title: Topoisomerase V relaxes supercoiled DNA by a constrained swiveling mechanism.
abstract: 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.
authors.affiliation: Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.
authors.forename: Bhupesh
authors.initials: B
authors.lastname: Taneja
authors.forename: Bernhard
authors.initials: B
authors.lastname: Schnurr
authors.forename: Alexei
authors.initials: A
authors.lastname: Slesarev
authors.forename: John F
authors.initials: JF
authors.lastname: Marko
authors.forename: Alfonso
authors.initials: A
authors.lastname: Mondragón
mesh_terms: D002138:Calibration; D004264:DNA Topoisomerases, Type I / Q000235:genetics / Q000378:metabolism*; D004278:DNA, Superhelical / Q000737:chemistry* / Q000378:metabolism*; D034301:Deinococcus / Q000201:enzymology; D019605:Euryarchaeota / Q000201:enzymology; D016013:Likelihood Functions; D008280:Magnetics; D008958:Models, Molecular; D052898:Optical Tweezers; D011487:Protein Conformation; D014615:Vaccinia / Q000201:enzymology