High regularity of Z-DNA revealed by ultra high-resolution crystal structure at 0.55 A.
Publication Type:Journal Article
Source:Nucleic Acids Res, Volume 39, Issue 14, p.6238-48 (2011)
Keywords:Base Pairing, Crystallography, X-Ray, DNA, Z-Form, Models, Molecular, Stereoisomerism, Water
<p>The crystal structure of a Z-DNA hexamer duplex d(CGCGCG)(2) determined at ultra high resolution of 0.55 Å and refined without restraints, displays a high degree of regularity and rigidity in its stereochemistry, in contrast to the more flexible B-DNA duplexes. The estimations of standard uncertainties of all individually refined parameters, obtained by full-matrix least-squares optimization, are comparable with values that are typical for small-molecule crystallography. The Z-DNA model generated with ultra high-resolution diffraction data can be used to revise the stereochemical restraints applied in lower resolution refinements. Detailed comparisons of the stereochemical library values with the present accurate Z-DNA parameters, shows in general a good agreement, but also reveals significant discrepancies in the description of guanine-sugar valence angles and in the geometry of the phosphate groups.</p>