Altered cytochrome P-450 in a yeast mutant blocked in demethylating C-32 of lanosterol.
Spectroscopic and enzymatic analysis of a Saccharomyces cerevisiae mutant in sterol biosynthesis (SG1 (erg 11); Trocha, P. J., Jasne, S. J., and Sprinson, D. B. (1977) Biochemistry 16, 4721-4726) that was blocked in demethylating C-32 of lanosterol (4,4,14 alpha-trimethyl-5 alpha-cholesta-8,24-dien-3 beta-ol) showed that it contained low levels of cytochromes P-450 and b5 compared to those present in the parent strain D-587, while NADPH-cytochrome c reductase activity was elevated. The fungicide buthiobate (S-n-butyl S'-p-tert-butylbenzyl N-3-pyridyldithiocarbonimidate), which bound specifically to yeast cytochrome P450 responsible for demethylating C-32 of lanosterol and effected a Type II spectral change, did not react with SG1 cytochrome P-450. On the other hand, cholate-solubilized microsomes from SG1 formed a single precipitin line on Ouchterlony plates with antibodies raised against purified (Yoshida, Y., Aoyama, Y., Kumaoka, H., and Kubota, S. (1977) Biochem. Biophys. Res. Commun. 78, 1005-1010) yeast cytochrome P-450 specific for demethylating C-32 of lanosterol. Hence, mutant SG1 contained an altered protein which retained the antigenicity of cytochrome P-450 responsible for demethylating C-32 of lanosterol but lost its catalytic activity.
D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D004579:Electron Transport; D005659:Fungicides, Industrial / Q000494:pharmacology; D007096:Imidoesters / Q000494:pharmacology; D005779:Immunodiffusion; D007810:Lanosterol / Q000378:metabolism*; D009154:Mutation; D012441:Saccharomyces cerevisiae / Q000201:enzymology* / Q000235:genetics; D013053:Spectrophotometry
D005659:Fungicides, Industrial; D007096:Imidoesters; C016349:buthiobate; D007810:Lanosterol; D003577:Cytochrome P-450 Enzyme System