Studies of DNA-Replication at the Single Molecule Level Using Magnetic Tweezers

Abstract

The development of tools to manipulate single biomolecules has opened a new vista on the study of many cellular processes. In this review we will focus on the use of magnetic tweezers to study the behavior of enzymes involved in DNA replication. Depending on the DNA substrate used, magnetic tweezers give access either to the advancement in real time of the so-called replication fork or to the torsional state (the so-called supercoiled density) of the DNA molecule. We will show how the new tools at our disposal can be used to gain an unprecedented description of the kinetic properties of enzymes. The comparison of these results with theoretical models allows us to get insight into the mechanism used by the enzymes under study. This analysis is often out of reach of more classical, bulk techniques.