title: RNA-directed DNA methylation requires an AGO4-interacting member of the SPT5 elongation factor family.
abstract: 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.
authors.affiliation: Laboratoire Génome et Développement des Plantes, Université de Perpignan, 52 Avenue Paul Alduy, Bâtiment C, Perpignan Cedex 66860, France.
authors.forename: Natacha
authors.initials: N
authors.lastname: Bies-Etheve
authors.forename: Dominique
authors.initials: D
authors.lastname: Pontier
authors.forename: Sylvie
authors.initials: S
authors.lastname: Lahmy
authors.forename: Claire
authors.initials: C
authors.lastname: Picart
authors.forename: Danielle
authors.initials: D
authors.lastname: Vega
authors.forename: Richard
authors.initials: R
authors.lastname: Cooke
authors.forename: Thierry
authors.initials: T
authors.lastname: Lagrange