Promitochondria of Anaerobically Grown Yeast

Abstract

During anaerobic growth, Saccharomyces cerevisiae cells lose their normal mitochondria and accumulate respiration-deficient promitochondria. Upon aeration of the anaerobically grown cells, the promitochondria are converted to respiring mitochondria. The present study investigates the role of promitochondrial protein synthesis in this conversion. The proteins synthesized by promitochondria in vivo were selectively labeled by incubating the cells with radioactive leucine in the presence of cycloheximide. This antibiotic selectively inhibits cytoplasmic protein synthesis, and thereby prevents the oxygen-induced conversion of promitochondria to mitochondria. Electrophoretic comparison of the polypeptides labeled in the presence and absence of oxygen revealed that oxygen controlled the promitochondrial synthesis of a specific class of proteins. This effect of oxygen was inhibited by glucose. During respiratory adaptation, the promitochondrial protein-synthesizing system can thus respond to oxygen and to glucose independently of cytoplasmic protein synthesis.