Mec1 Autophosphorylation and Ddc2 Phosphorylation Regulates DNA Damage Checkpoint Signaling.

In budding yeast, a single DNA double-strand break (DSB) triggers the activation of Mec1-dependent DNA damage checkpoint. After about 12 h, cells turn off the checkpoint signaling and adapt despite the persistence of the DSB. We report that the adaptation involves the autophosphorylation of Mec1 at site S1964.