5mpb
26S proteasome in presence of AMP-PNP (s3)26S proteasome in presence of AMP-PNP (s3)
Structural highlights
FunctionPSA3_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 PubMedIn eukaryotic cells, the ubiquitin-proteasome system (UPS) is responsible for the regulated degradation of intracellular proteins. The 26S holocomplex comprises the core particle (CP), where proteolysis takes place, and one or two regulatory particles (RPs). The base of the RP is formed by a heterohexameric AAA+ ATPase module, which unfolds and translocates substrates into the CP. Applying single-particle cryo-electron microscopy (cryo-EM) and image classification to samples in the presence of different nucleotides and nucleotide analogs, we were able to observe four distinct conformational states (s1 to s4). The resolution of the four conformers allowed for the construction of atomic models of the AAA+ ATPase module as it progresses through the functional cycle. In a hitherto unobserved state (s4), the gate controlling access to the CP is open. The structures described in this study allow us to put forward a model for the 26S functional cycle driven by ATP hydrolysis. Structural insights into the functional cycle of the ATPase module of the 26S proteasome.,Wehmer M, Rudack T, Beck F, Aufderheide A, Pfeifer G, Plitzko JM, Forster F, Schulten K, Baumeister W, Sakata E Proc Natl Acad Sci U S A. 2017 Feb 7;114(6):1305-1310. doi:, 10.1073/pnas.1621129114. Epub 2017 Jan 23. PMID:28115689[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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