title: Molecular cloning and functional characterization of two CYP619 cytochrome P450s involved in biosynthesis of patulin in Aspergillus clavatus.
abstract: Patulin is an acetate-derived tetraketide mycotoxin produced by several fungal species, especially Aspergillus, Penicillium and Byssochlamys species. The health risks due to patulin consumption by humans have led many countries to regulate it in human food. Previous studies have shown the involvement of cytochrome P450 monooxygenases in the hydroxylation of two precursors of patulin, m-cresol and m-hydroxybenzylalcohol. In the present study, two cytochrome P450 genes were identified in the genome sequence of Aspergillus clavatus, a patulin-producing species. Both mRNAs were strongly co-expressed during patulin production. CYP619C2, encoded by the first gene, consists of 529 aa, while the second cytochrome, CYP619C3, consists of 524 aa. The coding sequences were used to perform the heterologous expression of functional enzymes in Saccharomyces cerevisiae. The bioconversion assays showed that CYP619C3 catalysed the hydroxylation of m-cresol to yield m-hydroxybenzyl alcohol. CYP619C2 catalysed the hydroxylation of m-hydroxybenzyl alcohol and m-cresol to gentisyl alcohol and 2,5-dihydroxytoluene (toluquinol), respectively. Except for the last compound, all enzyme products are known precursors of patulin. Taken together, these data strongly suggest the involvement of CYP619C2 and CYP619C3 in the biosynthesis of patulin. CYP619C2 and CYP619C3 are located near to two other genes involved in patulin biosynthesis, namely the 6-methylsalicylic acid synthase (6msas) and isoepoxydon dehydrogenase (idh) genes. The current data associated with an analysis of the sequence of A. clavatus suggest the presence of a cluster of 15 genes involved in patulin biosynthesis.
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Marie Pierre
authors.initials: MP
authors.lastname: Artigot
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Loiseau
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Joelle
authors.initials: J
authors.lastname: Laffitte
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Lina
authors.initials: L
authors.lastname: Mas-Reguieg
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Souria
authors.initials: S
authors.lastname: Tadrist
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Isabelle P
authors.initials: IP
authors.lastname: Oswald
authors.affiliation: INRA, UR66 Pharmacologie-Toxicologie, F-31931 Toulouse, France.
authors.forename: Olivier
authors.initials: O
authors.lastname: Puel
mesh_terms: D000595:Amino Acid Sequence; D001230:Aspergillus / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics; D003001:Cloning, Molecular; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D007700:Kinetics; D008969:Molecular Sequence Data; D010365:Patulin / Q000096:biosynthesis*; D016415:Sequence Alignment
chemical_list: D005656:Fungal Proteins; D003577:Cytochrome P-450 Enzyme System; D010365:Patulin