The tRNA-Tyr gene family of Saccharomyces cerevisiae: agents of phenotypic variation and position effects on mutation frequency.
Journal Article (Journal Article)
Extensive phenotypic diversity or variation exists in clonal populations of microorganisms and is thought to play a role in adaptation to novel environments. This phenotypic variation or instability, which occurs by multiple mechanisms, may be a form of cellular differentiation and a stochastic means for modulating gene expression. This work dissects a case of phenotypic variation in a clinically derived Saccharomyces cerevisiae strain involving a cox15 ochre mutation, which acts as a reporter. The ochre mutation reverts to sense at a low frequency while tRNA-Tyr ochre suppressors (SUP-o) arise at a very high frequency to produce this phenotypic variation. The SUP-o mutations are highly pleiotropic. In addition, although all SUP-o mutations within the eight-member tRNA-Tyr gene family suppress the ochre mutation reporter, there are considerable phenotypic differences among the different SUP-o mutants. Finally, and of particular interest, there is a strong position effect on mutation frequency within the eight-member tRNA-Tyr gene family, with one locus, SUP6, mutating at a much higher than average frequency and two other loci, SUP2 and SUP8, mutating at much lower than average frequencies. Mechanisms for the position effect on mutation frequency are evaluated.
- Ito-Harashima, S; Hartzog, PE; Sinha, H; McCusker, JH
- August 2002
Volume / Issue
- 161 / 4
Start / End Page
- 1395 - 1410
Pubmed Central ID
International Standard Serial Number (ISSN)
Digital Object Identifier (DOI)
- United States