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Crystal structure of A. aeolicus argonaute, a site-specific DNA-guided endoribonuclease, provides insights into RISC-mediated mRNA cleavage.

Argonaute (Ago) proteins constitute a key component of the RNA-induced silencing complex (RISC). We report the crystal structure of Aquifex aeolicus Ago (Aa-Ago) together with binding and cleavage studies, which establish this eubacterial Ago as a bona fide guide DNA strand-mediated site-specific RNA endonuclease. We have generated a stereochemically robust model of the complex, where the guide DNA-mRNA duplex is positioned within a basic channel spanning the bilobal interface, such that the 5' phosphate of the guide strand can be anchored in a basic pocket, and the mRNA can be positioned for site-specific cleavage by RNase H-type divalent cation-coordinated catalytic Asp residues of the PIWI domain. Domain swap experiments involving chimeras of human Ago (hAgo1) and cleavage-competent hAgo2 reinforce the role of the PIWI domain in "slicer" activity. We propose a four-step Ago-mediated catalytic cleavage cycle model, which provides distinct perspectives into the mechanism of guide strand-mediated mRNA cleavage within the RISC.

Pubmed ID: 16061186


  • Yuan YR
  • Pei Y
  • Ma JB
  • Kuryavyi V
  • Zhadina M
  • Meister G
  • Chen HY
  • Dauter Z
  • Tuschl T
  • Patel DJ


Molecular cell

Publication Data

August 5, 2005

Associated Grants

  • Agency: NIGMS NIH HHS, Id: R01 GM068476-01

Mesh Terms

  • Amino Acid Sequence
  • Argonaute Proteins
  • Bacteria
  • Bacterial Proteins
  • Binding Sites
  • Catalytic Domain
  • Cations, Divalent
  • Crystallography, X-Ray
  • DNA, Single-Stranded
  • Endoribonucleases
  • Eukaryotic Initiation Factor-2
  • Eukaryotic Initiation Factors
  • Humans
  • Models, Chemical
  • Models, Molecular
  • Molecular Sequence Data
  • Oligonucleotides
  • Peptide Initiation Factors
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • RNA, Double-Stranded
  • RNA, Messenger
  • RNA-Induced Silencing Complex
  • Recombinant Fusion Proteins
  • Recombinant Proteins
  • Sequence Homology, Amino Acid
  • Static Electricity