Studies on a temperature sensitive nuclear petite mutant of Saccharomyces cerevisiae: Phenotypic reversibility of the mitochondrial functions

Summary

• 1. We have studied the pleiotropic effect of a single-gene mutation of the pts mutant strain 1511 grown at 23° C and 36° C.

• 2. Growth of the mutant at the non-permissive temperature results in a decrease of respiration rate to about 50% after one generation and to less than 5% after five generations. The cytochrome spectra analysis revealed that only cytochrome c was present after growth at 36° C.

• 3. Mitochondrial protein synthesis experiments in vivo demonstrated that the protein synthesizing system was not as rapidly inactivated by high temperature as the respiratory system.

• 4. The recovery of the respiratory capacity of the cells at 23° C is complete but dependent on the de novo synthesis of a temperature sensitive protein.