Maintenance of the DNA-damage checkpoint requires DNA-damage-induced mediator protein oligomerization.
Oligomeric assembly of Brca1 C-terminal (BRCT) domain-containing mediator proteins occurs at sites of DNA damage. However, the functional significance and regulation of such assemblies are not well understood. In this study, we defined the molecular mechanism of DNA-damage-induced oligomerization of the S. cerevisiae BRCT protein Rad9. Our data suggest that Rad9's tandem BRCT domain mediates Rad9 oligomerization via its interaction with its own Mec1/Tel1-phosphorylated SQ/TQ cluster domain (SCD). Rad53 activation is unaffected by mutations that impair Rad9 oligomerization, but checkpoint maintenance is lost, indicating that oligomerization is required to sustain checkpoint signaling. Once activated, Rad53 phosphorylates the Rad9 BRCT domain, which attenuates the BRCT-SCD interaction. Failure to phosphorylate the Rad9 BRCT results in cytologically visible Rad9 foci. This suggests a feedback loop wherein Rad53 activity and Rad9 oligomerization are regulated to tune the DNA-damage response.
Usui
Takehiko
T
Laboratory of Chromosome Biology, Sloan-Kettering Institute, New York, NY 10065, USA.
Foster
Steven S
SS
Petrini
John H J
JH
D001665:Binding Sites; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism*; D064447:Checkpoint Kinase 2; D004249:DNA Damage / Q000502:physiology*; D004271:DNA, Fungal / Q000378:metabolism*; D018816:Genes, cdc; D047908:Intracellular Signaling Peptides and Proteins / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D017434:Protein Structure, Tertiary; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D015398:Signal Transduction
D018797:Cell Cycle Proteins; D004271:DNA, Fungal; D047908:Intracellular Signaling Peptides and Proteins; D029701:Saccharomyces cerevisiae Proteins; C069930:rad9 protein; D064447:Checkpoint Kinase 2; C088937:MEC1 protein, S cerevisiae; D017346:Protein Serine-Threonine Kinases; C513623:TEL1 protein, S cerevisiae; C067022:RAD53 protein, S cerevisiae