title: Biosynthesis of the 2-pyridone tenellin in the insect pathogenic fungus Beauveria bassiana.
abstract: Genomic DNA from the insect pathogenic fungus Beauveria bassiana was used as a template in a PCR with degenerate primers designed to amplify a fragment of a C-methyl transferase (CMeT) domain from a highly reduced fungal polyketide synthase (PKS). The resulting 270-bp PCR product was homologous to other fungal PKS CMeT domains and was used as a probe to isolate a 7.3-kb fragment of genomic DNA from a BamH1 library. Further library probing and TAIL-PCR then gave a 21.9-kb contig that encoded a 12.9-kb fused type I PKS-NRPS ORF together with ORFs encoding other oxidative and reductive enzymes. A directed knockout experiment with a BaR cassette, reported for the first time in B. bassiana, identified the PKS-NRPS as being involved in the biosynthesis of the 2-pyridone tenellin. Other fungal PKS-NRPS genes are known to be involved in the formation of tetramic acids in fungi, and it thus appears likely that related compounds are precursors of 2-pyridones in fungi. B. bassiana tenellin KO and WT strains proved to be equally pathogenic towards insect larvae; this indicated that tenellin is not involved in insect pathogenesis.
authors.affiliation: School of Chemistry, University of Bristol, Cantock's Close, Bristol, BS8 1TS, UK.
authors.forename: Kirstin L
authors.initials: KL
authors.lastname: Eley
authors.forename: Laura M
authors.initials: LM
authors.lastname: Halo
authors.forename: Zhongshu
authors.initials: Z
authors.lastname: Song
authors.forename: Henry
authors.initials: H
authors.lastname: Powles
authors.forename: Russell J
authors.initials: RJ
authors.lastname: Cox
authors.forename: Andrew M
authors.initials: AM
authors.lastname: Bailey
authors.forename: Colin M
authors.initials: CM
authors.lastname: Lazarus
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Simpson
mesh_terms: D000595:Amino Acid Sequence; D052982:Beauveria / Q000235:genetics* / Q000378:metabolism*; D003001:Cloning, Molecular; D018390:Gene Targeting; D008969:Molecular Sequence Data; D015394:Molecular Structure; D011728:Pyridones / Q000737:chemistry* / Q000378:metabolism*; D016415:Sequence Alignment
chemical_list: D011728:Pyridones; C015528:tenellin