DNA-repair scaffolds dampen checkpoint signalling by counteracting the adaptor Rad9

• Published in: Nature (London) 2013-01, Vol.493 (7430), p.120-124
• Main Authors: Ohouo, Patrice Y., Bastos de Oliveira, Francisco M., Liu, Yi, Ma, Chu Jian, Smolka, Marcus B.
• Format: Article
• Language: English
• Subjects: 631/208/200; 631/337/1427/2567; 631/337/151; 631/80/86/2371; Analytical, structural and metabolic biochemistry; Binding, Competitive; Biological and medical sciences; Cell Cycle Checkpoints - physiology; Cell Cycle Proteins - antagonists & inhibitors; Cell Cycle Proteins - deficiency; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cellular signal transduction; Checkpoint Kinase 2; Cyclin-dependent kinases; Deoxyribonucleic acid; DNA; DNA damage; DNA Damage - drug effects; DNA Repair - drug effects; DNA Repair - physiology; DNA Replication - drug effects; Dna, deoxyribonucleoproteins; Endodeoxyribonucleases - deficiency; Endodeoxyribonucleases - metabolism; Enzyme Activation; Fundamental and applied biological sciences. Psychology; Histones - chemistry; Histones - genetics; Histones - metabolism; Humanities and Social Sciences; Hydroxyurea - pharmacology; Hypersensitivity; Intracellular Signaling Peptides and Proteins - metabolism; Kinases; Lesions; letter; multidisciplinary; Mutation; Nuclear Proteins - deficiency; Nuclear Proteins - metabolism; Nucleic acids; Observations; Phosphorylation; Properties; Protein Binding; Protein-Serine-Threonine Kinases - genetics; Protein-Serine-Threonine Kinases - metabolism; Proteins; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - drug effects; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - genetics; Saccharomyces cerevisiae Proteins - metabolism; Science; Signal Transduction; Stress, Physiological - drug effects
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/nature11658

DNA damage or replication stress induces the activation of checkpoint kinases, pausing the cell cycle so that DNA repair can take place; checkpoint activation must be regulated to prevent the cell-cycle arrest from persisting after damage is repaired, and now the Slx4–Rtt107 complex is shown to regulate checkpoint kinase activity by directly monitoring DNA-damage signalling. Scaffolding proteins alleviate cell-cycle arrest DNA damage or replication stress induces the activation of checkpoint kinases, which pause the cell cycle so that DNA repair can take place. However, checkpoint activation must be regulated to prevent the cell-cycle arrest from persisting after damage is repaired. Marcus Smolka and colleagues have determined that a complex formed by the DNA repair scaffold proteins Slx4 and Rtt107 interacts with Dpb11 and phosphorylated histone H2A, which are positive regulators of the checkpoint adaptor, Rad9, that activates Rad53 kinase. In this way, Slx4–Rtt107 regulates checkpoint kinase activity by directly monitoring DNA damage, as measured by Dpb11 binding and H2A phosphorylation In response to genotoxic stress, a transient arrest in cell-cycle progression enforced by the DNA-damage checkpoint (DDC) signalling pathway positively contributes to genome maintenance 1 . Because hyperactivated DDC signalling can lead to a persistent and detrimental cell-cycle arrest 2 , 3 , cells must tightly regulate the activity of the kinases involved in this pathway. Despite their importance, the mechanisms for monitoring and modulating DDC signalling are not fully understood. Here we show that the DNA-repair scaffolding proteins Slx4 and Rtt107 prevent the aberrant hyperactivation of DDC signalling by lesions that are generated during DNA replication in Saccharomyces cerevisiae . On replication stress, cells lacking Slx4 or Rtt107 show hyperactivation of the downstream DDC kinase Rad53, whereas activation of the upstream DDC kinase Mec1 remains normal. An Slx4–Rtt107 complex counteracts the checkpoint adaptor Rad9 by physically interacting with Dpb11 and phosphorylated histone H2A, two positive regulators of Rad9-dependent Rad53 activation. A decrease in DDC signalling results from hypomorphic mutations in RAD53 and H2A and rescues the hypersensitivity to replication stress of cells lacking Slx4 or Rtt107. We propose that the Slx4–Rtt107 complex modulates Rad53 activation by a competition-based mechanism that balances the engagement of Rad9 at replication-induced