Molecular cloning and nucleotide sequence of the nuclear PET122 gene required for expression of the mitochondrial COX3 gene in S. cerevisiae.

AUTOR(ES)

Ohmen, J D

RESUMO

The nuclear PET122 gene from S. cerevisiae is necessary for translation of a single mitochondrial mRNA that encodes subunit III of cytochrome c oxidase. We report here the cloning and nucleotide sequence of PET122, and properties of the predicted protein product, which consists of 242 residues. Analysis of PET122-lacZ translational fusions confirms that the PET122 coding region is translated in vivo and indicates that the PET122 protein product is targeted to mitochondria. A 117 residue domain located in the carboxy-terminal half of the PET122 protein, at least part of which is shown by characterization of mutants to be critical for PET122 function, exhibits 24% identity and 59% similarity to a portion of the catalytic domain of E. coli alanyl-tRNA synthetase. However, pet122 mutants are not defective in mitochondrial translation per se, as would be expected if PET122 encoded a tRNA synthetase. Instead, the PET122 protein may carry out one or more activities in common with tRNA synthetases, such as binding of ATP or RNA.

Documentos Relacionados

• Identification of a third nuclear protein-coding gene required specifically for posttranscriptional expression of the mitochondrial COX3 gene is Saccharomyces cerevisiae.
• Genetic evidence that different functional domains of the PET54 gene product facilitate expression of the mitochondrial genes COX1 and COX3 in Saccharomyces cerevisiae.
• Divergent overlapping transcripts at the PET122 locus in Saccharomyces cerevisiae.
• Molecular cloning and sequence determination of the nuclear gene coding for mitochondrial elongation factor Tu of Saccharomyces cerevisiae.
• Interactions among three proteins that specifically activate translation of the mitochondrial COX3 mRNA in Saccharomyces cerevisiae.