This Article Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Reprints and Permissions Copyright Information Books from ASM Press MicrobeWorld Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Yu, J. Articles by Cleveland, T. E. Search for Related Content PubMed PubMed Citation Articles by Yu, J. Articles by Cleveland, T. E. Agricola Articles by Yu, J. Articles by Cleveland, T. E.

 Previous Article  |  Next Article 

Appl. Environ. Microbiol., 04 1997, 1349-1356, Vol 63, No. 4
Copyright © 1997, American Society for Microbiology

avnA, a gene encoding a cytochrome P-450 monooxygenase, is involved in the conversion of averantin to averufin in aflatoxin biosynthesis in Aspergillus parasiticus

J Yu, PK Chang, JW Cary, D Bhatnagar and TE Cleveland
Southern Regional Research Center, USDA Agricultural Research Service, New Orleans, Louisiana 70179, USA.

Recent studies have shown that at least 17 genes involved in the aflatoxin biosynthetic pathway are clustered within a 75-kb DNA fragment in the genome of Aspergillus parasiticus. Several additional transcripts have also been mapped to this gene cluster. A gene, avnA (previously named ord-1), corresponding to one of the two transcripts identified earlier between the ver-1 and omtA genes on the gene cluster was sequenced. The nucleotide sequence of the avnA gene contains a coding region for a protein of 495 amino acids with a calculated molecular mass of 56.3 kDa. The gene consists of three exons and two introns. Disruption of the avnA gene in the wild-type aflatoxigenic A. parasiticus strain (SU1-N3) resulted in a nonaflatoxigenic mutant which accumulated a bright yellow pigment. Thin-layer chromatographic studies with six different solvent systems showed that the migration patterns of the accumulated metabolite were identical to those of averantin, a known aflatoxin precursor. Precursor feeding studies with this mutant showed that norsolorinic acid and averantin were not converted to aflatoxin whereas 5'-hydroxyaverantin, averufanin, averufin, versicolorin A. sterigmatocystin, and O-methylsterigmatocystin were converted to aflatoxins. Southern blot analysis of the wild-type strain and avnA-disrupted mutant strain indicated that the avnA gene was disrupted in the mutant strain. A search of the GenBank database for similarity indicated that the avnA gene encodes a cytochrome P-450-type monooxygenase, and it has been assigned to a new P-450 gene family named CYP60A1. We have therefore concluded that the avnA gene encodes a fungal cytochrome P-450-type enzyme which is involved in the conversion of averantin to averufin in the aflatoxin biosynthetic pathway in A. parasiticus.

This article has been cited by other articles:

• Smith, C. A., Woloshuk, C. P., Robertson, D., Payne, G. A. (2007). Silencing of the Aflatoxin Gene Cluster in a Diploid Strain of Aspergillus flavus Is Suppressed by Ectopic aflR Expression. Genetics 176: 2077-2086 [Abstract] [Full Text]  
• Tominaga, M., Lee, Y.-H., Hayashi, R., Suzuki, Y., Yamada, O., Sakamoto, K., Gotoh, K., Akita, O. (2006). Molecular Analysis of an Inactive Aflatoxin Biosynthesis Gene Cluster in Aspergillus oryzae RIB Strains. Appl. Environ. Microbiol. 72: 484-490 [Abstract] [Full Text]  
• Ehrlich, K. C., Chang, P.-K., Yu, J., Cotty, P. J. (2004). Aflatoxin Biosynthesis Cluster Gene cypA Is Required for G Aflatoxin Formation. Appl. Environ. Microbiol. 70: 6518-6524 [Abstract] [Full Text]  
• Yu, J., Chang, P.-K., Ehrlich, K. C., Cary, J. W., Bhatnagar, D., Cleveland, T. E., Payne, G. A., Linz, J. E., Woloshuk, C. P., Bennett, J. W. (2004). Clustered Pathway Genes in Aflatoxin Biosynthesis. Appl. Environ. Microbiol. 70: 1253-1262 [Full Text]  
• Sakuno, E., Yabe, K., Nakajima, H. (2003). Involvement of Two Cytosolic Enzymes and a Novel Intermediate, 5'-Oxoaverantin, in the Pathway from 5'-Hydroxyaverantin to Averufin in Aflatoxin Biosynthesis. Appl. Environ. Microbiol. 69: 6418-6426 [Abstract] [Full Text]  
• Chang, P.-K., Yu, J., Ehrlich, K. C., Boue, S. M., Montalbano, B. G., Bhatnagar, D., Cleveland, T. E. (2000). adhA in Aspergillus parasiticus Is Involved in Conversion of 5'-Hydroxyaverantin to Averufin. Appl. Environ. Microbiol. 66: 4715-4719 [Abstract] [Full Text]  
• Kues, U. (2000). Life History and Developmental Processes in the Basidiomycete Coprinus cinereus. Microbiol. Mol. Biol. Rev. 64: 316-353 [Abstract] [Full Text]  
• Keller, N. P., Watanabe, C. M. H., Kelkar, H. S., Adams, T. H., Townsend, C. A. (2000). Requirement of Monooxygenase-Mediated Steps for Sterigmatocystin Biosynthesis by Aspergillus nidulans. Appl. Environ. Microbiol. 66: 359-362 [Abstract] [Full Text]  
• Yu, J., Chang, P.-K., Ehrlich, K. C., Cary, J. W., Montalbano, B., Dyer, J. M., Bhatnagar, D., Cleveland, T. E. (1998). Characterization of the Critical Amino Acids of an Aspergillus parasiticus Cytochrome P-450 Monooxygenase Encoded by ordA That Is Involved in the Biosynthesis of Aflatoxins B1, G1, B2, and G2. Appl. Environ. Microbiol. 64: 4834-4841 [Abstract] [Full Text]  
• Meyers, D. M., Obrian, G., Du, W. L., Bhatnagar, D., Payne, G. A. (1998). Characterization of aflJ, a Gene Required for Conversion of Pathway Intermediates to Aflatoxin. Appl. Environ. Microbiol. 64: 3713-3717 [Abstract] [Full Text]