331d | pdb_0000331d

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

spinqualitylabelsall models 331d, resolution 1.65Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 331d is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Ligands: NCO Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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