title: Limiting amounts of budding yeast Rad53 S-phase checkpoint activity results in increased resistance to DNA alkylation damage.
abstract: The Saccharomyces cerevisiae protein kinase Rad53 plays a key role in maintaining genomic integrity after DNA damage and is an essential component of the 'intra-S-phase checkpoint'. In budding yeast, alkylating chemicals, such as methyl methanesulfonate (MMS), or depletion of nucleotides by hydroxyurea (HU) stall DNA replication forks and thus activate Rad53 during S-phase. This stabilizes stalled DNA replication forks and prevents the activation of later origins of DNA replication. Here, we report that a reduction in the level of Rad53 kinase causes cells to behave very differently in response to DNA alkylation or to nucleotide depletion. While cells lacking Rad53 are unable to activate the checkpoint response to HU or MMS, so that they rapidly lose viability, a reduction in Rad53 enhances cell survival only after DNA alkylation. This reduction in the level of Rad53 allows S-phase cells to maintain the stability of DNA replication forks upon MMS treatment, but does not prevent the collapse of forks in HU. Our results may have important implications for cancer therapies, as they suggest that partial impairment of the S-phase checkpoint Rad53/Chk2 kinase provides cells with a growth advantage in the presence of drugs that damage DNA.
authors.affiliation: Instituto de Biología Molecular y Celular del Cáncer, Departamento de Microbiología y Genética, Universidad de Salamanca/CSIC, 37007 Salamanca, Spain.
authors.forename: Violeta
authors.initials: V
authors.lastname: Cordón-Preciado
authors.forename: Sandra
authors.initials: S
authors.lastname: Ufano
authors.forename: Avelino
authors.initials: A
authors.lastname: Bueno
mesh_terms: D000483:Alleles; D018906:Antineoplastic Agents, Alkylating / Q000633:toxicity*; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D004261:DNA Replication; D004351:Drug Resistance; D017353:Gene Deletion; D006918:Hydroxyurea / Q000633:toxicity; D008741:Methyl Methanesulfonate / Q000633:toxicity; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism*; D016196:S Phase / Q000187:drug effects* / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000201:enzymology* / Q000235:genetics; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic
chemical_list: D018906:Antineoplastic Agents, Alkylating; D018797:Cell Cycle Proteins; C115052:SML1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D008741:Methyl Methanesulfonate; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae; D006918:Hydroxyurea