Cloning of the Aspergillus parasiticus apa-2 gene associated with the regulation of aflatoxin biosynthesis.
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.
Chang
P K
PK
Department of Cell and Molecular Biology, Tulane University, New Orleans, Louisiana 70118.
Cary
J W
JW
Bhatnagar
D
D
Cleveland
T E
TE
Bennett
J W
JW
Linz
J E
JE
Woloshuk
C P
CP
Payne
G A
GA
D000348:Aflatoxins / Q000096:biosynthesis* / Q000235:genetics*; D001230:Aspergillus / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism*; D001483:Base Sequence; D002874:Chromosome Mapping; D003001:Cloning, Molecular; D004252:DNA Mutational Analysis; D004271:DNA, Fungal / Q000235:genetics; D005800:Genes, Fungal; D005809:Genes, Regulator; D006358:Hot Temperature; D008969:Molecular Sequence Data; D009566:Nitrates / Q000494:pharmacology; D012689:Sequence Homology, Nucleic Acid; D014170:Transformation, Genetic
D000348:Aflatoxins; D004271:DNA, Fungal; D009566:Nitrates