Environmental study of subunit i, a F(o) component of the yeast ATP synthase.
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.
Paumard
P
P
Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Segalen, Bordeaux 2,1 rue Camille Saint-Saëns, 33077 Bordeaux Cedex, France.
Vaillier
J
J
Napias
C
C
Arselin
G
G
Brèthes
D
D
Graves
P V
PV
Velours
J
J
D017354:Point Mutation; D011487:Protein Conformation; D006180:Proton-Translocating ATPases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000201:enzymology*; D013329:Structure-Activity Relationship
D006180:Proton-Translocating ATPases