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United States Department of Agriculture

Agricultural Research Service

Title: A POLYKETIDE SYNTHASE GENE REQUIRED FOR THE BIOSYNTHESIS OF FUMONISIN MYCOTOXINS IN GIBBERELLA FUJIKUROI MATING POPULATION A)

Author
item Proctor, Robert
item Desjardins, Anne
item Plattner, Ronald
item Hohn, Thomas

Submitted to: Fungal Genetics Conference Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 3/28/1999
Publication Date: N/A
Citation:

Interpretive Summary:

Technical Abstract: Fumonisins are toxins produced by the maize pathogen Gibberella fujikuroi mating population A (MP-A) and are associated with mycotoxicoses in both humans and animals. Structural and precursor feeding studies indicate fumonisins are products of either polyketide or fatty acid metabolism. We attempted to isolate a polyketide synthase (PKS) gene involved in fumonisin biosynthesis via PCR with degenerate PKS primers and a cDNA template prepared from a fumonisin-producing culture of G. fujikuroi. Nucleotide sequence analysis of the single PCR product and flanking DNA from a cosmid clone revealed a gene (FUM5) with a 7.8 kb coding region interrupted by 5 introns. The predicted FUM5 translation product had conserved amino acid sequences indicative of the ketoacyl synthase, acyl transferase, ketoreductase, dehydratase, enoyl reductase, and acyl carrier protein domains present in Type I bacterial and fungal PKSs. Transformation of a cosmid clone that included FUM5 into G. fujikuroi increased the levels of production in three strains and restored wild-type production in a fumonisin-nonproducing strain. Disruption of FUM5 reduced fumonisin production by over 99% in G. fujikuroi MP-A. These results indicate that FUM5 is a PKS gene required for fumonisin biosynthesis and, further, that fumonisins are products of polyketide rather than fatty acid metabolism.

Last Modified: 8/24/2016
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