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The versatile thymine DNA‐glycosylase: a comparative characterization of the human, Drosophila and fission yeast orthologs

Hardeland, Ulrike ; Bentele, Marc ; Jiricny, Josef ; Schär, Primo

In: Nucleic Acids Research, 2003, vol. 31, no. 9, p. 2261-2271

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    Titre
    • The versatile thymine DNA‐glycosylase: a comparative characterization of the human, Drosophila and fission yeast orthologs
    Auteur
    • Hardeland, Ulrike. Institute of Molecular Cancer Research, University of Zürich, August Forel Strasse 7, CH‐8008 Zürich, Switzerland
    • Bentele, Marc. Institute of Molecular Cancer Research, University of Zürich, August Forel Strasse 7, CH‐8008 Zürich, Switzerland
    • Jiricny, Josef. Institute of Molecular Cancer Research, University of Zürich, August Forel Strasse 7, CH‐8008 Zürich, Switzerland
    • Schär, Primo. Institute of Molecular Cancer Research, University of Zürich, August Forel Strasse 7, CH‐8008 Zürich, Switzerland
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Nucleic Acids Research, 2003, vol. 31, no. 9, p. 2261-2271. Oxford University Press
    Autre version électronique
    Classification
    • Santé
    Identifiant OAI-PMH
    • oai:doc.rero.ch:294419
    Summary
    Human thymine‐DNA glycosylase (TDG) is well known to excise thymine and uracil from G·T and G·U mismatches, respectively, and was therefore proposed to play a central role in the cellular defense against genetic mutation through spontaneous deamination of 5‐methylcytosine and cytosine. In this study, we characterized two newly discovered orthologs of TDG, the Drosophila melanogaster Thd1p and the Schizosaccharomyces pombe Thp1p proteins, with an objective to address the function of this subfamily of uracil‐DNA glycosylases from an evolutionary perspective. A systematic biochemical comparison of both enzymes with human TDG revealed a number of biologically significant facts. (i) All eukaryotic TDG orthologs have broad and species‐specific substrate spectra that include a variety of damaged pyrimidine and purine bases; (ii) the common most efficiently processed substrates of all are uracil and 3,N4‐ ethenocytosine opposite guanine and 5‐fluorouracil in any double‐stranded DNA context; (iii) 5‐methylcytosine and thymine derivatives are processed with an appreciable efficiency only by the human and the Drosophila enzymes; (iv) none of the proteins is able to hydrolyze a non‐damaged 5′‐methylcytosine opposite G; and (v) the double strand and mismatch dependency of the enzymes varies with the substrate and is not a stringent feature of this subfamily of DNA glycosylases. These findings advance our current view on the role of TDG proteins and document that they have evolved with high structural flexibility to counter a broad range of DNA base damage in accordance with the specific needs of individual species