14-3-3 protein Bmh1 triggers short-range compaction of mitotic chromosomes by recruiting sirtuin deacetylase Hst2

Mitotic chromosome compaction is licensed by kinetochores in yeast. Recruitment of Aurora kinase B elicits a cascade of events starting with phosphorylation of H3 S10, which signals the recruitment of lysine deacetylase Hst2 and the removal of H4 K16ac. The unmasked H4 tails interact with the acidic patch of neighbouring nucleosomes to drive short-range compaction of chromatin. Here, we demonstrate that the interaction of Hst2 with H3 S10ph is mediated by 14-3-3 protein Bmh1. As a homodimer, Bmh1 binds simultaneously to H3 S10ph and the phosphorylated C-terminus of Hst2. The Hst2-Bmh1 interaction is cell cycle dependent, reaching its maximum in M phase. Furthermore, we show that phosphorylation of C-terminal residues of Hst2 stimulates its deacetylase activity. Hence, the data presented here identify Bmh1 as a key player in the mechanism of licensing of chromosome compaction in mitosis. Key Points 14-3-3 protein Bmh1 bridges the interaction of Hst2 with phosphorylated H3 tails Hst2 is multiply phosphorylated on its unstructured C-terminal tail The interaction of Bmh1 with Hst2 is cell cycle dependent Hst2 phosphorylation enhances its enzymatic activity