title: The violacein biosynthetic enzyme VioE shares a fold with lipoprotein transporter proteins.
abstract: VioE, an unusual enzyme with no characterized homologues, plays a key role in the biosynthesis of violacein, a purple pigment with antibacterial and cytotoxic properties. Without bound cofactors or metals, VioE, from the bacterium Chromobacterium violaceum, mediates a 1,2 shift of an indole ring and oxidative chemistry to generate prodeoxyviolacein, a precursor to violacein. Our 1.21 A resolution structure of VioE shows that the enzyme shares a core fold previously described for lipoprotein transporter proteins LolA and LolB. For both LolB and VioE, a bound polyethylene glycol molecule suggests the location of the binding and/or active site of the protein. Mutations of residues near the bound polyethylene glycol molecule in VioE have identified the active site and five residues important for binding or catalysis. This structural and mutagenesis study suggests that VioE acts as a catalytic chaperone, using a fold previously associated with lipoprotein transporters to catalyze the production of its prodeoxyviolacein product.
authors.affiliation: Department of Biology and Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
authors.forename: Katherine S
authors.initials: KS
authors.lastname: Ryan
authors.forename: Carl J
authors.initials: CJ
authors.lastname: Balibar
authors.forename: Kaitlyn E
authors.initials: KE
authors.lastname: Turo
authors.forename: Christopher T
authors.initials: CT
authors.lastname: Walsh
authors.forename: Catherine L
authors.initials: CL
authors.lastname: Drennan
mesh_terms: D000900:Anti-Bacterial Agents / Q000096:biosynthesis / Q000737:chemistry; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites / Q000502:physiology; D002352:Carrier Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D002384:Catalysis; D002861:Chromobacterium / Q000201:enzymology* / Q000235:genetics; D018360:Crystallography, X-Ray; D003603:Cytotoxins / Q000096:biosynthesis / Q000737:chemistry; D029968:Escherichia coli Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D007211:Indoles / Q000737:chemistry* / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D009154:Mutation; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D033902:Periplasmic Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D040681:Structural Homology, Protein
chemical_list: D000900:Anti-Bacterial Agents; D001425:Bacterial Outer Membrane Proteins; D002352:Carrier Proteins; D003603:Cytotoxins; D029968:Escherichia coli Proteins; D007211:Indoles; C116111:LolA protein, E coli; C087012:LolB protein, E coli; D018832:Molecular Chaperones; D033902:Periplasmic Binding Proteins; D011092:Polyethylene Glycols; D010088:Oxidoreductases; C063155:violacein