Stimulation of yeast RNA synthesis by cycloheximide and 3',5'-cyclic AMP.

Abstract

THE respiratory adaptation of anaerobic yeast and aerobic glucose-derepression are usually induced in conditions of limited growth resulting from glucose or nitrogen downshift of the culture medium1. In these conditions, mitochondrial as well as cytoplasmic RNA and protein syntheses are required for the full development of functional mitochondria. Cycloheximide, which specifically blocks the cytoplasmic ribosomes2, is often added to the respiratory adaptation or glucose-derepression media to study the specific products of mitochondrial protein synthesis3. This inhibitor, however, probably disturbs the regulatory relationships that exist not only between mitochondrial and cytoplasmic protein syntheses but also between the latter and nucleic acid synthesis. It has been shown that cycloheximide depresses RNA synthesis in growing yeast4,5 although Fukuhara6 observed that during the respiratory adaptation of Saccharomyces cerevisiae, RNA synthesis is only slightly depressed by cycloheximide. In other circumstances, the occasional stimulation of RNA synthesis by cycloheximide has been reported7. Here we assert that the stimulation of RNA synthesis by cycloheximide during metabolic starvation presents several analogies with the release of stringent bacterial control by chloramphenicol.