Dm. Meyers et al., CHARACTERIZATION OF AFLJ, A GENE REQUIRED FOR CONVERSION OF PATHWAY INTERMEDIATES TO AFLATOXIN, Applied and environmental microbiology (Print), 64(10), 1998, pp. 3713-3717
The genes encoding the aflatoxin biosynthetic pathway enzymes have bee
n localized as a cluster to a 75 kb DNA fragment. The enzymatic functi
ons 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 af
lJ. This gene resides in the cluster adjacent to the pathway regulator
y gene, aflR, and the two genes are divergently transcribed. Disruptio
n of aflJ in Aspergillus flavus results in a failure to produce aflato
xins and a failure to convert exogenously added pathway intermediates
norsolorinic acid, sterigmatocystin, and O-methylsterigmatocystin to a
flatoxin, The disrupted strain do es, however, accumulate pksA, nor-1,
ver-1, and omtA transcripts under conditions conducive to aflatoxin b
iosynthesis, Therefore, disruption of aflJ does not affect transcripti
on of these genes, and aflJ does not appear to have a regulatory funct
ion similar to that of aflR. Sequence analysis of aflJ and its putativ
e peptide, AflJ, did not reveal any enzymatic domains or significant s
imilarities to proteins of known function. The putative peptide does c
ontain three regions predicted to be membrane-spanning domains and a m
icrobodies C-terminal targeting signal.