1sww

Crystal structure of the phosphonoacetaldehyde hydrolase D12A mutant complexed with magnesium and substrate phosphonoacetaldehyde

spinqualitylabelsall models 1sww, resolution 2.30Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1sww is a 2 chain structure with sequence from Bacillus cereus. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: X-ray diffraction, Resolution 2.3Å Ligands: MG, POA Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PHNX_BACCE Involved in phosphonate degradation. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMed The 2-haloalkanoic acid dehalogenase (HAD) family, which contains both carbon and phosphoryl transferases, is one of the largest known enzyme superfamilies. HAD members conserve an alpha,beta-core domain that frames the four-loop active-site platform. Each loop contributes one or more catalytic groups, which function in mediating the core chemistry (i.e., group transfer). In this paper, we provide evidence that the number of carboxylate residues on loop 4 and their positions (stations) on the loop are determinants, and therefore reliable sequence markers, for metal ion activation among HAD family members. Using this predictor, we conclude that the vast majority of the HAD members utilize a metal cofactor. Analysis of the minimum requirements for metal cofactor binding was carried out using Mg(II)-activated Bacillus cereus phosphonoacetaldehyde hydrolase (phosphonatase) as an experimental model for metal-activated HAD members. Mg(II) binding occurs via ligation to the loop 1 Asp12 carboxylate and Thr14 backbone carbonyl and to the loop 4 Asp186 carboxylate. The loop 4 Asp190 forms a hydrogen bond to the Mg(II) water ligand. X-ray structure determination of the D12A mutant in the presence of the substrate phosphonoacetaldehyde showed that replacement of the loop 1 Asp, common to all HAD family members, with Ala shifts the position of Mg(II), thereby allowing innersphere coordination to Asp190 and causing a shift in the position of the substrate. Kinetic analysis of the loop 4 mutants showed that Asp186 is essential to cofactor binding while Asp190 simply enhances it. Within the phosphonatase subfamily, Asp186 is stringently conserved, while either position 185 or position 190 is used to position the second loop 4 Asp residue. Retention of a high level of catalytic activity in the G185D/D190G phosphonatase mutant demonstrated the plasticity of the metal binding loop, reflected in the variety of combinations in positioning of two or three Asp residues along the seven-residue motif of the 2700 potential HAD sequences that were examined. Investigation of metal ion binding in phosphonoacetaldehyde hydrolase identifies sequence markers for metal-activated enzymes of the HAD enzyme superfamily.,Zhang G, Morais MC, Dai J, Zhang W, Dunaway-Mariano D, Allen KN Biochemistry. 2004 May 4;43(17):4990-7. PMID:15109258 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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