Recent studies of yeast G1 DNA damage response have identified characteristic changes in chromatin adjacent to double-strand breaks (DSBs). Histone H2A (yeast H2AX) is rapidly phosphorylated on S129 by the kinase Tel1 (ATM) over a domain extending kilobases from the DSB. The adaptor protein Rad9 (53BP1) is recruited to this chromatin domain through binding of its tudor domains to histone H3 diMe-K79. Multisite phosphorylation of Rad9 by Mec1 (ATR) then activates the signaling kinase Rad53 (CHK2) to induce a delay in G1. Here, we report a previously undescribed role for Tel1 in G1 checkpoint response and show that H2A is the likely phosphorylation target, in a much as S129 mutation to Ala confers defects in G1 checkpoint arrest, Rad9 phosphorylation, and Rad53 activation. Importantly, Rad9 fails to bind chromatin adjacent to DSBs in H2A-S129A mutants. Previous work showed that H2A phosphorylation allows binding of NuA4, SWR, and INO80 chromatin remodeling complexes, perhaps exposing H3 diMe-K79. Yet, mutants lacking SWR or INO80 remain checkpoint competent, whereas loss of NuA4-dependent histone acetylation leads to G1 checkpoint persistence, suggesting that H2A phosphorylation promotes two independent events, rapid Rad9 recruitment to DSBs and subsequent remodeling by NuA4, SWR, and INO80.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|