title: Fusarium graminearum PKS14 is involved in orsellinic acid and orcinol synthesis.
abstract: The available genome sequences show that the number of secondary metabolite genes in filamentous fungi vastly exceeds the number of known products. This is also true for the global plant pathogenic fungus Fusarium graminearum, which contains 15 polyketide synthase (PKS) genes, of which only 6 have been linked to products. To help remedy this, we focused on PKS14, which has only been shown to be expressed during plant infections or when cultivated on rice or corn meal (RM) based media. To enhance the production of the resulting product we introduced a constitutive promoter in front of PKS14 and cultivated two of the resulting mutants on RM medium. This led to the production of two compounds, which were only detected in the PKS14 overexpressing mutants and not in the wild type or PKS14 deletion mutants. The two compounds were tentatively identified as orsellinic acid and orcinol by comparing spectroscopic data (mass spectroscopy and chromatography) to authentic standards. NMR analysis of putative orcinol isolated from the PKS14 overexpressing mutant supported our identification. Orcinol and orsellinic acid, not previously detected in Fusarium, have primarily been detected in lichen fungi. Orsellinic acid is hypothesized to be the PKS release product which is transformed to orcinol through decarboxylation. Phylogenetic analyses of PKSs placed PKS14 in a subclade of known OA synthases. Expression analysis by microarray of 55 experiments identified seven genes near PKS14 that were expressed in a similar manner. One of the seven genes encodes a predicted carboxylase, which could be responsible for transforming orsellinic acid to orcinol.
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
authors.forename: Simon Hartung
authors.initials: SH
authors.lastname: Jørgensen
authors.affiliation: Department of Systems Biology, Technical University of Denmark, Søltofts Plads, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Rasmus John Norman
authors.initials: RJ
authors.lastname: Frandsen
authors.affiliation: Department of Systems Biology, Technical University of Denmark, Søltofts Plads, DK-2800 Kgs. Lyngby, Denmark.
authors.forename: Kristian Fog
authors.initials: KF
authors.lastname: Nielsen
authors.affiliation: Department of Plant Health and Plant Protection, Bioforsk-Norwegian Institute of Agricultural and Environmental Research, 1432 Ås, Norway.
authors.forename: Erik
authors.initials: E
authors.lastname: Lysøe
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
authors.forename: Teis Esben
authors.initials: TE
authors.lastname: Sondergaard
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Wimmer
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark.
authors.forename: Henriette
authors.initials: H
authors.lastname: Giese
authors.affiliation: Department of Biotechnology, Chemistry and Environmental Engineering, Aalborg University, Sohngaardsholmsvej 49, DK-9000 Aalborg, Denmark. Electronic address: jls@bio.aau.dk.
authors.forename: Jens Laurids
authors.initials: JL
authors.lastname: Sørensen
mesh_terms: D003653:Decarboxylation; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D005670:Fusarium / Q000235:genetics / Q000378:metabolism*; D005810:Multigene Family; D009154:Mutation; D010802:Phylogeny; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism*; D012118:Resorcinols / Q000378:metabolism*
chemical_list: D005656:Fungal Proteins; D012118:Resorcinols; C501612:orsellinic acid; C005282:orcinol; D048630:Polyketide Synthases
keywords: Fusarium; Overexpression; Polyketide synthase 14; Regulation; Secondary metabolites