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Proc Natl Acad Sci U S A. 2007 Sep 11;104(37):14670-5. Epub 2007 Sep 5.

Topoisomerase V relaxes supercoiled DNA by a constrained swiveling mechanism.

Author information

1
Department of Biochemistry, Molecular Biology, and Cell Biology, Northwestern University, 2205 Tech Drive, Evanston, IL 60208, USA.

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.

PMID:
17804808
PMCID:
PMC1976220
DOI:
10.1073/pnas.0701989104
[Indexed for MEDLINE]
Free PMC Article

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