1kwc
The His145Ala mutant of 2,3-dihydroxybiphenyl dioxygenase in complex with 2,3-dihydroxybiphenyl
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OverviewOverview
BphC derived from Pseudomonas sp. strain KKS102 is an extradiol-cleaving, catecholic dioxygenase. This enzyme contains a non-heme iron atom and, plays an important role in degrading biphenyl/polychlorinated biphenyls, (PCBs) in the microbe. To elucidate detailed structures of BphC reaction, intermediates, crystal structures of the substrate-free form, the, BphC-substrate complex, and the BphC-substrate-NO (nitric oxide) complex, were determined. These crystal structures revealed (1) the binding site of, the O(2) molecule in the coordination sphere and (2) conformational, changes of His194 during the catalytic reaction. On the basis of these, findings, we propose a catalytic mechanism for the extradiol-cleaving, catecholic dioxygenase in which His194 seems to play three distinct roles., At the early stage of the catalytic reaction, His194 appears to act as a, catalytic base, which likely deprotonates the hydroxyl group of the, substrate. At the next stage, the protonated His194 seems to stabilize a, negative charge on the O2 molecule located in the hydrophobic O2-binding, cavity. Finally, protonated His194 seems to function as a proton donor, whose existence has been proposed.
About this StructureAbout this Structure
1KWC is a Single protein structure of sequence from Pseudomonas sp. with BPY as ligand. Active as Biphenyl-2,3-diol 1,2-dioxygenase, with EC number 1.13.11.39 Full crystallographic information is available from OCA.
ReferenceReference
Crystal structures of the reaction intermediate and its homologue of an extradiol-cleaving catecholic dioxygenase., Sato N, Uragami Y, Nishizaki T, Takahashi Y, Sazaki G, Sugimoto K, Nonaka T, Masai E, Fukuda M, Senda T, J Mol Biol. 2002 Aug 23;321(4):621-36. PMID:12206778
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