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Applied and Environmental Microbiology, October 1998, p. 3713-3717, Vol. 64, No. 10
North Carolina State University, Raleigh,
North Carolina 27695,1 and
USDA
Southern Regional Research Center, New Orleans, Louisiana
701242
Received 12 February 1998/Accepted 21 July 1998
The genes encoding the aflatoxin biosynthetic pathway enzymes have
been localized as a cluster to a 75-kb DNA fragment. The enzymatic
functions of the products of most of the genes in the cluster are
known, but there are a few genes that have not yet been characterized.
We report here the characterization of one of these genes, a gene
designated aflJ. This gene resides in the cluster adjacent
to the pathway regulatory gene, aflR, and the two genes are
divergently transcribed. Disruption of aflJ in
Aspergillus flavus results in a failure to produce
aflatoxins and a failure to convert exogenously added pathway
intermediates norsolorinic acid, sterigmatocystin, and
O-methylsterigmatocystin to aflatoxin. The disrupted strain
does, however, accumulate pksA, nor-1,
ver-1, and omtA transcripts under conditions
conducive to aflatoxin biosynthesis. Therefore, disruption of
aflJ does not affect transcription of these genes, and
aflJ does not appear to have a regulatory function similar
to that of aflR. Sequence analysis of aflJ and
its putative peptide, AflJ, did not reveal any enzymatic domains or
significant similarities to proteins of known function. The putative
peptide does contain three regions predicted to be membrane-spanning
domains and a microbodies C-terminal targeting signal.
0099-2240/98/$04.00+0
Copyright © 1998, American Society for Microbiology. All rights reserved.
Characterization of aflJ, a Gene
Required for Conversion of Pathway Intermediates to
Aflatoxin
*
Corresponding author. Mailing address: Department of
Plant Pathology, Box 7616, North Carolina State University, Raleigh, NC
27695-7616. Phone: (919) 515-6994. Fax: (919) 515-7716. E-mail: Gary_Payne{at}ncsu.edu.
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