8ieg
From Proteopedia
Bre1(mRBD-RING)/Rad6-Ub/nucleosome complex
Structural highlights
FunctionBRE1_YEAST E3 ubiquitin-protein ligase that mediates monoubiquitination of histone H2B to form H2BK123ub1 in association with the E2 enzyme RAD6/UBC2. H2BK123ub1 gives a specific tag for epigenetic transcriptional activation, elongation by RNA polymerase II, telomeric silencing, and is also a prerequisite for H3K4me and H3K79me formation. It thereby plays a central role in histone code and gene regulation. Also modulates the formation of double-strand breaks during meiosis.[1] [2] [3] [4] [5] Publication Abstract from PubMedHistone H2B monoubiquitylation plays essential roles in chromatin-based transcriptional processes. A RING-type E3 ligase (yeast Bre1 or human RNF20/RNF40) and an E2 ubiquitin-conjugating enzyme (yeast Rad6 or human hRAD6A), together, precisely deposit ubiquitin on H2B K123 in yeast or K120 in humans. Here, we developed a chemical trapping strategy and successfully captured the transient structures of Bre1- or RNF20/RNF40-mediated ubiquitin transfer from Rad6 or hRAD6A to nucleosomal H2B. Our structures show that Bre1 and RNF40 directly bind nucleosomal DNA, exhibiting a conserved E3/E2/nucleosome interaction pattern from yeast to humans for H2B monoubiquitylation. We also find an uncanonical non-hydrophobic contact in the Bre1 RING-Rad6 interface, which positions Rad6 directly above the target H2B lysine residue. Our study provides mechanistic insights into the site-specific monoubiquitylation of H2B, reveals a critical role of nucleosomal DNA in mediating E3 ligase recognition, and provides a framework for understanding the cancer-driving mutations of RNF20/RNF40. Mechanistic insights into nucleosomal H2B monoubiquitylation mediated by yeast Bre1-Rad6 and its human homolog RNF20/RNF40-hRAD6A.,Deng Z, Ai H, Sun M, Tong Z, Du Y, Qu Q, Zhang L, Xu Z, Tao S, Shi Q, Li JB, Pan M, Liu L Mol Cell. 2023 Aug 17:S1097-2765(23)00607-X. doi: 10.1016/j.molcel.2023.08.001. PMID:37633270[6] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. References
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