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Etudes des topoisomérases de type II par micromanipulation d'ADN

Abstract : We have studied the behaviour of type II topoisomerases using a single DNA molecule micromanipulation setup. topoisomerases are enzymes responsible for regulating DNA topology in the cell, especially during replication, transcription, and chromosome condensation. In the first part of this thesis, we introduce the topological formalism required to understand the structure adopted by DNA molecules in solution. Next, we present the standard techniques used to investigate DNA topology. In the second part, we present the micromanipulation setup used to conduct experiments. The apparatus is based on a magnetic trap, which allows measurement of the elastic properties (stretching and twisting) of a single DNA molecule. It also permits braiding two DNA molecules around each other. Therefore, it is well suited to study decatenation or relaxation of DNA supercoiling by type II topoisomerases. In the third part, we relate the results we obtained on different topoisomerase enzymes. We show that single molecule experiments allow detailed analysis of the kinetic cycle of topoisomerases. Furthermore, we investigate and explain the basis of substrate recognition by topoisomerase IV. Finally, we present experiments describing the thermodynamic properties of these enzymes.
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Contributor : Gilles Charvin <>
Submitted on : Sunday, October 3, 2004 - 6:34:58 PM
Last modification on : Tuesday, December 8, 2020 - 3:33:38 AM
Long-term archiving on: : Friday, April 2, 2010 - 8:17:51 PM


  • HAL Id : tel-00007023, version 1


Gilles Charvin. Etudes des topoisomérases de type II par micromanipulation d'ADN. Biochimie [q-bio.BM]. Université Paris-Diderot - Paris VII, 2004. Français. ⟨tel-00007023⟩



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