title: Crystal structure of the NADH:quinone oxidoreductase WrbA from Escherichia coli.
abstract: The flavoprotein WrbA, originally described as a tryptophan (W) repressor-binding protein in Escherichia coli, has recently been shown to exhibit the enzymatic activity of a NADH:quinone oxidoreductase. This finding points toward a possible role in stress response and in the maintenance of a supply of reduced quinone. We have determined the three-dimensional structure of the WrbA holoprotein from E. coli at high resolution (1.66 A), and we observed a characteristic, tetrameric quaternary structure highly similar to the one found in the WrbA homologs of Deinococcus radiodurans and Pseudomonas aeruginosa. A similar tetramer was originally observed in an iron-sulfur flavoprotein involved in the reduction of reactive oxygen species. Together with other, recently characterized proteins such as YhdA or YLR011wp (Lot6p), these tetrameric flavoproteins may constitute a large family with diverse functions in redox catalysis. WrbA binds substrates at an active site that provides an ideal stacking environment for aromatic moieties, while providing a pocket that is structured to stabilize the ADP part of an NADH molecule in its immediate vicinity. Structures of WrbA in complex with benzoquinone and NADH suggest a sequential binding mechanism for both molecules in the catalytic cycle.
authors.affiliation: Institute for Microbiology and Genetics, Georg August University Göttingen, Justus von Liebig Weg 11, 37077 Göttingen, Germany. susana.andrade@bio.uni-goettingen.de
authors.forename: Susana L A
authors.initials: SL
authors.lastname: Andrade
authors.forename: Eric V
authors.initials: EV
authors.lastname: Patridge
authors.forename: James G
authors.initials: JG
authors.lastname: Ferry
authors.forename: Oliver
authors.initials: O
authors.lastname: Einsle
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D004268:DNA-Binding Proteins / Q000737:chemistry*; D034301:Deinococcus / Q000201:enzymology; D004926:Escherichia coli / Q000201:enzymology*; D029968:Escherichia coli Proteins / Q000737:chemistry*; D017434:Protein Structure, Tertiary; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D012097:Repressor Proteins / Q000737:chemistry*
chemical_list: D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012097:Repressor Proteins; C081759:WrbA protein, E coli