Reiterated WG/GW motifs form functionally and evolutionarily conserved ARGONAUTE-binding platforms in RNAi-related components (original) (raw)

  1. Mahmoud El-Shami1,4,
  2. Dominique Pontier1,4,
  3. Sylvie Lahmy1,4,
  4. Laurence Braun2,
  5. Claire Picart1,
  6. Danielle Vega1,
  7. Mohamed-Ali Hakimi2,
  8. Steven E. Jacobsen3,
  9. Richard Cooke1, and
  10. Thierry Lagrange1,5
  11. 1 Laboratoire Génome et Développement de Plantes, Centre National de la Recherche Scientifique/Institut de Recherche pour le Développement/Université de Perpignan 5096, 66860 Perpignan Cedex, France;
  12. 2 Institut Jean Roget, Université Joseph Fourier, BP170, 38042 Grenoble Cedex 9, France;
  13. 3 Department of Molecular, Cell and Developmental Biology, Howard Hughes Medical Institute, University of California at Los Angeles, Los Angeles, California 90095, USA
  14. ↵4 These authors contributed equally to this work.

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.

Footnotes