9v33

Calypso/Asx/NCP-ub complex

spinqualitylabelsall models 9v33, resolution 5.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 9v33 is a 15 chain structure with sequence from Drosophila melanogaster, Escherichia coli, Homo sapiens and Xenopus laevis. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 5.9Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function A0A310TTQ1_XENLA Publication Abstract from PubMed The Polycomb repressive complex 1 (PRC1) and PR-DUB constitute a canonical pair of histone-modifying enzymes that deposit and remove monoubiquitinated H2A at lysine 119 (H2AK119ub1), serving as a model of dynamic epigenetic regulation. In humans, PR-DUB, composed of BAP1 and ASXL1, functions as a monomeric complex, while the Drosophila homolog Calypso/Asx forms a bidentate dimer (Calypso(2): Asx(2)) with an unclear chromatin engagement mechanism. Here, we present its cryo-EM structure bound to a nucleosome, revealing the molecular basis of interaction. Surprisingly, only one Calypso/Asx unit engages the nucleosome in a conformation similar to human BAP1/ASXL1, while the second remains disengaged. Structural and biochemical analysis of the positively charged Calypso C terminus suggests a "spreading" potential of the bidentate complex along chromatin, which was validated in vitro using nucleosome arrays. These findings support a model in which the bidentate Calypso/Asx complex enables processive deubiquitination along chromatin via alternating or cooperative engagement. Structural basis of nucleosome deubiquitination by the bidentate Calypso/Asx complex.,Wang C, Sun F, Zhao H, Zhang N, Guan J, Zhou Y, Shuai W, Zheng H, He J iScience. 2026 Feb 10;29(3):114958. doi: 10.1016/j.isci.2026.114958. eCollection , 2026 Mar 20. PMID:41782825 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

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