Change in P-450 Content Accompanying Aerobic Formation of Mitochondria in Yeast

Abstract

The content of P-450, a CO-binding hemoprotein, in wild-type yeast cells grown anaerobically decreased sharply on exposure to aerobic conditions. This change paralleled the formation of mitochondria within the cells. High concentrations of glucose and chloramphenicol inhibited both the decrease in P-450 and the development of mito-chondrial type of respiration. A similar decrease in P-450 was also observed when cells of a semi-anaerobically grown respiration-deficient mutant were aerated. The weak respiration of anaerobically and semi-anaerobically grown wild-type yeast and semi-anaerobically grown mutant yeast cells was insensitive to antimycin A. The rate of this insensitive respiration was proportional to the content of P-450 in various types of cells. Possible relationships between P-450 and mitochondrial synthesis are discussed.