The Enzyme Database

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EC 1.14.13.175      
Transferred entry: aflatoxin B synthase. Now EC 1.14.14.117, aflatoxin B synthase
[EC 1.14.13.175 created 2013, deleted 2018]
 
 
EC 1.14.14.117     
Accepted name: aflatoxin B synthase
Reaction: (1) 8-O-methylsterigmatocystin + 2 [reduced NADPH—hemoprotein reductase] + 2 O2 = aflatoxin B1 + 2 [oxidized NADPH—hemoprotein reductase] + H2O + methanol + CO2
(2) 8-O-methyldihydrosterigmatocystin + 2 [reduced NADPH—hemoprotein reductase] + 2 O2 = aflatoxin B2 + 2 [oxidized NADPH—hemoprotein reductase] + H2O + methanol + CO2
For diagram of aflatoxin biosynthesis (part 4), click here
Glossary: aflatoxin B1 = (6aR,9aS)-4-methoxy-2,3,6a,9a-tetrahydrocyclopenta[c]furo[3′,2′:4,5]furo[2,3-h][1]benzopyran-1,11-dione
aflatoxin B2 = (6aR,9aS)-4-methoxy-2,3,6a,8,9,9a-hexahydrocyclopenta[c]furo[3′,2′:4,5]furo[2,3-h][1]benzopyran-1,11-dione
8-O-methylsterigmatocystin = 6,8-dimethoxy-3a,12c-dihydrofuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
8-O-methyldihydrosterigmatocystin = 6,8-dimethoxy-1,2,3a,12c-tetrahydrofuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
Other name(s): ordA (gene name)
Systematic name: 8-O-methylsterigmatocystin,[reduced NADPH—hemoprotein reductase]:oxygen oxidoreductase (aflatoxin-B forming)
Comments: A cytochrome P-450 (heme-thiolate) protein. Isolated from the mold Aspergillus parasiticus.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc
References:
1.  Bhatnagar, D., Cleveland, T.E. and Kingston, D.G. Enzymological evidence for separate pathways for aflatoxin B1 and B2 biosynthesis. Biochemistry 30 (1991) 4343–4350. [PMID: 1902378]
2.  Yu, J., Chang, P.K., Ehrlich, K.C., Cary, J.W., Montalbano, B., Dyer, J.M., Bhatnagar, D. and Cleveland, T.E. Characterization of the critical amino acids of an Aspergillus parasiticus cytochrome P-450 monooxygenase encoded by ordA that is involved in the biosynthesis of aflatoxins B1, G1, B2, and G2. Appl. Environ. Microbiol. 64 (1998) 4834–4841. [PMID: 9835571]
3.  Udwary, D.W., Casillas, L. K. and Townsend, C.A. Synthesis of 11-hydroxyl O-methylsterigmatocystin and the role of a cytochrome P-450 in the final step of aflatoxin biosynthesis. J. Am. Chem. Soc. 124 (2002) 5294–5303. [DOI] [PMID: 11996570]
[EC 1.14.14.117 created 2013 as EC 1.14.13.175, transferred 2018 to EC 1.14.14.117]
 
 
EC 2.1.1.110     
Accepted name: sterigmatocystin 8-O-methyltransferase
Reaction: (1) S-adenosyl-L-methionine + sterigmatocystin = S-adenosyl-L-homocysteine + 8-O-methylsterigmatocystin
(2) S-adenosyl-L-methionine + dihydrosterigmatocystin = S-adenosyl-L-homocysteine + 8-O-methyldihydrosterigmatocystin
For diagram of sterigmatocystin biosynthesis, click here
Glossary: sterigmatocystin = 3a,12c-dihydro-8-hydroxy-6-methoxyfuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
dihydrosterigmatocystin = 1,2,3a,12c-tetrahydro-8-hydroxy-6-methoxyfuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
8-O-methylsterigmatocystin = 6,8-dimethoxy-3a,12c-dihydrofuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
8-O-methyldihydrosterigmatocystin = 6,8-dimethoxy-1,2,3a,12c-tetrahydrofuro[3′,2′:4,5]furo[2,3-c]xanthen-7-one
Other name(s): sterigmatocystin methyltransferase; O-methyltransferase II; sterigmatocystin 7-O-methyltransferase (incorrect); S-adenosyl-L-methionine:sterigmatocystin 7-O-methyltransferase (incorrect); OmtA
Systematic name: S-adenosyl-L-methionine:sterigmatocystin 8-O-methyltransferase
Comments: Dihydrosterigmatocystin can also act as acceptor. Involved in the biosynthesis of aflatoxins in fungi.
Links to other databases: BRENDA, EXPASY, KEGG, MetaCyc, CAS registry number: 116958-29-3
References:
1.  Bhatnagar, D., McCormick, S.P., Lee, L.S. and Hill, R.A. Identification of O-methylsterigmatocystin as an aflatoxin B1 and G1 precursor in Aspergillus parasiticus. Appl. Environ. Microbiol. 53 (1987) 1028–1033. [PMID: 3111363]
2.  Yabe, K., Ando, Y., Hashimoto, J. and Hamasaki, T. 2 distinct O-methyltransferases in aflatoxin biosynthesis. Appl. Environ. Microbiol. 55 (1989) 2172–2177. [PMID: 2802602]
3.  Yu, J., Cary, J.W., Bhatnagar, D., Cleveland, T.E., Keller, N.P. and Chu, F.S. Cloning and characterization of a cDNA from Aspergillus parasiticus encoding an O-methyltransferase involved in aflatoxin biosynthesis. Appl. Environ. Microbiol. 59 (1993) 3564–3571. [PMID: 8285664]
4.  Lee, L.W., Chiou, C.H. and Linz, J.E. Function of native OmtA in vivo and expression and distribution of this protein in colonies of Aspergillus parasiticus. Appl. Environ. Microbiol. 68 (2002) 5718–5727. [DOI] [PMID: 12406770]
[EC 2.1.1.110 created 1992, modified 2005, modified 2013]
 
 


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