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 ATM (Tel1) and ATR (Mec1)-dependent phosphorylation of histone H2A (γ-H2AX) around the DSB. We describe Mec1- and Tel1-dependent phosphorylation of γ-H2B at H2B-T129. γ-H2B formation is impaired by γ-H2AX and its binding partner, Rad9. High-density microarray analyses show similar γ-H2AX and γ-H2B distributions, but γ-H2B is absent near telomeres. Both γ-H2AX and γ-H2B are strongly diminished over highly transcribed regions. When transcription of GAL genes are turned off, γ-H2AX is restored within 5 min, in a Mec1 dependent manner; when these genes are again induced, γ-H2AX is rapidly lost. Moreover, when a DSB is induced near CEN2, γ-H2AX spreads to all other centromeric regions, again depending on Mec1. Taken together, our data provide new insights on the function and establishment of the phosphorylation events occurring onto chromatin after DSB induction.