RT Journal Article
SR Electronic
T1 Subdomains of the Pol V largest subunit CTD mediate locus-specific 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/2017/02/25/111831.abstract
AB RNA Polymerase V transcription recruits siRNA-Argonaute protein complexes to chromatin, thereby specifying sites of RNA-directed DNA methylation (RdDM) and transcriptional gene silencing in plants. Pol V's largest subunit, NRPE1, has an extensive carboxyl-terminal domain (CTD) that is dispensable for catalytic activity in vitro, yet essential in vivo. A CTD subdomain, DeCL, named for its similarity to a chloroplast protein, DEFECTIVE CHLOROPLASTS AND LEAVES, is required for Pol V function at virtually all loci, similar to mutants defective for Pol V recruitment. Deletions removing three other CTD subdomains affect overlapping subsets of loci, similar to mutants lacking proteins that bind Pol V or its transcripts. A yeast two-hybrid screen for CTD-interactors identified the 3'->5' exoribonuclease, RRP6L1 as an interactor with the DeCL subdomain and the adjacent QS subdomain, named for its numerous glutamine-serine (QS) repeats. These RRP6L1-binding subdomains immediately follow the Argonaute-binding subdomain. Experimental evidence indicates that RRP6L1 trims the 3’ ends of Pol V transcripts sliced by ARGONAUTE 4 (AGO4), suggesting a model whereby the adjacent CTD subdomains enable the spatial and temporal coordination of AGO4 and RRP6L1 RNA processing activities.