First identification of an amber nonsense mutation in Schizosaccharomyces pombe: major differences in the efficiency of homologous versus heterologous yeast suppressor tRNA genes
✍ Scribed by Krupp, Guido ;Thuriaux, Pierre ;Willis, Ian ;Gamulin, Vera ;Söll, Dieter
- Publisher
- Springer
- Year
- 1985
- Tongue
- English
- Weight
- 700 KB
- Volume
- 201
- Category
- Article
- ISSN
- 0026-8925
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✦ Synopsis
In Saccharomyces cerevisiae ochre and opal, as well as amber mutations are known, whereas in the fission yeast Schizosaccharomyces pombe no amber alleles have been described. We have characterized trp1-566, an amber allele in the trpl locus of S. pombe. The identification of trpl-566 as an amber allele is based on the following results:
(a) The nonsense allele can be converted to an ochre allele by nitrosoguanidine mutagenesis. (b) trpl-566 is suppressed by a bonafide S. pombe amber suppressor tRNA, supSI. The supS1 gene was obtained by primer-directed in vitro mutagenesis of a tRNASer from S. pombe. Unexpectedly, an S. cerevisiae amber suppressor tRNASer, supR21, transformed into S. pombe, failed to suppress trp1-566. Northern analysis of S. pombe transformants, containing supRL1 or S. cerevisiae tRNA Le" or tRNA Tyr genes reveals that these genes are not transcribed in the fission yeast. As an additional tool for the analysis of nonsense mutations in S. pombe, we obtained by nitrosoguanidine mutagenesis two unlinked amber suppressor alleles, sup13 and sup14, which act on trp1-566.