1OSU

The structure of r(UUCGCG) has a 5'-UU-overhang exhibiting Hoogsteen-like trans U.U base pairs.

(1996) Nat Struct Biol 3: 24-31

• PubMed: 8548450 Search on PubMed
• DOI: https://doi.org/10.1038/nsb0196-24
• Primary Citation of Related Structures:  
  1OSU


• PubMed Abstract: 
  

  The crystal structure of the RNA fragment, 5'-r(UUCGCG)-3', has been determined at 1.4 A resolution by a combination of single isomorphous replacement and molecular search methods. The 3'-terminal CGCG portion of the hexamer engages in Watson-Crick hydrogen bonding while the 5'-terminal UU-overhang forms novel Hoogsteen-like U.U self-base pairs with the overhang of an adjacent duplex. The U.U pairs display a single conventional hydrogen bond between O4 (U1) and N3 (U8) and a CH-O hydrogen bond between C5-H (U1) and O4 (U8), through the Hoogsteen face of the pyrimidine base U1. This unusual arrangement of one of the bases results in a trans U.U pair on antiparallel strands in contrast to the usual cis base pairs. The structure emphasizes the pronounced polymorphism of U.U pairs and has implications for folding of RNA molecules.

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Organizational Affiliation: 

Ohio State University, Department of Chemistry, Columbus 43210, USA.