Cloning of the Aspergillus parasiticus apa-2 gene associated with the regulation of aflatoxin biosynthesis

P. K. Chang, J. W. Cary, D. Bhatnagar, T. E. Cleveland, J. W. Bennett, J. E. Linz, C. P. Woloshuk, G. A. Payne

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Abstract

An Aspergillus parasiticus gene, designated apa-2, was identified as a regulatory gene associated with aflatoxin biosynthesis. The apa-2 gene was cloned on the basis of overproduction of pathway intermediates following transformation of fungal strains with cosmid DNA containing the aflatoxin biosynthetic genes nor-1 and ver-1. Transformation of an O- methylsterigmatocystin-accumulating strain, A. parasiticus SRRC 2043, with a 5.5-kb HindIII-XbaI DNA fragment containing apa-2 resulted in overproduction of all aflatoxin pathway intermediates analyzed. Specific enzyme activities associated with the conversion of norsolorinic acid and sterigmatocystin were increased approximately twofold. The apa-2 gene was found to complement an A. flavus afl-2 mutant strain for aflatoxin production, suggesting that apa-2 is functionally homologous to afl-2. Comparison of the A. parasiticus apa-2 gene DNA sequence with that of the A. flavus afl-2 gene (G. A. Payne, G. J. Nystorm, D. Bhatnagar, T. E. Cleveland, and C. P. Woloshuk, Appl. Environ. Microbiol. 59:156-162, 1993) showed that they shared >95% DNA homology. Physical mapping of cosmid subclones placed apa-2 approximately 8 kb from ver-1.

Original languageEnglish (US)
Pages (from-to)3273-3279
Number of pages7
JournalApplied and environmental microbiology
Volume59
Issue number10
DOIs
StatePublished - 1993
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Biotechnology
  • Food Science
  • Applied Microbiology and Biotechnology
  • Ecology

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