Crystal structure of a group I ribozyme domain: principles of RNA packing

Science. 1996 Sep 20;273(5282):1678-85. doi: 10.1126/science.273.5282.1678.


Group I self-splicing introns catalyze their own excision from precursor RNAs by way of a two-step transesterification reaction. The catalytic core of these ribozymes is formed by two structural domains. The 2.8-angstrom crystal structure of one of these, the P4-P6 domain of the Tetrahymena thermophila intron, is described. In the 160-nucleotide domain, a sharp bend allows stacked helices of the conserved core to pack alongside helices of an adjacent region. Two specific long-range interactions clamp the two halves of the domain together: a two-Mg2+-coordinated adenosine-rich corkscrew plugs into the minor groove of a helix, and a GAAA hairpin loop binds to a conserved 11-nucleotide internal loop. Metal- and ribose-mediated backbone contacts further stabilize the close side-by-side helical packing. The structure indicates the extent of RNA packing required for the function of large ribozymes, the spliceosome, and the ribosome.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Adenine / chemistry
  • Animals
  • Base Composition
  • Base Sequence
  • Binding Sites
  • Catalysis
  • Crystallography, X-Ray
  • Hydrogen Bonding
  • Introns*
  • Magnesium / chemistry
  • Models, Molecular
  • Molecular Sequence Data
  • Nucleic Acid Conformation*
  • Phosphates / chemistry
  • Phylogeny
  • RNA Splicing
  • RNA, Catalytic / chemistry*
  • RNA, Catalytic / metabolism
  • RNA, Protozoan / chemistry*
  • RNA, Protozoan / metabolism
  • Ribose / chemistry
  • Tetrahymena thermophila / genetics


  • Phosphates
  • RNA, Catalytic
  • RNA, Protozoan
  • Ribose
  • Magnesium
  • Adenine