title: Genome-wide replication profiles of S-phase checkpoint mutants reveal fragile sites in yeast.
abstract: The S-phase checkpoint kinases Mec1 and Rad53 in the budding yeast, Saccharomyces cerevisiae, are activated in response to replication stress that induces replication fork arrest. In the absence of a functional S-phase checkpoint, stalled replication forks collapse and give rise to chromosome breakage. In an attempt to better understand replication dynamics in S-phase checkpoint mutants, we developed a replication origin array for budding yeast that contains 424 of 432 previously identified potential origin regions. As expected, mec1-1 and rad53-1 mutants failed to inhibit late origin activation. Surprisingly however, 17 early-firing regions were not replicated efficiently in these mutants. This was not due to a lack of initiation, but rather to problems during elongation, as replication forks arrested in close proximity to these origins, resulting in the accumulation of small replication intermediates and eventual replication fork collapse. Importantly, these regions were not only prone to chromosome breakage in the presence of exogenous stress but also in its absence, similar to fragile sites in the human genome.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Miruthubashini
authors.initials: M
authors.lastname: Raveendranathan
authors.forename: Sharbani
authors.initials: S
authors.lastname: Chattopadhyay
authors.forename: Yung-Tsi
authors.initials: YT
authors.lastname: Bolon
authors.forename: Justin
authors.initials: J
authors.lastname: Haworth
authors.forename: Duncan J
authors.initials: DJ
authors.lastname: Clarke
authors.forename: Anja-Katrin
authors.initials: AK
authors.lastname: Bielinsky
mesh_terms: D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D064447:Checkpoint Kinase 2; D043283:Chromosome Fragile Sites; D004261:DNA Replication; D015966:Gene Expression Regulation, Fungal; D016681:Genome, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D009154:Mutation; D020411:Oligonucleotide Array Sequence Analysis; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D018741:Replication Origin; D016196:S Phase / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism
chemical_list: D018797:Cell Cycle Proteins; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae