8t08

Preholo-Proteasome from Pre1-1 Pre4-1 Double Mutant

spinqualitylabelsall models 8t08, resolution 3.00Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 8t08 is a 20 chain structure with sequence from Saccharomyces cerevisiae S288C. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Method: Electron Microscopy, Resolution 3Å Resources: FirstGlance, OCA, PDBe, RCSB, PDBsum, ProSAT Function PSA1_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. Publication Abstract from PubMed Assembly of the proteasome's core particle (CP), a barrel-shaped chamber of four stacked rings, requires five chaperones and five subunit propeptides. Fusion of two half-CP precursors yields a complete structure but remains immature until active site maturation. Here, using Saccharomyces cerevisiae, we report a high-resolution cryogenic electron microscopy structure of preholoproteasome, a post-fusion assembly intermediate. Our data reveal how CP midline-spanning interactions induce local changes in structure, facilitating maturation. Unexpectedly, we find that cleavage may not be sufficient for propeptide release, as residual interactions with chaperones such as Ump1 hold them in place. We evaluated previous models proposing that dynamic conformational changes in chaperones drive CP fusion and autocatalytic activation by comparing preholoproteasome to pre-fusion intermediates. Instead, the data suggest a scaffolding role for the chaperones Ump1 and Pba1/Pba2. Our data clarify key aspects of CP assembly, suggest that undiscovered mechanisms exist to explain CP fusion/activation, and have relevance for diseases of defective CP biogenesis. Structure of the preholoproteasome reveals late steps in proteasome core particle biogenesis.,Walsh RM Jr, Rawson S, Schnell HM, Velez B, Rajakumar T, Hanna J Nat Struct Mol Biol. 2023 Oct;30(10):1516-1524. doi: 10.1038/s41594-023-01081-w. , Epub 2023 Aug 31. PMID:37653242 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also Proteasome 3D structures

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