Structure of an RNA double helix including uracil-uracil base pairs in an internal loop.
The crystal structure of the RNA dodecamer 5'-GGACUUUGGUCC-3' has been determined from X-ray diffraction data to 2.6 A resolution. This oligomer forms an asymmetric double helix in the crystal. Four consecutive non-Watson-Crick base-pairs are formed in the middle of the duplex including the first intrahelical U-U (or T-T) pairs observed in an oligonucleotide crystal structure. Two different conformations of U-U pairs are observed in the context of the surrounding sequence. One of these pairs is highly twisted, allowing a bound water to bridge across strands in the major groove. The crystal packing illustrates a new form of RNA helix-helix interaction.
Baeyens
K J
KJ
Structural Biology Division, Lawrence Berkeley Laboratory, University of California, Berkeley 94720.
De Bondt
H L
HL
Holbrook
S R
SR
D001482:Base Composition; D001483:Base Sequence; D018360:Crystallography, X-Ray; D004260:DNA Repair; D006860:Hydrogen Bonding; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009843:Oligoribonucleotides / Q000737:chemistry*; D012330:RNA, Double-Stranded / Q000737:chemistry*; D014498:Uracil / Q000737:chemistry*; D014867:Water / Q000737:chemistry
D009843:Oligoribonucleotides; D012330:RNA, Double-Stranded; D014867:Water; D014498:Uracil