title: Catalytic mechanism of Escherichia coli isopentenyl diphosphate isomerase involves Cys-67, Glu-116, and Tyr-104 as suggested by crystal structures of complexes with transition state analogues and irreversible inhibitors.
abstract: Isopentenyl diphosphate (IPP):dimethylallyl diphosphate (DMAPP) isomerase is a key enzyme in the biosynthesis of isoprenoids. The reaction involves protonation and deprotonation of the isoprenoid unit and proceeds through a carbocationic transition state. Analysis of the crystal structures (2 A) of complexes of Escherichia coli IPP.DMAPPs isomerase with a transition state analogue (N,N-dimethyl-2-amino-1-ethyl diphosphate) and a covalently attached irreversible inhibitor (3,4-epoxy-3-methyl-1-butyl diphosphate) indicates that Glu-116, Tyr-104, and Cys-67 are involved in the antarafacial addition/elimination of protons during isomerization. This work provides a new perspective about the mechanism of the reaction.
authors.affiliation: Institut de Recherches Microbiologiques J.M. Wiame, 1 av E. Gryzon 1070 Bruxelles, Belgium. jwouters@dbm.ulb.ac.be
authors.forename: J
authors.initials: J
authors.lastname: Wouters
authors.forename: Y
authors.initials: Y
authors.lastname: Oudjama
authors.forename: Sam J
authors.initials: SJ
authors.lastname: Barkley
authors.forename: C
authors.initials: C
authors.lastname: Tricot
authors.forename: V
authors.initials: V
authors.lastname: Stalon
authors.forename: L
authors.initials: L
authors.lastname: Droogmans
authors.forename: C Dale
authors.initials: CD
authors.lastname: Poulter
mesh_terms: D019748:Carbon-Carbon Double Bond Isomerases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D020134:Catalytic Domain; D003461:Crystallography; D003545:Cysteine / Q000737:chemistry; D004852:Epoxy Compounds / Q000494:pharmacology; D004926:Escherichia coli / Q000201:enzymology*; D018698:Glutamic Acid / Q000737:chemistry; D045782:Hemiterpenes; D007700:Kinetics; D009943:Organophosphorus Compounds / Q000494:pharmacology; D017433:Protein Structure, Secondary; D014443:Tyrosine / Q000737:chemistry
chemical_list: D004852:Epoxy Compounds; D045782:Hemiterpenes; D009943:Organophosphorus Compounds; C077385:3-methyl-3,4-epoxybutyl diphosphate; D018698:Glutamic Acid; D014443:Tyrosine; D019748:Carbon-Carbon Double Bond Isomerases; C021453:isopentenyldiphosphate delta-isomerase; D003545:Cysteine