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
Notes: --- - "Cited By (since 1996): 7" - "Export Date: 30 November 2010" - "CODEN: MOCEF" - "Source: Scopus"
Citation Impact
MSK Authors
  1. Hai-Tao Li
    18 Li
  2. Dinshaw J Patel
    466 Patel
  3. Zhan-Xin Wang
    11 Wang