Environmental Study of Subunit i , a F o Component of the Yeast ATP Synthase
2000; American Chemical Society; Volume: 39; Issue: 14 Linguagem: Inglês
10.1021/bi992438l
ISSN1943-295X
AutoresPatrick Paumard, Jacques Vaillier, Christian Napias, Geneviève Arselin, Daniel Brèthes, Pierre‐Vincent Graves, Jean Velours,
Tópico(s)Photosynthetic Processes and Mechanisms
ResumoThe topology of subunit i, a component of the yeast FoF1-ATP synthase, was determined by the use of cysteine-substituted mutants. The Nin−Cout 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 α-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 FoF1-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.
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