RT Journal Article SR Electronic T1 Functional dissection of the Pol V large subunit CTD in RNA-directed DNA methylation JF bioRxiv FD Cold Spring Harbor Laboratory SP 111831 DO 10.1101/111831 A1 Jered M. Wendte A1 Jeremy R. Haag A1 Jasleen Singh A1 Anastasia McKinlay A1 Olga M. Pontes A1 Craig S. Pikaard YR 2017 UL http://biorxiv.org/content/early/2017/03/14/111831.abstract AB Plant multisubunit RNA Polymerase V transcription recruits Argonaute siRNA complexes that specify sites of RNA-directed DNA methylation (RdDM) for gene silencing. Pol V's largest subunit, NRPE1, evolved from the largest subunit of Pol II but has a distinctive carboxyl-terminal domain (CTD). We show that the Pol V CTD is dispensable for catalytic activity in vitro, yet essential in vivo. One CTD subdomain (DeCL), is required for Pol V function at virtually all loci. other CTD subdomains have locusspecific effects. In a yeast two-hybrid screen, the 3'->5' exoribonuclease, RRP6L1 was identified as an interactor with the DeCL subdomain and DeCL and glutamine-serine-rich (QS) subdomains, located downstream from an Argonaute-binding repeat subdomain. Experimental evidence indicates that RRP6L1 trims the 3’ ends of Pol V transcripts sliced by ARGONAUTE 4 (AGO4), suggesting a model whereby the CTD enables the spatial and temporal coordination of AGO4 and RRP6L1 RNA processing activities.