Starvation-associated mutagenesis in yeast Saccharomyces cerevisiae is affected by Ras2/cAMP signaling pathway.

The number of revertants with restored ability to form colony increases in a time-dependent manner during long-term selective starvation of dense mutant microbial cultures. This is due to starvation-associated (also called adaptive) mutations that arise in a replication independent manner. Here we report that in Saccharomyces cerevisiae the frequency of starvation-associated reversions of mutant genes whose products are necessary for amino acids biosynthesis are influenced by Ras2/cAMP signaling pathway. This signaling pathway is a yeast general regulatory pathway involved in nutritional sensing, UV response, sporulation control and life span control and its changes are manifested in both, cell cycle and life cycle. Inactivation of the RAS2 gene causes an increase in number of starvation-associated revertants in comparison to an isogenic wild type strain and a strain with constitutively activated Ras2/cAMP signaling pathway. Therefore, we suggest that starvation-associated mutagenesis is different from spontaneous mutagenesis and is related to the cellular capacity to adopt distinct physiological states in response to environmental signals.