This protein family includes Monodechloroaminopyrrolnitrin synthase PrnB from Pseudomonas fluorescens and similar bacterial proteins. PrnB is involved in the biosynthesis of the antifungal compound pyrrolnitrin. It is organised into two domains: a small N-terminal capping domain that consists of 7 alpha-helices and the core helical domain, which is related to myoglobin. PrnB shows structural homology to the heme b-dependent two-domain indoleamine 2,3-dioxygenase enzyme (IDO, Pfam:PF01231) and to the tryptophan 2,3-dioxygenase (TDO, Pfam:PF03301) family [1,2].

1: The second enzyme in pyrrolnitrin biosynthetic pathway is related to the heme-dependent dioxygenase superfamily. De Laurentis W, Khim L, Anderson JL, Adam A, Johnson KA, Phillips RS, Chapman SK, van Pee KH, Naismith JH; Biochemistry. 2007;46:12393-12404. PMID:17924666

2: The ternary complex of PrnB (the second enzyme in the pyrrolnitrin biosynthesis pathway), tryptophan, and cyanide yields new mechanistic insights into the indolamine dioxygenase superfamily. Zhu X, van Pee KH, Naismith JH; J Biol Chem. 2010;285:21126-21133. PMID:20421301