Schizosaccharomyces pombeKAT5 contributes to resection and repair of a DNA double strand break

Chromatin remodeling is essential for effective repair of a DNA double strand break. KAT5 ( S. pombe Mst1, human TIP60) is a MYST family histone acetyltransferase conserved from yeast to humans that coordinates various DNA damage response activities at a DNA double strand break (DSB), including histone remodeling and activation of the DNA damage checkpoint. In S. pombe , mutations in mst1 + causes sensitivity to DNA damaging drugs. Here we show that Mst1 is recruited to DSBs. Mutation of mst1 + disrupts recruitment of repair proteins and delays resection. These defects are partially rescued by deletion of pku70 , which has been previously shown to antagonize repair by homologous recombination. These phenotypes of mst1 are similar to pht1-4KR , a non-acetylatable form of histone variant H2A.Z, which has been proposed to affect resection. Our data suggest that Mst1 functions to direct repair of DSBs towards homologous recombination pathways by modulating resection at the double strand break.