Abstract
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.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Amino Acid Motifs
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Amino Acid Sequence
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Arabidopsis / genetics*
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Arabidopsis / metabolism*
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Arabidopsis Proteins / genetics
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Arabidopsis Proteins / metabolism*
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Argonaute Proteins
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Conserved Sequence
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DNA Methylation
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DNA-Directed RNA Polymerases / chemistry
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DNA-Directed RNA Polymerases / genetics
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DNA-Directed RNA Polymerases / metabolism
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Evolution, Molecular
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Humans
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Molecular Sequence Data
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Mutagenesis, Site-Directed
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Plants, Genetically Modified
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Protein Binding
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Protein Structure, Tertiary
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Protein Subunits
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RNA Interference
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Repetitive Sequences, Amino Acid
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Sequence Homology, Amino Acid
Substances
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AGO4 protein, Arabidopsis
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Arabidopsis Proteins
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Argonaute Proteins
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Protein Subunits
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RNA polymerase IV, Arabidopsis
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DNA-Directed RNA Polymerases