[Association between defects of karyogamy and translation termination in yeast Saccharomyces cerevisiae]

Mutants capable of a high frequency of cytoduction (Hfc+) were obtained in a haploid strain of Saccharomyces cerevisiae, suggesting impaired cytogamy. Nine of the 68 Hfc+ mutants showed the antisuppressor effect with respect to mutations of the SUP35 and SUP45 genes, which code for translation termination factors, or to the [PSI+] factor, which is the prion form of Sup35. Cosegregation of the characters "higher frequency of cytoduction" and "antisuppression" was demonstrated for three Hfc+ mutants. One (HFC12-2) of the Hfc+ mutations exerted a dominant antisuppressor effect with respect to [PSI+] and had no effect on [PSI+] maintenance. On the strength of the results, an interaction was assumed for translation termination components and cytoskeleton proteins, which play a role in karyogamy in yeasts.