Properties of P503 (Prototetrahydroporphyrin IX) in Cells and Extracts of Saccharomyces cerevisiae

Abstract

Both ρ+ and ρ− strains of Saccharomyces cerevisiae accumulate P503 during the early logarithmic phase of growth when cytochrome synthesis is repressed. Yeast cells grown on non-fermentable carbon sources (e.g. glycerol) did not accumulate P503. Cell-free extracts containing P503 were prepared from anaerobically grown (ρ+) S. cerevisiae. The addition to these extracts of mitochondria from ρ+ cells grown aerobically on galactose caused the immediate disappearance of P503. Escherichia coli respiratory particles had a similar effect on P503. Mitochondrial preparations from ρ− cells or from anaerobically grown ρ+ cells did not affect P503. Coprotetrahydroporphyrin III was not oxidized by aerobic S. cerevisiae mitochondria nor by E. coli respiratory particles.