Suppressors of ICR-induced mutations that exhibit behavior similar to bacterial frameshift suppressors have been identified in the yeast Saccharomyces cerevisiae. The yeast suppressors have been divided into two groups. Previous evidence indicated that suppressors of one group (Group II: SUFI, SUF3, SUF4, SUF5 and SUF6) represent mutations in the structural genes for glycyl-tRNA's. Suppressors of the other group (Group III: SUF2 and SUF7) were less well characterized. Although they suppressed some ICR-revertible mutations, they failed to suppress Group II frameshift mutations. This communication provides a more thorough characterization of the Group III suppressors and describes the isolation and properties of four new suppressors in that group (SUF1, SUF9, SUF10 and suf11).—In our original study, Group III suppressors were isolated as revertants of the Group III mutations his4-712 and his4-713. All suppressors obtained as ICR-induced revertants of these mutations mapped at the SUF2 locus near the centromere of chromosome III. Suppressors mapping at other loci were obtained in this study by analyzing spontaneous and UV-induced revertants of the Group III mutations. SUF2 and SUF10 suppress both Group III his4 mutations, whereas SUF7, SUF8, SUF9 and suf11 suppress his4-713, but not his4-712. All of the suppressors except suf11 are dominant in diploids homozygous for his4-713. The suppressors fail to suppress representative UAA, UAG and UGA nonsense mutations.—SUP9 is linked to the centromere of chromosome VI, and SUF10 is linked to the centromere of chromosome XIV. A triploid mapping procedure was used to determine the chromosome locations of SUF7 and SUF8. Subsequent standard crosses revealed linkage of SUF7 to cdc5 on chromosome XIII and linkage of SUF8 to cdcl2 and pet3 on chromosome VIII.
- Received October 18, 1979.