6j2c
Yeast proteasome in translocation competent state (C3-a)
Structural highlights
FunctionPSB1_YEAST The proteasome degrades poly-ubiquitinated proteins in the cytoplasm and in the nucleus. It is essential for the regulated turnover of proteins and for the removal of misfolded proteins. The proteasome is a multicatalytic proteinase complex that is characterized by its ability to cleave peptides with Arg, Phe, Tyr, Leu, and Glu adjacent to the leaving group at neutral or slightly basic pH. It has an ATP-dependent proteolytic activity. PRE3 and PRE4 are necessary for the peptidyl-glutamyl-peptide-hydrolyzing activity. This subunit is necessary for the peptidylglutamyl-peptide hydrolyzing activity. Publication Abstract from PubMedThe 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-alpha2 interaction. Our results enabled us to put forward a model of a functional cycle for proteasomes induced by tetraUb and nucleotide. Structural Snapshots of 26S Proteasome Reveal Tetraubiquitin-Induced Conformations.,Ding Z, Xu C, Sahu I, Wang Y, Fu Z, Huang M, Wong CCL, Glickman MH, Cong Y Mol Cell. 2019 Feb 12. pii: S1097-2765(19)30038-3. doi:, 10.1016/j.molcel.2019.01.018. PMID:30792173[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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