title: Coordinated control of replication and transcription by a SAPK protects genomic integrity.
abstract: Upon environmental changes or extracellular signals, cells are subjected to marked changes in gene expression. Dealing with high levels of transcription during replication is critical to prevent collisions between the transcription and replication pathways and avoid recombination events. In response to osmostress, hundreds of stress-responsive genes are rapidly induced by the stress-activated protein kinase (SAPK) Hog1 (ref. 6), even during S phase. Here we show in Saccharomyces cerevisae that a single signalling molecule, Hog1, coordinates both replication and transcription upon osmostress. Hog1 interacts with and phosphorylates Mrc1, a component of the replication complex. Phosphorylation occurs at different sites to those targeted by Mec1 upon DNA damage. Mrc1 phosphorylation by Hog1 delays early and late origin firing by preventing Cdc45 loading, as well as slowing down replication-complex progression. Regulation of Mrc1 by Hog1 is completely independent of Mec1 and Rad53. Cells carrying a non-phosphorylatable allele of MRC1 (mrc1(3A)) do not delay replication upon stress and show a marked increase in transcription-associated recombination, genomic instability and Rad52 foci. In contrast, mrc1(3A) induces Rad53 and survival in the presence of hydroxyurea or methyl methanesulphonate. Therefore, Hog1 and Mrc1 define a novel S-phase checkpoint independent of the DNA-damage checkpoint that permits eukaryotic cells to prevent conflicts between DNA replication and transcription, which would otherwise lead to genomic instability when both phenomena are temporally coincident.
authors.affiliation: Cell Signaling Unit, Departament de Ciències Experimentals i de la Salut, Universitat Pompeu Fabra, Barcelona E-08003, Spain.
authors.forename: Alba
authors.initials: A
authors.lastname: Duch
authors.forename: Irene
authors.initials: I
authors.lastname: Felipe-Abrio
authors.forename: Sonia
authors.initials: S
authors.lastname: Barroso
authors.forename: Gilad
authors.initials: G
authors.lastname: Yaakov
authors.forename: María
authors.initials: M
authors.lastname: García-Rubio
authors.forename: Andrés
authors.initials: A
authors.lastname: Aguilera
authors.forename: Eulàlia
authors.initials: E
authors.lastname: de Nadal
authors.forename: Francesc
authors.initials: F
authors.lastname: Posas
mesh_terms: D000483:Alleles; D059447:Cell Cycle Checkpoints; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D004249:DNA Damage; D004261:DNA Replication; D004268:DNA-Binding Proteins / Q000378:metabolism; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal / Q000235:genetics*; D042822:Genomic Instability / Q000235:genetics; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D009997:Osmotic Pressure; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D011995:Recombination, Genetic; D018741:Replication Origin / Q000235:genetics; D016196:S Phase; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics* / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D013312:Stress, Physiological; D013379:Substrate Specificity; D013997:Time Factors; D014158:Transcription, Genetic
chemical_list: C102209:CDC45 protein, S cerevisiae; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D047908:Intracellular Signaling Peptides and Proteins; C441579:MRC1 protein, S cerevisiae; D009687:Nuclear Proteins; D029701:Saccharomyces cerevisiae Proteins; C489404:CDC7 protein, S cerevisiae; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C088589:HOG1 protein, S cerevisiae; D020928:Mitogen-Activated Protein Kinases