A CPF-like phosphatase module links transcription termination to chromatin silencing

The interconnections between co-transcriptional regulation, chromatin environment and transcriptional output remain poorly understood. Here, we investigate the mechanism underlying RNA 3’ processing-mediated Polycomb silencing of Arabidopsis FLOWERING LOCUS C ( FLC ). We show a requirement for APRF1, a homologue of yeast Swd2 and human WDR82, known to regulate RNA Pol II during transcription termination. APRF1 interacts with TOPP4 (yeast Glc7/human PP1) and LD, the latter showing structural features found in Ref2/PNUTS; all components of the yeast and human phosphatase module of the CPF 3’end processing machinery. LD has been shown to co-associate in vivo with the histone H3 K4 demethylase FLD. We show APRF1 and LD couple CPF-mediated cleavage and polyadenylation with removal of H3K4 monomethylation in the body of FLC , and this influences subsequent transcription. This work shows how transcription termination can change the local chromatin environment to modulate transcription of Arabidopsis FLC and affect flowering time. ### Competing Interest Statement The authors have declared no competing interest.