title: Crystal structures of Pseudomonas syringae pv. tomato DC3000 quinone oxidoreductase and its complex with NADPH.
abstract: Zeta-crystallin-like quinone oxidoreductase is NAD(P)H-dependent and catalyzes one-electron reduction of certain quinones to generate semiquinone. Here we present the crystal structures of zeta-crystallin-like quinone oxidoreductase from Pseudomonas syringae pv. tomato DC3000 (PtoQOR) and its complexes with NADPH determined at 2.4 and 2.01A resolutions, respectively. PtoQOR forms as a homologous dimer, each monomer containing two domains. In the structure of the PtoQOR-NADPH complex, NADPH locates in the groove between the two domains. NADPH binding causes obvious conformational changes in the structure of PtoQOR. The putative substrate-binding site of PtoQOR is wider than that of Escherichia coli and Thermus thermophilus HB8. Activity assays show that PtoQOR has weak 1,4-benzoquinone catalytic activity, and very strong reduction activity towards large substrates such as 9,10-phenanthrenequinone. We propose a model to explain the conformational changes which take place during reduction reactions catalyzed by PtoQOR.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, PR China.
authors.forename: Xiaowei
authors.initials: X
authors.lastname: Pan
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhang
authors.forename: Yu
authors.initials: Y
authors.lastname: Gao
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.forename: Wenrui
authors.initials: W
authors.lastname: Chang
mesh_terms: D001665:Binding Sites; D002384:Catalysis; D003461:Crystallography; D004926:Escherichia coli / Q000201:enzymology; D016660:NAD(P)H Dehydrogenase (Quinone) / Q000737:chemistry*; D009249:NADP / Q000737:chemistry*; D011487:Protein Conformation; D044224:Pseudomonas syringae / Q000201:enzymology*; D016963:Thermus thermophilus / Q000201:enzymology
chemical_list: D009249:NADP; D016660:NAD(P)H Dehydrogenase (Quinone)