Ce projet a été soutenu par des subventions aux CJJ de la National Science Foundation et la Société des sciences biomoléculaires.

1. Jour 1: MexB de Pseudomonas aeruginosa est codée par pFB101. Le gène a été amplifié à partir MexB P. ADN génomique aeruginosa et inséré dans le Ndel et des sites de restriction Xhol du vecteur pET30b +. La construction comporte une étiquette hexahistidine C-terminale. <ol><li> Le plasmide est utilisé pour transformer E. coli souche C43 (DE3) 12, et les transformants sont étalés sur gélose LB contenant 30 ug / ml de kanamycine. </li></ol> 2. Jour 2: cultures de la nuit: <ol start="2"><li> Dans la soirée, 4 X 3 cultures LB ml contenant 30 ug / ml de kanamycine sont inoculés à partir des colonies transformantes frais. Alternativement, les cultures peuvent être inoculés à partir d&#39;un perm congelés. Ces petites cultures sont cultivées sur un rouleau à 37 ° C pendant la nuit. </li></ol> 3. Jour 3: Grandir 6 litres cultures: <ol start="3"><li> Dans la matinée, l&#39;utilisation des cultures durant la nuit pour inoculer 150 ml LB contenant 30 ug / ml de kanamycine. Cultiver la culture à 37 ° C sur un agitateur. </li><li> Dans l&#39;après-midi, utilisez la petite culture pour inoculer 6 x 1L 2xYT supports contenant 30 ug / ml de kanamycine dans des flacons Fernbach. (Utilisez 25 ml par la culture pour une dilution 1:40). Cultivez les cultures à 37 ° C jusqu&#39;à ce qu&#39;ils atteignent une DO 600 de 0,4-0,6, à environ 1,5 heures </li><li> Lorsque les cultures atteignent la bonne densité, induisent l&#39;expression des protéines en ajoutant 0,5 ml d&#39;IPTG 1M. Mettre tous les flacons de retour dans le shaker et continuer à les pousser à 30 ° C pendant la nuit. </li></ol> 4. Jour 4: prélèvement de cellules et de purification des protéines: <ol start="6"><li> Ajouter les inhibiteurs de protéase, DNAse, et le lysozyme aux solutions tampons comme suit: Pour 50 mL de tampon de resuspension cellulaire, ajoutez 10 mg DNaseI (0,1 mg / ml en concentration finale), 1 EDTA complète sans comprimé d&#39;inhibiteur de protéase, et une pincée de lysozyme . À 60 ml de tampon de resuspension membrane, ajouter 1 comprimé d&#39;inhibiteur de protéase. Pour une autre 50 ml de tampon de resuspension membrane, ajouter 1 comprimé d&#39;inhibiteur de protéase. Conservez tous les trois solutions sur la glace. </li><li> Centrifuger les cultures 30 min 5000 rpm à grande échelle centrifugeuse pour récolter les cellules. </li><li> Resuspendre les cellules dans 100 ml tampon de resuspension cellulaire (50 NaP mM, pH 7,0, NaCl 300 mM, MgCl2 2 mM, EDTA 1 complète sans comprimé d&#39;inhibiteur de protéase, 0,1 mg / mL DNAse I, une pincée de lysozyme) </li><li> Faire passer la solution de cellules à deux reprises grâce à une cellule de pression française à 12.000 psi (762 pression manométrique). Recueillir le lysat cellulaire dans une bouteille conservés au froid sur la glace. </li><li> Transférer le lysat cellulaire à la SS34 tubes à centrifuger et centrifuger pour enlever les débris cellulaires pendant 30 min à 10000 rpm à 4 ° C dans un rotor SS-34. </li><li> Retirer délicatement le surnageant dans des tubes d&#39;ultracentrifugation Ti647.5. Centrifuger 50 min à 40000 rpm à 4 ° C. Jeter le surnageant. </li><li> Reprendre le culot, qui contient les membranes cellulaires, à env. 25 ml de tampon de resuspension de membrane (50 NaP mM, pH 7,0, NaCl 300 mM, glycérol 5%, 1 EDTA complète sans comprimé d&#39;inhibiteur de protéase). </li><li> Transférer la suspension de membrane d&#39;un tube à centrifuger et centrifuger à nettoyer 40 000 rpm dans un rotor Ti647.5 pendant 50 min à 4 ° C. </li><li> Jeter le surnageant et remettre la membrane culot lavé dans 25 ml tampon de resuspension de membrane (50 NaP mM, pH 7,0, NaCl 300 mM, glycérol 5%, 1 EDTA complète sans comprimé d&#39;inhibiteur de protéase). </li></ol> 5. Solublization protéine TM: <ol start="15"><li> Pour les membranes en suspension (environ 25 ml), ajouter 6 mL DDM 10% (concentration finale de détergent DDM = 2%) Rock le mélange à 4 ° C pendant 2 heures. </li><li> Centrifuger le mélange à 40000 rpm pendant 40 min à 4 ° C dans le rotor Ti647.5 pour séparer les protéines des complexes solubles de détergent à partir des protéines insolubles. Enregistrer le surnageant, qui contient les complexes protéiques MexB détergent. </li></ol> 6. IMAC: <ol start="17"><li> Mélanger le surnageant obtenu à partir de la rotation à haute vitesse avec des perles en métal Talon l&#39;affinité équilibrée dans le tampon de resuspension. Incuber pendant 1 heure sur un rouleau à 4 ° C. </li><li> Verser la pâte dans un corps de colonne à écoulement par gravité et jetez le débit à travers. </li><li> Laver la colonne avec 20 ml (10 volumes de colonne) de tampon de liaison et de laver IMAC (50 NaP mM, pH 7, NaCl 300 mM, glycérol 5%, 0,2% DDM) </li><li> Eluer la protéine avec le tampon d&#39;élution IMAC (50 NaP mM, pH 7,0, NaCl 300 mM, glycérol 5%, 250 mM imidazole, 0,2% DDM). </li><li> Prenez 15 uL échantillons des fractions d&#39;élution, mélanger chacune avec 15 pi de tampon d&#39;échantillon 2X SDS pour l&#39;analyse par électrophorèse sur gel de polyacrylamide. Spin de 30 secondes dans une microcentrifugeuse. Analyser les échantillons sur un 10% gel SDS de polyacrylamide d&#39;estimer la quantité et la pureté de MexB dans chaque fraction. </li><li> Piscine des fractions contenant les complexes de protéines et de détergent MexB les concentrer dans un concentrateur tournent à 4 ° C. Veillez à ce que la protéine n&#39;a pas précipiter à ce step. </li></ol> 7. Colonne de filtration sur gel: <ol start="23"><li> Pré-équilibrer une Superose 12 HL 30/10 colonne avec 24 ml de tampon de fonctionnement (50 NaP mM, pH 7,0, NaCl 300 mM, glycérol 5%, 0,2% de bêta-octylglucoside), et d&#39;attendre une base plate. </li><li> Rincer la boucle Akta système de chargement avec un tampon de course. </li><li> Filtrer la solution de protéines en utilisant un filtre à seringue avant de l&#39;appliquer à la colonne. </li><li> Chargez jusqu&#39;à 240 ul de la solution de protéines sur la colonne, avec une concentration en protéines d&#39;un maximum de 5 mg / ml. </li><li> Exécuter 1,5 volumes de colonne (36 ml) de tampon, de collecter 0,25 ml fractions. Les complexes protéiques MexB détergent doit éluer comme un pic autour de 10 - 15 ml de volume d&#39;élution. </li><li> Prenez 5 échantillons uL des fractions de pointe. Mélanger chaque échantillon avec le tampon de 01h01 2X échantillon de SDS. Analyser les échantillons sur un gel de polyacrylamide 10% à estimer la quantité et la pureté de MexB dans chaque fraction </li><li> Piscine des fractions contenant MexB pur. </li></ol> 8. Les résultats représentatifs: Figure 1 comprend un gel de polyacrylamide avec des fractions de colonne en commun de la colonne IMAC et fractions individuelles de la colonne de filtration sur gel. Après la colonne de filtration sur gel de la protéine semble pure par gel de polyacrylamide Coomassie tachés. La figure 2 comprend une trace de la colonne de filtration sur gel montrant le pic principal de l&#39;élution complexe protéique de détergent de la colonne. Le rendement moyen de protéines MexB est d&#39;environ 2 mg par 6 litres de culture 2xYT. <img src="/files/ftp_upload/2134/2134fig1.jpg" alt="Figure 1" /> Figure 1. Gel SDS-PAGE de la purification du PDC MexB. Lane 1, les marqueurs de poids moléculaire. 2, Pooled fractions IMAC. 3-7, les fractions sur colonne de gel filtration. <img src="/files/ftp_upload/2134/2134fig2.jpg" alt="Figure 2" /> Figure 2. Exemple de résultats filtration sur gel pour les complexes protéiques MexB détergents (PDC).

<ol>
	<li>Eda, S., Maseda, H., Nakae, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=An+elegant+means+of+self-protection+in+gram-negative+bacteria+by+recognizing+and+extruding+xenobiotics+from+the+periplasmic+space.">An elegant means of self-protection in gram-negative bacteria by recognizing and extruding xenobiotics from the periplasmic space.</a> J. Biol. Chem. 278, 2085-2088 (2003).</li><li>Li, X. Z., Ma, D., Livermore, D. M., Nikaido, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+efflux+pump(s)+in+intrinsic+resistance+of+Pseudomonas+aeruginosa:+active+efflux+as+a+contributing+factor+to+beta-lactam+resistance.">Role of efflux pump(s) in intrinsic resistance of Pseudomonas aeruginosa: active efflux as a contributing factor to beta-lactam resistance.</a> Antimicrob. Agents Chemother. 38, 1742-1752 (1994).</li><li>Li, X. Z., Nikaido, H., Poole, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Role+of+MexA-MexB-OprM+in+antibiotic+efflux+in+Pseudomonas+aeruginosa.">Role of MexA-MexB-OprM in antibiotic efflux in Pseudomonas aeruginosa.</a> Antimicrob. Agents Chemother. 39, 1948-1953 (1995).</li><li>Masuda, N., Sakagawa, E., Ohya, S., Gotoh, N., Tsujimoto, H., Nishino, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Substrate+specificities+of+MexAB-OprM,+MexCD-OprJ,+and+MexXY-oprM+efflux+pumps+in+Pseudomonas+aeruginosa.">Substrate specificities of MexAB-OprM, MexCD-OprJ, and MexXY-oprM efflux pumps in Pseudomonas aeruginosa.</a> Antimicrob. Agents Chemother. 44, 3322-3327 (2000).</li><li>Okusu, H., Ma, D., Nikaido, H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AcrAB+efflux+pump+plays+a+major+role+in+the+antibiotic+resistance+phenotype+of+Escherichia+coli+multiple-antibiotic-resistance+(Mar)+mutants.">AcrAB efflux pump plays a major role in the antibiotic resistance phenotype of Escherichia coli multiple-antibiotic-resistance (Mar) mutants.</a> J. Bacteriol. 178, 306-308 (1996).</li><li>Srikumar, R., Kon, T., Gotoh, N., Poole, K. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Expression+of+Pseudomonas+aeruginosa+multidrug+efflux+pumps+MexA-MexB-OprM+and+MexC-MexD-OprJ+in+a+multidrug-sensitive+Escherichia+coli+strain.">Expression of Pseudomonas aeruginosa multidrug efflux pumps MexA-MexB-OprM and MexC-MexD-OprJ in a multidrug-sensitive Escherichia coli strain.</a> Antimicrob. Agents Chemother. 42, 65-71 (1998).</li><li>Tikhonova, E. B., Zgurskaya, H. I. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=AcrA,+AcrB,+and+TolC+of+Escherichia+coli+Form+a+Stable+Intermembrane+Multidrug+Efflux.">AcrA, AcrB, and TolC of Escherichia coli Form a Stable Intermembrane Multidrug Efflux.</a> Complex. J. Biol. Chem. 279, 32116-3224 (2004).</li><li>Yoneyama, H., Ocakatan, A., Tsuda, M., Nakae, T. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+mex-gene+products+in+antibiotic+extrusion+in+Pseudomonas+aeruginosa.">The role of mex-gene products in antibiotic extrusion in Pseudomonas aeruginosa.</a> Biochem. Biophys. Res. Commun. 233, 611-618 (1997).</li><li>Berger, B. W., Gendron, C. M., Robinson, C. R., Kaler, E. W., Lenhoff, A. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+role+of+protein+and+surfactant+interactions+in+membrane-protein+crystallization.">The role of protein and surfactant interactions in membrane-protein crystallization.</a> Acta. Crystallogr. D Biol. Crystallogr. 61, 724-730 (2005).</li><li>Jones, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Surfactants+in+membrane+solubilisation.">Surfactants in membrane solubilisation.</a> Int. J. Pharm. 177, 137-159 (1999).</li><li>Maire, M. l. e., Champeil, P., Moller, J. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Interaction+of+membrane+proteins+and+lipids+with+solubilizing+detergents.">Interaction of membrane proteins and lipids with solubilizing detergents.</a> Biochim. Biophys. Acta. 1508, 86-111 (2000).</li><li>Miroux, B., Walker, J. E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Over-production+of+proteins+in+Escherichia+coli:+mutant+hosts+that+allow+synthesis+of+some+membrane+proteins+and+globular+proteins+at+high+levels.">Over-production of proteins in Escherichia coli: mutant hosts that allow synthesis of some membrane proteins and globular proteins at high levels.</a> J. Mol. Biol. 260, 289-298 (1996).</li></ol>

En plus de la multirésistance, de nombreuses activités vitales cellulaires, y compris le transport des ions, la communication cellulaire, le transport des vésicules, le maintien de la structure cellulaire et interactions hôtes-pathogènes, impliquent des protéines qui sont incorporés dans la membrane cellulaire. Protéines transmembranaires forment plus de 30% de protéines connues et sont la cible de la majorité des produits pharmaceutiques en usage aujourd&#39;hui. Le pliage incorrect ou l&#39;activité de prot...

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		<table border="1">
		<thead>
		<tr>
		<th>Material Name</th>
		<th>Type</th>
		<th>Company</th>
		<th>Catalogue Number</th>
		<th>Comment</th>
		</tr>
		</thead>
		<tbody>
		
<tr>
<td>SDS sample buffer</td>
<td>&nbsp;</td>
<td>Biorad</td>
<td>161-0737</td>
<td>&nbsp;</td>
<tr>
<td>C43(DE3) E. coli strain</td>
<td>&nbsp;</td>
<td>Lucigen</td>
<td>60345-1</td>
<td>&nbsp;</td>
<tr>
<td>kanamycin sulfate</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>K4378</td>
<td>&nbsp;</td>
<tr>
<td>2XYT media</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP2466-2</td>
<td>&nbsp;</td>
<tr>
<td>LB media</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>AC61189-5000</td>
<td>&nbsp;</td>
<tr>
<td>IPTG</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>I6758</td>
<td>&nbsp;</td>
<tr>
<td>DNaseI</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP3226-1</td>
<td>&nbsp;</td>
<tr>
<td>Lysozyme</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>L7651</td>
<td>&nbsp;</td>
<tr>
<td>Complete EDTA-free protease inhibitor tablets</td>
<td>&nbsp;</td>
<td>Roche</td>
<td>11 873 580 001</td>
<td>&nbsp;</td>
<tr>
<td>NaP monobasic</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>S6566</td>
<td>&nbsp;</td>
<tr>
<td>NaP dibasic</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>S5136</td>
<td>&nbsp;</td>
<tr>
<td>NaCl</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>S6191</td>
<td>&nbsp;</td>
<tr>
<td>MgCl2</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>M1028</td>
<td>&nbsp;</td>
<tr>
<td>Glycerol</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>BP229-1</td>
<td>&nbsp;</td>
<tr>
<td>n-dodecyl-&beta;-D-maltopyranoside</td>
<td>&nbsp;</td>
<td>Anatrace</td>
<td>D310</td>
<td>&nbsp;</td>
<tr>
<td>15ml tubes</td>
<td>&nbsp;</td>
<td>Corning</td>
<td>430052</td>
<td>&nbsp;</td>
<tr>
<td>See-Saw Rocker</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>SSL 4</td>
<td>&nbsp;</td>
<tr>
<td>Talon metal affinity resin</td>
<td>&nbsp;</td>
<td>Clontech</td>
<td>635503</td>
<td>&nbsp;</td>
<tr>
<td>imidazole</td>
<td>&nbsp;</td>
<td>Sigma-Aldrich</td>
<td>I5513</td>
<td>&nbsp;</td>
<tr>
<td>10% polyacrylamide SDS PAGE gels</td>
<td>&nbsp;</td>
<td>BioRad</td>
<td>161-1454</td>
<td>&nbsp;</td>
<tr>
<td>Tris/glycine/SDS PAGE running buffer</td>
<td>&nbsp;</td>
<td>BioRad</td>
<td>161-0732</td>
<td>&nbsp;</td>
<tr>
<td>Kaleidascope prestained molecular weight markers</td>
<td>&nbsp;</td>
<td>BioRad</td>
<td>161-0324</td>
<td>&nbsp;</td>
<tr>
<td>Superose 12 30/10 column</td>
<td>&nbsp;</td>
<td>GEHealthcareSuperose</td>
<td>12 10/300 GL</td>
<td>&nbsp;</td>
<tr>
<td>Amicon centrifugal concentrator</td>
<td>&nbsp;</td>
<td>Millipore</td>
<td>UFC801024</td>
<td>&nbsp;</td>
<tr>
<td>Syringe filter</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>SLFG R04 NL</td>
<td>&nbsp;</td>
<tr>
<td>Fernbach flasks</td>
<td>&nbsp;</td>
<td>Fisher</td>
<td>09-552-39</td>
<td>&nbsp;</td>
<tr>
<td>Shaker to hold Fernbach flasks</td>
<td>&nbsp;</td>
<td>Fisher Scientific</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Akta system</td>
<td>&nbsp;</td>
<td>GE Healthcare</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>J6 Large scale centrifuge with JLA-8.1000 rotor</td>
<td>&nbsp;</td>
<td>Beckman</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>1 l centrifuge bottles</td>
<td>&nbsp;</td>
<td>Beckman</td>
<td>969329</td>
<td>&nbsp;</td>
<tr>
<td>RC-5 centrifuge</td>
<td>&nbsp;</td>
<td>ThermoScientific</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>SS34 fixed-angle rotor and tubes</td>
<td>&nbsp;</td>
<td>ThermoScientific</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>Sorvall floor model Ultracentrifuge</td>
<td>&nbsp;</td>
<td>ThermoScientific</td>
<td>&nbsp;</td>
<td>&nbsp;</td>
<tr>
<td>T647.5 rotor and tubes with caps</td>
<td>&nbsp;</td>
<td>ThermoScientific</td>
<td>08322</td>
<td>&nbsp;</td>
<tr>
<td>French Pressure Cell</td>
<td>&nbsp;</td>
<td>ThermoScientific</td>
<td>FA-032</td>
<td>&nbsp;</td>		</tbody>
		</table>
		</div>

expression, detergent solubilization, and purification of a membrane transporter, the mexb multidrug resistance protein

La multirésistance (MDR), la capacité d&#39;une cellule cancéreuse ou pathogène pour être résistant à un large éventail de structurellement et fonctionnellement indépendantes des médicaments anticancéreux ou des antibiotiques, est un problème actuel graves en santé publique. Cette multirésistance est largement due à l&#39;énergie dépendant de pompes à efflux de médicaments. Les pompes à expulser les médicaments anti-cancer ou des antibiotiques dans le milieu extérieur, abaissant leur concentration intracellulaire en dessous d&#39;un seuil toxique. Nous étudions la multirésistance chez Pseudomonas aeruginosa, un pathogène opportuniste bactérienne qui provoque des infections chez les patients atteints de nombreux types de blessures ou de maladie, par exemple, de brûlures ou de fibrose kystique, et aussi dans l&#39;immuno-compromis du cancer, de dialyse, transplantation et les patients. Les pompes à efflux MDR majeurs dans P. aeruginosa sont des complexes tripartite composé d&#39;une membrane protonique-drogue antiporteur intérieure (RND), un canal de la membrane externe (OMF), et une protéine de liaison périplasmique (PMF) 1-8. Les protéines RND et OMF sont des protéines transmembranaires. Protéines transmembranaires forment plus de 30% de toutes les protéines et 65% sont des cibles pour les médicaments actuels. Les domaines transmembranaires hydrophobes fabriquer les protéines insolubles dans un tampon aqueux. Avant une protéine transmembranaire peut être purifié, il est nécessaire de trouver des conditions de tampon contenant un détergent doux qui permettent à la protéine d&#39;être solubilisé comme un complexe protéique de détergent (PDC) 9-11. Dans cet exemple, nous utilisons une protéine RND, le P. transporteur transmembranaire aeruginosa MexB, pour démontrer comment exprimer une forme recombinante d&#39;une protéine transmembranaire, solubiliser l&#39;utiliser de détergents, et ensuite de purifier les complexes protéiques de détergent. Cette méthode générale peut être appliquée à l&#39;expression, la purification et la solubilisation de nombreuses autres protéines membranaires par recombinaison exprimée. Les complexes protéiques de détergent peuvent ensuite être utilisés pour la caractérisation biochimique ou biophysique, y compris aux rayons X la structure cristalline de détermination ou d&#39;études de réticulation.

Watch this Scientific Journal Video about Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein at JoVE.com

Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein

Dans ce protocole, nous démontrons l&#39;expression, la solubilisation et la purification d&#39;une protéine membranaire exprimée par recombinaison, MexB, comme un complexe de protéines solubles de détergent. MexB est un transporteur de multirésistance membrane du opportunistes Pseudomonas aeruginosa bactérie pathogène.

Expression, Solubilisation détergent, et purification d&#39;un transporteur membranaire, la protéine MexB multirésistance

Multidrug resistance (MDR), the ability of a cancer cell or pathogen to be resistant to a wide range of structurally and functionally unrelated ...

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21.2K vues.  University of Illinois Chicago - UIC. Dans ce protocole, nous démontrons l'expression, la solubilisation et la purification d'une protéine membranaire exprimée par recombinaison, MexB, comme un complexe de protéines solubles de détergent. MexB est un transporteur de multirésistance membrane du opportunistes Pseudomonas aeruginosa bactérie pathogène.

Vidéo: Expression, Detergent Solubilization, and Purification of a Membrane Transporter, the MexB Multidrug Resistance Protein

The MODS method for diagnosis of tuberculosis and multidrug resistant tuberculosis

Patients with active pulmonary tuberculosis (TB) infect 10-15 other persons per year, making diagnosing active TB essential to both curing the patient and preventing new infections.  Furthermore, the emergence of multidrug resistant tuberculosis (MDRTB) means that detection of drug resistance is necessary for stopping the spread of drug-resistant strains.  The microscopic-observation drug-susceptibility (MODS) assay is a low-cost, low-tech tool for high-performance detection of TB and MDRTB.  The MODS assay is based on three principles: 1) mycobacterium tuberculosis (MTB) grows faster in liquid media than on solid media 2) microscopic MTB growth can be detected earlier in liquid media than waiting for the macroscopic appearance of colonies on solid media, and that growth is characteristic of MTB, allowing it to be distinguished from atypical mycobacteria or fungal or bacterial contamination 3) the drugs isoniazid and rifampicin can be incorporated into the MODS assay to allow for simultaneous direct detection of MDRTB, obviating the need for subculture to perform an indirect drug susceptibility test. Competing current diagnostics are hampered by low sensitivity with sputum smear, long delays until diagnosis with solid media culture, prohibitively high cost with existing liquid media culture methods, and the need to do subculture for indirect drug susceptibility testing to detect MDRTB.  In contrast, the non-proprietary MODS method has a high sensitivity for TB and MDRTB, is a relatively rapid culture method, provides simultaneous drug susceptibility testing for MDRTB, and is accessible to resource-limited settings at just under $3 for testing for TB and MDRTB.

The microscopic-observation drug-susceptibility (MODS) assay is a low-cost, low-tech tool for high-performance detection of tuberculosis (TB) and multidrug-resistant tuberculosis (MDRTB). This video describes the MODS liquid media culture method.

La méthode MODS pour le diagnostic de la tuberculose et la tuberculose multirésistante

Patients with active pulmonary tuberculosis (TB) infect 10-15 other persons per year, making diagnosing active TB essential to both curing the patient and ...

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Biologie

Staining of Proteins in Gels with Coomassie G-250 without Organic Solvent and Acetic Acid

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents (Methanol, Ethanol or 2-Propanol) and acetic acid are used for fixation, staining and destaining of proteins in a gel after SDS-PAGE. To speed up the procedure, heating the staining solution in the microwave oven for a short time is frequently used. This usually results in evaporation of toxic or hazardous Methanol, Ethanol or 2-Propanol and a strong smell of acetic acid in the lab which should be avoided due to safety considerations. In a protocol originally published in two patent applications by E.M. Wondrak (US2001046709 (A1), US6319720 (B1)), an alternative composition of the staining solution is described in which no organic solvent or acid is used. The CBB is dissolved in bidistilled water (60-80mg of CBB G-250 per liter) and 35 mM HCl is added as the only other compound in the staining solution. The CBB staning of the gel is done after SDS-PAGE and thorough washing of the gel in bidistilled water. By heating the gel during the washing and staining steps, the process can be finished faster and no toxic or hazardous compunds are evaporating. The staining of proteins occurs already within 1 minute after heating the gel in staining solution and is fully developed after 15-30 min with a slightly blue background that is destained completely by prolonged washing of the stained gel in bidistilled water, without affecting the stained protein bands.

A short protocol for protein staining with Coomassie Brilliant Blue (CBB) G-250 in polyacrylamide gels is described without using organic solvents or acetic acid as in the classical staining procedures with CBB.

Coloration des protéines dans les gels de Coomassie G-250, sans solvant et l&#39;acide acétique organique

In classical protein staining protocols using Coomassie Brilliant Blue (CBB), solutions with high contents of toxic and flammable organic solvents ...

Using the Gene Pulser MXcell Electroporation System to Transfect Primary Cells with High Efficiency

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser MXcell electroporation system and Gene Pulser electroporation buffer (Bio-Rad) were specifically developed to easily transfect nucleic acids into mammalian cells and difficult-to-transfect cells, such as primary and stem cells. We will demonstrate how to perform a simple experiment to quickly identify the best electroporation conditions. We will demonstrate how to run several samples through a range of electroporation conditions so that an experiment can be conducted at the same time as optimization is performed. We will also show how optimal conditions identified using 96-well electroporation plates can be used with standard electroporation cuvettes, facilitating the switch from electroporation plates to electroporation cuvettes while maintaining the same electroporation efficiency. In the video, we will also discuss some of the key factors that can lead to the success or failure of electroporation experiments.

This procedure shows how to use the Gene Pulser MXcell electroporation system to rapidly and easily identify the best electroporation conditions for mouse embryonic fibroblasts (MEFs) or other primary cells. Considerations for troubleshooting are also discussed in the associated video.

Utilisation du système d&#39;électroporation Gene Pulser MXcell à transfecter des cellules primaires à haut rendement

It is becoming increasingly apparent that electroporation is the most effective way to introduce plasmid DNA or siRNA into primary cells. The Gene Pulser ...

Purification of the M. magneticum Strain AMB-1 Magnetosome Associated Protein MamA&Delta;41

Magnetotactic bacteria comprise a diverse group of aquatic microorganisms that are able to orientate themselves along geomagnetic fields. This behavior is believed to aid their search for suitable environments (1). This capability is conferred by the magnetosome, a subcellular organelle that consists of a linear-chain assembly of lipid vesicles each able to biomineralize and enclose a ~50-nm crystal of magnetite or greigite. A principle component of the magnetosome that was shown to be required for the formation of functional vesicles is MamA. MamA is a highly abundant magnetosome-associated protein which is one of the most characterized magnetosome-associated proteins in vivo (2-6). This article focuses on the purification of MamA, which despite being studied in vivo, no clear functional or structural details have been identified for it. Bioinformatics analysis suggested that MamA is a tetra-tricopeptide repeat (TPR) containing protein. TPR is a structural motif found as such or forming part of a bigger fold in a wide range of proteins, it serves as a template for protein-protein interactions and mediates multi-protein complexes (7). TPRs are involved in many crucial tasks in eukaryotic cell organelle processes and many bacterial pathways (8-14). In order to understand MamA, a unique TPR containing protein, highly purified protein is required as a first step. In this article, we present the purification protocol for a stable MamA deletion mutant (MamA&Delta;41) from M. magneticum AMB-1.

Purification of the &lt;em&gt;M. magneticum&lt;/em&gt; Strain AMB-1 Magnetosome Associated Protein MamA&amp;Delta;41

MamA is a unique Magnetosome associated protein which was shown to be involved in magnetosome activation. Here we present the purification protocol of MamA deletion mutant (MamA&Delta;41) from M. magneticum AMB-1.

Purification de la M. magneticum Strain AMB-1 Protein magnétosome Associated MamAΔ41

Magnetotactic bacteria comprise a diverse group of aquatic microorganisms that are able to orientate themselves along geomagnetic fields. This behavior is ...

Using an Automated Cell Counter to Simplify Gene Expression Studies: siRNA Knockdown of IL-4 Dependent Gene Expression in Namalwa Cells

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only to study the effects of downregulating single genes, but also to interrogate signaling pathways and other complex interaction networks.  These pathway analyses require both the use of relevant cellular models and methods that cause less perturbation to the cellular physiology.  Electroporation is increasingly being used as an effective way to introduce siRNA and other nucleic acids into difficult to transfect cell lines and primary cells without altering the signaling pathway under investigation. There are multiple critical steps to a successful siRNA experiment, and there are ways to simplify the work while improving the data quality at several experimental stages.  To help you get started with your siRNA mediated gene knockdown project, we will demonstrate how to perform a pathway study complete from collecting and counting the cells prior to electroporation through post transfection real-time PCR gene expression analysis.  The following study investigates the role of the transcriptional activator STAT6 in IL-4 dependent gene expression of CCL17 in a Burkitt lymphoma cell line (Namalwa).  The techniques demonstrated are useful for a wide range of siRNA-based experiments on both adherent and suspension cells.  We will also show how to streamline cell counting with the TC10 automated cell counter, how to electroporate multiple samples simultaneously using the MXcell electroporation system, and how to simultaneously assess RNA quality and quantity with the Experion automated electrophoresis system.

This procedure describes a quick and easy workflow to introduce siRNA into difficult to transfect cell lines and follow gene expression by real-time PCR. Use of an automated cell counter, multi-well electroporation plate, and automated electrophoresis station provide quick and reliable results without the need for expensive robotic handling.

Aide d&#39;un compteur de cellules automatisé pour simplifier les études d&#39;expression génique: Knockdown siRNA de l&#39;IL-4 dans l&#39;expression des gènes dépendant cellules Namalwa

The use of siRNA mediated gene knockdown is continuing to be an important tool in studies of gene expression.  siRNA studies are being conducted not only ...

Purification of Hsp104, a Protein Disaggregase

Hsp104 is a hexameric AAA+ protein1 from yeast, which couples ATP hydrolysis to protein disaggregation2-10 (Fig. 1). This activity imparts two key selective advantages. First, renaturation of disordered aggregates by Hsp104 empowers yeast survival after various protein-misfolding stresses, including heat shock3,5,11,12. Second, remodeling of cross-beta amyloid fibrils by Hsp104 enables yeast to exploit myriad prions (infectious amyloids) as a reservoir of beneficial and heritable phenotypic variation13-22. Remarkably, Hsp104 directly remodels preamyloid oligomers and amyloid fibrils, including those comprised of the yeast prion proteins Sup35 and Ure223-30. This amyloid-remodeling functionality is a specialized facet of yeast Hsp104. The E. coli orthologue, ClpB, fails to remodel preamyloid oligomers or amyloid fibrils26,31,32.
Hsp104 orthologues are found in all kingdoms of life except, perplexingly, animals. Indeed, whether animal cells possess any enzymatic system that couples protein disaggregation to renaturation (rather than degradation) remains unknown33-35. Thus, we and others have proposed that Hsp104 might be developed as a therapeutic agent for various neurodegenerative diseases connected with the misfolding of specific proteins into toxic preamyloid oligomers and amyloid fibrils4,7,23,36-38. There are no treatments that directly target the aggregated species associated with these diseases. Yet, Hsp104 dissolves toxic oligomers and amyloid fibrils composed of alpha-synuclein, which are connected with Parkinson's Disease23 as well as amyloid forms of PrP39. Importantly, Hsp104 reduces protein aggregation and ameliorates neurodegeneration in rodent models of Parkinson's Disease23 and Huntington's disease38. Ideally, to optimize therapy and minimize side effects, Hsp104 would be engineered and potentiated to selectively remodel specific aggregates central to the disease in question4,7. However, the limited structural and mechanistic understanding of how Hsp104 disaggregates such a diverse repertoire of aggregated structures and unrelated proteins frustrates these endeavors30,40-42.
To understand the structure and mechanism of Hsp104, it is essential to study the pure protein and reconstitute its disaggregase activity with minimal components. Hsp104 is a 102kDa protein with a pI of ~5.3, which hexamerizes in the presence of ADP or ATP, or at high protein concentrations in the absence of nucleotide43-46. Here, we describe an optimized protocol for the purification of highly active, stable Hsp104 from E. coli. The use of E. coli allows simplified large-scale production and our method can be performed quickly and reliably for numerous Hsp104 variants. Our protocol increases Hsp104 purity and simplifies His6-tag removal compared to a previous purification method from E. coli47. Moreover, our protocol is more facile and convenient than two more recent protocols26,48.

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 de Hsp104, une protéine Disaggregase

Hsp104 is a hexameric AAA+ protein1 from yeast, which couples ATP hydrolysis to protein disaggregation2-10 (Fig. 1). This activity imparts two key ...

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel, that when mutated, can give rise to cystic fibrosis in humans.There is therefore considerable interest in this protein, but efforts to study its structure and activity have been hampered by the difficulty of expressing and purifying sufficient amounts of the protein1-3. Like many 'difficult' eukaryotic membrane proteins, expression in a fast-growing organism is desirable, but challenging, and in the yeast S. cerevisiae, so far low amounts were obtained and rapid degradation of the recombinant protein was observed 4-9. Proteins involved in the processing of recombinant CFTR in yeast have been described6-9 .In this report we describe a methodology for expression of CFTR in yeast and its purification in significant amounts. The protocol describes how the earlier proteolysis problems can be overcome and how expression levels of CFTR can be greatly improved by modifying the cell growth conditions and by controlling the induction conditions, in particular the time period prior to cell harvesting. The reagants associated with this protocol (murine CFTR-expressing yeast cells or yeast plasmids) will be distributed via the US Cystic Fibrosis Foundation, which has sponsored the research. An article describing the design and synthesis of the CFTR construct employed in this report will be published separately (Urbatsch, I.; Thibodeau, P. et al., unpublished). In this article we will explain our method beginning with the transformation of the yeast cells with the CFTR construct - containing yeast plasmid (Fig. 1). The construct has a green fluorescent protein (GFP) sequence fused to CFTR at its C-terminus and follows the system developed by Drew et al. (2008)10. The GFP allows the expression and purification of CFTR to be followed relatively easily. The JoVE visualized protocol finishes after the preparation of microsomes from the yeast cells, although we include some suggestions for purification of the protein from the microsomes. Readers may wish to add their own modifications to the microsome purification procedure, dependent on the final experiments to be carried out with the protein and the local equipment available to them. The yeast-expressed CFTR protein can be partially purified using metal ion affinity chromatography, using an intrinsic polyhistidine purification tag. Subsequent size-exclusion chromatography yields a protein that appears to be &gt;90% pure, as judged by SDS-PAGE and Coomassie-staining of the gel.

Expression and Purification of the Cystic Fibrosis Transmembrane Conductance Regulator Protein in Saccharomyces cerevisiae

Attempts to express the cystic fibrosis transmembrane conductance regulator (CFTR) in Saccharomyces cerevisiae have, until now, yielded relatively low amounts of protein. This protocol and the associated reagents distributed via the Cystic Fibrosis Foundation should allow the preparation of milligram amounts of this 'difficult' eukaryotic membrane protein.

Expression et purification de la protéine transmembranaire de la fibrose kystique conductance Regulator dans Saccharomyces cerevisiae

The  cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride  channel, that when mutated, can give rise to cystic fibrosis in  ...

siRNA Screening to Identify Ubiquitin and Ubiquitin-like System Regulators of Biological Pathways in Cultured Mammalian Cells

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that regulates diverse biological pathways including the hypoxia response, proteostasis, the DNA damage response and transcription.&#160; To better understand how UBLs regulate pathways relevant to human disease, we have compiled a human siRNA &#8220;ubiquitome&#8221; library consisting of 1,186 siRNA duplex pools targeting all known and predicted components of UBL system pathways. This library can be screened against a range of cell lines expressing reporters of diverse biological pathways to determine which UBL components act as positive or negative regulators of the pathway in question.&#160; Here, we describe a protocol utilizing this library to identify ubiquitome-regulators of the HIF1A-mediated cellular response to hypoxia using a transcription-based luciferase reporter.&#160; An initial assay development stage is performed to establish suitable screening parameters of the cell line before performing the screen in three stages: primary, secondary and tertiary/deconvolution screening. &#160;The use of targeted over whole genome siRNA libraries is becoming increasingly popular as it offers the advantage of reporting only on members of the pathway with which the investigators are most interested.&#160; Despite inherent limitations of siRNA screening, in particular false-positives caused by siRNA off-target effects, the identification of genuine novel regulators of the pathways in question outweigh these shortcomings, which can be overcome by performing a series of carefully undertaken control experiments.

Here, we describe a methodology to perform a targeted siRNA &#8220;ubiquitome&#8221; screen to identify novel ubiquitin and ubiquitin-like regulators of the HIF1A-mediated cellular response to hypoxia.&#160; This can be adapted to any biological pathway where a robust read out of reporter activity is available.

siRNA contrôle pour la ubiquitine et les régulateurs du système ubiquitine-comme des voies biologiques dans des cellules de mammifères en culture

Post-translational modification of proteins with ubiquitin and ubiquitin-like molecules (UBLs) is emerging as a dynamic cellular signaling network that ...

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and the inherent instability of many membrane proteins once solubilized in detergents. A protocol is described that combines ligation independent cloning of membrane proteins as GFP fusions with expression in Escherichia coli detected by GFP fluorescence. This enables the construction and expression screening of multiple membrane protein/variants to identify candidates suitable for further investment of time and effort. The GFP reporter is used in a primary screen of expression by visualizing GFP fluorescence following SDS polyacrylamide gel electrophoresis (SDS-PAGE). Membrane proteins that show both a high expression level with minimum degradation as indicated by the absence of free GFP, are selected for a secondary screen. These constructs are scaled and a total membrane fraction prepared and solubilized in four different detergents. Following ultracentrifugation to remove detergent-insoluble material, lysates are analyzed by fluorescence detection size exclusion chromatography (FSEC). Monitoring the size exclusion profile by GFP fluorescence provides information about the mono-dispersity and integrity of the membrane proteins in different detergents. Protein: detergent combinations that elute with a symmetrical peak with little or no free GFP and minimum aggregation are candidates for subsequent purification. Using the above methodology, the heterologous expression in E. coli of SED (shape, elongation, division, and sporulation) proteins from 47 different species of bacteria was analyzed. These proteins typically have ten transmembrane domains and are essential for cell division. The results show that the production of the SEDs orthologues in E. coli was highly variable with respect to the expression levels and integrity of the GFP fusion proteins. The experiment identified a subset for further investigation.

Green Fluorescent Protein-based Expression Screening of Membrane Proteins in Escherichia coli

A streamlined approach to screening for the expression of recombinant membrane proteins in Escherichia coli based on fusion to green fluorescent protein is presented.

Green Fluorescent Protein base Expression dépistage des protéines membranaires dans<em&gt; Escherichia coli</em

The production of recombinant membrane proteins for structural and functional studies remains technically challenging due to low levels of expression and ...

Determining Membrane Protein Topology Using Fluorescence Protease Protection (FPP)

The correct topology and orientation of integral membrane proteins are essential for their proper function, yet such information has not been established for many membrane proteins. A simple technique called fluorescence protease protection (FPP) is presented, which permits the determination of membrane protein topology in living cells. This technique has numerous advantages over other methods for determining protein topology, in that it does not require the availability of multiple antibodies against various domains of the membrane protein, does not require large amounts of protein, and can be performed on living cells. The FPP method employs the spatially confined actions of proteases on the degradation of green fluorescent protein (GFP) tagged membrane proteins to determine their membrane topology and orientation. This simple approach is applicable to a wide variety of cell types, and can be used to determine membrane protein orientation in various subcellular organelles such as the mitochondria, Golgi, endoplasmic reticulum and components of the endosomal/recycling system. Membrane proteins, tagged on either the N-termini or C-termini with a GFP fusion, are expressed in a cell of interest, which is subject to selective permeabilization using the detergent digitonin. Digitonin has the ability to permeabilize the plasma membrane, while leaving intracellular organelles intact. GFP moieties exposed to the cytosol can be selectively degraded through the application of protease, whereas GFP moieties present in the lumen of organelles are protected from the protease and remain intact. The FPP assay is straightforward, and results can be obtained rapidly.

Determining Membrane Protein Topology Using Fluorescence Protease Protection FPP

Here, we present a protocol to determine the orientation and topology of integral membrane proteins in living cells. This simple protocol relies on selective protease sensitivity of chimeras between the protein of interest and GFP.

Détermination Membrane Protein topologie utilisant la fluorescence protection protéase (FPP)

The correct topology and orientation of integral membrane proteins are essential for their proper function, yet such information has not been established ...