Effects of Antibiotics on the Development and Stability of Mitochondrial Enzymes in Saccharomyces cerevisiae

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Abstract
The effects of cycloheximide and chloramphenicol on the development of complex oxidase systems and of several parts of the respiratory chain of yeast mitochondria have been investigated. In repressed cells addition of cycloheximide has a stronger effect on the development of several mitochondrial activities than has the addition of chloramphenicol. Probably in this phase the derepression is primarily dependent on the synthesis of enzymic proteins on the cytoplasmic ribosomes. Incubation of partially derepressed cultures with chloramphenicol results in an inactivation of cytochrome oxidase and of the succinate and NADH oxidase systems and in a decrease in the respiratory control. After a lag the development of succinate and NADH dehydrogenase and of NADH‐cytochrome c oxidoreductase is severely inhibited. There are some remarkable parallels between the effects of incubation of the cells with chloramphenicol and treatment of the mitochondrial fractions with digitonin. This suggests that chloramphenicol may indirectly interfere with the structure or composition of mitochondrial membranes. The inhibition of the mitochondrial protein synthesis may affect mitochondrial membranes and interfere with some of the functions of the integrated oxidase systems. The inactivation of these systems suggests that their development and stability is dependent on a continual supply of some products of the mitochondrial protein‐synthesizing system.