Properties of phosphoenolpyruvate mutase, the first enzyme in the aminoethylphosphonate biosynthetic pathway in Trypanosoma cruzi

Mitali Sarkar, Christopher J. Hamilton, Alan H. Fairlamb

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    Abstract

    Phosphoenolpyruvate ( PEP) mutase catalyzes the conversion of phosphoenolpyruvate to phosphonopyruvate, the initial step in the formation of many naturally occurring phosphonate compounds. The phosphonate compound 2- aminoethylphosphonate is present as a component of complex carbohydrates on the surface membrane of many trypanosomatids including glycosylinositolphospholipids of Trypanosoma cruzi. Using partial sequence information from the T. cruzi genome project we have isolated a full- length gene with significant homology to PEP mutase from the free- living protozoan Tetrahymena pyriformis and the edible mussel Mytilus edulis. Recombinant expression in Escherichia coli confirms that it encodes a functional PEP mutase with a K-m apparent of 8 muM for phosphonopyruvate and a k(cat) of 12 s(-1). The native enzyme is a homotetramer with an absolute requirement for divalent metal ions and displays negative cooperativity for Mg2+ (S-0.5 0.4 muM; n = 0.46). Immunofluorescence and sub- cellular fractionation indicates that PEP mutase has a dual localization in the cell. Further evidence to support this was obtained by Western analysis of a partial sub- cellular fractionation of T. cruzi cells. Southern and Western analysis suggests that PEP mutase is unique to T. cruzi and is not present in the other medically important parasites, Trypanosoma brucei and Leishmania spp.
    Original languageEnglish
    Pages (from-to)22703-22708
    Number of pages6
    JournalJournal of Biological Chemistry
    Volume278
    Issue number25
    DOIs
    Publication statusPublished - 2003

    Keywords

    • PHOSPHATE DIKINASE
    • PYRUVATE
    • PHOSPHONOLIPIDS
    • TRYPANOTHIONE
    • PROTEINS
    • TETRAHYMENA-PYRIFORMIS
    • CARBON-PHOSPHORUS BOND
    • CLONING

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