331d
From Proteopedia
(New page: 200px<br /><applet load="331d" size="350" color="white" frame="true" align="right" spinBox="true" caption="331d, resolution 1.650Å" /> '''CRYSTAL STRUCTURE O...) |
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==Overview== | ==Overview== | ||
| - | The crystal structure of the DNA heptamer d(GCGCGCG) has been solved at | + | 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== | ==About this Structure== | ||
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[[Category: z-dna]] | [[Category: z-dna]] | ||
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Thu Feb 21 19:02:04 2008'' |
Revision as of 17:02, 21 February 2008
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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
Page seeded by OCA on Thu Feb 21 19:02:04 2008
Categories: Protein complex | Ban, C. | Pan, B. | Sundaralingam, M. | Wahl, M. | NCO | Double helix | Flipped-out base | Overhanging base | Z-dna
