title: Putative polyketide synthase and laccase genes for biosynthesis of aurofusarin in Gibberella zeae.
abstract: Mycelia of Gibberella zeae (anamorph, Fusarium graminearum), an important pathogen of cereal crops, are yellow to tan with white to carmine red margins. We isolated genes encoding the following two proteins that are required for aurofusarin biosynthesis from G. zeae: a type I polyketide synthase (PKS) and a putative laccase. Screening of insertional mutants of G. zeae, which were generated by using a restriction enzyme-mediated integration procedure, resulted in the isolation of mutant S4B3076, which is a pigment mutant. In a sexual cross of the mutant with a strain with normal pigmentation, the pigment mutation was linked to the inserted vector. The vector insertion site in S4B3076 was a HindIII site 38 bp upstream from an open reading frame (ORF) on contig 1.116 in the F. graminearum genome database. The ORF, designated Gip1 (for Gibberella zeae pigment mutation 1), encodes a putative laccase. A 30-kb region surrounding the insertion site and Gip1 contains 10 additional ORFs, including a putative ORF identified as PKS12 whose product exhibits about 40% amino acid identity to the products of type I fungal PKS genes, which are involved in pigment biosynthesis. Targeted gene deletion and complementation analyses confirmed that both Gip1 and PKS12 are required for aurofusarin production in G. zeae. This information is the first information concerning the biosynthesis of these pigments by G. zeae and could help in studies of their toxicity in domesticated animals.
authors.affiliation: School of Agricultural Biotechnology and Center for Agricultural Biomaterials, Seoul National University, Seoul, Korea.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Kim
authors.forename: Kap-Hoon
authors.initials: KH
authors.lastname: Han
authors.forename: Jianming
authors.initials: J
authors.lastname: Jin
authors.forename: Hun
authors.initials: H
authors.lastname: Kim
authors.forename: Jin-Cheol
authors.initials: JC
authors.lastname: Kim
authors.forename: Sung-Hwan
authors.initials: SH
authors.lastname: Yun
authors.forename: Yin-Won
authors.initials: YW
authors.lastname: Lee
mesh_terms: D000595:Amino Acid Sequence; D003470:Culture Media; D005874:Gibberella / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D001467:Hordeum / Q000382:microbiology; D042845:Laccase / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D008969:Molecular Sequence Data; D009154:Mutation; D025282:Mycelium / Q000254:growth & development; D009285:Naphthoquinones / Q000378:metabolism*; D010860:Pigments, Biological / Q000378:metabolism; D010935:Plant Diseases / Q000382:microbiology; D048630:Polyketide Synthases / Q000737:chemistry / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D014774:Virulence
chemical_list: D003470:Culture Media; D009285:Naphthoquinones; D010860:Pigments, Biological; D048630:Polyketide Synthases; D042845:Laccase; C083578:aurofusarin