2pfj
From Proteopedia
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Crystal Structure of T7 Endo I resolvase in complex with a Holliday Junction
Overview
The four-way (Holliday) DNA junction is the central intermediate in, homologous recombination, a ubiquitous process that is important in DNA, repair and generation of genetic diversity. The penultimate stage of, recombination requires resolution of the DNA junction into nicked-duplex, species by the action of a junction-resolving enzyme, examples of which, have been identified in a wide variety of organisms. These enzymes are, nucleases that are highly selective for the structure of branched DNA. The, mechanism of this selectivity has, however, been unclear in the absence of, structural data. Here we present the crystal structure of the, junction-resolving enzyme phage T7 endonuclease I in complex with a, synthetic four-way DNA junction. Although the enzyme is, structure-selective, significant induced fit occurs in the interaction, with changes in the structure of both the protein and the junction. The, dimeric enzyme presents two binding channels that contact the backbones of, the junction's helical arms over seven nucleotides. These interactions, effectively measure the relative orientations and positions of the arms of, the junction, thereby ensuring that binding is selective for branched DNA, that can achieve this geometry.
About this Structure
2PFJ is a Single protein structure of sequence from Enterobacteria phage t2 with as ligand. Active as Deoxyribonuclease IV (phage-T(4)-induced), with EC number 3.1.21.2 Full crystallographic information is available from OCA.
Reference
The structural basis of Holliday junction resolution by T7 endonuclease I., Hadden JM, Declais AC, Carr SB, Lilley DM, Phillips SE, Nature. 2007 Oct 4;449(7162):621-4. Epub 2007 Sep 16. PMID:17873858
Page seeded by OCA on Wed Jan 23 12:36:55 2008
