Mutagenic specificity of the base analog 6-N-hydroxylaminopurine in the LYS2 gene of yeast Saccharomyces cerevisiae.

We used the LYS2 gene mutational system to study mutation specificity of the base analog 6-N-hydroxylaminopurine (HAP) in yeast. We characterized phenotypes of mutations using codon-specific nonsense suppressors and the test employing inactivation of the release factor Sup35 due to overexpression and formation of prion-like derivative [PSI]. We have shown that HAP induces predominantly nonsense mutations.

Dosage-dependent translational suppression in yeast Saccharomyces cerevisiae.

The overexpression of SUP35 (SUP2) wild-type gene, caused by increase of its copy number, induces an omnipotent suppression similar to the phenotype of mutants for this gene. The effect of extra-SUP35 was detected for moderate or even low copy number. Moreover, overdosage of the fragment including only the 5'-flanking region and N-terminal 100 bp of protein-coding sequence of SUP35 leads to allosuppression.