Isolation and characterization of a mutant having an altered ribosomal protein in the yeast, Saccharomyces cerevisiae.

Abstract

A cycloheximide-resistant mutant which also displays coreversion of leu2-1 UAA and met8-1 UAG mutations was isolated and characterized in the yeast, S. cerevisiae. One of the ribosomal protein (L23) differed electrophoretically in the mutant strain from that of the parental one. Diploid cells heterozygous for the mutation contained both altered and normal proteins and gave rise to tetrads of 2:2 segregation for the protein alteration, indicating that a single structural gene coding for L23 protein was mutated.In the meiotic progenies, however, alteration of the L23 protein did not cosegregate with any phenotypes of cycloheximide-resistance or reversion of the nonsense mutations.Trisomic analysis was performed to determine the genetic locus for the L23 protein, suggesting that the gene may not be on the chromosomes I through XVI examined.

Natural cycloheximide resistance in yeast

“…Yao and Yao have also implicated this same protein as the cycloheximide-resistance determinant in Tetrahymena (Yao and Yao, 1991). In contrast to these results, Ishiguro has characterised a different class of cycloheximide-resistant mutants of S. cerevisiae and has claimed that resistance is associated with a ribosomal protein that he identifies as L23 (Ishiguro, 1985); the map location involved is not known.…”