RNA-directed DNA methylation requires an AGO4-interacting member of the SPT5 elongation factor family.
Recent studies have identified a conserved WG/GW-containing motif, known as the Argonaute (AGO) hook, which is involved in the recruitment of AGOs to distinct components of the eukaryotic RNA silencing pathways. By using this motif as a model to detect new components in plant RNA silencing pathways, we identified SPT5-like, ... a plant-specific AGO4-interacting member of the nuclear SPT5 (Suppressor of Ty insertion 5) RNA polymerase (RNAP) elongation factor family that is characterized by the presence of a carboxy-terminal extension with more than 40 WG/GW motifs. Knockout SPT5-like mutants show a decrease in the accumulation of several 24-nt RNAs and hypomethylation at different loci revealing an implication in RNA-directed DNA methylation (RdDM). Here, we propose that SPT5-like emerged in plants as a facultative RNAP elongation factor. Its plant-specific origin and role in RdDM might reflect functional interactions with plant-specific RNA Pols required for RdDM.
Mesh Terms:
Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Argonaute Proteins, Base Sequence, Chromosomal Proteins, Non-Histone, DNA Methylation, Models, Biological, Molecular Sequence Data, Mutation, Protein Binding, RNA, Plant, RNA, Small Interfering, Transcriptional Elongation Factors
Amino Acid Sequence, Arabidopsis, Arabidopsis Proteins, Argonaute Proteins, Base Sequence, Chromosomal Proteins, Non-Histone, DNA Methylation, Models, Biological, Molecular Sequence Data, Mutation, Protein Binding, RNA, Plant, RNA, Small Interfering, Transcriptional Elongation Factors
EMBO Rep.
Date: Jun. 01, 2009
PubMed ID: 19343051
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