Title: The isoepoxydon dehydrogenase gene of the patulin metabolic pathway in Penicillium species and in Byssochlamys nivea Author
|Dombrink Kurtzman, Mary Ann|
Submitted to: World Mycotoxin Forum, the Third Conference
Publication Type: Abstract Only
Publication Acceptance Date: November 6, 2006
Publication Date: November 6, 2006
Citation: Dombrink Kurtzman, M. 2006. The isoepoxydon dehydrogenase gene of the patulin metabolic pathway in Penicillium species and in Byssochlamys nivea [abstract]. World Mycotoxin Forum, the Fourth Conference. p. 127. Technical Abstract: Penicillium expansum is the fungus most often associated with production of the mycotoxin patulin in apples and apple juice. The sequence of the isoepoxydon dehydrogenase (idh) gene, which codes for the seventh enzyme in the patulin biosynthetic pathway, was determined in 12 different Penicillium species and in Byssochlamys nivea, all capable of producing patulin. Among patulin-producers, Byssochlamys nivea is unique because it can produce ascospores that survive pasteurization and cause spoilage of heat-processed fruit products worldwide. Primer pairs for DNA amplification by PCR and sequencing of the idh gene of Penicillium species were designed based on the P. griseofulvum idh gene deposited in GenBank. It was necessary to construct GenomeWalker libraries for determination of the B. nivea idh gene because its second intron was two-to-three fold larger than the introns in Penicillium species. The identity of all of the isolates was confirmed by sequencing rDNA (ITS1, 5.8 S, ITS2 and partial sequences of 28S rDNA). Maximum parsimony analysis showed trees based on idh and rDNA sequences to be congruent, suggesting that lateral gene transfer between the species examined had not occurred. Numerous nucleotide substitutions in the idh gene of the Penicillium species and B. nivea were present, but because the nucleotide differences occurred in the third coding position, the amino acid sequence was usually not affected. One significant amino acid difference among the fungi examined was the substitution of a conserved lysine residue by threonine. P. griseofulvum and closely related P. dipodomyicola were the only species containing lysine which is necessary for binding the cofactor NADP+. It is anticipated that the genetic information presented will aid in understanding the biosynthesis of patulin and serve as the basis for developing oligonucleotide probes to identify these mycotoxigenic species.