The Library
The structure of the C-C bond hydrolase MhpC provides insights into its catalytic mechanism
Tools
UNSPECIFIED (2005) The structure of the C-C bond hydrolase MhpC provides insights into its catalytic mechanism. Journal of Molecular Biology, 346 (1). pp. 253-265. doi:10.1016/j.jmb.2004.11.033 ISSN 0022-2836.
Research output not available from this repository.
Request-a-Copy directly from author or use local Library Get it For Me service.
Official URL: http://dx.doi.org/10.1016/j.jmb.2004.11.033
Abstract
2-Hydroxy-6-ketonona-2,4-diene-1,9-dioic acid 5,6-hydrolase (MhpC) is a 62 kDa homodimeric enzyme of the phenylpropionate degradation pathway of Escherichia coli. The 2.1 Angstrom resolution X-ray structure of the native enzyme determined from orthorhombic crystals confirms that it is a member of the alpha/beta hydrolase fold family, comprising eight beta-strands interconnected by loops and helices. The 2.8 Angstrom resolution structure of the enzyme co-crystallised with the non-hydrolysable substrate analogue 2,6-diketo-nona-1,9-dioic acid (DKNDA) confirms the location of the active site in a buried channel including Ser110, His263 and Asp235, postulated contributors to a serine protease-like catalytic triad in homologous enzymes. It appears that the ligand binds in two separate orientations. In the first, the C6 keto group of the inhibitor forms a hemi-ketal adduct with the Ser110 side-chain, the C9 carboxylate group interacts, via the intermediacy of a water molecule, with Arg188 at one end of the active site, while the C1 carboxylate group of the inhibitor comes close to His114 at the other end. In the second orientation, the C1 carboxylate group binds at the Arg188 end of the active site and the C9 carboxylate group at the His114 end. These arrangements implicated His114 or His263 as plausible contributors to catalysis of the initial enol/keto tautomerisation of the substrate but lack of conservation of His114 amongst related enzymes and mutagenesis results suggest that His263 is the residue involved. Variability in the quality of the electron density for the inhibitor amongst the eight molecules of the crystal asymmetric unit appears to correlate with alternative positions for the side-chain of His114. This might arise from half-site occupation of the dimeric enzyme and reflect the apparent dissociation of approximately 50% of the keto intermediate from the enzyme during the catalytic cycle. (C) 2004 Elsevier Ltd. All rights reserved.
Item Type: | Journal Article | ||||
---|---|---|---|---|---|
Subjects: | Q Science > QD Chemistry | ||||
Journal or Publication Title: | Journal of Molecular Biology | ||||
Publisher: | ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD | ||||
ISSN: | 0022-2836 | ||||
Official Date: | 11 February 2005 | ||||
Dates: |
|
||||
Volume: | 346 | ||||
Number: | 1 | ||||
Number of Pages: | 13 | ||||
Page Range: | pp. 253-265 | ||||
DOI: | 10.1016/j.jmb.2004.11.033 | ||||
Publication Status: | Published |
Data sourced from Thomson Reuters' Web of Knowledge
Request changes or add full text files to a record
Repository staff actions (login required)
View Item |