6j2n

Publication Abstract from PubMed

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-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.