Dynamics of yeast histone H2A and H2B phosphorylation in response to a double-strand break

In budding yeast, a single double-strand break (DSB) triggers extensive Tel1 (ATM)-and Mec1 (ATR)-dependent phosphorylation of histone H2A around the DSB, to form gamma-H2AX. We describe Mec1- and Tel1-dependent phosphorylation of histone H2B at T129. gamma-H2B formation is impaired by gamma-H2AX and its binding partner Rad9. High-density microarray analyses show similar gamma-H2AX and gamma-H2B distributions, but gamma-H2B is absent near telomeres. Both gamma-H2AX and gamma-H2B are strongly diminished over highly transcribed regions. When transcription of GAL7, GAL10 and GAL1 genes is turned off, gamma-H2AX is restored within 5 min, in a Mec1-dependent manner; after reinduction of these genes, gamma-H2AX is rapidly lost. Moreover, when a DSB is induced near CEN2, gamma-H2AX spreads to all other pericentromeric regions, again depending on Mec1. Our data provide new insights in the function and establishment of phosphorylation events occurring on chromatin after DSB induction.