title: Identification of important residues in diketoreductase from Acinetobacter baylyi by molecular modeling and site-directed mutagenesis.
abstract: Diketoreductase (DKR) from Acinetobacter baylyi exhibits a unique property of double reduction of a β, δ-diketo ester with excellent stereoselectivity, which can serve as an efficient biocatalyst for the preparation of an important chiral intermediate for cholesterol lowering statin drugs. Taken the advantage of high homology between DKR and human heart 3-hydroxyacyl-CoA dehydrogenase (HAD), a molecular model was created to compare the tertiary structures of DKR and HAD. In addition to the possible participation of His-143 in the enzyme catalysis by pH profile, three key amino acid residues, Ser-122, His-143 and Glu-155, were identified and mutated to explore the possibility of involving in the catalytic process. The catalytic activities for mutants S122A/C, H143A/K and E155Q were below detectable level, while their binding affinities to the diketo ester substrate and cofactor NADH did not change obviously. The experimental results were further supported by molecular docking, suggesting that Ser-122 and His-143 were essential for the proton transfer to the carbonyl functional groups of the substrate. Moreover, Glu-155 was crucial for maintaining the proper orientation and protonation of the imidazole ring of His-143 for efficient catalysis.
authors: Laboratory of Chemical Biology, China Pharmaceutical University, 24 Tongjia Street, Nanjing, Jiangsu Province 210009, People's Republic of China.
authors: Yan
authors: Y
authors: Huang
authors: Zhuo
authors: Z
authors: Lu
authors: Nan
authors: N
authors: Liu
authors: Yijun
authors: Y
authors: Chen
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D000150:Acinetobacter / Q000201:enzymology* / Q000235:genetics; D020816:Amino Acid Motifs; D019943:Amino Acid Substitution; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D055162:Biocatalysis; D004952:Esters / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000378:metabolism; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D009243:NAD / Q000378:metabolism; D010084:Oxidation-Reduction; D010088:Oxidoreductases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism
chemical_list: D001426:Bacterial Proteins; D004952:Esters; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011994:Recombinant Proteins; D009243:NAD; D010088:Oxidoreductases; D015094:3-Hydroxyacyl CoA Dehydrogenases; C108634:HSD17B10 protein, human