and heterobifunctional reagents. Our data suggest interactions between the unique membrane-spanning segment of subunit i and the first transmembranous alpha-helix of subunit 6 and a stoichiometry of 1 subunit i per complex. Cross-linked products between mutant subunits i and proteins loosely bound to the F(o)F(1)-ATP synthase suggest that subunit i is located at the periphery of the enzyme and interacts with proteins of the inner mitochondrial membrane that are not involved in the structure of the yeast ATP synthase.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Point Mutation
  • Protein Conformation
  • Proton-Translocating ATPases / chemistry
  • Proton-Translocating ATPases / genetics
  • Proton-Translocating ATPases / metabolism*
  • Saccharomyces cerevisiae / enzymology*
  • Structure-Activity Relationship

Substances

  • Proton-Translocating ATPases