PMID: 7719854

Authors:

Baeyens KJ, De Bondt HL, Holbrook SR

Title:

Structure of an RNA double helix including uracil-uracil base pairs in an internal loop.

Journal:

Nat Struct Biol. 1995 Jan;2(1):56-62.

Abstract:

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.