title: Checkpoint kinase phosphorylation in response to endogenous oxidative DNA damage in repair-deficient stationary-phase Saccharomyces cerevisiae.
abstract: Stationary-phase Saccharomyces cerevisiae can serve as a model for post-mitotic cells of higher eukaryotes. Phosphorylation and activation of the checkpoint kinase Rad53 was observed after more than 2 days of culture if two major pathways of oxidative DNA damage repair, base excision repair (BER) and nucleotide excision repair (NER), are inactive. The wild type showed a low degree of Rad53 phosphorylation when the incubation period was drastically increased. In the ber ner strain, Rad53 phosphorylation can be abolished by inclusion of antioxidants or exclusion of oxygen. Furthermore, this modification and enhanced mutagenesis in extended stationary phase were absent in rho degrees strains, lacking detectable mitochondrial DNA. This checkpoint response is therefore thought to be dependent on reactive oxygen species originating from mitochondrial respiration. There was no evidence for progressive overall telomere shortening during stationary-phase incubation. Since Rad50 (of the MRN complex) and Mec1 (the homolog of ATR) were absolutely required for the observed checkpoint response, we assume that resected random double-strand breaks are the critical lesion. Single-strand resection may be accelerated by unrepaired oxidative base damage in the vicinity of a double-strand break.
authors.affiliation: Department of Cell Biology and Anatomy, University of North Texas Health Science Center, Fort Worth, TX 76107, USA.
authors.forename: Vaibhav
authors.initials: V
authors.lastname: Pawar
authors.forename: Liu
authors.initials: L
authors.lastname: Jingjing
authors.forename: Nila
authors.initials: N
authors.lastname: Patel
authors.forename: Nimrat
authors.initials: N
authors.lastname: Kaur
authors.forename: Paul W
authors.initials: PW
authors.lastname: Doetsch
authors.forename: Gerald S
authors.initials: GS
authors.lastname: Shadel
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.forename: Wolfram
authors.initials: W
authors.lastname: Siede
mesh_terms: D018797:Cell Cycle Proteins / Q000378:metabolism; D000071877:Checkpoint Kinase 1; D064447:Checkpoint Kinase 2; D004249:DNA Damage; D015966:Gene Expression Regulation, Fungal; D006657:Histones / Q000737:chemistry; D008928:Mitochondria / Q000378:metabolism; D008954:Models, Biological; D008957:Models, Genetic; D016296:Mutagenesis; D009711:Nucleotides / Q000737:chemistry; D010100:Oxygen / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011494:Protein Kinases / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics* / Q000502:physiology*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D016615:Telomere / Q000648:ultrastructure
chemical_list: D018797:Cell Cycle Proteins; D006657:Histones; D009711:Nucleotides; D029701:Saccharomyces cerevisiae Proteins; D011494:Protein Kinases; D064447:Checkpoint Kinase 2; D000071877:Checkpoint Kinase 1; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae; D010100:Oxygen