Two forms of RNA Polymerase IV (PolIVa/PolIVb) have been implicated in RNA-directed DNA methylation (RdDM) in Arabidopsis. Prevailing models imply a distinct function for PolIVb by association of Argonaute4 (AGO4) with the C-terminal domain (CTD) of its largest subunit NRPD1b. Here we show that the extended CTD of NRPD1b-type proteins exhibits conserved Argonaute-binding capacity through a WG/GW-rich region that functionally distinguishes Pol IVb from Pol IVa, and that is essential for RdDM. Site-specific mutagenesis and domain-swapping experiments between AtNRPD1b and the human protein GW182 demonstrated that reiterated WG/GW motifs form evolutionarily and functionally conserved Argonaute-binding platforms in RNA interference (RNAi)-related components.
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http://dx.doi.org/10.1101/gad.451207 | DOI Listing |
Methods Mol Biol
March 2018
School of Plant Sciences, The University of Arizona, 1140 E. South Campus Drive, P.O. Box 210036, Tucson, AZ, 85721, USA.
ARGONAUTE (AGO) proteins are eukaryotic RNA silencing effectors that interact with their binding partners via short peptide motifs known as AGO hooks. AGO hooks tend to cluster in one region of the protein to create an AGO-binding platform. In addition to the presence of AGO hooks, AGO-binding platforms are intrinsically disordered, contain tandem repeat arrays, and have weak sequence conservation even between close relatives.
View Article and Find Full Text PDFNew Phytol
December 2016
The School of Plant Sciences, The University of Arizona, Tucson, AZ, 85721-0036, USA.
Argonaute (Ago) proteins are important effectors in RNA silencing pathways, but they must interact with other machinery to trigger silencing. Ago hooks have emerged as a conserved motif responsible for interaction with Ago proteins, but little is known about the sequence surrounding Ago hooks that must restrict or enable interaction with specific Argonautes. Here we investigated the evolutionary dynamics of an Ago-binding platform in NRPE1, the largest subunit of RNA polymerase V.
View Article and Find Full Text PDFNucleic Acids Res
December 2011
Department of Molecular and Cellular Biochemistry, University of Kentucky, Lexington, KY, 40536, USA.
We describe a new method that allows cloning of double-stranded RNAs (dsRNAs) that are generated in RNase protection experiments. We demonstrate that the mouse C/D box snoRNA MBII-85 (SNORD116) is processed into at least five shorter RNAs using processing sites near known functional elements of C/D box snoRNAs. Surprisingly, the majority of cloned RNAs from RNase protection experiments were derived from endogenous cellular RNA, indicating widespread antisense expression.
View Article and Find Full Text PDFBioinformatics
May 2011
Laboratory of Computational Genomics, Institute of Molecular Biology and Biotechnology, Faculty of Biology, Adam Mickiewicz University, Poznan, Poland.
Motivation: AGO(Argonaute)-binding domains, composed of repeated motifs, in which only binary combinations of tryptophan and glycine are conserved, bind AGO proteins and are essential during RNAi-mediated gene silencing. The amino acid sequence of this domain is extremely divergent and therefore very difficult to detect. Commonly used bioinformatic tools fail to identify tryptophan-glycine and/or glycine-tryptophan motifs (WG/GW) domains and currently there is no publicly available software which can detect these weakly conserved, but functional AGO-binding segments.
View Article and Find Full Text PDFPLoS Pathog
July 2010
Centre for Research in Agricultural Genomics, CRAG, CSIC-IRTA-UAB, Barcelona, Spain.
RNA silencing is an evolutionarily conserved sequence-specific gene-inactivation system that also functions as an antiviral mechanism in higher plants and insects. To overcome antiviral RNA silencing, viruses express silencing-suppressor proteins. These viral proteins can target one or more key points in the silencing machinery.
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