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The GR-Maturation Complex: Glucocorticoid Receptor in complex with Hsp90 and co-chaperone p23
Structural highlights
FunctionHS90A_HUMAN Molecular chaperone that promotes the maturation, structural maintenance and proper regulation of specific target proteins involved for instance in cell cycle control and signal transduction. Undergoes a functional cycle that is linked to its ATPase activity. This cycle probably induces conformational changes in the client proteins, thereby causing their activation. Interacts dynamically with various co-chaperones that modulate its substrate recognition, ATPase cycle and chaperone function.[1] [2] Publication Abstract from PubMedHsp90 is a conserved and essential molecular chaperone responsible for the folding and activation of hundreds of 'client' proteins(1-3). The glucocorticoid receptor (GR) is a model client that constantly depends on Hsp90 for activity(4-9). GR ligand binding was previously shown to nr inhibited by Hsp70 and restored by Hsp90, aided by the co-chaperone p23(10). However, a molecular understanding of the chaperone-mediated remodelling that occurs between the inactive Hsp70-Hsp90 'client-loading complex' and an activated Hsp90-p23 'client-maturation complex' is lacking for any client, including GR. Here we present a cryo-electron microscopy (cryo-EM) structure of the human GR-maturation complex (GR-Hsp90-p23), revealing that the GR ligand-binding domain is restored to a folded, ligand-bound conformation, while being simultaneously threaded through the Hsp90 lumen. In addition, p23 directly stabilizes native GR using a C-terminal helix, resulting in enhanced ligand binding. This structure of a client bound to Hsp90 in a native conformation contrasts sharply with the unfolded kinase-Hsp90 structure(11). Thus, aided by direct co-chaperone-client interactions, Hsp90 can directly dictate client-specific folding outcomes. Together with the GR-loading complex structure(12), we present the molecular mechanism of chaperone-mediated GR remodelling, establishing the first, to our knowledge, complete chaperone cycle for any Hsp90 client. Structure of Hsp90-p23-GR reveals the Hsp90 client-remodelling mechanism.,Noddings CM, Wang RY, Johnson JL, Agard DA Nature. 2022 Jan;601(7893):465-469. doi: 10.1038/s41586-021-04236-1. Epub 2021 , Dec 22. PMID:34937936[3] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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