Noncatalytic assembly of ribonuclease III with double-stranded RNA

Structure. 2004 Mar;12(3):457-66. doi: 10.1016/j.str.2004.02.004.


Ribonuclease III (RNase III) represents a family of double-stranded RNA (dsRNA) endonucleases. The simplest bacterial enzyme contains an endonuclease domain (endoND) and a dsRNA binding domain (dsRBD). RNase III can affect RNA structure and gene expression in either of two ways: as a dsRNA-processing enzyme that cleaves dsRNA, or as a dsRNA binding protein that binds but does not cleave dsRNA. We previously determined the endoND structure of Aquifex aeolicus RNase III (Aa-RNase III) and modeled a catalytic complex of full-length Aa-RNase III with dsRNA. Here, we present the crystal structure of Aa-RNase III in complex with dsRNA, revealing a noncatalytic assembly. The major differences between the two functional forms of RNase III.dsRNA are the conformation of the protein and the orientation and location of dsRNA. The flexibility of a 7 residue linker between the endoND and dsRBD enables the transition between these two forms.

MeSH terms

  • Amino Acid Sequence
  • Binding Sites
  • Magnesium / metabolism
  • Models, Molecular
  • Molecular Sequence Data
  • Mutation
  • Protein Structure, Quaternary
  • Protein Structure, Tertiary
  • RNA, Double-Stranded / metabolism*
  • Ribonuclease III / chemistry
  • Ribonuclease III / genetics
  • Ribonuclease III / metabolism*


  • RNA, Double-Stranded
  • Ribonuclease III
  • Magnesium

Associated data

  • PDB/1RC5
  • PDB/1RC7