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    pH Dependence of Catalysis by Pseudomonas aeruginosa Isochorismate-Pyruvate Lyase: Implications for Transition State Stabilization and the Role of Lysine 42

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    Issue Date
    2011-08-23
    Author
    Olucha, José
    Ouellette, Andrew Nicholas
    Luo, Qianyi
    Lamb, Audrey L.
    Publisher
    ACS
    Type
    Article
    Article Version
    Scholarly/refereed, author accepted manuscript
    Rights
    Copyright © 2011 American Chemical Society
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    Abstract
    An isochorismate-pyruvate lyase with adventitious chorismate mutase activity from Pseudomonas aerugionsa (PchB) achieves catalysis of both pericyclic reactions in part by the stabilization of reactive conformations and in part by electrostatic transition-state stabilization. When the active site loop Lys42 is mutated to histidine, the enzyme develops a pH dependence corresponding to a loss of catalytic power upon deprotonation of the histidine. Structural data indicate that the change is not due to changes in active site architecture, but due to the difference in charge at this key site. With loss of the positive charge on the K42H sidechain at high pH, the enzyme retains lyase activity at approximately 100-fold lowered catalytic efficiency, but loses detectable mutase activity. We propose that both substrate organization and electrostatic transition state stabilization contribute to catalysis. However, the dominant reaction path for catalysis is dependent on reaction conditions, which influence the electrostatic properties of the enzyme active site amino acid sidechains.
    Description
    This publication was made possible by funds from the American Lung Association of Kansas and from the Kansas Masonic Cancer Research Institute, by the Graduate Training Program in Dynamic Aspects of Chemical Biology NIH grant T32 GM08545 (J.O.) from the National Institute of General Medical Sciences, by NIH grant P20 RR016475 from the INBRE Program of the National Center for Research Resources, and by NIH grants R01 AI77725 and K02 AI093675 from the National Institute for Allergy and Infectious Disease.
    URI
    http://hdl.handle.net/1808/23708
    DOI
    https://doi.org/10.1021/bi200599j
    Collections
    • Molecular Biosciences Scholarly Works [581]
    Citation
    Olucha, J., Ouellette, A. N., Luo, Q., & Lamb, A. L. (2011). pH Dependence of Catalysis by Pseudomonas aeruginosa Isochorismate-Pyruvate Lyase: Implications for Transition State Stabilization and the Role of Lysine 42. Biochemistry, 50(33), 7198–7207. http://doi.org/10.1021/bi200599j

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    Contact KU ScholarWorks
    785-864-8983
    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    785-864-8983

    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    Image Credits
     

     

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