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- Title
Structural characterization of 2,6-dichloro- p-hydroquinone 1,2-dioxygenase ( PcpA) from Sphingobium chlorophenolicum, a new type of aromatic ring-cleavage enzyme.
- Authors
Hayes, Robert P.; Green, Abigail R.; Nissen, Mark S.; Lewis, Kevin M.; Xun, Luying; Kang, ChulHee
- Abstract
PcpA (2,6-dichloro- p-hydroquinone 1,2-dioxygenase) from Sphingobium chlorophenolicum, a non-haem Fe( II) dioxygenase capable of cleaving the aromatic ring of p-hydroquinone and its substituted variants, is a member of the recently discovered p-hydroquinone 1,2-dioxygenases. Here we report the 2.6 Å structure of PcpA, which consists of four βαβββ motifs, a hallmark of the vicinal oxygen chelate superfamily. The secondary co-ordination sphere of the Fe( II) centre forms an extensive hydrogen-bonding network with three solvent exposed residues, linking the catalytic Fe( II) to solvent. A tight hydrophobic pocket provides p-hydroquinones access to the Fe( II) centre. The p-hydroxyl group is essential for the substrate-binding, thus phenols and catechols, lacking a p-hydroxyl group, do not bind to PcpA. Site-directed mutagenesis and kinetic analysis confirm the critical catalytic role played by the highly conserved His10, Thr13, His226 and Arg259. Based on these results, we propose a general reaction mechanism for p-hydroquinone 1,2-dioxygenases.
- Subjects
HYDROQUINONE; PHENOLS; ENZYMES; DIOXYGENASES; CHLOROPHENOLS
- Publication
Molecular Microbiology, 2013, Vol 88, Issue 3, p523
- ISSN
0950-382X
- Publication type
Article
- DOI
10.1111/mmi.12204