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A S Borkhsenius

Publications and source records attributed to A S Borkhsenius.

4 recordsLinked to original sources
PubMed2003

[Suppression of nonsense and frameshift mutations obtained by different methods for inactivating the translation termination factor eRF3 in yeast Saccharomyces cerevisiae].

Mutations in genes of omnipotent nonsense suppressors SUP35 and SUP45 in yeast Saccharomyces cerevisiae encoding translation termination factors eRF3 and eRF1, respectively, and prionization of the eRF3 protein may lead to the suppression of some frameshift mutations (CPC mutations). Partial inactivation of the translation termination factor eRF3 was studied in strains with unstable genetically modified prions and also in transgenic yeast S. cerevisiae strains with the substitution of the indigenous SUP35 gene for its homolog from Pichia methanolica or for a recombinant S. cerevisiae SUP35 gene. It was shown that this partial inactivation leads not only to nonsense suppression, but also to suppression of the frameshift lys2-90 mutation. Possible reasons for the correlation between nonsense suppression and suppression of the CPC lys2-90 mutation and mechanisms responsible for the suppression of CPC mutations during inactivation of translation termination factors are discussed.

Codon, Nonsense↗
PubMed2002

[Chimeric yeast prions with unstable inheritance].

The Saccharomyces cerevisiae [PSI] factor, a cytoplasmic omnipotent nonsense suppressor, is a conformationally changed (prion) form of translation termination factor eRF3 (Sup35p). Induction and maintenance of the [PSI] factor depend on the prionizing peptide located in the N domain of Sup35p. The N domain of Sup35p was fused with phosphoribosylaminoimidazole carboxylase (Ade2p), a purine biosynthesis enzyme, and the hybrid protein (NM-Sup35p::Ade2p) was tested for induction of the [PSI] factor. Transformation with a centromeric plasmid carrying the gene for NM-Sup35p::Ade2p induced a [PSI]-like factor in yeast cells, which was evident from efficient nonsense suppression. The suppressory effect depended on the presence of the prionizing peptide both in the hybrid protein and in Sup35p synthesized from the chromosomal gene, as well as on the presence of the prion-like [PIN] factor in the cell.

Carboxy-Lyases↗
PubMed2001

[Suppression of frameshift mutation as a result of partial inactivation of translation termination factors in Saccharomyces cerevisiae yeast].

Special search for frameshift mutations, which are suppressed by the cytoplasmic [PSI] factor and by omnipotent nonsense suppressors (recessive mutations in the SUP35 and SUP45 genes), partially inactivating a translation termination complex, was initiated in the LYS2 gene in the yeast Saccharomyces cerevisiae. Mutations were obtained after exposure to UV light and treatment with a mixture consisting of 1.6- and 1.8-dinitropyrene (DNP). This mixture was shown to induce mutations of the frameshift type with a high frequency. The majority of these mutations were insertions of one A or T, which is in good agreement with the data obtained in studies of DNP-induced mutagenesis in other eukaryotes. Frameshift suppression in yeast was first shown on the example of the mutation obtained in this work (lys2-90), which carried the insertion of an extra T in the sequence of five T. This frameshift suppression was shown to occur in the presence of the [PSI] factor (i.e., due to the prion form of the translation release factor eRF3) and as a result of mutations in genes SUP35 or SUP45, which partially inactivate translation termination factors eRF3 and eRF1, respectively. Alternative mechanisms of programmed translational frameshifting in the course of translation and the possibility of enhancing the effectiveness of such frameshifting in the presence of the [PSI] factor are considered.

Base Sequence↗