Download MendeleyCrystal structure of d(GCGCGCG) with 5'-overhang G residues.
Pan, B., Ban, C., Wahl, M.C., Sundaralingam, M.(1997) Biophys J 73: 1553-1561
- PubMed: 9284322
- DOI: https://doi.org/10.1016/S0006-3495(97)78187-6
- Primary Citation of Related Structures:
331D - PubMed Abstract:
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.
Organizational Affiliation:
Biological Macromolecular Structure Center, Department of Chemistry, The Ohio State University, Columbus 43210-1002, USA.
