Fig. 2

Violacein biosynthesis. A Biosynthetic gene cluster of VioABCDE operon of Janthinobacterium lividum GCA 900451145 (Gene ID: NCTC9796_03462) [56] that code for key enzymes in the five-step biosynthesis of violacein. B Biosynthetic pathway of violacein production. VioA encodes L-tryptophan oxidase which is the first enzyme required for IPA imine formation; this enzyme functions with an FAD co-factor. The VioB gene encodes an oxidase with a heme moiety, then utilizes IPA imine intermediate as a substrate to form the IPA imine dimer. The VioE-encoded enzyme in turn uses the dimer as a substrate, transforming it into intermediates for use by VioD and VioC-encoded enzymes. VioD and VioC encode FAD dependent-monooxygenases and both lead to the formation of violacein and deoxyviolacein