3M6K : Crystal Structure of N-terminal 44 kDa fragment of topoisomerase V in the presence of guanidium hydrochloride



Experimental Technique/Method:X-RAY DIFFRACTION
Release Date:2010-08-04
Deposition Date:2010-03-15
Revision Date:2011-07-13
Molecular Weight:88748.94
Macromolecule Type:Protein
Residue Count:760
Atom Site Count:5986

Topoisomerase V is an archaeal type I topoisomerase that is unique among topoisomerases due to presence of both topoisomerase and DNA repair activities in the same protein. It is organized as an N-terminal topoisomerase domain followed by 24 tandem helix-hairpin-helix (HhH) motifs. Structural studies have shown that the active site is buried by the (HhH) motifs. Here we show that the N-terminal domain can relax DNA in the absence of any HhH motifs and that the HhH motifs are required for stable protein-DNA complex formation. Crystal structures of various topoisomerase V fragments show changes in the relative orientation of the domains mediated by a long bent linker helix, and these movements are essential for the DNA to enter the active site. Phosphate ions bound to the protein near the active site helped model DNA in the topoisomerase domain and show how topoisomerase V may interact with DNA.
Date made available2010

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