1.76 A structure of a pyrimidine start alternating A-RNA hexamer r(CGUAC)dG.
The crystal structure of the alternating RNA r(CGUAC)dG with a 3'-terminal deoxy G residue has been determined at 1.76 A resolution. The crystal belongs to the orthorhombic space group C2221, unit-cell dimensions a = 29.53, b = 44.61 and c = 94.18 A, with two independent duplexes (I and II) per asymmetric unit. The structure was solved by the molecular-replacement method. The final R factor was 18.8% using 4757 reflections in the resolution range 8.0-1.76 A. The model contains a total of 496 atoms and 85 solvent molecules. The two duplexes form the repeating unit and stack in the usual head-to-tail (5',3'/5',3') fashion into a pseudocontinuous helical column. Almost all of the 2'-hydroxyl groups are engaged in the three modes of water-mediated interactions to the base N3/O2 atoms, the sugar O4' atoms and the backbone phosphates. Thus, the 2'-hydroxyl group of RNA is probably contributing to the stability of the duplexes.
Biological Macromolecular Structure Center, Departments of Chemistry, Biochemistry and The Ohio State Biochemistry Program, The Ohio State University, 100 West 18th Avenue, Columbus, OH 43210, USA.
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Sundaralingam
D001704:Biopolymers; D018360:Crystallography, X-Ray; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry*; D012313:RNA / Q000737:chemistry*
D001704:Biopolymers; D009843:Oligoribonucleotides; D012313:RNA