title: Ser7 phosphorylation of the CTD recruits the RPAP2 Ser5 phosphatase to snRNA genes.
abstract: The carboxy-terminal domain (CTD) of the large subunit of RNA polymerase II (Pol II) comprises multiple heptapeptide repeats of the consensus Tyr1-Ser2-Pro3-Thr4-Ser5-Pro6-Ser7. Reversible phosphorylation of Ser2, Ser5, and Ser7 during the transcription cycle mediates the sequential recruitment of transcription/RNA processing factors. Phosphorylation of Ser7 is required for recruitment of the gene type-specific Integrator complex to the Pol II-transcribed small nuclear (sn)RNA genes. Here, we show that RNA Pol II-associated protein 2 (RPAP2) specifically recognizes the phospho-Ser7 mark on the Pol II CTD and also interacts with Integrator subunits. siRNA-mediated knockdown of RPAP2 and mutation of Ser7 to alanine cause similar defects in snRNA gene expression. In addition, we show that RPAP2 is a CTD Ser5 phosphatase. Taken together, our results indicate that during transcription of snRNA genes, Ser7 phosphorylation facilitates recruitment of RPAP2, which in turn both recruits Integrator and dephosphorylates Ser5.
authors.affiliation: Sir William Dunn School of Pathology, University of Oxford, Oxford OX1 3RE, UK.
authors.forename: Sylvain
authors.initials: S
authors.lastname: Egloff
authors.forename: Justyna
authors.initials: J
authors.lastname: Zaborowska
authors.forename: Clélia
authors.initials: C
authors.lastname: Laitem
authors.forename: Tamás
authors.initials: T
authors.lastname: Kiss
authors.forename: Shona
authors.initials: S
authors.lastname: Murphy
mesh_terms: D000595:Amino Acid Sequence; D002352:Carrier Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010766:Phosphorylation; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D012319:RNA Polymerase II / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology; D012342:RNA, Small Nuclear / Q000235:genetics*; D012694:Serine / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D002352:Carrier Proteins; D012342:RNA, Small Nuclear; C571028:RPAP2 protein, human; D012694:Serine; D012319:RNA Polymerase II