467d
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(New page: 200px<br /><applet load="467d" size="350" color="white" frame="true" align="right" spinBox="true" caption="467d, resolution 2.16Å" /> '''The structure of a d...)
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Revision as of 19:44, 29 January 2008
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The structure of a decamer forming a four-way junction
Overview
DNA recombination is a universal biological event responsible both for the, generation of genetic diversity and for the maintenance of genome, integrity. A four-way DNA junction, also termed Holliday junction, is the, key intermediate in nearly all recombination processes. This junction is, the substrate of recombination enzymes that promote branch migration or, catalyze its resolution. We have determined the crystal structure of a, four-way DNA junction by multiwavelength anomalous diffraction, and, refined it to 2.16 A resolution. The structure has two-fold symmetry, with, pairwise stacking of the double-helical arms, which form two continuous, B-DNA helices that run antiparallel, cross in a right-handed way, and, contain two G-A mismatches. The exchanging backbones form a compact, structure with strong van der Waals contacts and hydrogen bonds, implying, that a conformational change must occur for the junction to branch-migrate, or isomerize. At the branch point, two phosphate groups from one helix, occupy the major groove of the other one, establishing sequence-specific, hydrogen bonds. These interactions, together with different stacking, energies and steric hindrances, explain the preference for a particular, junction stacked conformer.
About this Structure
467D is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Crystal structure of a DNA Holliday junction., Ortiz-Lombardia M, Gonzalez A, Eritja R, Aymami J, Azorin F, Coll M, Nat Struct Biol. 1999 Oct;6(10):913-7. PMID:10504723
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