title: The Nucleosome Acidic Patch Regulates the H2B K123 Monoubiquitylation Cascade and Transcription Elongation in Saccharomyces cerevisiae.
abstract: Eukaryotes regulate gene expression and other nuclear processes through the posttranslational modification of histones. In S. cerevisiae, the mono-ubiquitylation of histone H2B on lysine 123 (H2B K123ub) affects nucleosome stability, broadly influences gene expression and other DNA-templated processes, and is a prerequisite for additional conserved histone modifications that are associated with active transcription, namely the methylation of lysine residues in H3. While the enzymes that promote these chromatin marks are known, regions of the nucleosome required for the recruitment of these enzymes are undefined. To identify histone residues required for H2B K123ub, we exploited a functional interaction between the ubiquitin-protein ligase, Rkr1/Ltn1, and H2B K123ub in S. cerevisiae. Specifically, we performed a synthetic lethal screen with cells lacking RKR1 and a comprehensive library of H2A and H2B residue substitutions, and identified H2A residues that are required for H2B K123ub. Many of these residues map to the nucleosome acidic patch. The substitutions in the acidic patch confer varying histone modification defects downstream of H2B K123ub, indicating that this region contributes differentially to multiple histone modifications. Interestingly, substitutions in the acidic patch result in decreased recruitment of H2B K123ub machinery to active genes and defects in transcription elongation and termination. Together, our findings reveal a role for the nucleosome acidic patch in recruitment of histone modification machinery and maintenance of transcriptional integrity.
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Christine E
authors.initials: CE
authors.lastname: Cucinotta
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Alexandria N
authors.initials: AN
authors.lastname: Young
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Kristin M
authors.initials: KM
authors.lastname: Klucevsek
authors.affiliation: Department of Biological Sciences, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America.
authors.forename: Karen M
authors.initials: KM
authors.lastname: Arndt
mesh_terms: D010450:Endopeptidases / Q000235:genetics; D015966:Gene Expression Regulation, Fungal; D055786:Gene Knockout Techniques; D006657:Histones / Q000737:chemistry / Q000378:metabolism*; D008745:Methylation; D009707:Nucleosomes / Q000378:metabolism; D054730:Protein Interaction Domains and Motifs; D012319:RNA Polymerase II / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D061805:Transcription Elongation, Genetic; D044767:Ubiquitin-Protein Ligases / Q000235:genetics; D054875:Ubiquitination
chemical_list: D006657:Histones; D009707:Nucleosomes; D029701:Saccharomyces cerevisiae Proteins; C519403:Rkr1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D012319:RNA Polymerase II; D010450:Endopeptidases; C503322:UBP8 protein, S cerevisiae