Bovine Coupling Factor 6, with Just 14.5% Shared Identity, Replaces Subunit h in the Yeast ATP Synthase

Institut de Biochimie et Génétique Cellulaires du CNRS, Université Victor Ségalen, Bordeaux 2, 1 rue Camille Saint Saëns, 33077 Bordeaux, cedex France.
Journal of Biological Chemistry (Impact Factor: 4.57). 04/2001; 276(11):8602-7. DOI: 10.1074/jbc.M008123200
Source: PubMed


The mammalian mitochondrial ATP synthase is composed of at least 16 polypeptides. With the exception of coupling factor F6, there are likely yeast homologs for each of these polypeptides. There are no obvious yeast homologs of F6, as predicted from primary sequence comparison of the putative peptides encoded by the open reading frames in the yeast genome.
In this manuscript, we demonstrate that expression of bovine F6 complements a null mutant in ATP14 gene in yeast Saccharomyces cerevisiae. Subunit h of the yeast ATP synthase is encoded by ATP14 and is just 14.5% identical to bovine F6. Expression of bovine F6 in an atp14 null mutant strain recovers oxidative phosphorylation, and the ATP synthase is active, although functioning with
a lower efficiency than the wild type enzyme. Like subunith, bovine F6 is shown to interact mainly with subunit 4 (subunit b), a component of the second stalk of the enzyme. These data indicated the subunith is the yeast homolog of mammalian coupling factor F6.

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    • "The subunit h shares only 15% identity with the bovine coupling factor F 6 and is 16 residues longer than F 6 (Velours et al., 2001). Two helices linked by a proline rich loop are predicted at the N-terminal while the C-terminal part appeared as an unstructured tail in agreement with the bovine structures (Dickson et al., 2006; Rees et al., 2009). "
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    • "Mitochondrial F 1 F 0 ATP synthase was assayed in mitochondrial preparations as described [22]. Oligomycin at 6 μg/ml, an inhibitor of this enzyme [23], was used for background subtraction. Mitochondria were prepared as described [19]. "
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    • "In the light of the C-terminal localisation of yeast F 6 (subunit h) close to the membrane surface [51], it seemed more likely that F 6 assembled in the peripheral stalk would have an extended linear conformation oriented approximately along the long axis of the peripheral stalk, with the N-terminus nearer the top and the C-terminus pointing towards the membrane (Fig. 8) [51]. The sequences of bovine F 6 and its yeast homologue, subunit h, are 14.5% identical [56]. The yeast protein is 16 residues longer than the bovine protein. "
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