FUNCTIONS ENCODED BY PYRROLNITRIN BIOSYNTHETIC GENES FROM PSEUDOMONAS-FLUORESCENS

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 pyrroln itrin. In the work presented here, we describe the function of each pr n gene product. The four genes encode proteins identical in size and s erology to proteins present in wild-type Pseudomonas fluorescens, but absent from a mutant from which the entire prn gene region had been de leted. The prnA gene product catalyzes the chlorination of L-tryptopha n to form 7-chloro-L-tryptophan. The prnB gene product catalyzes a rin g rearrangement and decarboxylation to convert 7-chloro-L-tryptophan t o monodechloroaminopyrrolnitrin. The prnC gene product chlorinates mon odechloroaminopyrrolnitrin 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 organizat ion of the prn genes in the operon is identical to the order of the re actions in the biosynthetic pathway.