Translation termination efficiency can be regulated in Saccharomyces cerevisiae by environmental stress through a prion-mediated mechanism.
[PSI+] is a protein-based heritable phenotype of the yeast Saccharomyces cerevisiae which reflects the prion-like behaviour of the endogenous Sup35p protein release factor. [PSI+] strains exhibit a marked decrease in translation termination efficiency, which permits decoding of translation termination signals and, presumably, the production of abnormally extended polypeptides. We have examined whether the [PSI+]-induced expression of such an altered proteome might confer some selective growth advantage over [psi-] strains. Although otherwise isogenic [PSI+] and [psi-] strains show no difference in growth rates under normal laboratory conditions, we demonstrate that [PSI+] strains do exhibit enhanced tolerance to heat and chemical stress, compared with [psi-] strains. Moreover, we also show that the prion-like determinant [PSI+] is able to regulate translation termination efficiency in response to environmental stress, since growth in the presence of ethanol results in a transient increase in the efficiency of translation termination and a loss of the [PSI+] phenotype. We present a model to describe the prion-mediated regulation of translation termination efficiency and discuss its implications in relation to the potential physiological role of prions in S.cerevisiae and other fungi.
Eaglestone
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SS
Research School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
Cox
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BS
Tuite
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MF
D005656:Fungal Proteins / Q000235:genetics*; D005800:Genes, Fungal; D006358:Hot Temperature; D008954:Models, Biological; D010454:Peptide Termination Factors; D010641:Phenotype; D011328:Prions / Q000235:genetics*; D014176:Protein Biosynthesis; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000254:growth & development; D029701:Saccharomyces cerevisiae Proteins; D013489:Suppression, Genetic
D005656:Fungal Proteins; D010454:Peptide Termination Factors; D011328:Prions; C068068:SUP35 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins