Analysis of the DNA topoisomerase-II-mediated cleavage of the long terminal repeat of Drosophila 1731 retrotransposon

Authors

  • Evelyne NAHON,

    Corresponding author
    1. URA Centre National de la Recherche Scientifique 1135, Groupe de Génétique Moléculaire et Cellulaire, Université Pierre et Marie Curie, Paris, France
      Correspondence to E. Nahon, URA CNRS 1135, Groupe de Génétique Moléculaire et Cellulaire, Université Pierre et Marie Curie, 7, Quai St. Bernard, F-75005 Paris, France
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  • Martin BEST-BELPOMME,

    1. URA Centre National de la Recherche Scientifique 1135, Groupe de Génétique Moléculaire et Cellulaire, Université Pierre et Marie Curie, Paris, France
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  • Jean-Marie SAUCIER

    1. URA Centre National de la Recherche Scientifique 147, U 140 INSERM, Institut Gustave-Roussy, Villejuif, France
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  • Note. The nucleic acid sequence data published here have been submitted to the EMBL sequence data bank and are available under accession number X07656.

    This work was supported by Centre National de la Recherche Scientifique, Institut National de la Santé et de la Recherche Médicale, Association pour la Recherche sur le Cancer, Ligue Nationale Française contre le Cancer and Fondation pour la Recherche Médicale.

Correspondence to E. Nahon, URA CNRS 1135, Groupe de Génétique Moléculaire et Cellulaire, Université Pierre et Marie Curie, 7, Quai St. Bernard, F-75005 Paris, France

Abstract

The interaction of DNA topoisomerase II with the long terminal repeat (LTR) of the Drosophila melanogaster 1731 retrotransposon was studied. The covalent binding of topoisomerase II to the LTR was strongly stimulated by different inhibitors of the enzyme 4′-demethylepipodophyllotoxin-9-(4,6-O-2-ethylidene-β->-glucopyranoside (VP-16), 4′-(9-acridinylamino)methanesulfon-m-anisidine) (m-AMSA) and an ellipticine derivative. Enzyme-mediated DNA cleavage could be observed in the absence of inhibitors and was stimulated in their presence. Cleavage occurred predominantly at sites located within or at the boundary of alternating purine/pyrimidine tracts in agreement with previous observations [Spitzner, J. R., Chung, I. K. & Muller, M. T. (1990) Eukaryotic topoisomerase II preferentially cleaves alternating purine-pyrimidine repeats, Nucleic Acids Res. 18, 1–11]. In addition, all of the cleavage sites observed in the absence of inhibitor were located in the U3 region of the LTR. The site specificity of drug-induced cleavage was studied and the conformity of the cleavage sites with previously established consensus sequences was examined. Our results suggest that DNA topoisomerase II, through its ability to alter the degree of DNA supercoiling, might be involved in the control of different functions of the LTR.

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