The Saccharomyces cerevisiae syn- mitochondrial mutant G116-40 isolated by Berlani et al. (Berlani, R. E., Pentella, C., Macino, G., and Tzagoloff, A. (1980) J. Bacteriol. 141, 1086-1097) is shown to have a mutation in the tyrosyl-tRNA gene by genetic data combined with restriction analysis and DNA sequencing of the appropriate rho- mitochondrial DNAs derived from wild-type and mutant strains. The new region sequenced spans 685 base pairs located between 9.5 and 10.4 map units, the gene being located at 10.0 units. The tRNA structure, as deduced from the DNA sequence, is in agreement with the data derived from sequencing the purified tyrosyl-tRNA reported by Sibler et al. (Sibler, A., Dirheimer, G., and Martin, R.P. (1983) FEBS Lett. 152, 153-156). No in vitro tyrosyl-tRNA aminoacylation could be detected using mitochondrial RNA from the mutant. S1 nuclease mapping experiments showed that the mutant produces a transcript that is identical to the wild-type at its 5'-end. The same analysis carried out with the mitochondrial RNA from a rho- strain with the tyrosyl-tRNA region of mitochondrial DNA reveals a 5'-end shorter by about 3 nucleotides. The mutant gene has a single substitution (C----T) at the penultimate nucleotide near the 3'-end of the molecule creating an acceptor stem that lacks the two terminal Watson-Crick base pairs.

• PMID: 2419326
• PubMed

Reference Type

Journal Article | Research Support, Non-U.S. Gov't

Authors

Nóbrega MP, Nóbrega FG

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