[Overexpression of genes encoding tRNA(Tyr) AND tRNA(Gln) improves viability of nonsense mutants in SUP45 gene in yeast Saccharomyces cerevisiae].

The variety of mechanisms providing viability of organisms bearing nonsense-mutations in the essential genes is unknown at present. In yeast Saccharomyces cerevisiae nonsense-mutants containing premature stop-codon in mRNA of the essential SUP45 gene were obtained. These strains are viable in the absence of mutant suppressor tRNA, therefore it is supposed that there are alternative mechanisms providing nonsense-suppression and mutants viability. Analysis of transformants obtained by transformation of strain bearing nonsense-mutant allele of SUP45 gene with multicopy yeast genomic library revealed three genes encoding wild type tRNA(Tyr) and four genes encoding wild type tRNA(Gln) that improve nonsense-mutants viability. Moreover, overexpression of these genes leads to the increase in the amount of full-length eRF1 protein in cell and compensates nonsense-mutants sensitivity to high temperature. Probable mechanisms of tRNA(Tyr) and tRNA(Gln) influence on the increase of viability of nonsense-mutants in SUP45 gene are discussed in this work.