Mycopathologia

, Volume 147, Issue 2, pp 105–112

Repressor-AFLR interaction modulates aflatoxin biosynthesis in Aspergillus parasiticus

Authors

  • Perng-Kuang Chang
    • U.S. Department of AgricultureSouthern Regional Research Center, Agriculture Research Service
  • Jiujiang Yu
    • U.S. Department of AgricultureSouthern Regional Research Center, Agriculture Research Service
  • Deepak Bhatnagar
    • U.S. Department of AgricultureSouthern Regional Research Center, Agriculture Research Service
  • Thomas E. Cleveland
    • U.S. Department of AgricultureSouthern Regional Research Center, Agriculture Research Service
Article

DOI: 10.1023/A:1007157309168

Cite this article as:
Chang, P., Yu, J., Bhatnagar, D. et al. Mycopathologia (1999) 147: 105. doi:10.1023/A:1007157309168

Abstract

Regulation of aflatoxin (AF) biosynthesis likely involves a complex interplay of positive- and negative-acting factors that are affected by physiological cues responsive to internal and external stimuli. These factors, presumably, modulate the expression of the AF pathway-specific regulatory gene, aflR, whose product, AFLR, a zinc cluster transcription factor, then turns on or off the transcription of other AF genes. To determine if the AFLR carboxyl region (AFLRC) interacts with positive-or negative-acting proteins, we fused the Aspergillus parasiticus aflR carboxyl coding region(aflRC) to the promoter of A. parasiticusnitrite reductase gene (niiA(p)::aflRC), and transformed it into A. parasiticus SRRC 2043. Transformants that contained two copies of niiA(p)::aflRC, one at the niaD locus and another at the aflR locus, over produced AF precursors independent of the nitrogen source. The higher copy number of the integrated niiA(p)::aflRC correlated with increased production of AF precursors by the transformants as well as increased expression of both aflRC and native aflR in potato dextrose broth and A & M medium. Since aflRC does not encode a DNA-binding domain, the expressed AFLRC should not bind to the promoters of AF pathway genes and affect transcription directly. The results are consistent with AFLRC titrating out a putative repressor that interacts with AFLR under different growth conditions and modulates AF biosynthesis. This interaction also indirectly affects sclerotial development.

AflatoxinaflRAspergillus parasiticusrepressorsclerotia

Copyright information

© Kluwer Academic Publishers 1999