Functional Dissection of the Pol V Largest Subunit CTD in RNA-Directed DNA Methylation

• DOI: 10.1016/j.celrep.2017.05.091
• Publication Date: 2017-06-27T16:46:02Z
• Authors: Jered M. Wendte; Jeremy R. Haag; Jasleen Singh; Anastasia McKinlay; Olga M. Pontes; Craig S. Pikaard
• Keywords: Argonaute; Exoribonuclease; CTD; RNA polymerase II; Processivity; RNA-induced silencing complex

Plant multisubunit RNA polymerase V (Pol V) transcription recruits Argonaute-small interfering (siRNA) complexes that specify sites of RNA-directed DNA methylation (RdDM) for gene silencing. Pol V's largest subunit, NRPE1, evolved from the subunit II but has a distinctive C-terminal domain (CTD). We show CTD is dispensable catalytic activity in vitro yet essential vivo. One subdomain (DeCL) required function at virtually all loci. Other subdomains have locus-specific effects. In yeast two-hybrid screen, 3'→ 5' exoribonuclease RRP6L1 was identified as an interactor with DeCL and glutamine-serine (QS)-rich located downstream Argonaute-binding subdomain. Experimental evidence indicates trims 3' ends transcripts sliced by Argonaute 4 (AGO4), suggesting model whereby enables spatial temporal coordination AGO4 processing activities.