Nonfunctionality of Aspergillus sojae aflR in a strain of Aspergillus parasiticus with a disrupted aflR gene.
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.
Takahashi
Tadashi
T
Research and Development Division, Kikkoman Corporation, 399 Noda, Noda-City 278-0037, Japan. ttakahashi@mail.kikkoman.co.jp
Chang
Perng-Kuang
PK
Matsushima
Kenichiro
K
Yu
Jiujiang
J
Abe
Keietsu
K
Bhatnagar
Deepak
D
Cleveland
Thomas E
TE
Koyama
Yasuji
Y
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
C113837:AFLR protein, Aspergillus; D000880:Anthraquinones; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D011993:Recombinant Fusion Proteins; D014157:Transcription Factors; C005888:versicolorins; D000681:Amylases