Clustered Pathway Genes in Aflatoxin Biosynthesis

Clustered pathway genes in aflatoxin biosynthesis.

Predicted Roles of the Uncharacterized Clustered Genes in Aflatoxin Biosynthesis

Biosynthesis of the toxic and carcinogenic aflatoxins (AFs) requires the activity of more than 27 enzymes. The roles in biosynthesis of newly described enzymes are discussed in this review. We suggest that HypC catalyzes the oxidation of norsolorinic acid anthrone; AvfA (AflI), the ring-closure step in formation of hydroxyversicolorone; HypB, the second oxidation step in conversion of O-methyls...

Aflatoxin Biosynthetic Pathway and Pathway Genes

Among the over 185 known species within the genus Aspergillus, Aspergillus flavus is the most economically important because it produces the toxic and carcinogenic aflatoxins. Its non-aflatoxigenic relative A. oryzae is used extensively for food fermentations (Jelinek et al., 1989). It is one of the most abundant soil-borne molds on earth. A. flavus fungus is a saprobe mold that is capable of s...

Clustered genes involved in cyclopiazonic acid production are next to the aflatoxin biosynthesis gene cluster in Aspergillus flavus.

Cyclopiazonic acid (CPA), an indole-tetramic acid mycotoxin, is produced by many species of Aspergillus and Penicillium. In addition to CPA Aspergillus flavus produces polyketide-derived carcinogenic aflatoxins. Aflatoxin biosynthesis genes form a gene cluster in a subtelomeric region. Isolates of A. flavus lacking aflatoxin production due to the loss of the entire aflatoxin gene cluster and po...

Step of dichlorvos inhibition in the pathway of aflatoxin biosynthesis.

Dichlorvos (dimethyl 2,2-dichlorovinyl phosphate) inhibits the biosynthesis of aflatoxin by Aspergillus parasiticus. Cultures treated with dichlorvos excrete an orange pigment which can be converted into aflatoxin B(1) by the untreated mycelia. The orange pigment was partially identified as an acetyl derivative of versiconol-type compound. In the presence of dichlorvos, sterigmatocystin is conv...