Nonfunctionality of Aspergillus Sojae AflR in a Strain of Aspergillus Parasiticus with a Disrupted AflR Gene

Overview

Journal Appl Environ Microbiol

Specialties Environmental Health
Microbiology

Date 2002 Jul 31

PMID 12147467

Citations 17

Authors

Tadashi Takahashi

Perng-Kuang Chang

Kenichiro Matsushima

Jiujiang Yu

Keietsu Abe

Deepak Bhatnagar

Thomas E Cleveland

Yasuji Koyama

Affiliations

Soon will be listed here.

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.

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