Biogenesis of mitochondria: DNA sequence analysis ofmit−mutations in the mitochondrialoli1gene coding for mitochondrial ATPase subunit 9 inSaccharomyces cerevisiae

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Abstract
The nucleotide sequence of the yeast mitochondrial oli1 gene has been obtained in a series of mit− mutants with mutations in this gene, which codes for subunit 9 of of the mitochondrial ATPase complex. Subunit 9 is the proteolipid, 76 amino acids in length, necessary for the proton translocation function of the membrane FO −sector. These mutants were classified on the basis of their rescue by a petite strain shown here to retain the entire wild-type oli1 gene. The mutation in one mit− strain removes a positively charged residue (Arg39 → Met) which is likely to be located in a segment of subunit 9 that protrudes from the inner mitochoridrial membrane. In a second mit− mutant, a negatively charged residue replaces a conserved glycine residue (Gly18 → Asp) in a glycine-rich segment of the protein that is most likely embedded within the membrane. Other mit− mutations result in frameshifts with predicted products 7, 65 and 68 amino acid residues long. In each mit− mutant, there is the loss of one or more of the amino acid residues that are highly conserved among diverse species. The location and nature of specific changes pinpoint amino acid residues in subunit 9 essential to the activity of the mitochondrial ATPase complex.