Methionine analogs and cell division regulation in the yeast Saccharomyces cerevisiae.

Abstract

Methionine analogs such as ethionine, selenomethionine and trifluoromethionine all arrest growth and division of the yeast S. cerevisiae. One analog, ethionine, caused cells of the yeast to arrest specifically within Gl; reciprocal shift experiments showed that ethionine and .alpha.-factor arrested cells at the same step (start). The major effect of ethionine on synthesis of macromolecules was to reduce both the rate of appearance of 35S ribosomal precursor RNA and the rate of production of mature rRNA. Synthesis of protein was relatively unaffected by ethionine. Selenomethionine and trifluoromethionine caused cells to arrest randomly in the cell division cycle. Although treatment of cells with either selenomethionine or trifluoromethionine also reduced the rate of total RNA- synthesis, each of these analogs had other effects that presumably prohibited completion of the cell cycle. Probably the rate of rRNA production is an important regulatory event in the cell cycle.