Crystal structure of A. aeolicus argonaute, a site-specific DNA-guided endoribonuclease, provides insights into RISC-mediated mRNA cleavage.
Journal:
Mol. Cell 2005 AugAuthors:
Yuan YR, Pei Y, Ma JB, Kuryavyi V, Zhadina M, Meister G, Chen HY, Dauter Z, Tuschl T, Patel DJ
Abstract
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'
...[more]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.[less]
Mesh Headings:
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