Name: Purification and Refolding to Amyloid Fibrils of (His)6-tagged Recombinant Shadoo Protein Expressed as Inclusion Bodies in E. coli (Video) | JoVE Journal
Uploaded: 2015-12-19T14:00:00.000+00:00
Duration: 9 min 43 s
Description: Learn to purify recombinant Shadoo protein from E. coli inclusion bodies using two-step chromatography and refold it into amyloid fibrils. This method enables rapid, cost-effective study of protein conformational disorders.

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5 minutes

The authors would like to acknowledge Natalie Doude and David Westerway (University of Alberta) for providing us Sho cDNA, Christophe Chevalier (INRA) for plasmid construction, Michel Br&#233;mont (INRA) for providing us BL21Sol bacteria; Christine Longin (INRA) for TEM assistance and Edith Pajot-Augy (INRA) for comments and proofreading.

1. Generation of Plasmid and Shadoo Expression
Note: The gene encoding murine Shadoo protein (Shadoo25-122), was subcloned into the expression vector pET-28 11. This clone was transformed into E. coli SoluBL21 bacterial strain, to express Shadoo protein with a N-terminal hexahistidine tag, (HHHHHHHHHHSSGHIDDDDKHMKGGRGGARGSARGVRGGARGASRVRVRP APRYGSSLRVAAAGAAAGAAAGVAAGLATGSGWRRTSGPGELGLEDDENGAMGGNGTDRGVYSYWAWTSG) as explained previously 11. The plasmid can be requested from the authors. The molecular weight of Shadoo calculated from its amino acid sequence is 12,243.2 Da.
Note: Perform all manipulations with bacteria under a laminal flow hood or close to Bunsen flame.
<ol>
	<li>Transform competent SoluBL21 bacteria with the pET-28-His6-Shadoo plasmid, using a standard heat shock protocol. For this mix 1 to 5 µl of the plasmid (typically 10 pg to 100 ng) into 50 µl of the bacteria in a tube. Perform the heat shock at 42 °C for 45 sec.</li>
	<li>Culture transformed bacteria at 37 °C until A600 of 0.5-0.7 in Luria-Bertani medium supplemented with 40 mg/ml kanamycin (Figure 1B).</li>
	<li>Induce Shadoo expression O/N by adding 240 µg/ml isopropyl-β-D-thiogalactopyranoside, ITPG, to the culture. Culture bacteria under shaking at 150 rpm at 37 °C. Note: Typically, bacterial culture reaches A600 of 3 O/N. 
		Note: Transformed bacteria can be stored at -80 °C for future protein production. For this, add 10%-50% (v/v) sterile glycerol into bacterial culture aliquots and freeze them at -80 °C.</li>
</ol>
<img alt="Shadoo protein cloning diagram: gene transformation, bacterial culture, expression process." src="/files/ftp_upload/53432/53432fig1.jpg" data-altupdatedat="1787630408000" data-alt="Figure 1"> 
	Figure 1. Scheme of Shadoo expression construct, bacteria transformation and induction of Shadoo expression (as described in step 1). (A) The expression construct for Shadoo encodes a hexahistidine tag fused to the N-terminus of the protein, Nt. The scheme shows that Shadoo protein contains basic arginine/glycine repeats (green cylinder), a hydrophobic domain (HD), and a single N-glycosylation site (CHO), followed by a C-terminus (Ct). (B) pET-28-His6-Shadoo plasmid is transformed into SoluBL21 bacteria by heat shock for 45 sec at 42 °C. Transformed bacteria are plated on selective agar containing 40 µg/ml kanamycin. A single colony from the plate is used to inoculate a culture in a 1,000-3,000 ml shaker flask. Expression of the recombinant protein is induced with 1 mM IPTG. <a href="https://www.jove.com/files/ftp_upload/53432/53432fig1highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
2. Purification of Shadoo Protein by Low Pressure Liquid Chromatography (LPLC)
<ol>
	<li>Cell lysis and Inclusion bodies preparation
		<ol>
			<li>Collect the bacterial suspension and transfer it into centrifugation tubes (Figure 2).</li>
			<li>Spin at 2,500 x g, for 20 min at 4 °C. Remove supernatant by decanting and resuspend pellets in 15 ml buffer (50 mM Tris, 10 mM EDTA, pH 8 with anti-protease cocktail) for each pellet derived from 500 ml of cell culture. 
				Note: Resuspended pellets can be frozen and stored at -20 °C for several days. Freezing facilitates bacterial cells lysis.</li>
			<li>Check the over-expression of recombinant protein using crude bacteria pellets by SDS-PAGE analysis and Coomassie staining.
				<ol>
					<li>For this, centrifuge 1 ml of bacterial culture to pellet cells. Add 100 µl Laemmli denaturation solution (277.8 mM Tris-HCl, pH 6.8, 4.4% SDS, 44.4% w/v glycerol, 0.02% bromophenol blue) to pellet and heat at 100 °C for 5 min.</li>
					<li>Load 10 µl of the sample to a 12% acrylamide gel, run SDS-PAGE and visualize separated proteins by Coomassie staining.</li>
				</ol>
			</li>
			<li>Add Triton X-100 to 0.5% final concentration to the completely resuspended pellet from 2.1.2).</li>
			<li>Incubate the suspension in water bath at 37 °C for 30 min.</li>
			<li>Sonicate the suspension for 5 min at 6-12 microns peak-to-peak amplitude in ice-cold water to lyse bacterial cells.</li>
			<li>Transfer sonicated suspension into clean 50 ml centrifugation tubes.</li>
			<li>Centrifuge tubes at 15,000 x g for 15 min at 4 °C.</li>
			<li>Remove supernatant by decanting and add 5 ml of the binding buffer (20 mM Tris-HCl buffer, pH 7.4, 0.5 M NaCl, 8 M Urea, 5 mM Imidazole) per tube.</li>
			<li>Place tubes on the rotating wheel O/N to completely resuspend proteins from inclusion bodies.</li>
		</ol>
	</li>
</ol>
<img alt="Bacterial protein extraction diagram; centrifugation, incubation, sonication; SDS-PAGE analysis." src="/files/ftp_upload/53432/53432fig2.jpg" data-altupdatedat="1787630408000" data-alt="Figure 2"> 
	Figure 2. Scheme of purification of inclusion bodies (as described in step 2.1). Transformed bacteria expressing Shadoo are harvested by centrifugation and resuspended in the lysis buffer. The suspension is incubated at 37 °C for 30 min, and then sonicated to mechanically break bacterial cells. Sonication is done on ice to prevent sample heating. Broken cells are harvested by centrifugation and resuspended in a buffer containing 8 M urea to solubilize proteins from inclusion bodies. <a href="https://www.jove.com/files/ftp_upload/53432/53432fig2highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="2">
	<li>Ni 2+-affinity chromatography 
		Note: Chromatography is performed on FPLC System using a Ni2+-charged, 5 ml Sepharose chelating column (Figure 3A). All solutions are loaded on the column with a flow rate of 1 ml/min.
		<ol>
			<li>Inject 10 ml of 0.2 M NiSO4 water solution into the Sepharose column in order to charge it with Ni2+-ions.</li>
			<li>Equilibrate the column charged with Ni2+-ions by injecting 30-50 ml of the binding buffer containing a low concentration of imidazole (20 mM Tris-HCl buffer, pH 7.4, 0.5 M NaCl, 8 M Urea, 5 mM Imidazole).</li>
			<li>Load the urea-solubilized proteins with a 50 ml injection loop.</li>
			<li>Recover the flow-through fraction by thoroughly washing the column with 10 ml low imidazole binding buffer (20 mM Tris-HCl buffer, pH 7.4, 0.5 M NaCl, 8 M Urea, 5 mM Imidazole) in order to remove a maximum of unbound proteins from the column.</li>
			<li>Wash the column with 50-100 ml of the washing buffer (20 mM Tris-HCl, pH 7.4, 0.5 M NaCl, 8 M urea, 80 mM imidazole) to elute proteins non-specifically bound to the column.</li>
			<li>Apply a 15 min linear gradient of 80-800 mM Imidazole in the buffer containing 20 mM Tris-HCl, pH 7.4, 0.5 M NaCl, 8 M Urea. Collect 1 ml fractions during the gradient application. Note: His-tagged-proteins are eluted with a gradient of imidazole-containing buffer (used as a competitor).</li>
			<li>Take a 8 µl aliquot of each fraction and add 4 µl 4x Laemmli denaturation solution (see 2.1.3.1). Heat solutions at 100 °C for 5 min.</li>
			<li>Load 10 µl of protein size marker and 10 µl of each sample to the 12% acrylamide gel, run SDS-PAGE and visualize separated proteins by Coomassie staining. Note: The molecular weight of Shadoo calculated form its amino acids sequence is 12,243.2 Da.</li>
			<li>Pool all fractions containing Shadoo.</li>
		</ol>
	</li>
</ol>
<img alt="Three-step protein purification with Ni²⁺ column, size-exclusion, desalt; SDS-PAGE results." src="/files/ftp_upload/53432/53432fig3.jpg" data-altupdatedat="1787630408000" data-alt="Figure 3"> 
	Figure 3. Purification procedure (as described in steps 2.2-2.4). (A) Ni2+-ions can be coordinated by histidine residues, which allows the selective purification of polyhistidine-tagged proteins. Imidazole is used to elute the protein, through its ability to coordinate with the Ni2+-ion and displace the bound protein. (B) Proteins of varying hydrodynamic radius that were retained on the Ni2+-column are separated onto a size exclusion column. Proteins are eluted from the largest to the smallest ones. (C) Prior to use, fractions containing Shadoo are pooled and desalted to remove urea, imidazole and salts. Quality control assays include SDS-PAGE/Coomassie staining, Western blotting. Purified Shadoo can be freeze-dried. Lyophilized Shadoo is stable for months when stored at -20 °C. <a href="https://www.jove.com/files/ftp_upload/53432/53432fig3highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol start="3">
	<li>Size exclusion chromatography 
		Note: A second purification step consists in the size exclusion chromatography which separates Shadoo protein from the other proteins co-eluted during the first purification step (Figure 3B).
		<ol>
			<li>Equilibrate Superdex column of 120 ml total bed volume by injecting 250 ml of 20 mM Tris-HCl buffer, pH 7.4, 0.5 M NaCl, 8 M Urea at the flow rate of 1.5 ml/min.</li>
			<li>Load pooled fractions containing Shadoo from 2.2.9 on the equilibrated column. Collect 1 ml fractions after the column-void volume of 40 ml upon the constant flow of the above buffer.</li>
			<li>Take a 10 µl aliquot of each fraction and perform a SDS-PAGE analysis and Coomassie staining as described above to find out which fractions contain Shadoo.</li>
			<li>Pool fractions containing Shadoo.</li>
		</ol>
	</li>
	<li>Desalting 
		Note: Desalting procedure removes salts, imidazole and urea to obtain recombinant Shadoo protein in a buffer suitable for further biophysical and biochemical studies (Figure 3C). The same result can be obtained by dialyzing samples against the buffer.
		<ol>
			<li>Equilibrate a desalting column of 53 ml with 150 ml of 10 mM ammonium acetate buffer, pH 5, at flow rate of 5 ml/min.</li>
			<li>Load pooled Shadoo fractions on the column. Upon injection of the ammonium acetate buffer collect manually fractions that show an increase of the signal at 280 nm at the output of the UV detector.</li>
			<li>Freeze-dry the desalted Shadoo and store it at -20 °C.</li>
			<li>Dissolve lyophilized Shadoo in an adequate buffer, such as 10 mM sodium acetate buffer, pH 5, prior to use. 
				Note: The polyhistidine tag can be removed with enterokinase.</li>
		</ol>
	</li>
</ol>
3. In Vitro Assembling of Shadoo into Amyloid Fibrils at Physiological pH
Note: The Shadoo protein aggregates and spontaneously forms fibrils at pH ≥ 7 11.
<img alt="Protein aggregation diagram with pH and Gdn-HCl, unfolding to amyloid fibrils at 37°C." src="/files/ftp_upload/53432/53432fig4.jpg" data-altupdatedat="1787630408000" data-alt="Figure 4"> 
	Figure 4. Scheme of Shadoo refolding to amyloid fibrils (as described in step 3). Purified Shadoo spontaneously converts to amyloid fibrils when dissolved in buffer of pH ≥ 7. In an acidic solution, Shadoo converts to amyloid fibrils upon incubation with 1 M Gdn-HCl while shaking. Quality control assays include electronic microscopy and ThT staining. <a href="https://www.jove.com/files/ftp_upload/53432/53432fig4highres.jpg" target="_blank">Please click here to view a larger version of this figure.</a>
<ol>
	<li>Dilute Shadoo to a final concentration of 2 µM in a 20 mM Tris-HCl buffer, pH 7.4. Measure the concentration by measuring the optical density of the solution at 280 nm and using the extinction coefficient deduced from Shadoo amino acid composition of 20,970.</li>
	<li>Incubate 500 µl of the solution in a conical plastic tube at 4 °C for a couple of weeks, to allow spontaneous protein conversion to amyloid structures (Figure 4).</li>
	<li>Add freshly prepared thioflavin T (ThT) to a final concentration of 10 µM to a 100 µl aliquot of the Shadoo solution. Incubate the solution for 5 min at RT. Measure fluorescence emission from 460 to 520 nm using an excitation wavelength of 435 nm to verify the presence of amyloid structures 17.</li>
</ol>
4. In Vitro Assembling of Shadoo to Amyloid Fibrils at Acidic pHs
<ol>
	<li>Dilute Shadoo in 1 M GdnHCl, 20 mM Na-acetate buffer, pH 5 to a final concentration of 2 µM.</li>
	<li>Incubate 500 µl of this solution in a conical tube with continuous shaking at 37 °C, for 3-7 days.</li>
	<li>Check the presence of amyloid fibrils by adding ThT to an aliquot of the solution as in 3.3.</li>
	<li>Dialyze obtained suspension against 10 mM Na-acetate buffer, pH 5.0, to purify Shadoo amyloid fibrils.</li>
	<li>Store purified fibrils at +4 °C.</li>
</ol>
<img alt="SDS-PAGE analysis, Coomassie stained gels A, B, protein fractionation, Western blot result C." src="/files/ftp_upload/53432/53432fig5.jpg" data-altupdatedat="1787630408000" data-alt="Figure 5"> 
	Figure 5. Representative results. Protein fractions eluted from Ni2+-charged chelating column (A) and size exclusion column (B) were analyzed using SDS-PAGE and Coomassie staining. Identification of purified Shadoo was assessed using SPRN anti-Shadoo antibody (C). <a href="https://www.jove.com/files/ftp_upload/53432/53432fig5large.jpg" target="_blank">Please click here to view a larger version of this figure.</a>

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The authors have nothing to disclose.

An easy and efficient protocol for both expression and purification of a large amount of recombinant mouse Shadoo protein is presented. The method described allows successful solubilization and purification of (His6)-tagged recombinant Shadoo protein. It is important, as pointed out in the title, that when expressed in a prokaryotic bacterium E. coli Shadoo accumulates in inclusion bodies. Prior to Shadoo purification, bacteria have to be lysed by sonication in a buffer containing Triton X-100. Subseq...

Prion neurodegenerative diseases, which include bovine spongiform encephalopathy in cattle, scrapie in sheep and Creutzfeldt-Jakob disease in humans, are fatal and incurable. Prion diseases are characterized by conformational changes of cellular prion protein mainly composed of &#945;-helices, into the cross-&#946;-sheet enriched amyloid conformer 1,2. Cross-&#946;-structures contain densely packed and highly ordered crystalline-like &#946;-sheets stabilized with hydrogen bonds 3,4. Prion amyloids can self-replicate due to the &#946;-strands at the growing edge that provide a template for recruiting and converting a monomeric protein unit.
According to the &#34;protein only&#34; hypothesis, the amyloid conformer of prion protein is the sole infectious agent. However, some other biomolecules have been proposed to be essential to prion disorders. For instance, cell membranes are thought to be a place where conversion takes place and some negatively charged lipids have been shown to enhance the conversion process 5,6. In addition, some proteins may also be involved in prion pathologies. Specifically, there are two other members of the prion protein family: Doppel and Shadoo 7,8. Doppel has a relatively rigid structure stabilized with di-sulfide bridges and fails to self-polymerize and aggregate to amyloid fibrils 9. In contrast, similar to prion protein, Shadoo can adopt a &#946;-sheet-enriched structure and self-associate into amyloid fibril structures. It was shown that Shadoo can fibrillate under native conditions or upon binding negatively charged membranes 10,11. Conversion of Shadoo into amyloid-like fibers may be associated with pathologies. Indeed, the mechanisms by which amyloid-like structures cause disease are poorly understood.
Shadoo bears a hydrophobic domain (HD) and a series of tandem Arg/Gly repeats similar to the N-terminal part of prion protein (Figure 1A). As the N-terminal part of prion protein, Shadoo is highly positively charged and appears to be a natively unstructured protein 11,12. Shadoo seems to be functionally related to prion disorders since it can directly bind prion protein. In addition, its expression is down regulated during prion pathology 13,14. However, the role of Shadoo in prion disease is not yet established.
We developed a plasmid carrying the coding sequence of the mouse Shadoo gene. The plasmid was used to transform E. coli for production of N-terminal His6 fusion Shadoo protein. This expression system is well established in our laboratory and is commonly used in our ongoing projects 6,15,16. An important issue for expression of Shadoo is the choice of the E. coli strain. While competent BL21 bacterial strain is commonly used for expression of recombinant proteins Shadoo was successfully expressed and purified only from the transformed SoluBL21 bacterial strain. SoluBL21 competent E. coli is an improved mutant of BL21 host strain developed for the production of proteins whose expression in the parent BL21 gave no detectable soluble product. High-level expression of Shadoo in SoluBL21 E. coli leads to accumulation of the protein in inclusion bodies. As a general feature, when a non-native protein is highly expressed in E. coli, this protein tends to accumulate in insoluble inclusion bodies. Shadoo probably aggregates through non-covalent hydrophobic or ionic interactions (or a combination of both) to highly enriched dynamic structures formed by the protein folded to various degrees. In consequence, the purification comprises at least two steps: (i) a selective separation of the protein from other biomolecules in a denaturation medium, and (ii) a renaturation of the purified protein using in vitro folding techniques.
The selective separation of Shadoo was achieved in a buffer solution containing 8M urea (or alternatively 6M Guanidine-HCl). The urea removal and the renaturation of the protein can be done by applying various protocols: (i) renaturation in an acidic pH solution to obtain an unstructured monomeric Shadoo protein, or (ii) renaturation in a solution of pH &#8805; 7 to obtain Shadoo polymerized into stable amyloid fibers with characteristic cross-&#946;-sheet motifs.

<table><tbody><tr><td>AKTA FPLC&amp;nbsp;</td><td>GE, Amersham</td><td># 1363</td><td></td></tr><tr><td>HiLoad 16/60 Superdex</td><td>GE Healthcare</td><td>17-1069-01</td><td></td></tr><tr><td>HiTrap IMAC</td><td>GE Healthcare</td><td>GE17-0920-05</td><td></td></tr><tr><td>HiPrep26/10 Desalting column</td><td>GE Healthcare</td><td>GE17-5087-01</td><td></td></tr><tr><td>SoluBL21 Competent E. coli</td><td>Genlantis</td><td>C700200</td><td></td></tr><tr><td>pET-28b+</td><td>Novogen</td><td>69865-3</td><td></td></tr><tr><td>IPTG</td><td>Sigma-Aldrich</td><td>I6758</td><td></td></tr><tr><td>LB-Broth medium</td><td>Sigma-Aldrich</td><td>L3022</td><td></td></tr><tr><td>Eppendorf Biophotometar</td><td>Eppendorf</td><td>550507804</td><td></td></tr><tr><td>Trito X-100</td><td>Life Technologies</td><td>85111</td><td></td></tr><tr><td>NiSO4</td><td>Sigma-Aldrich</td><td>656895</td><td></td></tr><tr><td>EDTA</td><td>Sigma-Aldrich</td><td>E6758</td><td></td></tr><tr><td>Tris-HCl</td><td>Sigma-Aldrich</td><td>RES3098T</td><td></td></tr><tr><td>Protease Inhibitor Cocktail Tablets</td><td>Roche</td><td>4693116001</td><td></td></tr><tr><td>NaCl</td><td>Sigma-Aldrich</td><td>746398</td><td></td></tr><tr><td>Imidazol</td><td>Sigma-Aldrich</td><td>I5513</td><td></td></tr><tr><td>Gdn-HCl</td><td>Sigma-Aldrich</td><td>G4505</td><td></td></tr><tr><td>protein size marker&amp;nbsp;</td><td>Thermo Fisher Scientific</td><td>26620</td><td></td></tr></tbody></table>

purification and refolding to amyloid fibrils of (his)6-tagged recombinant shadoo protein expressed as inclusion bodies in e. coli

Purification and Refolding to Amyloid Fibrils of (His)6-tagged Recombinant Shadoo Protein Expressed as Inclusion Bodies in E. coli

The Escherichia coli expression system is a powerful tool for the production of recombinant eukaryotic proteins. We use it to produce Shadoo, a protein belonging to the prion family. A chromatographic method for the purification of (His)6-tagged recombinant Shadoo expressed as inclusion bodies is described. The inclusion bodies are solubilized in 8 M urea and bound to a Ni2+-charged column to perform ion affinity chromatography. Bound proteins are eluted by a gradient of imidazole. Fractions containing Shadoo protein are subjected to size exclusion chromatography to obtain a highly purified protein. In the final step purified Shadoo is desalted to remove salts, urea and imidazole. Recombinant Shadoo protein is an important reagent for biophysical and biochemical studies of protein conformation disorders occurring in prion diseases. Many reports demonstrated that prion neurodegenerative diseases originate from the deposition of stable, ordered amyloid fibrils. Sample protocols describing how to fibrillate Shadoo into amyloid fibrils at acidic and neutral/basic pHs are presented. The methods on how to produce and fibrillate Shadoo can facilitate research in laboratories working on prion diseases, since it allows for production of large amounts of protein in a rapid and low cost manner.

About 5-10 mg of purified Shadoo protein is obtained per liter of bacterial culture. A two-step purification is needed to obtain recombinant Shadoo of high purity. The first step is performed by affinity chromatography with a Ni2+-charged column that retains His-tagged-proteins. Eluted fractions are subjected to SDS-PAGE and stained with Coomassie Brilliant Blue (Figure 5A). Fractions containing Shadoo protein are pooled and further purified by size-exclusion chromatography which separates pro...

A two-step chromatographic method is described for the purification of recombinant Shadoo protein expressed as inclusion bodies in Escherichia coli, as well as a protocol to fibrillate purified Shadoo into amyloid structures.

The Escherichia coli expression system is a powerful tool for the production of recombinant eukaryotic proteins. We use it to produce Shadoo, a protein ...

The overall goal of this procedure is to purify a recombinant shadu protein expressed as inclusion bodies in Esia coli and to refold it into the amyloid fibrils. This method can help answer key questions in the field of molecular mechanisms of protein conformational disorders such as those occurring in pre diseases. The main advantage of this technique is that it allows the prediction of a large amounts of protein in a rapid and low cost manner To transform competent solu BBL 21 bacteria with the PET 28, his six SHADU plasmid Mix 10 to 100 picograms of plasmid or one to five microliters into 50 microliters of bacteria in a tube.Heat shock the cells at 42 degrees Celsius for 45 seconds. Add lb medium supplemented with 40 milligrams per milliliter of can mycin and bacteria and culture. The transformed bacteria at 37 degrees Celsius until they reach an absorbance of 0.5 to 0.7 at 600 nanometers, induce shadow expression by adding 240 micrograms per milliliter of IPTG and culture.The bacteria at 37 degrees Celsius and 150 RPM overnight. To purify the protein, transfer the bacterial suspension into centrifuge tubes and spin it 2, 500 times G and four degrees Celsius for 20 minutes. Use 15 milliliters of 50 millimolar triss, 10 millimolar, EDTA pH eight and protease cocktail to resuspend.Each pellet derived from 500 milliliters of cell culture. After checking for overexpression, according to the text protocol, add Triton X 100 to the resuspended pellets at a final concentration of 0.5%Then incubate the suspension in a water bath at 37 degrees Celsius. Next, sonicate the suspension in ice cold water at six to 12 microns.Peak tope amplitude for five minutes to slice the bacterial cells. Then transfer the sonicated suspension into clean 50 milliliter centrifugation tubes. Centrifuge the tubes at 15, 000 times g and four degrees Celsius for 15 minutes.Decant to remove the S supernatant and add five milliliters of binding buffer per tube. Place the tubes on the rotating wheel overnight to completely resuspend proteins from inclusion bodies. To carry out nickel chromatography.Inject 10 milliliters of 0.2 molar nickel sulfate water solution into the spheros column to charge it with nickel ions. Equilibrate the column by injecting 30 to 50 milliliters of the binding buffer with low ole. Then use an injection loop to load the urea solubilized proteins.Next, with 10 milliliters of low ole binding buffer, thoroughly wash the column to remove unbound proteins. Then use 50 to 100 milliliters of washing buffer to wash the column and elute the non-specifically bound proteins. To elute the hist tagged protein.Apply a 15 milliliter linear gradients of 80 to 800 millimolar ole in binding buffer at a flow rate of one milliliter per minute. Collect one milliliter fractions, aliquot eight microliters from each fraction into separate tubes, and add four microliters of four X lamely denaturation solution. Then keep the tubes at 100 degrees Celsius for five minutes.Carry out STS page by running 10 microliters each of marker and samples on a 12%poly acrylamide gel and stain with kumasi blue. The calculated molecular weight of shadow is 12243.2 Daltons pool. All shadow containing fractions for size exclusion chromatography equilibrate A 120 milliliter total bed volume SUEx column by injecting 250 milliliters of 20 millimolar tris, HCL buffer pH 7.4 0.5 molar sodium chloride, and eight molar urea at a flow rate of 1.5 milliliters per minute.Load the pooled shadu fractions onto the column and after eluding a column void volume of 40 milliliters. Collect one milliliter fractions of the protein. After verifying the fractions containing shadu, pool the protein as before to desalt the sample.Use 150 milliliters of 10 millimolar ammonium acetate pH five to equilibrate a 53 milliliter desalting column at a flow rate of five milliliters per minute. Load the pool onto the desalting column using a UV detector at 280 nanometers. Begin collecting fractions that show an increase in the signal from the UV detector to assemble shadow into amyloid fis.At physiological pH. Use 20 micromolar triss pH 7.4 to dilute shadow with a spectrophotometer at 280 nanometers and the extinction coefficient deduced from the amino acid composition of 20, 970. Calculate the concentration, transfer 500 microliters of the solution into a conical plastic two and incubate at four degrees Celsius for a couple of weeks to allow spontaneous protein conversion to amyloid structures.After the incubation, add freshly prepared thio flavin tea or THT to 100 microliters of shadu solution. Then incubate the solution at room temperature for five minutes. Measure fluorescent emission from 460 to 520 nanometers using an excitation wavelength of 435 nanometers to verify the presence of amyloid structures to assemble shadu into amyloid fibrils at acidic phs.Dilute shadu in one molar guine hydrochloride 20 millimolar sodium acetate pH five to a final concentration of two micromolar, transfer 500 microliters into a conical tube and incubate with continuous shaking at 37 degrees Celsius for three to seven days. Check the presence of amyloid fibrils by adding THT to the sample and measuring fluorescence as just demonstrated. Finally, dialyze the suspension against 10 millimolar sodium acetate buffer pH 5.0 to purify the amyloid fibrils shown here are fractions containing his six tag shadow protein collected through affinity chromatography and subjected to SDS page.In this figure, the shadu containing fractions were pooled and purified by size exclusion chromatography. The molecular weight of shadu is 12 kilodaltons. The presence of shadu was also verified by Western blot using a specific antis shadu antibody, SPRN, that binds to a sensitive epitope between 76 to 105 amino acids from the protein C terminal region.In this graph, Shadu refolding to amyloid fibrils is verified by THT staining. That increases in intensity in response to the conversion of shadu to amyloid structures. Negative staining electron microscopy also verifies refolding of shadu to amyloid fis Following this procedure.Other methods like those based on nickel magnetic beads can be performed in order to replace the nickel affinity column after its development. This technique paved the way for researchers in the field of protein biophysics and biochemistry to explore in vitro various proteins involved in different ProPath.

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JoVE Journal

Biology

Here, we describe a protocol for the purification of highly active Hsp104, a hexameric AAA+ protein from yeast, which couples ATP hydrolysis to protein disaggregation. This scheme exploits a His6-tagged construct for affinity purification from E. coli followed by anion-exchange chromatography, His6-tag removal with TEV protease, and size-exclusion chromatography.

Purification of Hsp104, a Protein Disaggregase

A method for large-scale purification of the APP intracellular domain (AICD) is described. We also describe methodology to induce in vitro AICD aggregation and visualization by atomic force microscopy. The methods described are useful for biochemical/structural characterization of the AICD and the effects of molecular chaperones on its aggregation.

Purification and Aggregation of the Amyloid Precursor Protein Intracellular Domain

Proteins can either adopt a native structure or misfold into insoluble amyloid. Conditions that favor the misfolding pathway lead to the formation of different types of amyloid fibrils. The methods described here allow rapid conversion of native proteins into amyloid in vitro.

Rapid Generation of Amyloid from Native Proteins In vitro

β-barrel outer membrane proteins (OMPs) serve many functions within the outer membranes of Gram-negative bacteria, mitochondria, and chloroplasts. Here, we hope to alleviate a known bottleneck in structural studies by presenting protocols for the production of β-barrel OMPs in sufficient quantities for structure determination by X-ray crystallography or NMR spectroscopy.

From Constructs to Crystals &#8211; Towards Structure Determination of &#946;-barrel Outer Membrane Proteins

Herein we report a tailored HPLC purification protocol that yields high-purity amyloid beta 42 (Aβ42) and amyloid beta 40 (Aβ40) peptides, capable of oligomer formation. Amyloid beta is a highly aggregation prone, hydrophobic peptide implicated in Alzheimer's disease. The amyloidogenic nature of the peptide makes its purification a challenge.

A Tailored HPLC Purification Protocol That Yields High-purity Amyloid Beta 42 and Amyloid Beta 40 Peptides, Capable of Oligomer Formation

Biochemical and structural analyses of glycosylated proteins require relatively large amounts of homogeneous samples. Here, we present an efficient chemical method for site-specific glycosylation of recombinant proteins purified from bacteria by targeting reactive Cys thiols.

Targeting Cysteine Thiols for in Vitro Site-specific Glycosylation of Recombinant Proteins

A procedure is presented for the refolding of the dCACHE periplasmic ligand binding domain of Campylobacter jejuni chemoreceptor Tlp3 from inclusion bodies and the purification to yield milligram quantities of protein.

Method for Efficient Refolding and Purification of Chemoreceptor Ligand Binding Domain

Here, we describe a method for purifying histidine-tagged pyrophosphokinase enzymes and utilizing thin layer chromatography of radiolabelled substrates and products to assay for the enzymatic activity in vitro. The enzyme activity assay is broadly applicable to any kinase, nucleotide cyclase, or phosphor-transfer reaction whose mechanism includes nucleotide triphosphate hydrolysis.

A Purification and In Vitro Activity Assay for a (p)ppGpp Synthetase from Clostridium difficile

Expression and purification of fumarylacetoacetate hydrolase domain-containing proteins is described with examples (expression in E. coli, FPLC). Purified proteins are used for crystallization and antibody production and employed for enzyme assays. Selected photometric assays are presented to display the multi-functionality of FAHD1 as oxaloacetate decarboxylase and acylpyruvate hydrolase.

Expression, Purification, Crystallization, and Enzyme Assays of Fumarylacetoacetate Hydrolase Domain-Containing Proteins

This biochemical purification method with mass spectrometry-based proteomic analysis facilitates the robust characterization of amyloid fibril cores, which may accelerate the identification of targets for preventing Alzheimer's disease.

Biochemical Purification and Proteomic Characterization of Amyloid Fibril Cores from the Brain

Learn to purify recombinant Shadoo protein from E. coli inclusion bodies using two-step chromatography and refold it into amyloid fibrils. This method enables rapid, cost-effective study of protein conformational disorders.

Purification and Refolding to Amyloid Fibrils of (His)6-tagged Recombinant Shadoo Protein Expressed as Inclusion Bodies in E. coli (Video) | JoVE Journal

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