Environmental Study of Subunit i, a F sub(o) Component of the Yeast ATP Synthase

The topology of subunit i, a component of the yeast F sub(o)F sub(l)-ATP synthase, was determined by the use of cysteine-substituted mutants. The N sub(in)-C sub(out) orientation of this intrinsic subunit was confirmed by chemical modification of unique cysteine residues with 4-acetamido-4'-mal...

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Bibliographic Details
Published in:Biochemistry (Easton) 2000-04, Vol.39 (14), p.4199-4205
Main Authors: Paumard, P, Vaillier, J, Napias, C, Arselin, G, Brethes, D, Graves, P-V, Velours, J
Format: Article
Language:English
Subjects:
4-acetamido-4'-maleimidylstilbene-2,2'-disulfonic acid
ATP synthase
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Summary:The topology of subunit i, a component of the yeast F sub(o)F sub(l)-ATP synthase, was determined by the use of cysteine-substituted mutants. The N sub(in)-C sub(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 sub(o)F sub(l)-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.
ISSN:0006-2960
DOI:10.1021/bi992438l