Evidence for a Dual Osmoregulatory Mechanism in the Yeast Saccharomyces cerevisiae

Abstract

Osmoadaptation in S. cerevisiae occurs through intracellular accumulation of glycerol in response to an increase in osmolarity of the surrounding environment. Analysis of ssvl-2, a strain carrying a mutation in a gene required for vacuole biogenesis, protein-sorting and osmohomeostasis, shows that the strain is terminally inactivated by 1.5 M NaCl within 10 seconds while the isogenic wild type maintains slow growth and accumulates glycerol within 18 hours. This study provides the first evidence that the vacuole participates in an immediate osmoregulatory process permitting survival until the osmoadaptive glycerol accumulation allows growth under osmotically unfavorable conditions.