Crystal structure of d(GCGCGCG) with 5'-overhang G residues.

AUTOR(ES)

Pan, B

RESUMO

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.

Documentos Relacionados

• Induction of the Z conformation in poly(dG-dC).poly(dG-dC) by binding of N-2-acetylaminofluorene to guanine residues.
• Molecular mechanical simulations on double intercalation of 9-amino acridine into d(CGCGCGC) X d(GCGCGCG): analysis of the physical basis for the neighbor-exclusion principle.
• Molecular interactions of a semisynthetic glycopeptide antibiotic with D-alanyl-D-alanine and D-alanyl-D-lactate residues.
• Comparison of bisulfite modification of 5-methyldeoxycytidine and deoxycytidine residues.
• The crystal structure of rabbit phosphoglucose isomerase complexed with 5-phospho-d-arabinonohydroxamic acid