title: A spontaneous albino mutant of Ceratocystis resinifera results from a point mutation in the polyketide synthase gene, PKS1.
abstract: We characterized a spontaneous albino mutant of Ceratocystis resinifera. Compared with the wild-type progenitor strain, the albino mutant had a reduced linear growth on culture medium, but its growth on lodgepole pine sapwood was unaffected. The albino mutant did not produce any coloured pigment on agar media or wood. However, upon exposure to exogenous scytalone, an intermediate metabolite of the melanin pathway, the production of a brownish melanin was restored. This suggests that the albino phenotype resulted from a mutation affecting the melanin synthesis pathway, upstream of the scytalone synthesis step. Melanin production was restored in the mutant by transforming it with a wild-type copy of the Ceratocystis resinifera polyketide synthase gene, PKS1. The complemented transformants produced melanin, indicating that the PKS1 gene was defective in the albino mutant. Sequence analysis revealed that the PKS1 allele found in the albino contained a single point mutation that resulted in an amino acid change from serine to proline at the 3' end of the beta-ketoacyl synthase motif.
authors.affiliation: Department of Wood Science, The University of British Columbia, Vancouver, Canada.
authors.forename: P
authors.initials: P
authors.lastname: Tanguay
authors.forename: P
authors.initials: P
authors.lastname: Loppnau
authors.forename: C
authors.initials: C
authors.lastname: Morin
authors.forename: L
authors.initials: L
authors.lastname: Bernier
authors.forename: C
authors.initials: C
authors.lastname: Breuil
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D004271:DNA, Fungal / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015252:Deoxyribonucleases, Type II Site-Specific / Q000378:metabolism; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal / Q000235:genetics; D005816:Genetic Complementation Test; D008543:Melanins / Q000096:biosynthesis / Q000378:metabolism; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000235:genetics / Q000378:metabolism; D010641:Phenotype; D017354:Point Mutation / Q000235:genetics*; D048630:Polyketide Synthases / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
chemical_list: D004271:DNA, Fungal; D005656:Fungal Proteins; D008543:Melanins; D009097:Multienzyme Complexes; D048630:Polyketide Synthases; C034510:CTCGAG-specific type II deoxyribonucleases; D015252:Deoxyribonucleases, Type II Site-Specific