In vitro biosynthesis of violacein from L-tryptophan by the enzymes VioA-E from Chromobacterium violaceum.
The purple chromobacterial pigment violacein arises by enzymatic oxidation and coupling of two molecules of l-tryptophan to give a rearranged pyrrolidone-containing scaffold in the final pigment. We have purified five contiguously encoded proteins VioA-E after expression in Escherichia coli and demonstrate the full 14-electron oxidation pathway to yield the final chromophore. The flavoenzyme VioA and the heme protein VioB work in conjunction to oxidize and dimerize l-tryptophan to a nascent product that can default to the off pathway metabolite chromopyrrolic acid. In the presence of VioE, the intermediate instead undergoes on-pathway [1,2] indole rearrangement to prodeoxyviolacein. The last two enzymes in the pathway are flavin-dependent oxygenases, VioC and VioD, that act sequentially. VioD hydroxylates one indole ring at the 5-position to yield proviolacein, and VioC then acts on the other indole ring at the 2-position to create the oxindole and complete violacein formation.
Balibar
Carl J
CJ
Department of Biological Chemistry & Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115.
Walsh
Christopher T
CT
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D002861:Chromobacterium / Q000201:enzymology* / Q000378:metabolism; D006900:Hydroxylation; D007211:Indoles / Q000737:chemistry / Q000378:metabolism*; D007700:Kinetics; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism*; D019159:Nonheme Iron Proteins / Q000235:genetics / Q000378:metabolism*; D010105:Oxygenases / Q000235:genetics / Q000378:metabolism*; D048630:Polyketide Synthases / Q000235:genetics / Q000378:metabolism*; D011760:Pyrrolidinones / Q000138:chemical synthesis; D015398:Signal Transduction; D000637:Transaminases / Q000235:genetics / Q000378:metabolism*; D014364:Tryptophan / Q000737:chemistry / Q000378:metabolism*
D001426:Bacterial Proteins; D007211:Indoles; D019159:Nonheme Iron Proteins; D011760:Pyrrolidinones; D048630:Polyketide Synthases; D014364:Tryptophan; D006899:Mixed Function Oxygenases; D010105:Oxygenases; C497198:vioC protein, Chromobacterium violaceum; C023204:tryptophan 2-monooxygenase; D000637:Transaminases; C497199:VioD aminotransferase; C063155:violacein