Structure and conserved RNA binding of the PAZ domain. The crystal structure of the Argonaute2 PAZ domain reveals an RNA binding motif in RNAi effector complexes. Structure and nucleic-acid binding of the Drosophila Argonaute 2 PAZ domain. An RNA-dependent RNA polymerase gene in Arabidopsis is required for posttranscriptional gene silencing mediated by a transgene but not by a virus. On the role of RNA amplification in dsRNA-triggered gene silencing. RITS acts in cis to promote RNA interference-mediated transcriptional and post-transcriptional silencing. Two RNAi complexes, RITS and RDRC, physically interact and localize to noncoding centromeric RNAs. Role for a bidentate ribonuclease in the initiation step of RNA interference. RNAi-mediated targeting of heterochromatin by the RITS complex. Regulation of heterochromatic silencing and histone H3 lysine-9 methylation by RNAi. Small RNAs correspond to centromere heterochromatic repeats. Argonaute2 is the catalytic engine of mammalian RNAi. Crystal structure of Argonaute and its implications for RISC slicer activity. The Argonaute family: tentacles that reach into RNAi, developmental control, stem cell maintenance, and tumorigenesis. RNA interference and heterochromatin in the fission yeast Schizosaccharomyces pombe. Heterochromatin and epigenetic control of gene expression. MicroRNAs: genomics, biogenesis, mechanism, and function.
Mechanisms of gene silencing by double-stranded RNA. Finally, we show that slicer activity is required for the siRNA-dependent association of Ago1 with chromatin and for the spreading of histone H3-K9 methylation. Consistent with this observation, purified Arb1 inhibits the slicer activity of Ago1 in vitro, and purified catalytically inactive Ago1 contains only double-stranded siRNA. Furthermore, whereas siRNAs in the RITS complex are mostly single-stranded, siRNAs associated with ARC are mostly double-stranded, indicating that Arb1 and Arb2 inhibit the release of the siRNA passenger strand from Ago1. Here, we identify a second fission yeast Argonaute complex (Argonaute siRNA chaperone, ARC), which contains, in addition to Ago1, two previously uncharacterized proteins, Arb1 and Arb2, both of which are required for histone H3 Lys9 (H3-K9) methylation, heterochromatin assembly and siRNA generation. The RNA-induced transcriptional silencing (RITS) complex, containing Ago1, Chp1, Tas3 and centromeric small interfering RNAs (siRNAs), is required for heterochromatic gene silencing at centromeres.
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