Conservation of structure and function of the aflatoxin regulatory geneaflR fromAspergillus nidulans andA. flavus
- Cite this article as:
- Yu, JH., Butchko, R.A.E., Fernandes, M. et al. Curr Genet (1996) 29: 549. doi:10.1007/BF02426959
Under limiting growth conditions,Aspergillus nidulans produces a carcinogenic secondary metabolite related to aflatoxin and called sterigmatocystin (ST). The genes for ST biosynthesis are co-ordinately regulated and are all found within an approximately 60-kilobase segment of DNA. One of the genes within this region is predicted to encode a CX2CX6CX6CX2CX6CX2 zinc binuclear cluster DNA-binding protein that is related to theAspergillus flavus andAspergillus parasiticus aflatoxin regulatory geneaflR. Deletion of theA. nidulans aflR homolog resulted in an inability to induce expression of genes within the ST gene cluster and a loss of ST production. BecauseA. nidulans aflR mRNA accumulates specifically under conditions that favor ST production we expect that activation of ST biosynthetic genes is determined byA. nidulans aflR. In support of this hypothesis, we demonstrated that induced expression of theA. flavus aflR gene inA. nidulans, under conditions that normally suppress ST gene expression, resulted in activation of genes in the ST biosynthetic pathway. This result demonstrates that AflR function is conserved betweenAspergillus spp. and thataflR expression is sufficient to activate genes in the ST pathway.