Sterigmatocystin (ST) is a carcinogenic polyketide produced by several filamentous fungi including Aspergillus nidulans. Expression of ST biosynthetic genes (stc genes) requires activity of a Zn(II)2Cys6 transcription factor, AflR. aflR is transcriptionally and post-transcriptionally regulated by a G-protein/cAMP/protein kinase A (PkaA) signaling pathway involving FlbA, an RGS (regulator of G-p...

The aflR gene from Aspergillus parasiticus and Aspergillus flavus may be involved in the regulation of aflatoxin biosynthesis. The aflR gene product, AFLR, possesses a GAL4-type binuclear zinc finger DNA-binding domain. A transformant, SU1-N3 (pHSP), containing an additional copy of aflR, showed increased transcription of aflR and the aflatoxin pathway structural genes, nor-1, ver-1, and omt-1,...

AFLR, a DNA-binding protein of 444 amino acids, transactivates the expression of aflatoxin biosynthesis genes in Aspergillus parasiticus and Aspergillus flavus, as well as the sterigmatocystin synthesis genes in Aspergillus nidulans. We show here by fusion of various aflR coding regions to the GAL4 DNA-binding coding region that the AFLR carboxyl terminus contained a region that activated GAL1:...

Aflatoxins are polyketide-derived secondary metabolites produced by Aspergillus spp. The toxic effects of aflatoxins have adverse consequences for human health and agricultural economics. The aflR gene, a regulatory gene for aflatoxin biosynthesis, encodes a protein containing a zinc-finger DNA-binding motif. AFLR-Protein three-dimensional model was generated using Robetta server. The modeled A...

Aflatoxins (AFs) are carcinogenic secondary metabolites of Aspergillus parasiticus. In previous studies, non-toxigenic A. parasiticus sec- (for secondary metabolism negative) variants were generated through serial transfer of mycelia from their toxigenic sec+ (for secondary metabolism positive) parents for genetic and physiological analysis for understanding regulation of AF biosynthesis. Previ...

Aflatoxins are the most potent naturally occurring carcinogens of fungal origin. Biosynthesis of aflatoxin involves the coordinated expression of more than 25 genes. The function of one gene in the aflatoxin gene cluster, aflJ, is not entirely understood but, because previous studies demonstrated a physical interaction between the Zn2Cys6 transcription factor AflR and AflJ, AflJ was proposed to...

Aspergillus flavus and Aspergillus parasiticus are important pathogens of cotton, corn, peanuts and other oil-seed crops, producing toxins both in the field and during storage. We have designed three siRNA sequences (Nor-Ia, Nor-Ib, Nor-Ic) to target the mRNA sequence of the aflD gene to examine the potential for using RNA silencing technology to control aflatoxin production. Thus, the effect of...

Aflatoxin contamination of foods and feeds is a world-wide agricultural problem. Aflatoxin production requires expression of the biosynthetic pathway regulatory gene, aflR, which encodes a Cys6Zn2-type DNA-binding protein. Homologs of aflR from Aspergillus nomius, bombycis, parasiticus, flavus, and pseudotamarii were compared to investigate the molecular basis for variation among aflatoxin-prod...

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...