MetaCyc Enzyme: C-22 sterol desaturase

Gene: ERG5 Accession Number: YMR015C (MetaCyc)

Synonyms: CYP61

Species: Saccharomyces cerevisiae

When a cytochrome P450 protein was purified from microsomal fractions of a strain of Saccharomyces cerevisiae defective in CYP51A1, it was found to be a different P450 enzyme that functions as a sterol Δ 22-desaturase, involved in ergosterol biosynthesis [Kelly95]. The ERG5 gene encoding the enzyme was subsequently cloned and its molecular function demonstrated by functional complementation [Skaggs96].

The enzyme, which is indeed a cytochrome P450, is not essential for cell viability [Skaggs96]. Two P450 enzymes are involved in ergosterol biosynthesis in yeast, the other one is cytochrome P450 51, encoded by ERG11 [Hata83].

Map Position: [300,868 <- 302,484] (32.55 centisomes)

Molecular Weight of Polypeptide: 58.0 kD (experimental) [Kelly95 ]

Unification Links: Entrez-gene:855029 , Mint:MINT-1323986 , Protein Model Portal:P54781 , SGD:S000004617 , SMR:P54781 , String:4932.YMR015C , UniProt:P54781

Relationship Links: Entrez-Nucleotide:PART-OF:U34636 , InterPro:IN-FAMILY:IPR001128 , InterPro:IN-FAMILY:IPR002403 , InterPro:IN-FAMILY:IPR017972 , Pfam:IN-FAMILY:PF00067 , Prints:IN-FAMILY:PR00465 , Prosite:IN-FAMILY:PS00086

Gene-Reaction Schematic: ?

Gene-Reaction Schematic

Created 21-Dec-2004 by Hong E , Saccharomyces Genome Database
Revised 30-Oct-2008 by Caspi R , SRI International

Enzymatic reaction of: C-22 sterol desaturase

5-dehydro episterol + NADPH + H+ + oxygen <=> 5,7,22,24(28)-ergostatetraenol + NADP+ + 2 H2O

The reaction direction shown, that is, A + B ↔ C + D versus C + D ↔ A + B, is in accordance with the direction in which it was curated.

The reaction is favored in the direction shown.

In Pathways: superpathway of ergosterol biosynthesis I , ergosterol biosynthesis I

Inhibitors (Other): carbon monoxide [Kelly95]


Hata83: Hata S, Nishino T, Katsuki H, Aoyama Y, Yoshida Y (1983). "Two species of cytochrome P-450 involved in ergosterol biosynthesis of yeast." Biochem Biophys Res Commun 116(1);162-6. PMID: 6357195

Kelly95: Kelly SL, Lamb DC, Corran AJ, Baldwin BC, Parks LW, Kelly DE (1995). "Purification and reconstitution of activity of Saccharomyces cerevisiae P450 61, a sterol delta 22-desaturase." FEBS Lett 377(2);217-20. PMID: 8543054

Skaggs96: Skaggs BA, Alexander JF, Pierson CA, Schweitzer KS, Chun KT, Koegel C, Barbuch R, Bard M (1996). "Cloning and characterization of the Saccharomyces cerevisiae C-22 sterol desaturase gene, encoding a second cytochrome P-450 involved in ergosterol biosynthesis." Gene 169(1);105-9. PMID: 8635732

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Please cite the following article in publications resulting from the use of MetaCyc: Caspi et al, Nucleic Acids Research 42:D459-D471 2014
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