A conserved motif in Argonaute-interacting proteins mediates functional interactions through the Argonaute PIWI domain.
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.
Till
Susanne
S
European Molecular Biology Laboratory, Meyerhofstrasse 1, 69117 Heidelberg, Germany.
Lejeune
Erwan
E
Thermann
Rolf
R
Bortfeld
Miriam
M
Hothorn
Michael
M
Enderle
Daniel
D
Heinrich
Constanze
C
Hentze
Matthias W
MW
Ladurner
Andreas G
AG
D000595:Amino Acid Sequence; D060565:Argonaute Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism; D015852:Eukaryotic Initiation Factor-2 / Q000235:genetics / Q000378:metabolism; D020868:Gene Silencing; D006801:Humans; D008969:Molecular Sequence Data; D016297:Mutagenesis, Site-Directed; D011485:Protein Binding; D014176:Protein Biosynthesis; D011487:Protein Conformation; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D016601:RNA-Binding Proteins; D012568:Schizosaccharomyces / Q000235:genetics / Q000378:metabolism; D029702:Schizosaccharomyces pombe Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D020798:Two-Hybrid System Techniques
C466422:AGO2 protein, human; C481643:Ago1 protein, S pombe; D060565:Argonaute Proteins; D002352:Carrier Proteins; D018797:Cell Cycle Proteins; C115018:Chp1 protein, S pombe; D015852:Eukaryotic Initiation Factor-2; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins; D029702:Schizosaccharomyces pombe Proteins; C499720:Tas3 protein, S pombe