The importance of being supercoiled: How DNA mechanics regulate dynamic processes

Through dynamic changes in structure resulting from DNA–protein interactions and constraints given by the structural features of the double helix, chromatin accommodates and regulates different DNA-dependent processes. All DNA transactions (such as transcription, DNA replication and chromosomal segregation) are necessarily linked to strong changes in the topological state of the double helix known as torsional stress or supercoiling. As virtually all DNA transactions are in turn affected by the torsional state of DNA, these changes have the potential to serve as regulatory signals detected by protein partners. This two-way relationship indicates that DNA dynamics may contribute to the regulation of many events occurring during cell life. In this review we will focus on the role of DNA supercoiling in the cellular processes, with particular emphasis on transcription. Besides giving an overview on the multiplicity of factors involved in the generation and dissipation of DNA torsional stress, we will discuss recent studies which give new insight into the way cells use DNA dynamics to perform functions otherwise not achievable. This article is part of a Special Issue entitled: Chromatin in time and space.

► It has been speculated that DNA topology might play a regulatory role in chromosome biology. ► The review focuses on the most recent approaches developed to evaluate this possibility. ► Multiple factors contribute to dynamic changes in DNA topology. ► These changes are involved in the moment-to-moment guidance of crucial processes. ► This real-time regulation is necessary for rapid cellular responses to physiological stimuli.