Relationship between methionyl transfer ribonucleic acid cellular content and synthesis of methionine enzymes in Saccharomyces cerevisiae.

Derepression of some methionine biosynthetic enzymes (methionine group I enzymes) obtained in methionine limitation has been found to be accompanied by a significant lack of in vivo charging of bulk methionine transfer ribonucleic acid (tRNA(Met)) and in addition by a decreased rate of synthesis of all tRNAs. Under the same conditions, methionyl-tRNA synthetase (MTS) was derepressed rather than repressed. These results are in agreement with those previously published based on studies of a mutant with an impaired MTS (5) and reinforce the idea that the rate of synthesis of methionine group I enzymes can be related to the total content of methionyl (Met)-tRNA (Met) per cell. They also render unlikely that MTS could be a constituent of the regulatory signal.