Oxa1p, which is required for cytochrome c oxidase and ATP synthase complex formation, is embedded in the mitochondrial inner membrane

Abstract

We have previously isolated the yeast nuclear gene OXA1 and showed that Oxa1p is required for the formation of the cytochrome c oxidase and ATP synthase complexes. We have expressed Oxa1p in E. coli and shown that it is toxic and rapidly degraded. Nevertheless, a truncated protein was successfully expressed and antibodies have been raised against this truncated protein. These antibodies recognise a protein in mitochondrially enriched fractions. In vitro mitochondrial import experiments demonstrate that the import of Oxa1p is accompanied by the cleavage of a long pre-sequence. Osmotic swelling and alkaline carbonate extraction show that Oxa1p is an integral membrane protein located in the inner membrane of mitochondria. The relationships between the sub-mitochondrial location and the function of Oxa1p are discussed.

Peripheral Mitochondrial Inner Membrane Protein, Mss2p, Required for Export of the Mitochondrially Coded Cox2p C Tail in Saccharomyces cerevisiae

“…In addition to Mss2p, three other proteins are known to have roles in exporting domains of Cox2p through the inner membrane. N-tail export requires the activity of Oxa1p (21, 23), a conserved integral inner membrane protein (4,7,9,25,27,49), which interacts directly with mitochondrially synthesized polypeptides (24). Cox2p C-tail export is also dependent upon Oxa1p (21,23), but this could be an indirect effect if C-tail export is dependent for other reasons upon prior translocation of the N-tail.…”

Translation Initiation inSaccharomyces cerevisiaeMitochondria: Functional Interactions Among Mitochondrial Ribosomal Protein Rsm28p, Initiation Factor 2, Methionyl-tRNA-Formyltransferase and Novel Protein Rmd9p

“…RMD9 has also been isolated independently in a screen for high-copy suppressors of a temperaturesensitive oxa1 mutation (Nouet et al 2007). Oxa1p is a highly conserved integral inner membrane protein that participates in the membrane insertion of mitochondrially encoded proteins (Bauer et al 1994;Bonnefoy et al 1994;He and Fox 1997;Hell et al 1997;Kermorgant et al 1997). The homologous bacterial protein, YidC, has similar functions with respect to …”

Functional Overlap but Lack of Complete Cross-Complementation of Streptococcus mutans and Escherichia coli YidC Orthologs

“…Indeed, the initial discovery of YidC members and their role in membrane biogenesis came from studies in mitochondria (for a review, see reference 42). The mitochondrial YidC ortholog Oxa1 was shown to be required for the incorporation of the F 1 F o ATPase and cytochrome bo oxidase into the inner membranes of mitochondria (1,2,6,7,23). Later studies revealed that Oxa1 was critical for the insertion of subunit II of cytochrome c oxidase and an artificial F 1 F o ATPase Su9 derivative (Su9 is homologous to subunit c of the bacterial F 1 F o ATPase) into the mitochondrial inner membrane (16)(17)(18).…”