Completed sequence of aflatoxin pathway gene cluster in Aspergillus parasiticus¹

Abstract

An 82-kb Aspergillus parasiticus genomic DNA region representing the completed sequence of the well-organized a£atoxin pathway gene cluster has been sequenced and annotated. In addition to the 19 reported and characterized a£atoxin pathway genes and the four sugar utilization genes in this cluster, we report here the identi¢cation of six newly identi¢ed genes which are putatively involved in a£atoxin formation. The function of these genes, the cluster organization and its signi¢cance in gene expression are discussed.

A systems approach to model the relationship between aflatoxin gene cluster expression, environmental factors, growth and toxin production by Aspergillus flavus

“…In A. flavus, the clustered pathway genes have been detailed, and in some cases new gene names have recently been given [3,4]. Some of the key genes in the aflatoxin biosynthesis include aflF (old name; norB), aflD (¼nor-1) and aflE (norA), which encode a dehydrogenase and two reductases which convert norsolorinic acid to averantin; aflM (¼ver-1) is a dehydrogenase which converts versicolorin A to demethylsterigmatocystin; aflaO (¼omtB) is a O-methyltransferase I or O-methyltransferase B, which is involved in the conversion of demethylsterigmatocystin to sterigmatocystin and dihydro-demethylsterigmostocystin to dihydrosterigmatocystin; aflP (¼omtA) is an O-methyltransferase A or II which converts sterigmatocystin to O-methylsterigmatocystin as well as demethylsterigmatocystin to dihydro-O-methylsterigmatocystin; other genes such as aflQ (¼ordA) and aflX (¼ordB) have been shown to be involved in the final part of the biosynthetic pathway, as oxidoreductase-P450 monooxygenase and monoxygenase oxidase.…”

Aflatoxins Biochemistry and Molecular Biology - Biotechnological Approaches for Control in Crops

“…Amplification of specific DNA fragments using polymerase chain reaction (PCR) and specific gene probes is extremely sensitive and has the potential to detect the presence of A. flavus in agricultural commodities (Manonmani et al, 2005). Since all of the genes involved in the aflatoxin biosynthesis pathway have been identified and cloned (Yu et al, 2004a(Yu et al, , 2004b, and the entire genome of A. flavus sequenced , molecular methods for the detection of Aspergillus should be fairly readily adapted by using biosynthetic pathway genes as probes, as evidenced by the recent work differentiating toxigenic and atoxigenic A. flavus-utilizing aflatoxin gene expression using the reverse transcriptionpolymerase chain reaction (RT-PCR) (Degola et al, 2007). Application of these molecular techniques to A. flavus soil ecology should greatly enhance our understanding of this fungus.…”

Control of Aflatoxin Biosynthesis in Aspergilli

“…In the pksA promoter region an additional AflR-binding site was found to be the AflR binding site for a short gene hypC (formerly hypB1), which encodes an enzyme necessary for oxidation of the AF precursor metabolite, norsolorinic acid anthrone. Lettering on lower line is the current nomenclature for the genes using the afl designation (Yu et al, 2004a). However, the aflR gene in each of the AF-producing species has fewer sites than those shown.…”