title: Genetic localization and in vivo characterization of a Monascus azaphilone pigment biosynthetic gene cluster.
abstract: Monascus spp. produce several well-known polyketides such as monacolin K, citrinin, and azaphilone pigments. In this study, the azaphilone pigment biosynthetic gene cluster was identified through T-DNA random mutagenesis in Monascus purpureus. The albino mutant W13 bears a T-DNA insertion upstream of a transcriptional regulator gene (mppR1). The transcription of mppR1 and the nearby polyketide synthase gene (MpPKS5) was significantly repressed in the W13 mutant. Targeted inactivation of MpPKS5 also gave rise to an albino mutant, confirming that mppR1 and MpPKS5 belong to an azaphilone pigment biosynthetic gene cluster. This M. purpureus sequence was used to identify the whole biosynthetic gene cluster in the Monascus pilosus genome. MpPKS5 contains SAT/KS/AT/PT/ACP/MT/R domains, and this domain organization is preserved in other azaphilone polyketide synthases. This biosynthetic gene cluster also encodes fatty acid synthase (FAS), which is predicted to assist the synthesis of 3-oxooactanoyl-CoA and 3-oxodecanoyl-CoA. These 3-oxoacyl compounds are proposed to be incorporated into the azaphilone backbone to complete the pigment biosynthesis. A monooxygenase gene (an azaH and tropB homolog) that is located far downstream of the FAS gene is proposed to be involved in pyrone ring formation. A homology search on other fungal genome sequences suggests that this azaphilone pigment gene cluster also exists in the Penicillium marneffei and Talaromyces stipitatus genomes.
authors.affiliation: Department of Biological Science, Myongji University, Yongin-si, Gyunggi-do 449-725, South Korea.
authors.forename: Bijinu
authors.initials: B
authors.lastname: Balakrishnan
authors.forename: Suman
authors.initials: S
authors.lastname: Karki
authors.forename: Shih-Hau
authors.initials: SH
authors.lastname: Chiu
authors.forename: Hyun-Ju
authors.initials: HJ
authors.lastname: Kim
authors.forename: Jae-Won
authors.initials: JW
authors.lastname: Suh
authors.forename: Bora
authors.initials: B
authors.lastname: Nam
authors.forename: Yeo-Min
authors.initials: YM
authors.lastname: Yoon
authors.forename: Chien-Chi
authors.initials: CC
authors.lastname: Chen
authors.forename: Hyung-Jin
authors.initials: HJ
authors.lastname: Kwon
mesh_terms: D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D032741:Monascus / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D005810:Multigene Family; D010860:Pigments, Biological / Q000096:biosynthesis*; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism
chemical_list: D005656:Fungal Proteins; D010860:Pigments, Biological; D048630:Polyketide Synthases; D006899:Mixed Function Oxygenases