FORMATION OF YEAST MITOCHONDRIA .2. EFFECTS OF ANTIBIOTICS ON ENZYME ACTIVITY DURING DEREPRESSION

Using the yeast, Saccharomyces cerecisiae, we have investigated long- and short-term effects of cycloheximide and chloramphenicol on the appearance of cytoplasmic and mitochondrial enzyme activities during release from glucose repression. The pattern exhibited is complex. (1) All of the enzymes studied, whether located in the cytoplasm or the mitochondria, were sensitive to cycloheximide. (2) Although enzymes located in the mitochondria, especially those of the inner membrane, were initially more sensitive to chloramphenicol, by 6 hr after the addition of the drug, both cytoplasmic and mitochondrial enzymes were affected. (3) Enzymes having similar locations, i.e., the parts of the respiratory chain such as reduced nicotinamide-adenine dinucleotide-ferricyanide reductase, antimycin A sensitive reduced nicotinamide-adenine dinucleotide-cytochrome c reductase, and cytochrome oxidase; the soluble enzymes of the cytoplasm, malic dehydrogenase and reduced nicotinamide-adenine dinucleotide-ferricyanide reductase; or the microsomal enzymes, reduced nicotinamide- adenine dinucleotide phosphate-cytochrome c reductase and antimycin-insensitive reduced nicotinamide- adenine dinucleotide-cytochrome c reductase, showed noncoordinated patterns of sensitivity to the drugs. A model for the formation of mitochondria during derepression is proposed. © 1968, American Chemical Society. All rights reserved.