RNA interference (RNAi) is critical for the assembly of heterochromatin at Schizosaccharomyces pombe centromeres. Central to this process is the RNA-induced initiation of transcriptional gene silencing (RITS) complex, which physically anchors small noncoding RNAs to chromatin ...
RNA interference (RNAi) is critical for the assembly of heterochromatin at Schizosaccharomyces pombe centromeres. Central to this process is the RNA-induced initiation of transcriptional gene silencing (RITS) complex, which physically anchors small noncoding RNAs to chromatin. RITS includes Ago1, the chromodomain protein Chp1, and Tas3, which forms a bridge between Chp1 and Ago1. Chp1 is a large protein with no recognizable domains, apart from its chromodomain. Here we describe how the structured C-terminal half of Chp1 binds the Tas3 N-terminal domain, revealing the tight association of Chp1 and Tas3. The structure also shows a PIN domain at the C-terminal tip of Chp1 that controls subtelomeric transcripts through a post-transcriptional mechanism. We suggest that the Chp1-Tas3 complex provides a solid and versatile platform to recruit both RNAi-dependent and RNAi-independent gene-silencing pathways for locus-specific regulation of heterochromatin.
Organizational Affiliation:
Keck Structural Biology Laboratory, Cold Spring Harbor Laboratory, Cold Spring Harbor, New York, USA.
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