The 26S proteasome is the ATP-dependent protease responsible for regulating the proteome of eukaryotic cells through degradation of mainly ubiquitin-tagged substrates. In order to understand how proteasome responds to ubiquitin signal, we resolved an ensemble of cryo-EM structures of proteasome in the presence of K48-Ub4, with three of them resolved at near-atomic resolution. We identified a conformation with stabilized ubiquitin receptors and a previously unreported orientation of the lid, assigned as a Ub-accepted state C1-b. We determined another structure C3-b with localized K48-Ub4 to the toroid region of Rpn1, assigned as a substrate-processing state. Our structures indicate that tetraUb induced conformational changes in proteasome could initiate substrate degradation. We also propose a CP gate-opening mechanism involving the propagation of the motion of the lid to the gate through the Rpn6-α2 interaction. Our results enabled us to put forward a model of a functional cycle for proteasomes induced by tetraUb and nucleotide.
Pubmed ID: 30792173 RIS Download
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Collection of data of protein sequence and functional information. Resource for protein sequence and annotation data. Consortium for preservation of the UniProt databases: UniProt Knowledgebase (UniProtKB), UniProt Reference Clusters (UniRef), and UniProt Archive (UniParc), UniProt Proteomes. Collaboration between European Bioinformatics Institute (EMBL-EBI), SIB Swiss Institute of Bioinformatics and Protein Information Resource. Swiss-Prot is a curated subset of UniProtKB.
View all literature mentionsA Python-based software suite for the automated determination of molecular structures using X-ray crystallography and other methods. Phenix includes programs for assessing data quality, experimental phasing, molecular replacement, model building, structure refinement, and validation. It also includes tools for reflection data and creating maps and models. Phenix can also be used for neutron crystallography. Tutorials and examples are available in the documentation tab.
View all literature mentionsSoftware for determination of cryo-EM structures. It employs an empirical Bayesian approach to refinement of (multiple) 3D reconstructions or 2D class averages in electron cryo-microscopy.
View all literature mentionsSoftware suite for processing data from transmission electron microscopes. Used in supercomputing facilities as a test application for large-scale computing. Used for single particle reconstruction, helical reconstruction, 2-D crystallography and whole-cell tomography.
View all literature mentionsThis unknown targets 20S alpha6 subunit
View all literature mentionsThis monoclonal targets Human USP14
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