Twisting DNA: single molecule studies

Abstract

Over the past 10 years a number of new techniques have emerged that allow the manipulation of single DNA molecules and other biopolymers (RNA, proteins, etc.). These experiments have permitted the measurement of the DNA stretching and twisting elasticity and have consequently revealed the essential role played by the DNA mechanical properties in its interactions with proteins. We shall first describe the different methods used to stretch and twist single DNA molecules. We will then focus on its behaviour under torsion, especially by discussing the different methods used to estimate its torsional modulus.

Acknowledgments

We acknowledge useful discussions and exchanges with C. Bustamante, N. Cozzarelli, A. Vologodskii, J. Marko, C. Bouchiat, M. Mézard, P. Nelson and D. Chatenay. This work was supported by grants from CNRS, ARC, the UE under the ‘MolSwitch’ program and the ‘ACI jeunes chercheur’ program.

Notes

The authors have been educated as physicists, but have switched in the past 5–10 years to more biologically oriented problems. They have studied the elastic properties of DNA for which they have developed the magnetic trap technique. They have then applied that technique to the study of DNA-protein interactions (topoisomerases, DNA and RNA-polymerases, helicases, DNA translocases, etc.).

Additional information

Notes on contributors

G Charvin

The authors have been educated as physicists, but have switched in the past 5–10 years to more biologically oriented problems. They have studied the elastic properties of DNA for which they have developed the magnetic trap technique. They have then applied that technique to the study of DNA-protein interactions (topoisomerases, DNA and RNA-polymerases, helicases, DNA translocases, etc.).