Structure of Hsp90–p23–GR reveals the Hsp90 client-remodelling mechanism

In the paper

“expression of p23 significantly enhanced GR activity relative to Sba1, consistent with a previous report32.”

What the sources say

• Disputed

  In “Effects of the yeast p23 homolog on IR activities” (page unavailable), the paper says p23 and Sba1p were “indistinguishable in their effects on receptors.” Its mammalian-cell results report that both increased GR activity two- to threefold, rather than p23 enhancing it significantly more than Sba1p. (LLM, conf=0.88)

  Checked by a reasoning model — may be wrong.

  cites [32] Freeman, B. C., Felts, S. J., Toft, D. O. & Yamamoto, K. R. The p23 molecular chaperones act at a late step in intracellular receptor action to differentially affect ligand efficacies. Genes Dev. 14, 422–434 (2000). sourceExperimental — accuracy not yet measured

In the paper

“Hsp90 is a conserved and essential molecular chaperone responsible for the folding and activation of hundreds of ‘client’ proteins1-3.”

What the sources say

• ?Not checked — no full text of the sourcecites [1] Taipale, M., Jarosz, D. F. & Lindquist, S. HSP90 at the hub of protein homeostasis: emerging mechanistic insights. Nat. Rev. Mol. Cell Biol. 11, 515–528 (2010). source
• ?Not checked — no full text of the sourcecites [2] Schopf, F. H., Biebl, M. M. & Buchner, J. The HSP90 chaperone machinery. Nat. Rev. Mol. Cell Biol. 18, 345–360 (2017). source
• Supported

  The Introduction (p. 2) describes HSP90 as a chaperone that promotes the folding and function of client proteins and discusses its roles across diverse organisms. The Discussion (p. 12) calls it an essential chaperone and reports interactions with almost 400 client proteins, supporting the claim's scale. (LLM, conf=0.90)

  cites [3] Taipale, M. et al. Quantitative analysis of HSP90–client interactions reveals principles of substrate recognition. Cell 150, 987–1001 (2012). source

In the paper

“Previously, we revealed GR ligand binding is inhibited by Hsp70 and restored by Hsp90, aided by the cochaperone p2310.”

What the sources say

• Supported

  The Results section, “Hsp70 Inhibits GR Ligand Binding by Partially Unfolding GR,” reports complete inhibition of GR ligand binding after preincubation with the Hsp70 system. “Hsp90 Recovers GR Ligand Binding” reports significant recovery with Hsp90 and p23, while noting that full recovery required both p23 and HOP. (LLM, conf=0.94)

  cites [10] Kirschke, E., Goswami, D., Southworth, D., Griffin, P. & Agard, D. Glucocorticoid receptor function regulated by coordinated action of the Hsp90 and Hsp70 chaperone cycles. Cell 157, 1685–1697 (2014). source

In the paper

“The kinase:Hsp90 structure11 first revealed how Hsp90 can stabilize an inactive client, but provided no insights to explain how Hsp90 can reactivate a client, such as GR.”

What the sources say

• Supported

  The section “Hsp90/Cdc37 capture and stabilize structural transitions within the kinase” (page unavailable) describes an unfolded Cdk4 conformation stabilized by Hsp90 and Cdc37. The “Life cycle of kinase:Hsp90:Cdc37 interactions” section (page unavailable) offers a tentative model for kinase folding but mentions the glucocorticoid receptor only to note uncertainty about whether kinases require similar chaperone assistance; it does not explain GR reactivation. (LLM, conf=0.87)

  cites [11] Verba, K. A. et al. Atomic structure of Hsp90–Cdc37–Cdk4 reveals that Hsp90 traps and stabilizes an unfolded kinase. Science 352, 1542–1547 (2016). source

In the paper

“Notably, Hsp90W320,F349 also make contact with GR in the loading complex12 and Hsp90W320 is critical for client activation in vivo20-22.”

What the sources say

• Supported

  The 'Unfolded GR is bound by Hsp90–Hop–Hsp70' section (Fig. 3e; Extended Data Fig. 7g) explicitly states that Hsp90 W320 and F349 directly contact GR in the loading complex. Citation 12 is attached to that contact claim; the separate in-vivo activation claim has other citations. (LLM, conf=0.95)

  cites [12] Wang, R. Y.-R. et al. Structure of Hsp90–Hsp70–Hop–GR reveals the Hsp90 client-loading mechanism. Nature https://doi.org/10.1038/s41586-021-04252-1 (2021). source
• Partly supported

  The Client Protein Binding Sites section (p. 8) reports that a yeast Hsp90 Trp300Ala mutant had severe defects in growth and in vivo v-Src activation, supporting the functional point. Our copy does not identify Trp300 as W320, so it does not directly establish the claim for the specifically numbered residue. The GR-loading-complex contact is attached to a different citation in the citing sentence. (LLM, conf=0.78)

  cites [20] Meyer, P. et al. Structural and functional analysis of the middle segment of Hsp90: implications for ATP hydrolysis and client protein and cochaperone interactions. Mol. Cell 11, 647–658 (2003). sourceExperimental — accuracy not yet measured
• Partly supported

  The Results section, “Tryptophan 300 is essential for viability and GR maturation” (page unavailable), reports that yeast Hsp90 W300A reduced GR activation by about 50% in an in vivo reporter assay. The paper studies W300 in yeast and W312 in human Hsp90β, but our copy does not identify or directly test W320; the loading-complex contact claim is attached to a different citation (12). (LLM, conf=0.84)

  cites [21] Rutz, D. A. et al. A switch point in the molecular chaperone Hsp90 responding to client interaction. Nat. Commun. 9, 1472 (2018). sourceExperimental — accuracy not yet measured
• Partly supported

  The Results (page unavailable) show that the W300A mutation in yeast Hsp90 strongly affects v-Src activation in vivo, but its effect depends on temperature; GR activity is only moderately affected. Our copy does not identify W300 as W320 or establish that W320 is critical for client activation generally. The separate claim about contact with GR is attached to citation 12, not this source. (LLM, conf=0.83)

  cites [22] Hawle, P. et al. The middle domain of Hsp90 acts as a discriminator between different types of client proteins. Mol. Cell. Biol. 26, 8385–8395 (2006). sourceExperimental — accuracy not yet measured

In the paper

“Only one p23 is bound to the Hsp90 dimer, consistent with a previous report8, although a 2-fold excess of p23 was added during complex preparation and two p23 molecules are in the yeast Hsp90:p23 structure16.”

What the sources say

• ?Not checked — no full text of the sourcecites [8] Lorenz, O. R. et al. Modulation of the Hsp90 chaperone cycle by a stringent client protein. 53, 941–953 (2014). source
• Supported

  Citation 16 supports the comparison with the yeast structure, not the citing paper’s observations of one bound p23 or excess p23 during preparation. The Architecture section (p. 3) describes the yeast complex as an (Hsp90)₂–(Sba1)₂ complex; Sba1 is the yeast homologue of p23. (LLM, conf=0.94)

  cites [16] Ali, M. M. U. et al. Crystal structure of an Hsp90–nucleotide–p23/Sba1 closed chaperone complex. Nature 440, 1013–1017 (2006). source

In the paper

“The Hsp90:p23 interface is comparable to the crystal structure of the yeast Hsp90:p23 complex (PDB ID 2CG9)16, where p23 makes extensive contacts with the N-terminal domains of Hsp90 (Hsp90NTDs) to stabilize the Hsp90 closed state (~1274Å2 BSA)”

What the sources say

• Partly supported

  The Structural basis section (p. 6) says p23/Sba1 contacts both Hsp90 N-terminal domains and that binding stabilizes the ATP-bound conformation. But our copy does not give the claimed ~1274 Ų buried surface area. The accession-code statement (p. 2) assigns 2CGE to the Hsp90–p23/Sba1 complex and 2CG9 to the separate M-C construct, contrary to the citing sentence’s identification of 2CG9 as the complex. (LLM, conf=0.91)

  cites [16] Ali, M. M. U. et al. Crystal structure of an Hsp90–nucleotide–p23/Sba1 closed chaperone complex. Nature 440, 1013–1017 (2006). sourceExperimental — accuracy not yet measured

In the paper

“Furthermore, a peptide corresponding to this region (p23118-131) was previously found to have helical propensity26 and an interaction between p23117-127 and GR has been suggested27.”

What the sources say

• ?Not checked — no full text of the sourcecites [26] Seraphim, T. V. et al. The C-terminal region of the human p23 chaperone modulates its structure and function. Arch. Biochem. Biophys. 565, 57–67 (2015). source
• Supported

  Citation 27 is attached to the suggested interaction between human p23 residues 117–127 and GR, not to the preceding peptide-helicity claim. In Results, ‘Interaction of p23 with the GR’ (Fig. 5b–d), the paper reports spectral changes in that segment upon binding to the GR ligand-binding domain and concludes that the tail helix contacts GR. (LLM, conf=0.93)

  cites [27] Biebl, M. M. et al. Structural elements in the flexible tail of the co-chaperone p23 coordinate client binding and progression of the Hsp90 chaperone cycle. Nat. Commun. 12, 828 (2021). source

In the paper

“The cochaperone p23 specifically binds and stabilizes the closed Hsp90 conformation16 and is required for full reactivation of GR ligand binding in vitro10 and proper GR function in vivo17.”

What the sources say

• Supported

  The citation to this paper is attached to the first clause, about p23 binding and stabilizing closed Hsp90. The Abstract (p. 2) says p23/Sba1 recognizes and stabilizes the ATP-bound conformation, and the structural analysis (p. 6) explains that its binding sites form in that conformation. The GR claims have separate citations and are not attributed to this source. (LLM, conf=0.94)

  cites [16] Ali, M. M. U. et al. Crystal structure of an Hsp90–nucleotide–p23/Sba1 closed chaperone complex. Nature 440, 1013–1017 (2006). source
• Supported

  The citation to this paper is attached to the in vitro reactivation claim. In Results (“Hsp90 Recovers GR Ligand Binding”), recovery of GR ligand binding is partial with Hsp90 and either HOP or p23, while full recovery requires both cochaperones. The other clauses have separate citations and are not attributed to this paper here. (LLM, conf=0.94)

  cites [10] Kirschke, E., Goswami, D., Southworth, D., Griffin, P. & Agard, D. Glucocorticoid receptor function regulated by coordinated action of the Hsp90 and Hsp70 chaperone cycles. Cell 157, 1685–1697 (2014). source
• ?Not checked — no full text of the sourcecites [17] Sahasrabudhe, P., Rohrberg, J., Biebl, M. M., Rutz, D. A. & Buchner, J. The plasticity of the Hsp90 co-chaperone system. Mol. Cell 67, 947–961.e945 (2017). source

In the paper

“Together with the GR-loading complex structure12, we present the molecular mechanism of chaperone-mediated GR remodeling, establishing the first complete chaperone cycle for any client.”

What the sources say

• Supported

  The citation identifies the GR-loading complex structure, and the source paper reports that structure in its Abstract. The sentence’s claim that 'we present' a molecular mechanism and complete cycle is the citing authors’ own contribution, not a claim attributed to this source. (LLM, conf=0.94)

  cites [12] Wang, R. Y.-R. et al. Structure of Hsp90–Hsp70–Hop–GR reveals the Hsp90 client-loading mechanism. Nature https://doi.org/10.1038/s41586-021-04252-1 (2021). source

In the paper

“although p23 has general Hsp90-independent chaperoning properties24,30,31.”

What the sources say

• ?Not checked — no full text of the sourcecites [24] Weikl, T., Abelmann, K. & Buchner, J. An unstructured C-terminal region of the Hsp90 co-chaperone p23 is important for its chaperone function. J. Mol. Biol. 293, 685–691 (1999). source
• Supported

  The Abstract explicitly describes p23’s passive chaperoning function as hsp90/ATP-independent. The Results report that p23 reduces aggregation of denatured citrate synthase, supporting the claim that it has chaperoning activity apart from its interaction with hsp90. (LLM, conf=0.93)

  cites [30] Weaver, A. J., Sullivan, W. P., Felts, S. J., Owen, B. A. L. & Toft, D. O. Crystal structure and activity of human p23, a heat shock protein 90 co-chaperone. J. Biol. Chem. 275, 23045–23052 (2000). source
• ?Not checked — no full text of the sourcecites [31] Freeman, B. C., Toft, D. O. & Morimoto, R. I. Molecular chaperone machines: chaperone activities of the cyclophilin Cyp-40 and the steroid aporeceptor-associated protein p23. Science 274, 1718–1720 (1996). source

In the paper

“This newly identified p23tail-helix was also predicted by multiple state-of-the-art secondary structure prediction algorithms and AlphaFold v2.0 25”

What the sources say

• Supported

  The citation follows “AlphaFold v2.0” and identifies the prediction method, rather than attributing the p23-tail analysis to Jumper et al. The AlphaFold network section describes the paper’s protein-structure prediction method; no page number is available in our copy. (LLM, conf=0.87)

  cites [25] Jumper, J. et al. Highly accurate protein structure prediction with AlphaFold. Nature 596, 583–589 (2021). source

In the paper

“We demonstrated that GR ligand binding is regulated by a cycle of GR:chaperone complexes in which GR is first inhibited by Hsp70, then loaded onto Hsp90:Hop (Hsp70/Hsp90 organizing protein) forming an inactive GR:Hsp90:Hsp70:Hop loading complex12.”

What the sources say

• Supported

  The introductory text following the Abstract (page not provided) describes Hsp70 inactivating GR ligand binding before Hop helps load Hsp70–GR onto Hsp90, forming an inactive GR–Hsp90–Hsp70–Hop complex. The “Unfolded GR is bound by Hsp90–Hop–Hsp70” section also states this sequence as the paper’s supported model. (LLM, conf=0.94)

  cites [12] Wang, R. Y.-R. et al. Structure of Hsp90–Hsp70–Hop–GR reveals the Hsp90 client-loading mechanism. Nature https://doi.org/10.1038/s41586-021-04252-1 (2021). source

In the paper

“In the loading complex, GRpre-Helix 1 is captured by Hsp70, GRHelix 1 is stabilized by Hop, and GRpost-Helix 1 is threaded through the semi-closed Hsp90 lumen.”

What the sources say

• Supported

  The Discussion describes Hsp70C capturing GR pre-Helix 1, GR Helix 1 engaging Hop, and the post-Helix 1 strand engaging the Hsp90 lumen. The Architecture section identifies Hsp90 in the loading complex as semi-closed, while the Unfolded GR section describes GR as threaded through its lumen. Page numbers are not provided in our copy. (LLM, conf=0.92)

  cites [12] Wang, R. Y.-R. et al. Structure of Hsp90–Hsp70–Hop–GR reveals the Hsp90 client-loading mechanism. Nature https://doi.org/10.1038/s41586-021-04252-1 (2021). source

In the paper

“In support of this essential p23:GR interaction, the p23tail-helix and GR hydrophobic groove are well conserved, and a helix in the yeast p23 tail supports GR transactivation in vivo27.”

What the sources say

• Partly supported

  The Results sections on p23-tail structure and GR maturation in vivo report a conserved p23 tail helix and show that deleting the yeast helix significantly reduces GR activation in a reporter assay (pages not provided). The cited paper does not establish that a GR hydrophobic groove is well conserved; its discussion of a binding cleft concerns Hsp90, not GR. (LLM, conf=0.86)

  cites [27] Biebl, M. M. et al. Structural elements in the flexible tail of the co-chaperone p23 coordinate client binding and progression of the Hsp90 chaperone cycle. Nat. Commun. 12, 828 (2021). sourceExperimental — accuracy not yet measured

In the paper

“The ligand-bound GR becomes protected from Hsp70 rebinding and re-inhibition once it is in the maturation complex, allowing protected nuclear translocation34,37,38.”

What the sources say

• ?Not checked — no full text of the sourcecites [34] Freeman, B. C. & Yamamoto, K. R. Disassembly of transcriptional regulatory complexes by molecular chaperones. Science 296, 2232–2235 (2002). source
• ?Not checked — no full text of the sourcecites [37] Czar, M. J., Galigniana, M. D., Silverstein, A. M. & Pratt, W. B. Geldanamycin, a heat shock protein 90-binding benzoquinone ansamycin, inhibits steroid-dependent translocation of the glucocorticoid receptor from the cytoplasm to the nucleus. Biochemistry 36, 7776–7785 (1997). source
• Partly supported

  The Results passage on FKBP52 domain I reports steroid-dependent GFP-GR nuclear translocation, and the Discussion links rapid movement to GR–hsp90 heterocomplexes. Neither passage establishes that ligand-bound GR is protected from Hsp70 rebinding or re-inhibition in a maturation complex; searches for those terms found no such mechanism in our copy. Page numbers were not available. (LLM, conf=0.84)

  cites [38] Galigniana, M. D., Radanyi, C., Renoir, J. M., Housley, P. R. & Pratt, W. B. Evidence that the peptidylprolyl isomerase domain of the hsp90-binding immunophilin FKBP52 is involved in both dynein interaction and glucocorticoid receptor movement to the nucleus. J. Biol. Chem. 276, 14884–14889 (2001). sourceExperimental — accuracy not yet measured

In the paper

“Indeed, where examined, SHR activity has been dependent on p2317 and the progesterone receptor (PR) requires the p23 tail for chaperone-mediated ligand-binding activity30.”

What the sources say

• ?Not checked — no full text of the sourcecites [17] Sahasrabudhe, P., Rohrberg, J., Biebl, M. M., Rutz, D. A. & Buchner, J. The plasticity of the Hsp90 co-chaperone system. Mol. Cell 67, 947–961.e945 (2017). source
• Supported

  Citation 30 attaches to the progesterone-receptor claim. The Results report that removing 50 residues from the p23 tail left only a slight increase in PR hormone binding, whereas removing 35 residues retained the full-length protein’s effect; the authors conclude that the tail region facilitates this activity. The separate claim about SHR activity is attached to citation 17, not this paper. (LLM, conf=0.90)

  cites [30] Weaver, A. J., Sullivan, W. P., Felts, S. J., Owen, B. A. L. & Toft, D. O. Crystal structure and activity of human p23, a heat shock protein 90 co-chaperone. J. Biol. Chem. 275, 23045–23052 (2000). source

In the paper

“Both clients are threaded through the closed Hsp90 lumen, suggesting a universal binding mode for Hsp90 clients11,35”

What the sources say

• Partly supported

  The section “The N-lobe of Cdk4 is significantly unfolded and threads through Hsp90” reports Cdk4 density passing through the Hsp90 lumen; “Hsp90 is in a closed conformation in the complex” establishes that Hsp90 is closed. This paper examines one client, Cdk4, and does not establish that both clients thread through the lumen or that this is a universal binding mode. (LLM, conf=0.88)

  cites [11] Verba, K. A. et al. Atomic structure of Hsp90–Cdc37–Cdk4 reveals that Hsp90 traps and stabilizes an unfolded kinase. Science 352, 1542–1547 (2016). sourceExperimental — accuracy not yet measured
• Supported

  The Discussion (page not supplied) states that partially unfolded clients pass through the Hsp90 lumen in all three complexes it compares, including TRAP1:SdhB. It describes their binding modes as broadly conserved, supporting the claim's suggested common mode. (LLM, conf=0.92)

  cites [35] Liu, Y., Elnatan, D., Sun, M., Myasnikov, A. G. & Agard, D. A. Cryo-EM reveals the dynamic interplay between mitochondrial Hsp90 and SdhB folding intermediates. Preprint at https://doi.org/10.1101/2020.10.06.327627 (2020). source

In the paper

“Following the split map approach19 to prevent and monitor overfitting, the Rosetta iterative backbone rebuilding procedure was used to refine models against one of the half maps obtained from RELION, with the other half map only used for validations.”

What the sources say

• Supported

  The Results describe fragment-based rebuilding against a training half-map and selection using an independent validation half-map to prevent overfitting. Materials and methods (‘Preparing maps for refinement’) likewise states that one split map was chosen for refinement and the other for validation. (LLM, conf=0.92)

  cites [19] Wang, R. Y. et al. Automated structure refinement of macromolecular assemblies from cryo-EM maps using Rosetta. eLife 5, e17219 (2016). source

In the paper

“Note that the dissociation constant (KD) between GR and F-dex is ~150 nM10.”

What the sources say

• Supported

  In Results, under “Purified GRLBD Binds Ligand without Hsp90,” the paper reports an equilibrium dissociation constant of 150±20 nM for F-dex binding to purified GR ligand-binding domain under its experimental conditions. This supports the cited approximate value. (LLM, conf=0.93)

  cites [10] Kirschke, E., Goswami, D., Southworth, D., Griffin, P. & Agard, D. Glucocorticoid receptor function regulated by coordinated action of the Hsp90 and Hsp70 chaperone cycles. Cell 157, 1685–1697 (2014). source

In the paper

“20 mM sodium molybdate (used to stabilize the closed conformation of Hsp9011,42,43, likely by acting as a γ-phosphate analog to stabilize the post-ATP hydrolysis transition state of Hsp90 (Extended Data Fig. 2c))”

What the sources say

• Supported

  In “Hsp90 is in a closed conformation in the complex,” the paper says molybdate may contribute to the closed state and proposes that ADP-molybdate acts as a post-hydrolysis transition-state inhibitor, helping stabilize that conformation. It also reports density at the γ-phosphate location. The paper qualifies that the closed state is likely also a consequence of the ternary complex. (LLM, conf=0.91)

  cites [11] Verba, K. A. et al. Atomic structure of Hsp90–Cdc37–Cdk4 reveals that Hsp90 traps and stabilizes an unfolded kinase. Science 352, 1542–1547 (2016). source
• Partly supported

  The sections “Molybdate and AMP-PNP Stabilization of p23 Complexes” and “Disruption of p23 Complexes by GA” report that sodium molybdate stabilizes Hsp90-containing complexes and discuss an ATP-like conformational change in Hsp90. They do not identify that conformation as closed or propose γ-phosphate mimicry of a post-ATP-hydrolysis transition state; the paper says the stabilizing mechanism is unknown. Page numbers were not available in our copy. (LLM, conf=0.87)

  cites [42] Johnson, J. L. & Toft, D. O. Binding of p23 and hsp90 during assembly with the progesterone receptor. Mol. Endocrinol. 9, 670–678 (1995). sourceExperimental — accuracy not yet measured
• ?Not checked — no full text of the sourcecites [43] Csermely, P. et al. Atp induces a conformational change of the 90-Kda heat-shock protein (Hsp90). J. Biol. Chem. 268, 1901–1907 (1993). source

In the paper

“Interface 2 is mainly comprised of the short GRHelix 1 (GR532-539) packing up against the amphipathic helical hairpin (Hsp90amphi-α) in the C-terminal domain of Hsp90B (Hsp90BCTD) and GRHelices 8 and 9 interacting with Hsp90BMD/CTD (~488Å2 BSA)”

In the paper

“In interface 3, the Hsp90Bamphi-α packs against GRHelix 3 and the conserved, solvent exposed hydrophobic residues Hsp90W320,F349, located in the middle domain of Hsp90A (Hsp90AMD), make contact with GRHelices 4 and 9 (~467Å2 BSA)”

In the paper

“At 37°C, in the absence of SBA1 (sba1), exogenous expression of full-length human p23 and p23Δtail rescued the sba1 growth defect and, in fact, exhibited enhanced viability compared to exogenous expression of Sba1.”

In the paper

“The structure reveals a fully closed, nucleotide-bound Hsp90 dimer (Hsp90A and B) (Extended Data Fig. 2c) complexed with a single GR and a single p23, which occupy the same side of Hsp90 (Fig. 1a,b).”

In the paper

“however, in the GR-maturation complex, while the putative dimerization interface is solvent accessible, the binding of a second GR would clash with the Hsp90BCTD”

In the paper

“This is the highest resolution Hsp90 structure to date and the first atomic resolution structure of a client bound to Hsp90 in a native conformation”

In the paper

“Surprisingly, in the maturation complex, despite being bound to Hsp90, GR adopts an active, folded conformation (Cα RMSD of 1.24Å to crystal structure Protein Data Bank (PDB) ID 1M2Z23).”

What the sources say

• ?Not checked — no full text of the sourcecites [23] Bledsoe, R. K. et al. Crystal structure of the glucocorticoid receptor ligand binding domain reveals a novel mode of receptor dimerization and coactivator recognition. 110, 93–105 (2002). source

In the paper

“The identified NCoA3 motif (FNSMMNQM) aligns with the p23tail-helix sequence (FSEMMNNM) and contains the key conserved hydrophobic residues that interact with GR”

In the paper

“Unexpectedly, p23 also makes direct and extensive contacts with GR (~702Å2 BSA) through the early part (p23112-133) of its ~58 residue C-terminal tail (p23103-160), while the following 27 tail residues (p23134-160) were not visible.”

In the paper

“Unlike the crystal structure, GRHelix 12 is not stabilized by a co-activator peptide, although co-activator peptide binding would be sterically allowed”

In the paper

“GR and Hsp90 have three major interfaces (Fig. 1c-e): (1) Hsp90 lumen:GRpre-Helix 1; (2) Hsp90MD/CTD:GRHelix 1, and (3) Hsp90MD/CTD:GRHelices 3, 4, and 9.”

In the paper

“Although the tail was previously thought to be unstructured24, we found a 13-residue helix (p23119-131, p23tail-helix) bound to GR”

What the sources say

• ?Not checked — no full text of the sourcecites [24] Weikl, T., Abelmann, K. & Buchner, J. An unstructured C-terminal region of the Hsp90 co-chaperone p23 is important for its chaperone function. J. Mol. Biol. 293, 685–691 (1999). source

In the paper

“p(p23 vs. no p23) = <0.0001”

In the paper

“p(p23 vs. p23Δtail) = 0.1512”

In the paper

“GR ligand binding behavior was affected by buffer conditions; therefore, reactions were always normalized such that each reaction had equivalent amounts of buffer reagents.”

In the paper

“The best focused classes were combined (140,217 particles) and refined to a nominal resolution of 2.56 Å.”

In the paper

“p(p23Δtail vs. p23Δhelix-tail) = 0.9721”

In the paper

“p(p23 vs. p23Δhelix-tail) = 0.0021”

In the paper

“We present the first atomic resolution structure of a client bound to Hsp90 in a native folded conformation, as well as the highest resolution structure of full-length Hsp90 to date.”

In the paper

“From the same GR:Hsp90:p23 dataset, we also obtained reconstructions of Hsp90:p23 (2.66Å resolution) (Extended Data Fig. 8a,b) and MBP:Hsp90:p23 (3.63Å resolution) (Extended Data Fig. 9a,b), which both contain Hsp90 lumen density”

In the paper

“Notably, MBP is partially unfolded, as density for the two C-terminal helices is missing.”

In the paper

“While previously thought to be a general cochaperone whose primary function is to stabilize closed Hsp90, our structure reveals that p23 also makes extensive contacts with GR through a previously unappreciated helix in the p23 tail.”

In the paper

“Fig. 2d and Extended Data Fig. 7b [Brown-Forsythe test p = 0.9966]”

In the paper

“This class was refined after per-particle CTF refinement and beam-tilt correction in RELION to a nominal resolution of 2.66 Å.”

In the paper

“p(p23 vs. p23Δhelix-tail) = 0.0002”

In the paper

“p(p23 vs. Sba1) = 0.0002”

In the paper

“There were 10 total hits on the motif, which included p23 and NCoA3/SRC-3.”

In the paper

“The best focused 3D classes were combined (31,556 particles) and refined to a nominal resolution of 3.63 Å after per-particle CTF refinement and beam-tilt correction in RELION.”

In the paper

“In the maturation complex, GR simultaneously threads through the closed Hsp90 lumen and adopts a native, ligand-bound conformation that is extensively stabilized by both Hsp90 and the p23tail-helix.”

In the paper

“Although the FSC showed slightly improvement over the pre-refined reconstruction at medium resolution range (5–10 Å), the nominal resolution at 0.143 FSC remained unchanged.”

In the paper

“Extended Data Fig. 7e [Brown-Forsythe test p = 0.1696]”

In the paper

“Extended Data Fig. 7c [Brown-Forsythe test p = 0.9224]”

In the paper

“p(e.v. vs. p23) = 0.0001”

In the paper

“p(p23 vs p23Δtail) = 0.0164”

In the paper

“The p23tail-helix also contacts the C-terminal strand of GR (GRH775), potentially allosterically stabilizing the dynamic GRHelix 12 (GR750-767) in the agonist-bound position”

In the paper

“The enhanced viability is dependent on the p23tail-helix, as p23ΔhelixΔtail abolished this enhancement, indicating the p23tail-helix is functionally important in vivo.”

In the paper

“The native, ligand-bound GR LBD is known to dimerize for function23”

What the sources say

• ?Not checked — no full text of the sourcecites [23] Bledsoe, R. K. et al. Crystal structure of the glucocorticoid receptor ligand binding domain reveals a novel mode of receptor dimerization and coactivator recognition. 110, 93–105 (2002). source

In the paper

“Particularly, Hsp90 functions as a constitutive dimer that undergoes an open-to-closed transition upon ATP binding and this conformational cycle is further regulated by cochaperones15.”

What the sources say

• ?Not checked — no full text of the sourcecites [15] Krukenberg, K. A., Street, T. O., Lavery, L. A. & Agard, D. A. Conformational dynamics of the molecular chaperone Hsp90. Q. Rev. Biophys. 44, 229–255 (2011). source

In the paper

“The GR hydrophobic patch at the p23:GR interface is also conserved across SHRs, which are thought to undergo similar regulation by Hsp90/Hsp70 (Extended Data Fig. 6c)5.”

What the sources say

• ?Not matched

  Couldn’t be matched to a paper in Crossref, so it can’t be checked.

  cites [5] Pratt, W. B. & Toft, D. O. Steroid receptor interactions with heat shock protein and immunophilin chaperones. Endocrine Rev. 18, 306–360 (1997).

In the paper

“Importantly, p23ΔhelixΔtail did not reduce the GR ligand-binding activity to the same extent as omitting p23, indicating the p23 core plays a distinct and critical role in stabilizing the closed Hsp90 conformation in the maturation complex.”

In the paper

“Upon ATP hydrolysis on Hsp90, Hsp70 and Hop are released, and p23 is incorporated to form an active GR:Hsp90:p23 maturation complex, restoring GR ligand binding with enhanced affinity.”

In the paper

“During this transition, Hsp90 twists to the p23-stabilized closed conformation, likely facilitating client sliding and rearranging the client-binding site to fully enclose GRpre-Helix 1”

In the paper

“Intriguingly, NCoA3 contains a p23tail-helix -like motif, suggesting other GR coregulators may utilize this novel helix motif to bind the hydrophobic groove on GR and compete with p23, potentially facilitating GR release.”

In the paper

“Although the overall Hsp90:client interactions are similar, the outcomes for folding and function of these two clients are opposing, demonstrating evolutionarily determined, client-specific conformational remodeling by Hsp90”

In the paper

“All experiments were performed at least three times.”

In the paper

“Note that the composite map was only used for presentation in Fig. 1a, but not used in atomic model building or refinement.”

In the paper

“This p23tail-helix is necessary for the enhanced GR ligand-binding activity in vitro; thus, p23 not only serves as a cochaperone to stabilize the closure of Hsp90, but also directly contributes to client maturation.”

In the paper

“The MBP is also in an apo state, consistent with the unfolding of the last two helices, which form part of its binding pocket”

In the paper

“suggesting ligand-free GR is either too dynamic or quickly released from the complex.”

In the paper

“Given that GRHelix 1 slides through the Hsp90 lumen, it is possible that Hsp90 can act processively to remodel other client domains beyond the one initially engaged, potentially explaining the other reconstructions.”

In the paper

“Then, GRpre-Helix 1 can slide into the Hsp90 lumen, allowing GRHelix 1 to refold onto the GR core, thereby generating a ligand binding capable, native GR, stabilized by the p23tail-helix”

In the paper

“The effect of deleting the unstructured part of the p23 tail (p23134-160) on GR activity in vivo may be related to p23-dependent regulation of GR functions downstream of ligand binding34, which may dominate any effect of the p23tail-helix on GR activation in vivo.”

What the sources say

• ?Not checked — no full text of the sourcecites [34] Freeman, B. C. & Yamamoto, K. R. Disassembly of transcriptional regulatory complexes by molecular chaperones. Science 296, 2232–2235 (2002). source