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Dr. Sandor Kasas

PI of the laboratory: Sandor Kasas
Tél: 021 693 04 58,

Direct supervisor (assistant): Livan Alonso
Tél: 021 693 04 58,

Department: LPMV
Address: Batiment Cubotron, EPFL



Observing Topoisomerase II in action by atomic force microscopy

Description of Project:

Topoisomerases are enzymes that can modify the topology of DNA, thus they relax supercoiled DNA and prevent the formation of DNA knots 1. In addition numerous anticancer drugs interfere with this complex what makes the study of Topo II a highly interesting topic. This project will consist in observing by atomic force microscopy (AFM) 2,3 the interaction between Topo II and DNA.

Question / Aim of the work: One of the goals of this project will consist in measuring the interaction forces between DNA and topoisomerase II and to observe the modulation of the interaction strength by different chemicals such as antitumor drugs. In a second, we plan to observe topoisomerase activity “live” in the imaging chamber of an AFM.

Techniques / methods applied: Electrophoresis, Atomic force microscopy, Computational data analysis

Expected outcome: We estimate that this project can lead to new insights into understanding of protein activity in general and in the mechanisms that permit topoisomerase to carry out its function in particular. Also, it will pave the way for the development of new protocols for imaging protein DNA interactions “live” with the new generation of high speed AFMs.

1. J. C. Wang, Nature reviews 3 (6), 430 (2002).
2. G. Charvin, T. R. Strick, D. Bensimon et al., Annual review of biophysics and biomolecular structure 34, 201 (2005).
3. G. Binnig, C. F. Quate, and C. Gerber, Physical Review Letters 56 (9), 930 (1986).

Link to the group web site


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Rue du Bugnon 9 - CH-1005 Lausanne  - Switzerland  -  Phone +41 21 692 51 00  -  Fax  +41 21 692 51 05