Topoisomerase V relaxes supercoiled DNA by a constrained swiveling mechanism

作者：Bhupesh Taneja, Bernhard Schnurr, Alexeï Slesarev, John F. Marko, Alfonso Mondragón · 发表于：Proceedings of the National Academy of Sciences · 年份：2007 · DOI：10.1073/pnas.0701989104 · 被引用次数：58 · 研究领域：Cancer therapeutics and mechanisms、Neuroblastoma Research and Treatments、Bioactive Compounds and Antitumor Agents

Topoisomerase V is a type I topoisomerase without structural or sequence similarities to other topoisomerases. Although it belongs to the type I subfamily of topoisomerases, it is unrelated to either type IA or IB enzymes. We used real-time single-molecule micromechanical experiments to show that topoisomerase V relaxes DNA via events that release multiple DNA turns, employing a constrained swiveling mechanism similar to that for type IB enzymes. Relaxation is powered by the torque in the supercoiled DNA and is constrained by friction between the protein and the DNA. Although all type IB enzymes share a common structure and mechanism and type IA and type II enzymes show marked structural and functional similarities, topoisomerase V represents a different type of topoisomerase that relaxes DNA in a similar overall manner as type IB molecules but by using a completely different structural and mechanistic framework.