title: A polyketide synthase gene required for biosynthesis of the aflatoxin-like toxin, dothistromin.
abstract: Dothistromin is a polyketide toxin, produced by a fungal forest pathogen, with structural similarity to the aflatoxin precursor versicolorin B. Biochemical and genetic studies suggested that there are common steps in the biosynthetic pathways for these metabolites and showed similarities between some of the genes. A polyketide synthase gene (pksA) was isolated from dothistromin-producing Dothistroma septosporum by hybridization with an aflatoxin ortholog from Aspergillus parasiticus. Inactivation of this gene in D. septosporum resulted in mutants that could not produce dothistromin but that could convert exogenous aflatoxin precursors, including norsolorinic acid, into dothistromin. The mutants also had reduced asexual sporulation compared to the wild type. So far four other genes are known to be clustered immediately alongside pksA. Three of these (cypA, moxA, avfA) are predicted to be orthologs of aflatoxin biosynthetic genes. The other gene (epoA), located between avfA and moxA, is predicted to encode an epoxide hydrolase, for which there is no homolog in either the aflatoxin or sterigmatocystin gene clusters. The pksA gene is located on a small chromosome of approximately 1.3 Mb in size, along with the dothistromin ketoreductase (dotA) gene.
authors.affiliation: National Centre for Advanced Bio-Protection Technologies, Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand. R.E.Bradshaw@massey.ac.nz
authors.forename: Rosie E
authors.initials: RE
authors.lastname: Bradshaw
authors.forename: Hongping
authors.initials: H
authors.lastname: Jin
authors.forename: Branwen S
authors.initials: BS
authors.lastname: Morgan
authors.forename: Arne
authors.initials: A
authors.lastname: Schwelm
authors.forename: Olivia R
authors.initials: OR
authors.lastname: Teddy
authors.forename: Carolyn A
authors.initials: CA
authors.lastname: Young
authors.forename: Shuguang
authors.initials: S
authors.lastname: Zhang
mesh_terms: D000595:Amino Acid Sequence; D000880:Anthraquinones / Q000378:metabolism*; D001203:Ascomycota / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism*; D001483:Base Sequence; D003001:Cloning, Molecular; D016521:Electrophoresis, Gel, Pulsed-Field; D008969:Molecular Sequence Data; D048630:Polyketide Synthases / Q000235:genetics* / Q000378:metabolism; D012331:RNA, Fungal / Q000737:chemistry / Q000235:genetics; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D014170:Transformation, Genetic
chemical_list: D000880:Anthraquinones; D012331:RNA, Fungal; C042735:dothistromin; D048630:Polyketide Synthases