1d87

CONFORMATIONAL INFLUENCE OF THE RIBOSE 2'-HYDROXYL GROUP: CRYSTAL STRUCTURES OF DNA-RNA CHIMERIC DUPLEXES

spinqualitylabelsall models 1d87, resolution 2.25Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 1d87 is a 2 chain structure. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Resources: FirstGlance, OCA, RCSB, PDBsum Publication Abstract from PubMed 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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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