title: A putative branched-chain-amino-acid transaminase gene required for HC-toxin biosynthesis and pathogenicity in Cochliobolus carbonum.
abstract: The cyclic tetrapeptide HC-toxin is required for pathogenicity of the filamentous fungus Cochliobolus carbonum on maize. HC-toxin production is controlled by a complex locus, TOX2. The isolation and characterization of a new gene of the TOX2 locus, TOXF, is reported. It is shown that TOXF is specifically required for HC-toxin production and pathogenicity. It is present as two or three copies in all HC-toxin-producing (Tox2+) isolates and is absent in toxin-non-producing strains. The deduced amino acid sequence of TOXF has moderate homology to many known or putative branched-chain-amino-acid transaminases from various species. A strain of C. carbonum with all copies of TOXF disrupted grew normally but lost HC-toxin production and pathogenicity. It is proposed that TOXF has a biosynthetic role in HC-toxin synthesis, perhaps to aminate a precursor of Aeo (2-amino-9,10-epoxi-8-oxodecanoic acid).
authors.affiliation: Department of Energy - Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 , USA1.
authors.forename: Yi-Qiang
authors.initials: YQ
authors.lastname: Cheng
authors.affiliation: Department of Energy - Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 , USA1.
authors.forename: Joong-Hoon
authors.initials: JH
authors.lastname: Ahn
authors.affiliation: Department of Energy - Plant Research Laboratory, Michigan State University, East Lansing, MI 48824 , USA1.
authors.forename: Jonathan D
authors.initials: JD
authors.lastname: Walton
mesh_terms: D000595:Amino Acid Sequence; D001203:Ascomycota / Q000201:enzymology* / Q000235:genetics* / Q000472:pathogenicity; D001483:Base Sequence; D002876:Chromosomes, Bacterial / Q000235:genetics; D018076:DNA, Complementary / Q000235:genetics; D005656:Fungal Proteins; D015723:Gene Library; D008969:Molecular Sequence Data; D010456:Peptides, Cyclic / Q000096:biosynthesis*; D010641:Phenotype; D011995:Recombination, Genetic; D017422:Sequence Analysis, DNA; D000637:Transaminases / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism; D014170:Transformation, Genetic; D003313:Zea mays / Q000382:microbiology
chemical_list: D018076:DNA, Complementary; D005656:Fungal Proteins; D010456:Peptides, Cyclic; C037654:HC toxin; C403891:TOXF protein, Cochliobolus carbonum; D000637:Transaminases; C019798:branched-chain-amino-acid transaminase