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Updated: Jan 13, 2026

In Vitro Ubiquitination and Deubiquitination Assays of Nucleosomal Histones
Published on: July 25, 2019
Allosteric activation of RNF20/RNF40-RAD6A-mediated H2BK120 monoubiquitylation by H2BS112 GlcNAcylation
Zhiheng Deng1,2,3, Shixian Tao2, Yunxiang Du2
1School of Pharmaceutical Sciences, Institute of Translational Medicine, Shanghai Key Laboratory for Antibody-Drug Conjugates with Innovative Target, Shanghai Frontiers Science Center of Drug Target Identification and Delivery, Shanghai Jiao Tong University, Shanghai, China.
Abstract:
The activation of H2B K120 monoubiquitylation (H2BK120ub) by H2B S112 GlcNAcylation (H2BS112GlcNAc) has an important role in regulating transcriptional activation, yet its mechanism remains unclear. Here we chemically synthesized H2BS112GlcNAc-modified nucleosomes and quantitatively evaluated how H2BS112GlcNAc stimulates ubiquitylation by RNF20/RNF40-RAD6A E3-E2 enzymes. Cryo-electron microscopy determination of a chemically trapped RNF20/RNF40-RAD6A-Ub-H2BS112GlcNAc nucleosome complex revealed that the H2BS112GlcNAc moiety interacts with the E2 enzyme RAD6A but not the E3 ligase RNF20/RNF40. Mutagenesis and kinetics analyses demonstrated that H2BS112GlcNAc allosterically stimulates ubiquitin transfer from the RAD6A~Ub thioester to H2B K120 by enhancing the nucleophilicity of H2B K120. Structure‒activity relationship analysis further identified the essential roles of the C2 N-acetyl group and the β-configuration of C1 on the H2BS112GlcNAc moiety. These findings provide the structural evidence of histone posttranslational modification crosstalk involving O-GlcNAcylation and reveal how O-GlcNAcylation can allosterically stimulate enzyme activity through substrate modification.
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