title: Nonfunctionality of Aspergillus sojae aflR in a strain of Aspergillus parasiticus with a disrupted aflR gene.
abstract: Aspergillus sojae belongs to the Aspergillus section Flavi but does not produce aflatoxins. The functionality of the A. sojae aflR gene (aflRs) was examined by transforming it into an DeltaaflR strain of A. parasiticus, derived from a nitrate-nonutilizing, versicolorin A (VERA)-accumulating strain. The A. parasiticus aflR gene (aflRp) transformants produced VERA, but the aflRs transformants did not. Even when aflRs was placed under the control of the amylase gene (amyB) promoter of Aspergillus oryzae, the amy(p)::aflRs transformants did not produce VERA. A chimeric construct containing the aflRs promoter plus the aflRs N- and aflRp C-terminal coding regions could restore VERA production, but a construct containing the aflRp promoter plus the aflRp N- and aflRs C-terminal coding regions could not. These results show that the A. sojae aflR promoter is functional in A. parasiticus and that the HAHA motif does not affect the function of the resulting hybrid AflR. We conclude that the lack of aflatoxin production by A. sojae can be attributed, at least partially, to the premature termination defect in aflRs, which deletes the C-terminal transcription activation domain that is critical for the expression of aflatoxin biosynthetic genes.
authors.affiliation: Research and Development Division, Kikkoman Corporation, 399 Noda, Noda-City 278-0037, Japan. ttakahashi@mail.kikkoman.co.jp
authors.forename: Tadashi
authors.initials: T
authors.lastname: Takahashi
authors.forename: Perng-Kuang
authors.initials: PK
authors.lastname: Chang
authors.forename: Kenichiro
authors.initials: K
authors.lastname: Matsushima
authors.forename: Jiujiang
authors.initials: J
authors.lastname: Yu
authors.forename: Keietsu
authors.initials: K
authors.lastname: Abe
authors.forename: Deepak
authors.initials: D
authors.lastname: Bhatnagar
authors.forename: Thomas E
authors.initials: TE
authors.lastname: Cleveland
authors.forename: Yasuji
authors.initials: Y
authors.lastname: Koyama
mesh_terms: D000681:Amylases / Q000235:genetics; D000880:Anthraquinones / Q000378:metabolism*; D001230:Aspergillus / Q000145:classification / Q000235:genetics* / Q000254:growth & development / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005656:Fungal Proteins; D017353:Gene Deletion; D005816:Genetic Complementation Test; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors; D015533:Transcriptional Activation; D014170:Transformation, Genetic
chemical_list: C113837:AFLR protein, Aspergillus; D000880:Anthraquinones; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C005888:versicolorins; D000681:Amylases