title: The Budding Yeast Ubiquitin Protease Ubp7 Is a Novel Component Involved in S Phase Progression.
abstract: DNA damage must be repaired in an accurate and timely fashion to preserve genome stability. Cellular mechanisms preventing genome instability are crucial to human health because genome instability is considered a hallmark of cancer. Collectively referred to as the DNA damage response, conserved pathways ensure proper DNA damage recognition and repair. The function of numerous DNA damage response components is fine-tuned by posttranslational modifications, including ubiquitination. This not only involves the enzyme cascade responsible for conjugating ubiquitin to substrates but also requires enzymes that mediate directed removal of ubiquitin. Deubiquitinases remove ubiquitin from substrates to prevent degradation or to mediate signaling functions. The Saccharomyces cerevisiae deubiquitinase Ubp7 has been characterized previously as an endocytic factor. However, here we identify Ubp7 as a novel factor affecting S phase progression after hydroxyurea treatment and demonstrate an evolutionary and genetic interaction of Ubp7 with DNA damage repair pathways of homologous recombination and nucleotide excision repair. We find that deletion of UBP7 sensitizes cells to hydroxyurea and cisplatin and demonstrate that factors that stabilize replication forks are critical under these conditions. Furthermore, ubp7Δ cells exhibit an S phase progression defect upon checkpoint activation by hydroxyurea treatment. ubp7Δ mutants are epistatic to factors involved in histone maintenance and modification, and we find that a subset of Ubp7 is chromatin-associated. In summary, our results suggest that Ubp7 contributes to S phase progression by affecting the chromatin state at replication forks, and we propose histone H2B ubiquitination as a potential substrate of Ubp7.
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213.
authors.forename: Stefanie
authors.initials: S
authors.lastname: Böhm
authors.affiliation: the Department of Molecular Oncology, Fondazione Istituto Fondazione Italiana per la Ricerca sul Cancro di Oncologia Molecolare, Milan 20139, Italy.
authors.forename: Barnabas
authors.initials: B
authors.lastname: Szakal
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213.
authors.forename: Benjamin W
authors.initials: BW
authors.lastname: Herken
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213.
authors.forename: Meghan R
authors.initials: MR
authors.lastname: Sullivan
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213.
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Mihalevic
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213.
authors.forename: Faiz F
authors.initials: FF
authors.lastname: Kabbinavar
authors.affiliation: the Department of Molecular Oncology, Fondazione Istituto Fondazione Italiana per la Ricerca sul Cancro di Oncologia Molecolare, Milan 20139, Italy.
authors.forename: Dana
authors.initials: D
authors.lastname: Branzei
authors.affiliation: the Department of Computational and Systems Biology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15213, and.
authors.forename: Nathan L
authors.initials: NL
authors.lastname: Clark
authors.affiliation: From the Department of Microbiology and Molecular Genetics, University of Pittsburgh School of Medicine, University of Pittsburgh Cancer Institute, Pittsburgh, Pennsylvania 15213, karab@pitt.edu.
authors.forename: Kara A
authors.initials: KA
authors.lastname: Bernstein
mesh_terms: D002843:Chromatin / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D002945:Cisplatin / Q000494:pharmacology; D003432:Cross-Linking Reagents / Q000494:pharmacology; D004260:DNA Repair; D004261:DNA Replication / Q000187:drug effects; D005656:Fungal Proteins / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D042822:Genomic Instability / Q000187:drug effects; D006657:Histones / Q000378:metabolism; D006918:Hydroxyurea / Q000494:pharmacology; D050296:Microbial Viability / Q000187:drug effects; D019384:Nucleic Acid Synthesis Inhibitors / Q000494:pharmacology; D016196:S Phase / Q000187:drug effects; D004718:Saccharomycetales / Q000166:cytology / Q000187:drug effects / Q000201:enzymology* / Q000254:growth & development; D064570:Ubiquitin-Specific Proteases / Q000235:genetics / Q000378:metabolism*
chemical_list: D002843:Chromatin; D003432:Cross-Linking Reagents; D005656:Fungal Proteins; D006657:Histones; D019384:Nucleic Acid Synthesis Inhibitors; D064570:Ubiquitin-Specific Proteases; D002945:Cisplatin; D006918:Hydroxyurea
keywords: DNA damage response; DNA replication; deubiquitination; deubiquitylation (deubiquitination); molecular evolution; yeast genetics