ABSTRACT:Monoubiquitination at lysine 119 of histone H2A (ubH2A) is a prevalent post-translational modification that isassociated with gene repression in the context of chromatin. However, the direct function of ubH2A on nucleosome is poorlyunderstood. Here we identified the effect of ubH2A on nucleosome using single-molecule magnetic tweezers. We revealed thatubH2A stabilizes the nucleosome by blocking the peeling of DNA from the histone octamer. Each ubH2A reinforces one-half of theouter wrap and introduces a robust asymmetry for nucleosome unfolding. Furthermore, a real-time deubiquitination processconfirmed that ubH2A-nucleosome is sequentially deubiquitinated and restored to the unmodified nucleosome state. These resultsprovide a novel mechanism to understand the repression of the passage of RNA or DNA polymerases through the ubH2A-nucleosome barrier during gene transcription or replication.

http://www.ccmu.edu.cn/docs/20200215084850509320.pdf