title: Structure of 2-haloacid dehalogenase from Pseudomonas syringae pv. tomato DC3000.
abstract: 2-Haloacid dehalogenases (2-HADs) catalyse the hydrolytic dehalogenation of 2-haloalkanoic acids, cleaving the carbon-halide bond at the C(α)-atom position and releasing a halogen atom. These enzymes are of interest for their potential use in bioremediation and in the synthesis of industrial chemicals. Here, the crystal structure of 2-HAD from Pseudomonas syringae pv. tomato DC3000 (ps-2-HAD) at 1.98 Å resolution solved using the single-wavelength anomalous dispersion method is reported. The ps-2-HAD molecule consists of two structurally distinct domains: the core domain and the subdomain. Enzymatic activity analysis of ps-2-HAD revealed its capacity to catalyse the dehalogenation of both L- and D-substrates; however, the structure of ps-2-HAD is completely different from that of DehI, which is the only DL-2-HAD enzyme that has been structurally characterized, but shows similar overall folding to L-HADs. Single mutations of four amino-acid residues at the putative active site showed that they are related to its enzymatic activity, yet three of them are nonconserved among HADs. These observations imply that ps-2-HAD has a novel active site and a unique catalytic behaviour compared with other HADs. This study provides a structural basis and biochemical evidence for further elucidation of the catalytic mechanism of 2-HAD.
authors.affiliation: National Laboratory of Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, 15 Datun Road, Chaoyang District, Beijing 100101, People's Republic of China.
authors.forename: Zhiqiang
authors.initials: Z
authors.lastname: Hou
authors.forename: Hongmei
authors.initials: H
authors.lastname: Zhang
authors.forename: Mei
authors.initials: M
authors.lastname: Li
authors.forename: Wenrui
authors.initials: W
authors.lastname: Chang
mesh_terms: D002384:Catalysis; D020134:Catalytic Domain; D006867:Hydrolases / Q000737:chemistry* / Q000235:genetics; D008958:Models, Molecular; D011487:Protein Conformation; D044224:Pseudomonas syringae / Q000201:enzymology* / Q000235:genetics; D013379:Substrate Specificity; D014961:X-Ray Diffraction
chemical_list: D006867:Hydrolases; C034507:2-haloacid dehalogenase
keywords: 2-haloacid dehalogenases; enzymatic activity; mutation