Loss of cytochrome oxidase in Saccharomyces cerevisiae during inhibition of mitochondrial protein synthesis by erythromycin and chloramphenicol.

There is a major reduction in respiratory competence, and inhibitionof growth, several hours after the addition of erythromycin or chloramphenicol to Saccharomyces cerevisiae growing in medium containing a non-fermentable carbon source. Spectrographic evidence is presented for a loss of cytochrome oxidase as a consequence of the antibiotic treatment. This loss is prevented by cyanide or oligomycin. When glucose is added, however, the loss occurs irrespective of the presence of the respiratory inhibitors. Cycloheximide does not affect respiratory competence or cause loss of cytochrome oxidase, and it prevents the loss elicited by erythromycin if both compounds are added together. However, if cycloheximide is added some time after the addition of erythromycin, it fails to block the response to the latter drug. The results cannot be accounted for on the basis of the segregation of a finite number of mitochondria into an increasing number of progeny cells but, rather, suggest that the mitochondria are modified during growth in chloramphenicol or erythromycin.