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Mitochondrial ATP synthase subunit 9 is not required for viability of the petite-negative yeast Kluyveromyces lactis
- Clark-Walker, G.D., Francois, F., Chen, X.J., Vieira Da Silva, M.R., Claisse, M.L.
- Current genetics 1997 v.31 no.6 pp. 488-493
- Kluyveromyces marxianus var. lactis, pyrophosphatases, mitochondrial DNA, introns, structural genes, ribosomal DNA, mutants, viability, nucleotide sequences, amino acid sequences, genetic recombination, phenotype, repetitive sequences
- Specific mutations in nuclear MGI genes encoding the or, alpha and beta and gamma subunits of the mitochondrial inner membrane F1-ATPase complex allow mitochondrial DNA (mtDNA) to be lost from K. lactis. In the absence of a mutation in any of these three nuclear genes, loss of mtDNA is lethal. These results imply that mtDNA encodes a gene that is essential. Likely candidates for such an essential role are the ATP6, 8 and 9 genes coding for proteins of the ATP synthase-F0 component. The present study removes ATP9 from contention as a vital mitochondrial gene because in a respiratory deficient mutant, Gly- 3.9, lacking a nuclear mgi mutation, we have found that a rearrangement in mtDNA has deleted 22 amino acids from the carboxy terminus of the 75 amino-acid subunit-9 protein. Rearrangement in mtDNA has occurred by recombination that a 23-bp repeated sequence in the introns of the ATP9 and large ribosomal RNA (LSU) subunit genes. These two introns, of 394 (ATP9) and 410 (LSU) nucleotides, both belong to group 1.