Mechanism of Death of Yeast Saccharomyces cerevisiae at Heat Shock. Effect of Cyclogeximide on this Process
It is shown that the mechanism of cell death after heat shock of yeast depends on the intensity of the heat exposure. Moderate (45°C) heat shock resulted in a significant enhancement of the generation of reactive oxygen species (ROS) and cell death. Prereatment with cycloheximide (at 30°C) suppressed the death, but it had no effect on ROS production. If cycloheximide was added just prior to heat exposure and incubated with it during the recovery period, the protective effect was absent. Protective effect of cycloheximide on the viability and ROS production were significantly decreased by the action of the hard (50°C) heat shock. Treatment with cycloheximide at 39°C inhibited the induction of Hsp104 synthesis and suppressed the development of induced thermotolerance to a hard shock (50°C), but it had no effect on the development of resistance under the action of mild (45°C) heat shock. At the same time, Hsp104 effectively protects cells from death independently of the intensity of exposure. These data indicate that under moderate heat shock of yeast, cell death occurs as a result of programmed cell death (PCD), and cycloheximide inhibits this process by inhibiting the overall protein synthesis.