title: Irreversible covalent modification of type I dehydroquinase with a stable Schiff base.
abstract: The irreversible inhibition of type I dehydroquinase (DHQ1), the third enzyme of the shikimic acid pathway, is investigated by structural, biochemical and computational studies. Two epoxides, which are mimetics of the natural substrate, were designed as irreversible inhibitors of the DHQ1 enzyme and to study the binding requirements of the linkage to the enzyme. The epoxide with the S configuration caused the covalent modification of the protein whereas no reaction was obtained with its epimer. The first crystal structure of DHQ1 from Salmonella typhi covalently modified by the S epoxide, which is reported at 1.4 Å, revealed that the modified ligand is surprisingly covalently attached to the essential Lys170 by the formation of a stable Schiff base. The experimental and molecular dynamics simulation studies reported here highlight the huge importance of the conformation of the C3 carbon of the ligand for covalent linkage to this type of aldolase I enzyme, revealed the key role played by the essential His143 as a Lewis acid in this process and show the need for a neatly closed active site for catalysis.
authors.affiliation: Centro Singular de Investigación en Química Biológica y Materiales Moleculares (CIQUS), Universidad de Santiago de Compostela, calle Jenaro de la Fuente s/n, 15782 Santiago de Compostela, Spain. concepcion.gonzalez.bello@usc.es.
authors.forename: Lorena
authors.initials: L
authors.lastname: Tizón
authors.forename: María
authors.initials: M
authors.lastname: Maneiro
authors.forename: Antonio
authors.initials: A
authors.lastname: Peón
authors.forename: José M
authors.initials: JM
authors.lastname: Otero
authors.forename: Emilio
authors.initials: E
authors.lastname: Lence
authors.forename: Sergio
authors.initials: S
authors.lastname: Poza
authors.forename: Mark J
authors.initials: MJ
authors.lastname: van Raaij
authors.forename: Paul
authors.initials: P
authors.lastname: Thompson
authors.forename: Alastair R
authors.initials: AR
authors.lastname: Hawkins
authors.forename: Concepción
authors.initials: C
authors.lastname: González-Bello
mesh_terms: D001426:Bacterial Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry*; D020134:Catalytic Domain; D018360:Crystallography, X-Ray; D004791:Enzyme Inhibitors / Q000138:chemical synthesis / Q000737:chemistry*; D004852:Epoxy Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D006639:Histidine / Q000737:chemistry; D006836:Hydro-Lyases / Q000037:antagonists & inhibitors / Q000737:chemistry*; D006860:Hydrogen Bonding; D007700:Kinetics; D008024:Ligands; D008239:Lysine / Q000737:chemistry; D056004:Molecular Dynamics Simulation; D011485:Protein Binding; D012485:Salmonella typhi / Q000737:chemistry / Q000201:enzymology; D012545:Schiff Bases / Q000737:chemistry*; D055672:Static Electricity
chemical_list: D001426:Bacterial Proteins; D004791:Enzyme Inhibitors; D004852:Epoxy Compounds; D008024:Ligands; D012545:Schiff Bases; D006639:Histidine; D006836:Hydro-Lyases; C020000:3-dehydroquinate dehydratase; D008239:Lysine