OMNIPOTENT SUPPRESSORS EFFECTIVE IN ⁺ STRAINS OF SACCHAROMYCES CEREVISIAE: RECESSIVENESS AND DOMINANCE

Bun-Ichiro Ono ¹, Nozomi Moriga ¹, Kiyomi Ishihara ¹, Junpei Ishiguro ², Yumiko Ishino ¹, and Sumio Shinoda ¹

¹ Laboratory of Environmental Hygiene Chemistry, Faculty of Pharmaceutical Sciences, Okayama University, Okayama 700, Japan
² Department of Biology, Faculty of Science, Konan University, Kobe 658, Japan

We have characterized recessive and dominant omnipotent suppressor mutations obtained by conversion of the leu2-1 UAA mutation and the met8-UAG mutation in a ⁺ strain of Saccharomyces cerevisiae. The suppressors that act recessively upon these markers fell into two complementation groups; the sup47 and sup36 suppressors show linkage to the tyr1 locus and the aro1 locus, respectively. Of the suppressors acting dominantly upon both markers, those linked to the tyr1 locus are alleles of the SUP46 ribosomal mutation. The sup47 suppressors differ from the SUP46 suppressors not only in their suppressor activities in heterozygous diploids but also in their map positions relative to the tyr1 locus and their effects on the S11 ribosomal protein. The remaining dominant suppressors are not alleles of sup36 as judged by linkage analysis. The recessive suppressors and the dominant suppressors also differ in their effects on cell growth.