title: H2B ubiquitylation acts as a barrier to Ctk1 nucleosomal recruitment prior to removal by Ubp8 within a SAGA-related complex.
abstract: Histone modifications play an important role in transcription. We previously studied histone H2B ubiquitylation on lysine 123 and subsequent deubiquitylation by SAGA-associated Ubp8. Unlike other histone modifications, both the addition and removal of ubiquitin are required for optimal transcription. Here we report that deubiquitylation of H2B is important for recruitment of a complex containing the kinase Ctk1, resulting in phosphorylation of the RNA polymerase II (Pol II) C-terminal domain (CTD), and for subsequent recruitment of the Set2 methyltransferase. We find that Ctk1 interacts with histones H2A and H2B, and that persistent H2B ubiquitylation disrupts these interactions. We further show that Ubp8 enters the GAL1 coding region through an interaction with Pol II. These findings reveal a mechanism by which H2B ubiquitylation acts as a barrier to Ctk1 association with active genes, while subsequent deubiquitylation by Ubp8 triggers Ctk1 recruitment at the appropriate point in activation.
authors.affiliation: Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA; University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Anastasia
authors.initials: A
authors.lastname: Wyce
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
authors.forename: Tiaojiang
authors.initials: T
authors.lastname: Xiao
authors.affiliation: Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: Whelan
authors.affiliation: Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA; University of Pennsylvania School of Medicine, Philadelphia, PA 19104, USA.
authors.forename: Christine
authors.initials: C
authors.lastname: Kosman
authors.affiliation: Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA.
authors.forename: Wendy
authors.initials: W
authors.lastname: Walter
authors.affiliation: Institute of Clinical Molecular Biology and Tumour Genetics, GSF-National Research Center for Environment and Health, Marchioninistrasse 25, D-81377 Munich, Germany.
authors.forename: Dirk
authors.initials: D
authors.lastname: Eick
authors.affiliation: Banting and Best Department of Medical Research, University of Toronto, Toronto, ON M5G 1L6, Canada.
authors.forename: Timothy R
authors.initials: TR
authors.lastname: Hughes
authors.affiliation: Department of Cellular and Molecular Pharmacology, University of California, San Francisco, San Francisco, CA 94143, USA.
authors.forename: Nevan J
authors.initials: NJ
authors.lastname: Krogan
authors.affiliation: Department of Biochemistry and Biophysics, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA.
authors.forename: Brian D
authors.initials: BD
authors.lastname: Strahl
authors.affiliation: Gene Expression and Regulation Program, The Wistar Institute, Philadelphia, PA 19104, USA. Electronic address: berger@wistar.org.
authors.forename: Shelley L
authors.initials: SL
authors.lastname: Berger
mesh_terms: D010450:Endopeptidases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005800:Genes, Fungal; D006657:Histones / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D008954:Models, Biological; D046912:Multiprotein Complexes; D009707:Nucleosomes / Q000378:metabolism; D016366:Open Reading Frames; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D012319:RNA Polymerase II / Q000737:chemistry / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D015534:Trans-Activators / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D025801:Ubiquitin / Q000378:metabolism*
chemical_list: C118305:CTDK-I protein complex, S cerevisiae; D006657:Histones; D046912:Multiprotein Complexes; D009707:Nucleosomes; C507785:SAGA complex, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D015534:Trans-Activators; D025801:Ubiquitin; D011494:Protein Kinases; D012319:RNA Polymerase II; D010450:Endopeptidases; C503322:UBP8 protein, S cerevisiae