Name: studies of chaperone-cochaperone interactions using homogenous bead-based assay
Uploaded: 2021-07-21T13:00:00
Description: Watch this Scientific Journal Video about Studies of Chaperone-Cochaperone Interactions using Homogenous Bead-Based Assay at JoVE.com

This study was supported by grants from Swedish Research Council (2018-02843), Brain Foundation (Fo 2019-0140), Foundation for Geriatric Diseases at Karolinska Institutet, Gunvor and Josef An&#233;rs Foundation, Magnus Bergvalls Foundation, Gun and Bertil Stohnes Foundation, Tore Nilssons Foundation for medical research, Margaretha af Ugglas foundation and the Foundation for Old Servants.

NOTE: An overview of this protocol is shown in Figure 2.
1. Expression and purification of GST-FKBP51 and GST-FKBP52 (Figure 2A)
<ol>
	<li>Plasmids 
	NOTE: Obtain cDNA clones for human FKBP51 (clone id: 5723416) and for human FKBP52 (clone id: 7474554) from IMAGE consortium.
	<ol>
		<li>Amplify the human FKBP51 DNA by PCR with primers (forward; 5`GGATCCATGACTACTGATGAAGGT-3`, reverse; 5`-CTCGAGCTATGCTTCTGTCTCCAC...

<ol>
	<li>Muchowski, P. J., Wacker, J. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Modulation+of+neurodegeneration+by+molecular+chaperones.">Modulation of neurodegeneration by molecular chaperones.</a> Nature Reviews Neuroscience. 6 (1), 11-22 (2005).</li><li>Eckl, J. M., Richter, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Functions+of+the+Hsp90+chaperone+system:+lifting+client+proteins+to+new+heights.">Functions of the Hsp90 chaperone system: lifting client proteins to new heights.</a> International Journal of Biochemistry and Molecular Biology. 4 (4), 157-165 (2013).</li><li>Yuno, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Clinical+evaluation+and+biomarker+profiling+of+Hsp90+inhibitors.">Clinical evaluation and biomarker profiling of Hsp90 inhibitors.</a> Methods in Molecular Biology. 1709, 426-441 (2018).</li><li>Dutta Gupta, S., Bommaka, M. K., Banerjee, A. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Inhibiting+protein-protein+interactions+of+Hsp90+as+a+novel+approach+for+targeting+cancer.">Inhibiting protein-protein interactions of Hsp90 as a novel approach for targeting cancer.</a> European Journal of Medicinal Chemistry. 178, 48-63 (2019).</li><li>Pavlov, P. F., Hutter-Paier, B., Havas, D., Windisch, M., Winblad, B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Development+of+GMP-1+a+molecular+chaperone+network+modulator+protecting+mitochondrial+function+and+its+assessment+in+fly+and+mice+models+of+Alzheimer's+disease.">Development of GMP-1 a molecular chaperone network modulator protecting mitochondrial function and its assessment in fly and mice models of Alzheimer's disease.</a> Journal of Cellular and Molecular Medicine. 22 (7), 3464-3474 (2018).</li><li>Young, J. C., Obermann, W. M., Hartl, F. U. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Specific+binding+of+tetratricopeptide+repeat+proteins+to+the+C-terminal+12-kDa+domain+of+hsp90.">Specific binding of tetratricopeptide repeat proteins to the C-terminal 12-kDa domain of hsp90.</a> Journal of Biological Chemistry. 273 (29), 18007-18010 (1998).</li><li>Scheufler, C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Structure+of+TPR+domain-peptide+complexes:+critical+elements+in+the+assembly+of+the+Hsp70-Hsp90+multichaperone+machine.">Structure of TPR domain-peptide complexes: critical elements in the assembly of the Hsp70-Hsp90 multichaperone machine.</a> Cell. 101 (2), 199-210 (2000).</li><li>Storer, C. L., Dickey, C. A., Galigniana, M. D., Rein, T., Cox, M. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=FKBP51+and+FKBP52+in+signaling+and+disease.">FKBP51 and FKBP52 in signaling and disease.</a> Trends in Endocrinology &amp; Metabolism. 22 (12), 481-490 (2011).</li><li>Ullman, E. F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Luminescent+oxygen+channeling+immunoassay:+measurement+of+particle+binding+kinetics+by+chemiluminescence.">Luminescent oxygen channeling immunoassay: measurement of particle binding kinetics by chemiluminescence.</a> Proceedings of the National Academy of Sciences of the United States of America. 91 (12), 5426-5430 (1994).</li><li>Wigle, T. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Screening+for+inhibitors+of+low-affinity+epigenetic+peptide-protein+interactions:+an+AlphaScreen-based+assay+for+antagonists+of+methyl-lysine+binding+proteins.">Screening for inhibitors of low-affinity epigenetic peptide-protein interactions: an AlphaScreen-based assay for antagonists of methyl-lysine binding proteins.</a> Journal of Biomolecular Screening. 15 (1), 62-71 (2010).</li><li>Guenat, S., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Homogeneous+and+nonradioactive+high-throughput+screening+platform+for+the+characterization+of+kinase+inhibitors+in+cell+lysates.">Homogeneous and nonradioactive high-throughput screening platform for the characterization of kinase inhibitors in cell lysates.</a> Journal of Biomolecular Screening. 11 (8), 1015-1026 (2006).</li><li>Sabatucci, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+new+methodological+approach+for+in+vitro+determination+of+the+role+of+DNA+methylation+on+transcription+factor+binding+using+AlphaScreen(R)+analysis:+Focus+on+CREB1+binding+at+hBDNF+promoter+IV.">A new methodological approach for in vitro determination of the role of DNA methylation on transcription factor binding using AlphaScreen(R) analysis: Focus on CREB1 binding at hBDNF promoter IV.</a> Journal of Neuroscience Methods. 341, 108720 (2020).</li><li>Mills, N. L., Shelat, A. A., Guy, R. K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Assay+Optimization+and+Screening+of+RNA-Protein+Interactions+by+AlphaScreen.">Assay Optimization and Screening of RNA-Protein Interactions by AlphaScreen.</a> Journal of Biomolecular Screening. 12 (7), 946-955 (2007).</li><li>Huang, X., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+competitive+alphascreen+assay+for+detection+of+hyaluronan.">A competitive alphascreen assay for detection of hyaluronan.</a> Glycobiology. 28 (3), 137-147 (2018).</li><li>Principles of alphascreen amplified luinescent proximmity homogenous assay. PerkinElmer Life Sciences Available from: <a target="_blank" href="https://www.perkinelmer.com/lab-solutions/resources/docs/APP_AlphaScreen_Principles.pdf">https://www.perkinelmer.com/lab-solutions/resources/docs/APP_AlphaScreen_Principles.pdf</a> (2021)</li><li>Zhang, J. H., Chung, T. D., Oldenburg, K. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+Simple+statistical+parameter+for+use+in+evaluation+and+validation+of+high+throughput+screening+assays.">A Simple statistical parameter for use in evaluation and validation of high throughput screening assays.</a> Journal of Biomolecular Screening. 4 (2), 67-73 (1999).</li></ol>

Here we describe a protocol using the assay for screening small molecules inhibiting interactions between Hsp90 and TPR-motif co-chaperones, especially FKBP51 and FKBP52. Its high Z' score (&gt;0.8) demonstrates the robustness and reliability for a high-throughput format. Results can be obtained within one hour, and small amounts of beads, protein and compounds are required. Moreover, this protocol could easily be extended to any Hsp90/Hsp70 - TPR-motif co-chaperone interactions of interest. Several TPR-motif co-chaperon...

Molecular chaperones contribute to protein homeostasis, including protein folding, transport, and degradation. They regulate several cellular processes and are linked to numerous diseases such as cancer and neurodegenerative diseases1. Heat shock protein 90 (Hsp90) is one of the most important chaperones whose function is dependent on conformational changes driven by ATP hydrolysis and binding with client proteins mediated by its co-chaperones2. Despite an obvious potential of Hsp90 as the therapeutic target, fine-tuning its function represents a big challenge. There are several Hsp90 inhibitors targeting the N-terminal ATP binding region, which have been evaluated in clinical trials, but none of them has been approved for marketing3. Due to the lack of a well-defined ligand-binding pocket4, targeting the C-terminal region of Hsp90 has had limited success4. Recently, disruption of Hsp90-cochaperone interactions by small molecules has been investigated as an alternative strategy5. Targeting the Hsp90-cochaperone interactions would not elicit general cell stress response and provides the possibility to specifically regulate various intracellular processes. The conserved MEEVD pentapeptide at the C-terminus of Hsp90 is responsible for the interaction with the tetratricopeptide repeat (TPR) motif of co-chaperones6. Of the 736 TPR motif-containing proteins annotated in the human protein database, ~20 different proteins interact with Hsp90 via this peptide7. Molecules competing for MEEVD peptide-binding would disrupt the interactions between Hsp90 and co-chaperones containing a TPR domain. The peptide binding site has similar tertiary structure but the overall homology between different TPR motif domains is relatively low7, providing an opportunity to identify molecules specifically capable of blocking interactions between Hsp90 and particular TPR-motif co-chaperones. Among these TPR-motif co-chaperones, FK506-binding protein (FKBP) 51 and FKBP52 are regulators of steroid hormone receptor (SHR) signaling and involved in several steroid hormone-dependent diseases including cancer, stress-related diseases, metabolic diseases, and Alzheimer&#39;s disease8. Although FKBP51 and FKBP52 share &#62; 80% sequence similarity, their functions differ: FKBP52 is a positive regulator of SHR activity, while FKBP51 is a negative regulator in most cases8. Therefore, identifying molecules, specifically blocking interactions between Hsp90 and FKBP51 or FKBP52, provides a promising therapeutic potential for related diseases.
Amplified Luminescent Proximity Homogenous Assay (AlphaScreen) was first developed in 1994 by Ullman EF et al.9. Now it is widely used to detect different types of biological interactions, such as peptide10, protein11, DNA12, RNA13, and sugar14. In this technique, there are two kinds of beads (diameter 200 nm), one is the donor bead and the other is the acceptor bead. The biomolecules are immobilized onto these beads; their biological interactions bring donor and acceptor beads into proximity. At 680 nm, a photosensitizer in the donor bead illuminates and converts oxygen to singlet oxygen. Because the singlet oxygen has a short lifetime, it can only diffuse up to 200 nm. If the acceptor bead is in proximity, its thioxene derivative reacts with the singlet oxygen generating chemiluminescence at 370 nm. This energy further activates fluorophores in the same acceptor bead to emit light at 520-620 nm15. If the biological interactions are disrupted, the acceptor bead and donor bead cannot reach proximity, resulting in the singlet oxygen decay and low produced signal.
Here we describe a protocol using this technique for screening small molecules inhibiting interactions between Hsp90 and TPR co-chaperones, especially FKBP51 and FKBP52.The 10 amino acid long peptides corresponding to Hsp90 extreme C-terminus are attached to acceptor beads. Purified GST-tagged TPR co-chaperones interact with glutathione-linked donor beads. When the interaction between Hsp90-derived peptides and TPR-motif co-chaperones brings the beads together, an amplified signal is produced (Figure 1A). If the screened small molecules can inhibit the interactions between Hsp90 and TPR-motif co-chaperones, this amplified signal will be decreased (Figure 1B). Their IC50 can be calculated by quantitative measurement. This protocol can be extended to any chaperone - TPR-motif co-chaperone interactions of interest and is of great importance in the development of novel molecules, specifically blocking the interaction between Hsp90 and FKBP51 or FKBP52.
<img alt="Figure 1" class="xfigimg" src="/files/ftp_upload/62762/62762fig01.jpg" /> 
Figure 1: The basic principle of this assay. (A) Purified GST-FKBP51 interacts with glutathione-linked donor beads. The 10 amino acid long peptides corresponding to the extreme C-terminus of Hsp90 are attached to acceptor beads. The interaction between Hsp90-derived peptides and TPR domain of FKBP51 brings the donor and acceptor beads into proximity. At 680 nm, a photosensitizer in the donor bead illuminates and converts oxygen to singlet oxygen. The thioxene derivative on the acceptor bead reacts with the singlet oxygen and generates chemiluminescence at 370 nm. This energy further activates fluorophores in the same acceptor bead to emit light at 520-620 nm. (B) When small molecules inhibit the interactions between Hsp90 and FKBP51, the donor and acceptor beads cannot reach proximity. Then the singlet oxygen with short lifetime decays, and no detectable signal is produced. <a href="https://www.jove.com/files/ftp_upload/62762/62762fig01large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>384-well plates</td>
			<td>Perkin Elmer</td>
			<td>6008350</td>
			<td>Assay volume 25 ml</td>
		</tr>
		<tr>
			<td>Amicon 10.000 MWCO centrifugation unit</td>
			<td>Millipore</td>
			<td>UFC901008</td>
			<td>Concentrate protein</td>
		</tr>
		<tr>
			<td>Ampicillin</td>
			<td>Sigma</td>
			<td>A0166</td>
			<td>Antibiotics</td>
		</tr>
		<tr>
			<td>Bacteria shaker Unimax 1010</td>
			<td>Heidolph</td>
			<td></td>
			<td>Culture bacteria</td>
		</tr>
		<tr>
			<td>cDNA clones for human FKBP51</td>
			<td>Source BioScience</td>
			<td>clone id: 5723416</td>
			<td>pCMV-SPORT6 vector</td>
		</tr>
		<tr>
			<td>cDNA clones for human FKBP52</td>
			<td>Source BioScience</td>
			<td>clone id: 7474554</td>
			<td>pCMV-SPORT6 vector</td>
		</tr>
		<tr>
			<td>Chemically Competent E. coli</td>
			<td>Invitrogen</td>
			<td>C602003</td>
			<td>One Shot BL21 Star (DE3)</td>
		</tr>
		<tr>
			<td>Data analysis software</td>
			<td>GraphPad Prism</td>
			<td>9.0.0</td>
			<td>Analysis data and make figures</td>
		</tr>
		<tr>
			<td>Data analysis software</td>
			<td>Excel</td>
			<td></td>
			<td>Analysis data</td>
		</tr>
		<tr>
			<td>DMSO</td>
			<td>Supelco</td>
			<td>1.02952.1000</td>
			<td>Dilute compounds</td>
		</tr>
		<tr>
			<td>DPBS</td>
			<td>Gibco</td>
			<td>14190-144</td>
			<td>Prepare solution</td>
		</tr>
		<tr>
			<td>EDTA</td>
			<td>Calbiochem</td>
			<td>344504</td>
			<td>Prevent proteolysis during sonication</td>
		</tr>
		<tr>
			<td>Glutathione</td>
			<td>Sigma</td>
			<td>G-4251</td>
			<td>Elute GST-tagged proteins</td>
		</tr>
		<tr>
			<td>Glutathione donor beads</td>
			<td>Perkin Elmer</td>
			<td>6765300</td>
			<td>Donor bead</td>
		</tr>
		<tr>
			<td>GST-trap column</td>
			<td>Cytiva (GE Healthcare)</td>
			<td>17528201</td>
			<td>Purify GST-tagged proteins</td>
		</tr>
		<tr>
			<td>Isopropyl-&#946;-D-thiogalactoside</td>
			<td>Thermo Fisher Scientific</td>
			<td>R0392</td>
			<td>Induce protein expression</td>
		</tr>
		<tr>
			<td>LB Broth (Miller)</td>
			<td>Sigma</td>
			<td>L3522</td>
			<td>Microbial growth medium</td>
		</tr>
		<tr>
			<td>PCR instrument</td>
			<td>BIO-RAD</td>
			<td>S1000 Thermal Cycler</td>
			<td>Amplification/PCR</td>
		</tr>
		<tr>
			<td>PD-10 column</td>
			<td>Cytiva (GE Healthcare)</td>
			<td>17085101</td>
			<td>Solution exchange</td>
		</tr>
		<tr>
			<td>pGEX-6P-1 vector</td>
			<td>Cytiva (GE Healthcare)</td>
			<td>28954648</td>
			<td>Plasmid</td>
		</tr>
		<tr>
			<td>pGEX-6P-2 vector</td>
			<td>Cytiva (GE Healthcare)</td>
			<td>28954650</td>
			<td>Plasmid</td>
		</tr>
		<tr>
			<td>Plate reader</td>
			<td>Perkin Elmer</td>
			<td>EnSpire 2300 Multilabel Reader</td>
			<td>Read alpha plate</td>
		</tr>
		<tr>
			<td>Plate reader software</td>
			<td>Perkin Elmer</td>
			<td>EnSpire Manager</td>
			<td>Plate reader software</td>
		</tr>
		<tr>
			<td>Plate reader software protocol</td>
			<td>Perkin Elmer</td>
			<td>Alpha 384-well Low volume</td>
			<td>Use this protocol to read plate</td>
		</tr>
		<tr>
			<td>PMSF</td>
			<td>Sigma</td>
			<td>P7626</td>
			<td>Prevent proteolysis during sonication</td>
		</tr>
		<tr>
			<td>protease inhibitor cocktail</td>
			<td>Sigma</td>
			<td>S8830</td>
			<td>Prevent proteolysis during sonication</td>
		</tr>
		<tr>
			<td>Sodium azide</td>
			<td>Sigma</td>
			<td>S2002</td>
			<td>As a preservative</td>
		</tr>
		<tr>
			<td>Sodium cyanoborohydride (NaBH3CN)</td>
			<td>Sigma</td>
			<td>156159</td>
			<td>Activates matrix for coupling</td>
		</tr>
		<tr>
			<td>Ten amino acid peptide NH2-EDASRMEEVD-COOH corresponding to amino acids 714-724 of human Hsp90 beta isoform</td>
			<td>Peptide 2.0 inc</td>
			<td></td>
			<td>Synthesize Hsp90 C-terminal peptide</td>
		</tr>
		<tr>
			<td>Test-Tube Rotator</td>
			<td>LABINCO</td>
			<td></td>
			<td>Make end-over-end agitation</td>
		</tr>
		<tr>
			<td>Tris-HCl</td>
			<td>Sigma</td>
			<td>10708976001</td>
			<td>Block unreacted sites of acceptor beads</td>
		</tr>
		<tr>
			<td>Tween-20</td>
			<td>Sigma</td>
			<td>P1379</td>
			<td>Prevent beads aggregation</td>
		</tr>
		<tr>
			<td>Ultra centrifuge Avanti J-20 XP</td>
			<td>Beckman Coulter</td>
			<td></td>
			<td>Centrifuge to get bacteria cell pellets</td>
		</tr>
		<tr>
			<td>Ultrasonic cell disruptor</td>
			<td>Microson</td>
			<td></td>
			<td>Sonicate cells to release protein</td>
		</tr>
		<tr>
			<td>Unconjugated acceptor beads</td>
			<td>Perkin Elmer</td>
			<td>6762003</td>
			<td>Acceptor beads</td>
		</tr>
		<tr>
			<td>XCell SureLock Mini-Cell and XCell II Blot Module</td>
			<td>Invitrogen</td>
			<td>EI0002</td>
			<td>SDS-PAGE</td>
		</tr>
	</tbody>
</table>

studies of chaperone-cochaperone interactions using homogenous bead-based assay

Targeting the heat shock protein 90 (Hsp90)-cochaperone interactions provides the possibility to specifically regulate Hsp90-dependent intracellular processes. The conserved MEEVD pentapeptide at the C-terminus of Hsp90 is responsible for the interaction with the tetratricopeptide repeat (TPR) motif of co-chaperones. FK506-binding protein (FKBP) 51 and FKBP52 are two similar TPR-motif co-chaperones involved in steroid hormone-dependent diseases with different functions. Therefore, identifying molecules specifically blocking interactions between Hsp90 and FKBP51 or FKBP52 provides a promising therapeutic potential for several human diseases. Here, we describe the protocol for an amplified luminescent proximity homogenous assay to probe interactions between Hsp90 and its partner co-chaperones FKBP51 and FKBP52. First, we have purified the TPR motif-containing proteins FKBP51 and FKBP52 in glutathione S-transferase (GST)-tagged form. Using the glutathione-linked donor beads with GST-fused TPR-motif proteins and the acceptor beads coupled with a 10-mer C-terminal peptide of Hsp90, we have probed protein-protein interactions in a homogeneous environment. We have used this assay to screen small molecules to disrupt Hsp90-FKBP51 or Hsp90-FKBP52 interactions and identified potent and selective Hsp90-FKBP51 interaction inhibitors.

In our assay, Z&#39; factor and S/B ratio are 0.82 and 13.35, respectively (Figure 3A), demonstrating that our assay is robust and reliable for high-throughput screening. We then used it to screen small molecular mass compounds. Figure 3B presents dose-dependent inhibition of chaperone-cochaperone interactions with a selected small molecule (D10). The dose-response curves for D10 are generated by nonlinear regression analysis, based on which the values of IC<sub...

Watch this Scientific Journal Video about Studies of Chaperone-Cochaperone Interactions using Homogenous Bead-Based Assay at JoVE.com

Studies of Chaperone-Cochaperone Interactions using Homogenous Bead-Based Assay

This protocol presents a technique for probing protein-protein interactions using glutathione-linked donor beads with GST-fused TPR-motif co-chaperones and acceptor beads coupled with an Hsp90-derived peptide. We have used this technique to screen small molecules to disrupt Hsp90-FKBP51 or Hsp90-FKBP52 interactions and identified potent and selective Hsp90-FKBP51 interaction inhibitors.

Targeting the heat shock protein 90 (Hsp90)-cochaperone interactions provides the possibility to specifically regulate Hsp90-dependent intracellular ...

We built a homogeneous bead-based assay to study chaperone-cochaperone interactions. Using this technique, we screen small molecules inhibiting interactions between Hsp90 and FKDP51 or FKBP52 and identify potent and selective inhibitors. This high throughput screening technique is robust and reliable.Results can be obtained within one hour, and it only requires small amounts of beads protein and compounds. Hsp90 interaction with this cochaperones was implicated in human disorders, such as Alzheimer's disease, Cancer, Autoimmune disease. This technique provides the opportunity to screen chaperone-cochaperone inhibitors with high medical importance.Here is the basic principle of this assay. When the interaction between Hsp90C-Terminal peptide and TPR domain of cochaperones brings the donor and acceptor beads into proximity, a highly amplified signal is generated. When the interaction inhibitors are added, the donor and acceptor beads cannot reach proximity, and no detectable signal is produced.Begin by diluting the Hsp90 peptide in PBS at one milligram per milliliter concentration. Dilute the unconjugated acceptor beads in PBS, and transfer the beads into a 1.5 milliliter tube. Centrifuge the diluted beads for washing, and then carefully remove the supernatant.For conjugating, set the acceptor beads in peptides at a ratio of 10 to 1. To the paletide beads at PBS diluted peptide, Tween 20 and Sodium cyanaboroughhydride solution, and incubate with end over end agitation on a rotary shaker. To block the unreacted sites, add 20 microliters of one molar Tris hydrochloride solution of pH 8.0 to the beads, and quench the reaction by incubating for one hour at 37 degrees Celsius.At the end of the incubation, wash the beads by centrifugation and re-suspend the bead pellet in one milliliter of Tris hydrochloride solution. Repeat the washing two more times. After the last washing, re-suspend the beads at one milligram per milliliter concentration in storage buffer and store the conjugated acceptor bead solution at 4 degrees Celsius protected from light.Add glutathione donor beads at 10 micrograms per milliliter concentration in PBS. Add GSTFKBP51 to a final concentration of 10 micrograms per milliliter and incubate the reaction for 10 minutes at 25 degrees Celsius in the dark. Make serial dilutions of the test compound in DMSO.Add 0.25 microliters of test compound dilutions and triplicate in the corner of each well of a 384 well plate. For negative control, add 0.25 microliters of DMSO and for positive control, add 0.25 microliters of Hsp90 C-Terminal peptide in the wells. Add 22.5 microliters of the solution containing glutathione donor beads with GST tagged proteins to each well.Shake the plate thoroughly with hands and incubate in the dark at 25 degrees Celsius for 15 minutes. Dilute the acceptor beads with the attached Hsp90C-Terminal peptide to 100 micrograms per milliliter concentration in 0.5 times PBS. Add 2.25 microliters of diluted acceptor beads to each well.Shake and incubate the plate in the dark for 15 minutes as demonstrated. Turn on the plate reader instrument, measure the signal of the plate and analyze the data as described in the text manuscript. Create an X-Y data table in the welcome dialog, select X numbers, Y and enter three replicate values in side-by-side columns.Import the concentration values to the X column and the signal values to the Y column. Click analyze, select transform concentration X, and then select transform to logarithms. Click analyze and choose nonlinear regression under X-Y analysis.Open the dose response inhibition option and choose log versus response variable slope equation. Click okay to view the results containing IC50 value and graphs. This assay was used for screening small molecules, inhibiting interactions between Hsp90 and FKBP51 or FKBP52.The Z score of more than 0.8 and signal to background ratio of 13.35, demonstrate the robustness and reliability for high throughput screening. The effect of small molecular weight test compound D10 on inhibition of chaperone-cochaperone interactions was assessed and IC50 values were calculated, where D10 showed dose dependent inhibition. The IC50 value for Hsp90 GSTFKBP51 interactions was 65 nanomolar.Whereas for Hsp90, GSTFKBP52 interactions, complete inhibition was not achieved with the highest compound concentration indicates that selective inhibition of protein-protein interaction with small molecules can be achieved. The critical step is the order of addition. We first form a complex between a small molecule and its TPR target.Otherwise longer incubation and higher compound concentrations are required. We can use this technique to screen for small molecules disrupting the interaction between Hsp90 and FKB51 or Hsp90 and FKB52. It can also be extended to any interaction between Hsp90, Hsp70 and a TPR motif containing cochaperone screening selective inhibitors.

Research

JoVE Journal

Biochemistry

Using Scaffold Liposomes to Reconstitute Lipid-proximal Protein-protein Interactions In Vitro

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