1d88
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(New page: 200px<br /><applet load="1d88" size="450" color="white" frame="true" align="right" spinBox="true" caption="1d88, resolution 2.000Å" /> '''CONFORMATIONAL INFL...)
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Revision as of 00:36, 25 November 2007
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CONFORMATIONAL INFLUENCE OF THE RIBOSE 2'-HYDROXYL GROUP: CRYSTAL STRUCTURES OF DNA-RNA CHIMERIC DUPLEXES
Overview
We have crystallized three double-helical DNA-RNA chimeric duplexes and, determined their structures by X-ray crystallography at resolutions, between 2 and 2.25 A. The two self-complementary duplexes, [r(G)d(CGTATACGC)]2 and [d(GCGT)r(A)d(TACGC)]2, as well as the Okazaki, fragment d(GGGTATACGC).r(GCG)d(TATACCC), were found to adopt A-type, conformations. The crystal structures are non-isomorphous, and the, crystallographic environments for the three chimeras are different. A, number of intramolecular interactions of the ribose 2'-hydroxyl groups, contribute to the stabilization of the A-conformation. Hydrogen bonds, between 2'-hydroxyls and 5'-oxygens or phosphate oxygens, in addition to, the previously observed hydrogen bonds to 1'-oxygens of adjacent riboses, and deoxyriboses, are observed in the DNA-RNA chimeric duplexes. The, crystalline chimeric duplexes do not show a transition between the DNA A-, and B-conformations. CD spectra suggest that the Okazaki fragment assumes, an A-conformation in solution as well. In this molecule the three RNA, residues may therefore lock the complete decamer in the A-conformation., Crystals of an all-DNA strand with the same sequence as the, self-complementary chimeras show a morphology which is different from, those of the chimera crystals. Moreover, the oligonucleotide does not, match any of the sequence characteristics of DNAs usually adopting the, A-conformation in the crystalline state (e.g., octamers with short, alternating stretches of purines and pyrimidines). In DNA-RNA chimeric, duplexes, it is therefore possible that a single RNA residue can drive the, conformational equilibrium toward the A-conformation.
About this Structure
1D88 is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
Conformational influence of the ribose 2'-hydroxyl group: crystal structures of DNA-RNA chimeric duplexes., Egli M, Usman N, Rich A, Biochemistry. 1993 Apr 6;32(13):3221-37. PMID:7681688
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