Structural and mechanistic insights into type II trypanosomatid tryparedoxin-dependent peroxidases

Magnus S. Alphey, Janine Konig, Alan H. Fairlamb

    Research output: Contribution to journalArticle

    20 Citations (Scopus)

    Abstract

    TbTDPX (Trypanosoma brucei tryparedoxin-dependent peroxidase) is a genetically validated drug target in the fight against African sleeping sickness. Despite its similarity to members of the GPX (glutathione peroxidase) family, TbTDPX2 is functional as a monomer, lacks a selenocysteine residue and relies instead on peroxidatic and resolving cysteine residues for catalysis and uses tryparedoxin rather than glutathione as electron donor. Kinetic studies indicate a saturable Ping Pong mechanism, unlike selenium-dependent GPXs, which display infinite K-m and V-max values. The structure of the reduced enzyme at 2.1 angstrom (0.21 nm) resolution reveals that the catalytic thiol groups are widely separated [19 angstrom (0.19 nm)] and thus unable to form a disulphide bond without a large conformational change in the secondary-structure architecture, as reported for certain plant GPXs. A model of the oxidized enzyme structure is presented and the implications for small-molecule inhibition are discussed.

    Original languageEnglish
    Pages (from-to)375-381
    Number of pages7
    JournalBiochemical Journal
    Volume414
    Issue number3
    DOIs
    Publication statusPublished - 15 Sep 2008

    Keywords

    • dithiol-dependent peroxidase
    • drug discovery
    • glutathione peroxidase
    • Leishmania
    • Trypanosoma
    • trypanothione
    • GLUTATHIONE-PEROXIDASE
    • TRYPANOTHIONE SYNTHETASE
    • THIOREDOXIN
    • BRUCEI
    • ELECTROSTATICS
    • REDUCTASE
    • MODEL
    • FOLD

    Cite this

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    title = "Structural and mechanistic insights into type II trypanosomatid tryparedoxin-dependent peroxidases",
    abstract = "TbTDPX (Trypanosoma brucei tryparedoxin-dependent peroxidase) is a genetically validated drug target in the fight against African sleeping sickness. Despite its similarity to members of the GPX (glutathione peroxidase) family, TbTDPX2 is functional as a monomer, lacks a selenocysteine residue and relies instead on peroxidatic and resolving cysteine residues for catalysis and uses tryparedoxin rather than glutathione as electron donor. Kinetic studies indicate a saturable Ping Pong mechanism, unlike selenium-dependent GPXs, which display infinite K-m and V-max values. The structure of the reduced enzyme at 2.1 angstrom (0.21 nm) resolution reveals that the catalytic thiol groups are widely separated [19 angstrom (0.19 nm)] and thus unable to form a disulphide bond without a large conformational change in the secondary-structure architecture, as reported for certain plant GPXs. A model of the oxidized enzyme structure is presented and the implications for small-molecule inhibition are discussed.",
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    Structural and mechanistic insights into type II trypanosomatid tryparedoxin-dependent peroxidases. / Alphey, Magnus S.; Konig, Janine; Fairlamb, Alan H.

    In: Biochemical Journal, Vol. 414, No. 3, 15.09.2008, p. 375-381.

    Research output: Contribution to journalArticle

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    AU - Konig, Janine

    AU - Fairlamb, Alan H.

    PY - 2008/9/15

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    N2 - TbTDPX (Trypanosoma brucei tryparedoxin-dependent peroxidase) is a genetically validated drug target in the fight against African sleeping sickness. Despite its similarity to members of the GPX (glutathione peroxidase) family, TbTDPX2 is functional as a monomer, lacks a selenocysteine residue and relies instead on peroxidatic and resolving cysteine residues for catalysis and uses tryparedoxin rather than glutathione as electron donor. Kinetic studies indicate a saturable Ping Pong mechanism, unlike selenium-dependent GPXs, which display infinite K-m and V-max values. The structure of the reduced enzyme at 2.1 angstrom (0.21 nm) resolution reveals that the catalytic thiol groups are widely separated [19 angstrom (0.19 nm)] and thus unable to form a disulphide bond without a large conformational change in the secondary-structure architecture, as reported for certain plant GPXs. A model of the oxidized enzyme structure is presented and the implications for small-molecule inhibition are discussed.

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