Reversal of histone H2B mono-ubiquitination is required for replication stress recovery

Mono-ubiquitination of histone H2B (H2B-Ub1) is a conserved modification that plays central role in regulating numerous biological processes including the DNA damage response, gene transcription, and DNA replication. Previous studies have revealed that H2B-Ub1 promotes recovery from replication stress by mediating Rad53 phosphorylation (Rad53-P), and activation of the intra-S replication checkpoint, in order to limit fork progression, and associated DNA damage. Since such mono-ubiquitination is a reversible process, we examined the role of H2B-Ub1 deubiquitination during replication stress. Using an experimental system in yeast which mimics H2B-Ub1 accumulation, we show that cells become sensitive to the replication stress induced by HU. This stress response was accompanied by Rad53-P accumulation, and delayed recovery from intra-S checkpoint arrest. Furthermore, we show that similar effects were recapitulated by the accumulation of endogenous H2B-Ub1, induced by the co-inactivation of the deubiquitinating enzyme, Ubp10, and Spt16, a FACT histone chaperone family member. While it has been well established that H2B mono-ubiquitination plays an essential role in recovering from replication stress, our data reveal that H2B-Ub1 deubiquitination is also essential for this process. •DNA is packaged in nucleosomes consisting of four histones proteins including H2B.•Histones undergo many modifications (PTM) that regulate various cellular processes.•It was shown that mono-ubiquitylation of H2B is critical for cell response to replication stress.•We show that the subsequent removal of H2B mono-ubiquitylation is a required step.