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Beta subunit of mitochondrial F1-ATPase from the fission yeast. Deduced sequence of the wild type protein and identification of a mutation that increases nucleotide binding.
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International audience. The Schizosaccharomyces pombe nuclear gene, atp2, encoding the beta subunit of the mitochondrial ATP synthase, was sequenced and found to contain a 1575-bp open reading frame. Two adjacent transcription-initiation sites were found at positions 34 and 44 nucleotides upstream of the translation-initiation codon. The deduced polypeptide sequence was composed of 525 amino acid residues (molecular mass = 56875 Da). The mature polypeptide starts at residue 45 (molecular mass = 51,685 Da), indicating the presence of a presequence of 44 residues, presumably involved in mitochondrial targeting. The atp2 mutant B59-1 [Boutry, M. & Goffeau, A. (1982) Eur. J. Biochem. 125, 471-477] and its related revertant allele R4-3 [Jault, J. M., Di Pietro, A., Falson, P., Gautheron, D. C., Boutry, M. & Goffeau, A. (1989) Biochem. Biophys. Res. Commun. 158, 392-399] were also cloned and sequenced. A single nonsense mutation, CAG (Gln170)----TAG (stop) in mutant B59-1, became a missense mutation, TAG (stop)----TAC (Tyr) in revertant R4-3. Gln170 is located between the first and second elements belonging to the nucleotide-binding site. Its substitution by a tyrosine residue increases the enzyme affinity towards ADP, the amount of endogenous nucleotides and the apparent negative cooperativity for ATPase activity.The Schizosaccharomyces pombe nuclear gene, atp2, encoding the beta subunit of the mitochondrial ATP synthase, was sequenced and found to contain a 1575-bp open reading frame. Two adjacent transcription-initiation sites were found at positions 34 and 44 nucleotides upstream of the translation-initiation codon. The deduced polypeptide sequence was composed of 525 amino acid residues (molecular mass = 56875 Da). The mature polypeptide starts at residue 45 (molecular mass = 51,685 Da), indicating the presence of a presequence of 44 residues, presumably involved in mitochondrial targeting. The atp2 mutant B59-1 [Boutry, M. & Goffeau, A. (1982) Eur. J. Biochem. 125, 471-477] and its related revertant allele R4-3 [Jault, J. M., Di Pietro, A., Falson, P., Gautheron, D. C., Boutry, M. & Goffeau, A. (1989) Biochem. Biophys. Res. Commun. 158, 392-399] were also cloned and sequenced. A single nonsense mutation, CAG (Gln170)----TAG (stop) in mutant B59-1, became a missense mutation, TAG (stop)----TAC (Tyr) in revertant R4-3. Gln170 is located between the first and second elements belonging to the nucleotide-binding site. Its substitution by a tyrosine residue increases the enzyme affinity towards ADP, the amount of endogenous nucleotides and the apparent negative cooperativity for ATPase activity.
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