331d

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spinqualitylabelsall models 331d, resolution 1.650Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image

CRYSTAL STRUCTURE OF D(GCGCGCG) WITH 5'-OVERHANG G'S

Overview

The crystal structure of the DNA heptamer d(GCGCGCG) has been solved at, 1.65 A resolution by the molecular replacement method and refined to an, R-value of 0.184 for 3598 reflections. The heptamer forms a Z-DNA, d(CGCGCG)2 with 5'-overhang G residues instead of an A-DNA d(GCGCGC)2 with, 3'-overhang G residues. The overhang G residues from parallel strands of, two adjacent duplexes form a trans reverse Hoogsteen G x G basepair that, stacks on the six Z-DNA basepairs to produce a pseudocontinuous helix. The, reverse Hoogsteen G x G basepair is unusual in that the displacement of, one G base relative to the other allows them to participate in a, bifurcated (G1)N2 . . . N7(G8) and an enhanced (G8)C8-H . . . O6(G1), hydrogen bond, in addition to the two usual hydrogen bonds. The, 5'-overhang G residues are anti and C2'-endo while the 3'-terminal G, residues are syn and C2'-endo. The conformations of both G residues are, different from the syn/C3'-endo for the guanosine in a standard Z-DNA. The, two cobalt hexammine ions bind to the phosphate groups in both GpC and CpG, steps in Z(I) and Z(II) conformations. The water structure motif is, similar to the other Z-DNA structures.

About this Structure

331D is a Protein complex structure of sequences from [1] with as ligand. Full crystallographic information is available from OCA.

Reference

Crystal structure of d(GCGCGCG) with 5'-overhang G residues., Pan B, Ban C, Wahl MC, Sundaralingam M, Biophys J. 1997 Sep;73(3):1553-61. PMID:9284322

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