title: Establishment of expression-state boundaries by Rif1 and Taz1 in fission yeast.
abstract: The Shelterin component Rif1 has emerged as a global regulator of the replication-timing program in all eukaryotes examined to date, possibly by modulating the 3D-organization of the genome. In fission yeast a second Shelterin component, Taz1, might share similar functions. Here, we identified unexpected properties for Rif1 and Taz1 by conducting high-throughput genetic screens designed to identify cis- and trans-acting factors capable of creating heterochromatin-euchromatin boundaries in fission yeast. The preponderance of cis-acting elements identified in the screens originated from genomic loci bound by Taz1 and associated with origins of replication whose firing is repressed by Taz1 and Rif1. Boundary formation and gene silencing by these elements required Taz1 and Rif1 and coincided with altered replication timing in the region. Thus, small chromosomal elements sensitive to Taz1 and Rif1 (STAR) could simultaneously regulate gene expression and DNA replication over a large domain, at the edge of which they established a heterochromatin-euchromatin boundary. Taz1, Rif1, and Rif1-associated protein phosphatases Sds21 and Dis2 were each sufficient to establish a boundary when tethered to DNA. Moreover, efficient boundary formation required the amino-terminal domain of the Mcm4 replicative helicase onto which the antagonistic activities of the replication-promoting Dbf4-dependent kinase and Rif1-recruited phosphatases are believed to converge to control replication origin firing. Altogether these observations provide an insight into a coordinated control of DNA replication and organization of the genome into expression domains.
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Tea
authors.initials: T
authors.lastname: Toteva
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Bethany
authors.initials: B
authors.lastname: Mason
authors.affiliation: Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamkitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Kanoh
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Peter
authors.initials: P
authors.lastname: Brøgger
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Daniel
authors.initials: D
authors.lastname: Green
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark.
authors.forename: Janne
authors.initials: J
authors.lastname: Verhein-Hansen
authors.affiliation: Department of Genome Medicine, Tokyo Metropolitan Institute of Medical Science, 2-1-6 Kamkitazawa, Setagaya-ku, Tokyo 156-8506, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Masai
authors.affiliation: Department of Biology, BioCenter, University of Copenhagen, 2200 Copenhagen N, Denmark; gen@bio.ku.dk.
authors.forename: Geneviève
authors.identifier: 0000-0001-8550-5945
authors.initials: G
authors.lastname: Thon
mesh_terms: D001483:Base Sequence; D004261:DNA Replication; D004271:DNA, Fungal / Q000235:genetics / Q000378:metabolism; D022041:Euchromatin / Q000648:ultrastructure; D015966:Gene Expression Regulation, Fungal / Q000235:genetics*; D006570:Heterochromatin / Q000648:ultrastructure; D057166:High-Throughput Screening Assays; D038101:Insulator Elements / Q000235:genetics*; D018741:Replication Origin; D012568:Schizosaccharomyces / Q000235:genetics*; D029702:Schizosaccharomyces pombe Proteins / Q000502:physiology*; D034501:Telomere-Binding Proteins / Q000502:physiology*
chemical_list: D004271:DNA, Fungal; D022041:Euchromatin; D006570:Heterochromatin; C570600:Rif1 protein, S pombe; D029702:Schizosaccharomyces pombe Proteins; D034501:Telomere-Binding Proteins; C104344:taz1 protein, S pombe
keywords: DNA replication program; chromatin boundaries; fission yeast; gene silencing; heterochromatin