Rif1 Regulates Initiation Timing of Late Replication Origins throughout the S. cerevisiae Genome

• Published in: PloS one Vol. 9; no. 5; p. e98501
• Main Authors: Peace, Jared M., Ter-Zakarian, Anna, Aparicio, Oscar M.
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 30.05.2014; Public Library of Science (PLoS)
• Subjects: Analysis; Baking yeast; Binding sites; Bioinformatics; Biology and life sciences; Cell cycle; Cell Cycle Proteins - genetics; Cells (Biology); Centromere - genetics; Centromeres; Chromatin; Chromosomes; Deoxyribonucleic acid; Deregulation; DNA; DNA biosynthesis; DNA damage; DNA replication; DNA Replication - genetics; DNA Replication Timing - genetics; Epigenetic inheritance; Epigenetics; Gene expression; Genome, Fungal - genetics; Genomes; Genomics; Kinases; Localization; Mammalian cells; Origins; Palmitoylation; Phosphatase; Protein binding; Proteins; Regulations; Replication; Replication initiation; Replication Origin - genetics; Replication origins; Repressor Proteins - genetics; Research and Analysis Methods; S Phase Cell Cycle Checkpoints - genetics; Saccharomyces cerevisiae; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae Proteins - genetics; Signaling; Telomerase; Telomere - genetics; Telomere-Binding Proteins - genetics; Telomeres; Yeast; Los Angeles California; United States > US; California
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0098501

Chromosomal DNA replication involves the coordinated activity of hundreds to thousands of replication origins. Individual replication origins are subject to epigenetic regulation of their activity during S-phase, resulting in differential efficiencies and timings of replication initiation during S-phase. This regulation is thought to involve chromatin structure and organization into timing domains with differential ability to recruit limiting replication factors. Rif1 has recently been identified as a genome-wide regulator of replication timing in fission yeast and in mammalian cells. However, previous studies in budding yeast have suggested that Rif1's role in controlling replication timing may be limited to subtelomeric domains and derives from its established role in telomere length regulation. We have analyzed replication timing by analyzing BrdU incorporation genome-wide, and report that Rif1 regulates the timing of late/dormant replication origins throughout the S. cerevisiae genome. Analysis of pfa4Δ cells, which are defective in palmitoylation and membrane association of Rif1, suggests that replication timing regulation by Rif1 is independent of its role in localizing telomeres to the nuclear periphery. Intra-S checkpoint signaling is intact in rif1Δ cells, and checkpoint-defective mec1Δ cells do not comparably deregulate replication timing, together indicating that Rif1 regulates replication timing through a mechanism independent of this checkpoint. Our results indicate that the Rif1 mechanism regulates origin timing irrespective of proximity to a chromosome end, and suggest instead that telomere sequences merely provide abundant binding sites for proteins that recruit Rif1. Still, the abundance of Rif1 binding in telomeric domains may facilitate Rif1-mediated repression of non-telomeric origins that are more distal from centromeres.