Partial Repression of Cytochrome P-450 by Adenosine 3′:5′-Cyclic Monophosphate in Protoplasts of Saccharomyces cerevisiae

Effect of carbon source on the accumulation of cytochrome P-450 in the yeast Saccharomyces cerevisiae

“…Metabolic events in the shift from fermentation to respiration have been screened in many ways. On the basis of the effects of aeration and glucose, it has been suggested that the accumulation of cytochrome P-450 in yeast requires a mitochondrial repression (Wiseman et al, 1975a,b) and that its production is controlled by the intracellular concentration of 3',5'-cyclic AMP (Wiseman, et al, 1975a(Wiseman, et al, , 1978. This suggestion is supported by the observation that the amount of cytochrome P-450 is so low in galactose-grown yeast that it cannot be detected in whole cells (Callen & Philpot, 1977).…”

Regulation of cytochrome P-450 biosynthesis in Saccharomyces cerevisiae: relationship to proposed location of some of adenylate cyclase in mitochondrial membrane

“…We have employed conditions of mitochondrial repression obtained by growth of yeast aerobically in at least 4% glucose-containing medium (usually 20%). The effect of a variety of concentrations of glucose on the time course of the yield of this enzyme has been reported by us (Wiseman et al, 1978). The enzyme is assayed spectrophotometrically by its peak at 450nm with carbon monoxide (sodium dithionite is added to reduce Fe(II1) to Fe(I1)).…”

“…Cytochrome P-450 concentrations display an inverse relationship with cyclic AMP and cytochrome a + a , concentration in the yeast (Qureshi et al, 1980). In addition, cyclic AMP added to a suspension of yeast protoplasts causes a 60% repression of the biosynthesis of cytochrome P-450 (Wiseman et al, 1978). Exogenous cyclic AMP can also remove glucose repression of a-glucosidase (Wiseman & Lim, 1977), and of mitochondrial enzymes in whole yeast (Mahler & Lin, 1978).…”

“…Inhibition of this enzyme by 591st MEETING, NEWCASTLE UPON TYNE Table 1. Requirements for cytochrome P-450 biosynthesis in Saccharomyces cerevisiae Repression of cytochrome P-450 was achieved by addition of cyclic AMP to growth medium (demonstrated for yeast protoplasts by Wiseman et al, 1978 the high glucose concentrations or assisted excretion of cyclic AMP out through the cell membrane could account for the glucose effect in repressions of many enzymes, and on the production of cytochrome P-450. The subcellular location of adenylate cyclase in S .…”

“…Solubilization was achieved by adding various detergents to the suspension of microsomes, stirring for 1 h, centrifuging at 50000rev./min (100000g) for 1 h and collecting the supernatant, which contained the solubilized cytochrome P-450. The concentration of cytochrome P-450 and cytochrome P-420 was determined by a spectrophometric method (Wiseman et al 1978), modified from that of Omura et al…”