Abstract
Pyrrolnitrin is a secondary metabolite derived from tryptophan and
has strong antifungal activity. Recently we described four genes,
prnABCD, from Pseudomonas fluorescens that encode the biosynthesis
of pyrrolnitrin. In the work presented here, we describe the function
of each prn gene product. The four genes encode proteins identical
in size and serology to proteins present in wild-type Pseudomonas
fluorescens, but absent from a mutant from which the entire prn
gene region had been deleted. The prnA gene product catalyzes the
chlorination of L-tryptophan to form 7-chloro-L-tryptophan. The
prnB gene product catalyzes a ring rearrangement and decarboxylation
to convert 7-chloro-L-tryptophan to monodechloroaminopyrrolnitrin.
The prnC gene product chlorinates monodechloroaminopyrrolnitrin
at the 3 position to form aminopyrrolnitrin. The prnD gene product
catalyzes the oxidation of the amino group of aminopyrrolnitrin
to a nitro group to form pyrrolnitrin. The organization of the prn
genes in the operon is identical to the order of the reactions in
the biosynthetic pathway.
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