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Nat Struct Biol. 1999 Apr;6(4):322-6.

Quaternary changes in topoisomerase II may direct orthogonal movement of two DNA strands.

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Whitehead Institute for Biomedical Research, Cambridge, Massachusetts 02140, USA.


Type II DNA topoisomerases mediate the passage of one DNA duplex through a transient break in another, an event essential for chromosome segregation and cell viability. The active sites of the type II topoisomerase dimer associate covalently with the DNA break-points and must separate by at least the width of the second DNA duplex to accommodate transport. A new structure of the Saccharomyces cerevisiae topoisomerase II DNA-binding and cleavage core suggests that in addition to conformational changes in the DNA-opening platform, a dramatic reorganization of accessory domains may occur during catalysis. These conformational differences have implications for both the DNA-breaking and duplex-transport events in the topo II reaction mechanism, suggest a mechanism by which two distinct drug-resistance loci interact, and illustrate the scope of structural changes in the cycling of molecular machines.

[Indexed for MEDLINE]

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