An Alpha Motif at Tas3 C Terminus Mediates RITS cis Spreading and Promotes Heterochromatic Gene Silencing Journal Article
| Authors: | Li, H.; Motamedi, M. R.; Yip, C. K.; Wang, Z.; Walz, T.; Patel, D. J.; Moazed, D. |
| Article Title: | An Alpha Motif at Tas3 C Terminus Mediates RITS cis Spreading and Promotes Heterochromatic Gene Silencing |
| Abstract: | RNA interference (RNAi) plays a pivotal role in the formation of heterochromatin at the fission yeast centromeres. The RNA-induced transcriptional silencing (RITS) complex, composed of heterochromatic small interfering RNAs (siRNAs), the siRNA-binding protein Ago1, the chromodomain protein Chp1, and the Ago1/Chp1-interacting protein Tas3, provides a physical tether between the RNAi and heterochromatin assembly pathways. Here, we report the structural and functional characterization of a C-terminal Tas3 α-helical motif (TAM), which self-associates into a helical polymer and is required for cis spreading of RITS in centromeric DNA regions. Site-directed mutations of key residues within the hydrophobic monomer-monomer interface disrupt Tas3-TAM polymeric self-association in vitro and result in loss of gene silencing, spreading of RITS, and a dramatic reduction in centromeric siRNAs in vivo. These results demonstrate that, in addition to the chromodomain of Chp1 and siRNA-loaded Ago1, Tas3 self-association is required for RITS spreading and efficient heterochromatic gene silencing at centromeric repeat regions. © 2009 Elsevier Inc. All rights reserved. |
| Keywords: | controlled study; unclassified drug; gene mutation; methylation; nonhuman; protein domain; protein function; protein motif; proteins; protein analysis; carboxy terminal sequence; protein; small interfering rna; rna, small interfering; rna interference; in vivo study; in vitro study; dna; chromatin immunoprecipitation; carrier proteins; gene loss; models, molecular; crystallography, x-ray; mutagenesis, site-directed; protein structure, tertiary; gene silencing; protein structure; site directed mutagenesis; argonaute protein; rna-induced silencing complex; histones; protein microarray; polymer; lysine; monomer; argonaute 1 protein; chp1 protein; rna induced silencing complex; tas3 protein; centromere; heterochromatin; protein polymerization; rna transcription; amino acid motifs; chromatin assembly and disassembly; chromatography, gel; schizosaccharomyces; schizosaccharomyces pombe proteins; schizosaccharomycetaceae |
| Journal Title: | Molecular Cell |
| Volume: | 34 |
| Issue: | 2 |
| ISSN: | 1097-2765 |
| Publisher: | Cell Press |
| Date Published: | 2009-04-24 |
| Start Page: | 155 |
| End Page: | 167 |
| Language: | English |
| DOI: | 10.1016/j.molcel.2009.02.032 |
| PUBMED: | 19394293 |
| PROVIDER: | scopus |
| PMCID: | PMC2756231 |
| DOI/URL: | |
| Notes: | --- - "Cited By (since 1996): 7" - "Export Date: 30 November 2010" - "CODEN: MOCEF" - "Source: Scopus" |
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