title: Mechanism and plasticity of isochorismate pyruvate lyase: a computational study.
abstract: The isochorismate pyruvate lyase (IPL) from Pseudomonas aeruginosa, designated as PchB, catalyzes the transformation of isochorismate into pyruvate and salicylate, but it also catalyzes the rearrangement of chorismate into prephenate, suggesting that both reactions may proceed by a pericyclic mechanism. In this work, molecular dynamics simulations employing hybrid quantum mechanics/molecular mechanics methods have been carried out to get a detailed knowledge of the reaction mechanism of PchB. The results provide a theoretical rate constant enhancement by comparison with the reaction in solution, in agreement with the experimental data, and confirm the pericyclic nature of the reaction mechanism. The robustness of this promiscuous enzyme has been checked by considering the impact of Ala37Ile mutation, previously proposed by us to improve the secondary chorismate mutase (CM) activity. The effect of this mutation, which was shown to increase the rate constant for the CM activity by a factor of 10(3), also increases the IPL catalytic efficiency, although only by a factor of 6.
authors.affiliation: Departament de Quimica Fisica i Analitica, Universitat Jaume I, 12071 Castellon, Spain.
authors.forename: Sergio
authors.initials: S
authors.lastname: Martí
authors.forename: Juan
authors.initials: J
authors.lastname: Andrés
authors.forename: Vicent
authors.initials: V
authors.lastname: Moliner
authors.forename: Estanislao
authors.initials: E
authors.lastname: Silla
authors.forename: Iñaki
authors.initials: I
authors.lastname: Tuñón
authors.forename: Juan
authors.initials: J
authors.lastname: Bertrán
mesh_terms: D002827:Chorismic Acid; D003509:Cyclohexanecarboxylic Acids; D053138:Cyclohexenes; D007700:Kinetics; D008956:Models, Chemical; D056004:Molecular Dynamics Simulation; D020125:Mutation, Missense; D007652:Oxo-Acid-Lyases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D011550:Pseudomonas aeruginosa / Q000201:enzymology; D019289:Pyruvic Acid
chemical_list: D003509:Cyclohexanecarboxylic Acids; D053138:Cyclohexenes; C052985:isochorismic acid; D019289:Pyruvic Acid; D007652:Oxo-Acid-Lyases; C075960:chorismate pyruvate lyase; D002827:Chorismic Acid; C005550:prephenic acid