CHARACTERIZATION OF UVI15(-INDUCIBLE GENE FROM SCHIZOSACCHAROMYCES-POMBE(), A STRESS)

The uvi15(+) gene of Schizosaccharomyces pombe is a member of a group of stress-inducible genes transcription levels of which increase in re sponse to DNA-damaging agents or heat shock. It encodes a polypeptide of calculated molecular mass 11641 Da, with no significant sequence si milarity to other known heat shock proteins. The steady-state level of the uvi15(+) gene product of about 12 kDa was increased by heat shock and canavanine, an amino acid analog. This gene also showed a transie nt increase in expression as cells moved into diauxic shift phase. Alt hough deletion of the uvi15(+) gene did not affect the mitotic growth or thermotolerance of cells, the mutant cells rapidly lost viability i n stationary phase and under starvation conditions. These cells also s howed a defect in sporulation ability. These results suggest that the uvi15(+) gene encodes a stress response protein involved in the mainte nance of cell viability during entry into stationary phase or under st arvation conditions.