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Publication Abstract from PubMed

Type IIA and type IIB topoisomerases each possess the ability to pass one DNA duplex through another in an ATP-dependent manner. The role of ATP in the strand passage reaction is poorly understood, particularly for the type IIB (topoisomerase VI) family. We have solved the structure of the ATP-binding subunit of topoisomerase VI (topoVI-B) in two states: an unliganded monomer and a nucleotide-bound dimer. We find that topoVI-B is highly structurally homologous to the entire 40-43 kDa ATPase region of type IIA topoisomerases and MutL proteins. Nucleotide binding to topoVI-B leads to dimerization of the protein and causes dramatic conformational changes within each protomer. Our data demonstrate that type IIA and type IIB topoisomerases have descended from a common ancestor and reveal how ATP turnover generates structural signals in the reactions of both type II topoisomerase families. When combined with the structure of the A subunit to create a picture of the intact topoisomerase VI holoenzyme, the ATP-driven motions of topoVI-B reveal a simple mechanism for strand passage by the type IIB topoisomerases.

Structure of the topoisomerase VI-B subunit: implications for type II topoisomerase mechanism and evolution.,Corbett KD, Berger JM EMBO J. 2003 Jan 2;22(1):151-63. PMID:12505993^[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.