A conserved motif in Argonaute-interacting proteins mediates functional interactions through the Argonaute PIWI domain

• Published in: Nature structural & molecular biology Vol. 14; no. 10; pp. 897 - 903
• Main Authors: Enderle, Daniel, Heinrich, Constanze, Thermann, Rolf, Bortfeld, Miriam, Hothorn, Michael, Hentze, Matthias W, Ladurner, Andreas G, Till, Susanne, Lejeune, Erwan
• Format: Journal Article
• Language: English
• Published: United States Nature Publishing Group 01.10.2007
• Subjects: Amino Acid Sequence; Argonaute Proteins; Carrier Proteins - genetics; Carrier Proteins - metabolism; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Nucleus - metabolism; DNA binding proteins; Eukaryotic Initiation Factor-2 - genetics; Eukaryotic Initiation Factor-2 - metabolism; Gene Silencing; Humans; MicroRNAs; Molecular biology; Molecular Sequence Data; Mutagenesis, Site-Directed; Mutation; Nucleic acids; Peptides; Physiological aspects; Protein Binding; Protein Biosynthesis; Protein Conformation; Proteins; RNA Interference; RNA, Small Interfering - genetics; RNA, Small Interfering - metabolism; RNA-Binding Proteins; Schizosaccharomyces - genetics; Schizosaccharomyces - metabolism; Schizosaccharomyces pombe; Schizosaccharomyces pombe Proteins - chemistry; Schizosaccharomyces pombe Proteins - genetics; Schizosaccharomyces pombe Proteins - metabolism; Sequence Alignment; Structure; Two-Hybrid System Techniques; Yeast; Yeasts; Switzerland; Basel Switzerland
• ISSN: 1545-9993; 1545-9985
• DOI: 10.1038/nsmb1302

Argonaute (Ago) proteins mediate silencing of nucleic acid targets by small RNAs. In fission yeast, Ago1, Tas3 and Chp1 assemble into a RITS complex, which silences transcription near centromeres. Here we describe a repetitive motif within Tas3, termed the 'Argonaute hook', that is conserved from yeast to humans and binds Ago proteins through their PIWI domains in vitro and in vivo. Site-directed mutation of key residues in the motif disrupts Ago binding and heterochromatic silencing in vivo. Unexpectedly, a PIWI domain pocket that binds the 5' end of the short interfering RNA guide strand is required for direct binding of the Ago hook. Moreover, wild-type but not mutant Ago hook peptides derepress microRNA-mediated translational silencing of a target messenger RNA. Proteins containing the conserved Ago hook may thus be important regulatory components of effector complexes in RNA interference.