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From Proteopedia
Atomic cryoEM structure of Hsp90-Hsp70-Hop-GR
Structural highlights
FunctionHS71A_HUMAN In cooperation with other chaperones, Hsp70s stabilize preexistent proteins against aggregation and mediate the folding of newly translated polypeptides in the cytosol as well as within organelles. These chaperones participate in all these processes through their ability to recognize nonnative conformations of other proteins. They bind extended peptide segments with a net hydrophobic character exposed by polypeptides during translation and membrane translocation, or following stress-induced damage. In case of rotavirus A infection, serves as a post-attachment receptor for the virus to facilitate entry into the cell. Essential for STUB1-mediated ubiquitination and degradation of FOXP3 in regulatory T-cells (Treg) during inflammation (PubMed:23973223).[1] [2] [3] Publication Abstract from PubMedMaintaining a healthy proteome is fundamental for the survival of all organisms(1). Integral to this are Hsp90 and Hsp70, molecular chaperones that together facilitate the folding, remodelling and maturation of the many 'client proteins' of Hsp90(2). The glucocorticoid receptor (GR) is a model client protein that is strictly dependent on Hsp90 and Hsp70 for activity(3-7). Chaperoning GR involves a cycle of inactivation by Hsp70; formation of an inactive GR-Hsp90-Hsp70-Hop 'loading' complex; conversion to an active GR-Hsp90-p23 'maturation' complex; and subsequent GR release(8). However, to our knowledge, a molecular understanding of this intricate chaperone cycle is lacking for any client protein. Here we report the cryo-electron microscopy structure of the GR-loading complex, in which Hsp70 loads GR onto Hsp90, uncovering the molecular basis of direct coordination by Hsp90 and Hsp70. The structure reveals two Hsp70 proteins, one of which delivers GR and the other scaffolds the Hop cochaperone. Hop interacts with all components of the complex, including GR, and poises Hsp90 for subsequent ATP hydrolysis. GR is partially unfolded and recognized through an extended binding pocket composed of Hsp90, Hsp70 and Hop, revealing the mechanism of GR loading and inactivation. Together with the GR-maturation complex structure(9), we present a complete molecular mechanism of chaperone-dependent client remodelling, and establish general principles of client recognition, inhibition, transfer and activation. Structure of Hsp90-Hsp70-Hop-GR reveals the Hsp90 client-loading mechanism.,Wang RY, Noddings CM, Kirschke E, Myasnikov AG, Johnson JL, Agard DA Nature. 2022 Jan;601(7893):460-464. doi: 10.1038/s41586-021-04252-1. Epub 2021 , Dec 22. PMID:34937942[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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