Trypanothione biosynthesis in Leishmania major

Sandra L. Oza (Lead / Corresponding author), Matthew P. Shaw, Susan Wyllie, Alan H. Fairlamb

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    82 Citations (Scopus)


    Trypanothione plays a crucial role in regulation of intracellular thiol redox balance and in defence against chemical and oxidant stress. Crithidia fasciculata requires two enzymes for the formation of trypanothione, namely glutathionylspermidine synthetase (GspS; EC and a glutathionylspermidine-dependent trypanothione synthetase (TryS; EC, whereas Trypanosoma cruzi and Trypanosoma brucei use a broad-specificity trypanothione synthetase to make trypanothione from glutathione (GSH) and spermidine. Here, we report the identification of two genes in Leishmania major with similarity to previously identified GSPS and TRYS. GSPS is an apparent pseudogene containing two frame shift mutations and two stop codons, whereas TRYS is in a single open-reading frame. The enzyme encoded by TRYS was expressed and found to catalyse formation of trypanothione with GSH and either spermidine or glutathionylspermidine. When GSH is varied as substrate the enzyme displays substrate inhibition (apparent Km = 89 μM, Kis = 1 mM, kcat = 2s-1). At a fixed GSH concentration, the enzyme obeys simple hyperbolic kinetics with the other substrates with apparent Km values for spermidine, glutathionylspermidine and MgATP of 940, 40 and 63 μM, respectively. Immunofluorescence and sub-cellular fractionation studies indicate that TryS localises to the cytosol of L. major promastigotes. Phylogenetic analysis of the GspS and TryS amino acid sequences suggest that in the trypanosomatids, TryS has evolved to replace the GspS/TryS complex in C. fasciculata. It also appears that the L. major still harbours a redundant GSPS pseudogene that may be currently in the process of being lost from its genome.

    Original languageEnglish
    Pages (from-to)107-116
    Number of pages10
    JournalMolecular and Biochemical Parasitology
    Issue number1
    Publication statusPublished - 1 Jan 2005


    • Drug discovery
    • Enzymology
    • Evolution
    • Trypanothione metabolism

    ASJC Scopus subject areas

    • Parasitology
    • Molecular Biology


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