title: Interchange of catalytic activity within the 2-enoyl-coenzyme A hydratase/isomerase superfamily based on a common active site template.
abstract: The structures and chemical pathways associated with the members of the 2-enoyl-CoA hydratase/isomerase enzyme superfamily are compared to show that a common active site design provides the members of this family with a CoA binding site, an expandable acyl binding pocket, an oxyanion hole for binding/polarizing the thioester C=O, and multiple active site stations for the positioning of acidic and basic amino acid side chains for use in proton shuttling. It is hypothesized that this active site template can be tailored to catalyze a wide range of chemical transformations through strategic positioning of acid/base residues among the active site stations. To test this hypothesis, the active site of one member of the 2-enoyl-CoA hydratase/isomerase family, 4-chlorobenzoyl-CoA dehalogenase, was altered by site-directed mutagenesis to include the two glutamate residues functioning in acid/base catalysis in a second family member, crotonase. Catalysis of the syn hydration of crotonyl-CoA, absent in the wild-type 4-chlorobenzoyl-CoA dehalogenase, was shown to occur with the structurally modified 4-chlorobenzoyl-CoA dehalogenase at kcat = 0.06 s-1 and Km = 50 microM.
authors.affiliation: Department of Chemistry, University of New Mexico, Albuquerque 87131, USA.
authors.forename: H
authors.initials: H
authors.lastname: Xiang
authors.forename: L
authors.initials: L
authors.lastname: Luo
authors.forename: K L
authors.initials: KL
authors.lastname: Taylor
authors.forename: D
authors.initials: D
authors.lastname: Dunaway-Mariano
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D001665:Binding Sites / Q000235:genetics; D002384:Catalysis; D018360:Crystallography, X-Ray; D004746:Enoyl-CoA Hydratase / Q000737:chemistry* / Q000235:genetics; D018698:Glutamic Acid / Q000737:chemistry / Q000235:genetics; D007527:Isoenzymes / Q000737:chemistry / Q000235:genetics; D007535:Isomerases / Q000737:chemistry* / Q000235:genetics; D007700:Kinetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000235:genetics; D016297:Mutagenesis, Site-Directed; D019906:Nuclear Magnetic Resonance, Biomolecular; D010446:Peptide Fragments / Q000737:chemistry / Q000235:genetics; D063994:Peroxisomal Bifunctional Enzyme; D015202:Protein Engineering; D017386:Sequence Homology, Amino Acid; D013237:Stereoisomerism; D013698:Templates, Genetic
chemical_list: D007527:Isoenzymes; D009097:Multienzyme Complexes; D010446:Peptide Fragments; D018698:Glutamic Acid; D015094:3-Hydroxyacyl CoA Dehydrogenases; D004746:Enoyl-CoA Hydratase; D063994:Peroxisomal Bifunctional Enzyme; D007535:Isomerases