Noi riconosciamo con gratitudine il supporto tecnico di Sini Miettinen, Minna Pollanen e Taru Rautavesi. Ringraziamo Helka Nurkkala per la fornitura di cellule HEK 293 esprimenti twin-Strep-tag GFP e Pekka Evijärvi per la fornitura di apparecchi registrazione suono. Questo lavoro è stato finanziato dall&#39;Accademia di Finlandia, concedere numeri 138.329, 134.684 e 258.978.

1. Cross-linking di Strep-Tactin Polimetacrilato resina con Bis (Sulfosuccinimidil) suberato (BS3) <ol><li> Equilibrare una provetta sigillata contenente 2 mg di BS3 reticolante a temperatura ambiente. ATTENZIONE: BS3 è una sostanza pericolosa. Indossare guanti e occhiali protettivi. </li><li> Risospendere Strep-Tactin resina di polimetacrilato (sospensione al 50% in 100 mM Tris-HCl, pH 8,0, 1 mM EDTA, 150 mM NaCl) di breve vigorosa agitazione e trasferire immediatamente 600 ml di sospensione ad una colonna di spin con un puntale con l&#39; end tagliata. </li><li> Centrifugare a 1500 xg per 30 secondi a temperatura ambiente. Scartare il flow-through e aggiungere 450 ml di tampone fosfato salino (PBS) alla colonna. </li><li> Ripetere il passaggio precedente 2 più volte per sostituire completamente tampone Tris con PBS e lasciare la resina in 430 ml di PBS a pH 8,0 dopo l&#39;ultima centrifugazione. </li><li> Forare il foglio della provetta con BS3 con un puntale contenente 1001; l di acqua ultrapura. Sciogliere la polvere BS3 in acqua pipettando gentilmente su e giù e immediatamente aggiungere 20 ml di soluzione alla colonna di spin. La concentrazione finale di BS3 nella reazione di reticolazione è ~ 1,2 mM. </li><li> Ruotare la colonna per 30 minuti a temperatura ambiente. Verificare che la resina viene miscelata correttamente con la soluzione BS3. </li><li> Per spegnere la reazione, aggiungere 6 ml di 3M Tris-HCl, pH 7.5 e ruotare la colonna per altri 15 minuti a temperatura ambiente. </li><li> Centrifugare a 1500 xg per 30 secondi a temperatura ambiente. Gettare il flow-through e risospendere la resina reticolata in 450 ml di soluzione salina tamponata Tris con Tween 20 (TBST). Ripetere la centrifugazione e lavare i passaggi altre due volte. Nell&#39;ultima fase, risospendere la resina in 450 ml di TBS. </li><li> Trasferire la sospensione di resina in una nuova provetta utilizzando una punta di pipetta con l&#39;estremità tagliata. Risospendere la resina nella colonna a sinistra con altri 450 ml di TBS e trasferimento al tubo stesso. Ripetere the ultimo passo nuovamente al massimo il trasferimento della resina dalla colonna al tubo. </li><li> Lasciare riposare la provetta per 10 minuti a temperatura ambiente e regolare il volume a 600 ml rimuovendo l&#39;eccesso di TBS. La resina è pronta per l&#39;uso immediato (raccomandato) o può essere conservato a 4 ° C, senza congelare. </li></ol> 2. Legame della proteina Bait Twin-Strep-tag e associate Complessi al Cross-linked Strep-Tactin Polimetacrilato Resina <ol><li> Centrifugare 1 ml del campione proteina esca in tampone di legame a 17.000 xg per 10 min a 4 ° C e trasferire il surnatante in una nuova provetta. </li><li> Per minimizzare legame di proteine ​​endogene biotinilati alla resina Strep-Tactin, aggiungere avidina ad una concentrazione finale di 100 pg / ml e ruotare per 15 min a 4 ° C. <ol><li> Se la resina reticolata dal punto 1.10 è stato conservato per un periodo di tempo prolungato a 4 ° C, raccogliere la resina mediante centrifugazione a 400 xg for 1 min a 4 ° C, scartare il surnatante e lavare la resina con 1 ml di TBST. Ripetere la centrifugazione e lavaggio passaggi altre due volte, prima con TBST e poi con TBS. Centrifugare la provetta a 400 xg per 1 min a 4 ° C e regolare al volume originale rimuovendo l&#39;eccesso di TBS. </li></ol></li><li> Risospendere il reticolato resina Strep-Tactin nel vortex. Immediatamente aggiungere 50 microlitri della sospensione resina per il tubo contenente il campione di proteina esca con una punta di pipetta taglio e ruotare per altri 30 min a 4 ° C. </li><li> Durante l&#39;attesa, impostare thermomixer a 55 ° C e preriscaldare 500 microlitri di tampone di eluizione per uso nel passaggio 3.1. </li><li> Centrifugare a 400 xg per 1 min a 4 ° C. Eliminare il supernatante e lavare la resina su un rotatore per 5 minuti a 4 ° C con 1 ml di pre-raffreddata tampone di lavaggio # 1. Ripetere la centrifugazione e lavare passi tre volte. Nell&#39;ultima fase, risospendere la resina in 250 ml di tampone di lavaggio # 2. </li><li> Tr<html> ansfer la sospensione resina per una colonna di spin fresco. Risospendere la resina rimanente nel tubo in altri 250 ml di tampone di lavaggio # 2 e trasferire alla stessa colonna. </li><li> Centrifugare a 400 xg per 3 min a 4 ° C, scartare il flow-through e trasferire la colonna di una fiala delfini naso 2 ml. Procedere immediatamente alla fase di eluizione sotto. </li></ol> 3. Eluizione di specifici complessi proteici <ol><li> Aggiungere 150 ml di tampone di eluizione preriscaldato dal punto 2.4 alla colonna di spin. </li><li> Incubare in thermomixer per 5 minuti a 55 ° C, agitando a 1.400 rpm. </li><li> Centrifugare a 1500 xg per 1 minuto a temperatura ambiente. </li><li> Eliminare la colonna e memorizzare le proteine ​​bersaglio purificate a ≤ -20 ° C. </li></ol><table border="0" cellpadding="0" cellspacing="0" width="598"><tbody><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Tampone fosfato salino (PBS) </td></tr>0 &quot;&gt; <td height="20" style="height:20px;width:299px;"> Na 2 HPO 4 </td><td style="width:299px;"> 10 mM </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> KH 2 PO 4 </td><td style="width:299px;"> 2mM </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaCl </td><td style="width:299px;"> 137 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> KCl </td><td style="width:299px;"> 2.7 mM </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> pH regolato a 7,4 se non diversamente specificato (pH 8.0 nella sezione 1.4) </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Tris soluzione salina tamponata (TBS) </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 7.4 </td><td style="width:299px;"> 50 mM </td></tr><tr height="20"><td hei<html> ght = stile &quot;20&quot; = &quot;height: 20px; width: 299px;&quot;&gt; NaCl </td><td style="width:299px;"> 150 mm </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Tris tamponata salina con Tween 20 (TBST) </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 7.4 </td><td style="width:299px;"> 50 mM </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaCl </td><td style="width:299px;"> 150 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tween 20 </td><td style="width:299px;"> 0,1% (v / v) </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Tampone di legame </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 8.0 </td><td style="width:299px;"> 25 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaCl </td>x &quot;&gt; 550 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaF </td><td style="width:299px;"> 5 mM </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> EDTA </td><td style="width:299px;"> 0,5 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Glicerina </td><td style="width:299px;"> 10% (v / v) </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> PMSF </td><td style="width:299px;"> 0,1 mm </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Lavare tampone # 1 </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 8.0 </td><td style="width:299px;"> 25 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaCl </td><td style="width:299px;"> 500 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaF </<html> td&gt; <td style="width:299px;"> 5 mM </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> EDTA </td><td style="width:299px;"> 0,4 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Igepal CA-630 </td><td style="width:299px;"> 0,2% (v / v) </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Glicerina </td><td style="width:299px;"> 5% (v / v) </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> PMSF </td><td style="width:299px;"> 0,1 mm </td></tr><tr height="20"><td colspan="2" height="20" style="height:20px;width:597px;"> Lavare tampone # 2 </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 8.0 </td><td style="width:299px;"> 25 mm </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> NaCl </td><td style="width:299px;"> 150 mm </td></tr><tr height="20">2 &quot;height =&quot; &quot;style =&quot; 20 height: 20px; width: 597px; &quot;&gt; tampone di eluizione </td></tr><tr height="20"><td height="20" style="height:20px;width:299px;"> Tris-HCl, pH 8.0 </td><td style="width:299px;"> 25 mm </td></tr><tr height="22"><td height="22" style="height:22px;width:299px;"> SDS </td><td style="width:299px;"> 1% (w / v) </td></tr></tbody></table> Tabella 1. Buffer utilizzati nel presente studio.

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Nessun conflitto di interessi dichiarati.

Il protocollo di cui sopra può essere usato per purificare qualsiasi proteina esca twin-Strep-tag di interesse e suoi complessi associati in qualsiasi tampone adatto che non contiene biotina o denaturanti forti. Nella versione attuale del protocollo, vincolante e lavaggio vengono eseguiti in condizioni relativamente restrittive in presenza di elevata sale e detergente non ionico. Anche se questo si traduce in meno sfondo, complessi proteici fragili possono dissociare in queste condizioni. Per conservare tali complessi ...

Negli ultimi anni, la tecnologia Strep-tag è stato ampiamente utilizzato in molti settori della ricerca biomedica, tra cui la proteomica e la biologia strutturale. Questa tecnologia purificazione della proteina, che si basa sulla fusione di proteine ​​ricombinanti ad una breve Strep-tag peptide, è maturata con l&#39;avvento di matrici di affinità che trasportano Strep-Tactin, una variante geneticamente di streptavidina con una migliore capacità di legame peptidico. 1, 2 proteine ​​di fusione contenenti due copie di Strep-tag II, designate twin-Strep-tag o SIII-tag, mostrano una maggiore affinità per le matrici Strep-Tactin di quelli contenenti un solo Strep-tag, garantendo la depurazione più efficiente delle proteine ​​ricombinanti e i loro partner di legame associate. Tuttavia, la maggiore affinità delle proteine ​​twin-Strep-tagged per Strep-Tactin ha anche il suo rovescio della medaglia. Eluizione concorrenziale di tali proteine ​​con eccesso di biotina può essere incompleta, con conseguente riduzione della resa di proteine ​​bersaglio. A mminerale efficiente alternativa è eluizione con SDS, ma porta alla contaminazione del campione indesiderato con Strep-Tactin rilasciato dalla resina, rendendo il test incompatibile con l&#39;analisi proteomica. Questo articolo presenta una tecnica per superare questa limitazione prima stabilizzazione del tetramero resina accoppiata di Strep-Tactin dal chimico cross-linking e quindi utilizzando SDS per eluire le proteine ​​twin-Strep-taggate e dei loro complessi associati dalla risultante resina reticolata. Così, sufficiente resa di proteine ​​può essere realizzata senza contaminazione del campione con Strep-Tactin, consentendo così un&#39;ulteriore analisi mediante spettrometria di massa. Il metodo è adatto per la purificazione di una proteina di fusione ricombinante con un SIII-tag-superficie esposta 3 o twin-Strep-tag (WSHPQFEK sequenza aminoacidica (GGGS) 3 WSHPQFEK e SAWSHPQFEK (GGGS) 2 GGSAWSHPQFEK, rispettivamente). La proteina può essere di origine animale, vegetale o batterica e può essere isolato da entrambi cellulare totalelisato o frazione organello arricchito. Come esempio, si descrive qui la purificazione di una proteina SIII-tag VPG-Pro di Potato virus A (PVA) 4 dalla frazione nucleare di PVA-infettati Nicotiana benthamiana. La frazione nucleare è stato isolato come descritto in precedenza 5, con le seguenti modifiche: cellule non sono state trattate con formaldeide, butirrato di sodio è stato sostituito in tutti i buffer con fluoruro di sodio 5 mM, inibitore della proteasi completo è stato sostituito con PMSF, Triton X-100 in concentrazione estrazione tampone # 2 è stato ridotto al 0,3% (v / v) e il pellet nucleare ottenuto mediante centrifugazione attraverso cuscino di saccarosio (tampone di estrazione # 3) è stato risospeso in 1,45 ml di tampone di legame pre-raffreddata e ruotata per 1,5 ore a 4 ° C. L&#39;estratto nucleare risultante contiene la proteina esca SIII-tag e complessi associati (campione proteina esca) è stato elaborato secondo il protocollo descritto di seguito (vedere paragrafo 2).

<table border="0" cellpadding="0" cellspacing="0" width="606">
	<tbody>
		<tr>
			<td>Bis(sulfosuccinimidyl) suberate (BS3), No-Weigh format, 8 x 2mg</td>
			<td>Pierce/Thermo Scientific</td>
			<td>21585</td>
			<td><a href="http://www.fishersci.com">www.fishersci.com CAUTION: Hazardous substance. Causes serious respiratory, skin and eye irritation. Wear protective gloves and eye protection.</a></td>
		</tr>
		<tr>
			<td>Strep-Tactin MacroPrep resin (50% suspension)</td>
			<td>IBA</td>
			<td>2-1505</td>
			<td><a href="http://www.iba-lifesciences.com/">www.iba-lifesciences.com</a></td>
		</tr>
		<tr>
			<td>Spin-X centrifuge tube filter, cellulose acetate membrane, pore size 0.45 &#956;m, non-sterile</td>
			<td>Costar (Corning)</td>
			<td>8163</td>
			<td><a href="http://www.corning.com/lifesciences/">www.corning.com/lifesciences/</a></td>
		</tr>
		<tr>
			<td>Dolphin-nose tubes</td>
			<td>Costar (Corning)</td>
			<td>3213</td>
			<td><a href="http://www.corning.com/lifesciences/">www.corning.com/lifesciences/</a></td>
		</tr>
		<tr>
			<td>Avidin&#160;</td>
			<td>IBA</td>
			<td>2-0204</td>
			<td><a href="http://www.iba-lifesciences.com/">www.iba-lifesciences.com</a></td>
		</tr>
	</tbody>
</table>

one-step purification of twin-strep-tagged proteins and their complexes on strep-tactin resin cross-linked with bis(sulfosuccinimidyl) suberate (bs3)

Purificazione per affinità di proteine ​​di fusione Strep-targhetta di resine che trasportano una streptavidina allestita (Strep-Tactin) è diventato un metodo ampiamente utilizzato per l&#39;isolamento di complessi proteici in condizioni fisiologiche. Proteine ​​di fusione contenenti due copie di Strep-tag II, designate twin-Strep-tag o SIII-tag, hanno il vantaggio di una maggiore affinità per Strep-Tactin rispetto a quelli che contengono un solo Strep-tag, permettendo così più efficiente purificazione di proteine. Tuttavia, questo vantaggio è compensato dal fatto che eluizione delle proteine ​​twin-Strep-taggate con biotina può essere incompleta, portando a basso recupero di proteine. Il recupero può essere notevolmente migliorata utilizzando denaturazione eluizione con sodio dodecil solfato (SDS), ma questo porta a campionare contaminazione con Strep-Tactin rilasciato dalla resina, rendendo il saggio incompatibile con analisi proteomica valle. Per superare questa limitazione, abbiamo sviluppato un metodo in base al quale tetramero resina accoppiata di Strep-Tactinè prima stabilizzato da covalente reticolazione con Bis (Sulfosuccinimidil) suberato (BS3) e la resina reticolata risultante viene poi utilizzato per purificare bersaglio complessi proteici in un singolo passaggio di purificazione batch. Eluizione efficiente con SDS assicura buon recupero proteina, mentre l&#39;assenza di contaminazione Strep-Tactin permette valle proteina analisi mediante spettrometria di massa. Come un proof of concept, descriviamo qui un protocollo per la purificazione della proteina virale SIII-tagged VPG-Pro da nuclei di N. infettato da virus piante benthamiana utilizzando la resina di polimetacrilato Strep-Tactin reticolato con BS3. Lo stesso protocollo può essere utilizzato per purificare qualsiasi proteina twin-Strep-tag di interesse e caratterizzare suoi partner di legame fisiologiche.

La procedura di purificazione è schematicamente illustrato in Figura 1, con una rappresentazione di problemi associati con altri metodi di purificazione esistenti. <img alt="Figura 1" fo:content-width="5.5in" src="/files/ftp_upload/51536/51536fig1highres.jpg" width="650" /> Figura 1. Rappresentazione schematica della procedura di purificazione. Il flusso di lavoro comprende stabilizzazione della Strep-Tactin tetram...

Watch this Scientific Journal Video about One-step Purification of Twin-Strep-tagged Proteins and Their Complexes on Strep-Tactin Resin Cross-linked With Bissulfosuccinimidyl Suberate BS3 at JoVE.com

One-step Purification of Twin-Strep-tagged Proteins and Their Complexes on Strep-Tactin Resin Cross-linked With Bissulfosuccinimidyl Suberate BS3

Un metodo è descritto per la purificazione efficiente di proteine ​​di fusione twin-Strep-tag e dei loro complessi specifiche in materia di streptavidina modificato (Strep-Tactin) resina covalentemente reticolato con Bis (Sulfosuccinimidil) suberato (BS3). Il metodo ha i vantaggi di velocità veloce, buon recupero proteina bersaglio ed elevata purezza, ed è compatibile con la successiva analisi mediante spettrometria di massa.

One-step purificazione di proteine ​​Twin-Strep-taggate e dei loro complessi su Strep-Tactin resina reticolato con Bis (Sulfosuccinimidil) suberato (BS3)

Affinity purification of Strep-tagged fusion proteins on resins carrying an engineered streptavidin (Strep-Tactin) has become a widely used method for ...

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Research

JoVE Journal

Biology

One-step Purification of Twin-Strep-tagged Proteins and Their Complexes on Strep-Tactin Resin Cross-linked With Bis(sulfosuccinimidyl) Suberate (BS3)

18.6K Views.  University of Helsinki.  Un metodo è descritto per la purificazione efficiente di proteine ​​di fusione twin-Strep-tag e dei loro complessi specifiche in materia di streptavidina modificato (Strep-Tactin) resina covalentemente reticolato con Bis (Sulfosuccinimidil) suberato (BS3). Il metodo ha i vantaggi di velocità veloce, buon recupero proteina bersaglio ed elevata purezza, ed è compatibile con la successiva analisi mediante spettrometria di massa. 

Video: One-step Purification of Twin-Strep-tagged Proteins and Their Complexes on Strep-Tactin Resin Cross-linked With Bissulfosuccinimidyl Suberate BS3

Purification and Visualization of Influenza A Viral Ribonucleoprotein Complexes

The influenza A viral genome consists of eight negative-sense, single stranded RNA molecules, individually packed with multiple copies of the influenza A nucleoprotein (NP) into viral ribonulceoprotein particles (vRNPs). The influenza vRNPs are enclosed within the viral envelope. During cell entry, however, these vRNP complexes are released into the cytoplasm, where they gain access to the host nuclear transport machinery. In order to study the nuclear import of influenza vRNPs and the replication of the influenza genome, it is useful to work with isolated vRNPs so that other components of the virus do not interfere with these processes. Here, we describe a procedure to purify these vRNPs from the influenza A virus. The procedure starts with the disruption of the influenza A virion with detergents in order to release the vRNP complexes from the enveloped virion. The vRNPs are then separated from the other components of the influenza A virion on a 33-70% discontinuous glycerol gradient by velocity sedimentation. The fractions obtained from the glycerol gradient are then analyzed on via SDS-PAGE after staining with Coomassie blue. The peak fractions containing NP are then pooled together and concentrated by centrifugation. After concentration, the integrity of the vRNPs is verified by visualization of the vRNPs by transmission electron microscopy after negative staining. The glycerol gradient purification is a modification of that from Kemler et al. (1994)1, and the negative staining has been performed by Wu et al. (2007).2

The genome of the influenza A virus consists of eight separate complexes of RNA and proteins, termed viral ribonucleoprotein complexes (vRNPs). This paper describes the glycerol gradient purification and transmission electron microscopy visualization of influenza A vRNPs.

Purificazione e visualizzazione di influenza A Complessi Ribonucleoproteina virale

The influenza A viral genome consists of eight negative-sense, single stranded RNA molecules, individually packed with multiple copies of the influenza A ...

Ricerca

Biologia

Identification of protein complexes with quantitative proteomics in S. cerevisiae

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as important intracellular signalling molecules. However, unlike proteins, lipids are small hydrophobic molecules that traffic primarily by poorly described nonvesicular routes, which are hypothesized to occur at membrane contact sites (MCSs). MCSs are regions where the endoplasmic reticulum (ER) makes direct physical contact with a partnering organelle, e.g., plasma membrane (PM). The ER portion of ER-PM MCSs is enriched in lipid-synthesizing enzymes, suggesting that lipid synthesis is directed to these sites and implying that MCSs are important for lipid traffic. Yeast is an ideal model to study ER-PM MCSs because of their abundance, with over 1000 contacts per cell, and their conserved nature in all eukaryotes. Uncovering the proteins that constitute MCSs is critical to understanding how lipids traffic is accomplished in cells, and how they act as signaling molecules. We have found that an ER called Scs2p localize to ER-PM MCSs and is important for their formation. We are focused on uncovering the molecular partners of Scs2p. Identification of protein complexes traditionally relies on first resolving purified protein samples by gel electrophoresis, followed by in-gel digestion of protein bands and analysis of peptides by mass spectrometry. This often limits the study to a small subset of proteins. Also, protein complexes are exposed to denaturing or non-physiological conditions during the procedure. To circumvent these problems, we have implemented a large-scale quantitative proteomics technique to extract unbiased and quantified data. We use stable isotope labeling with amino acids in cell culture (SILAC) to incorporate staple isotope nuclei in proteins in an untagged control strain. Equal volumes of tagged culture and untagged, SILAC-labeled culture are mixed together and lysed by grinding in liquid nitrogen. We then carry out an affinity purification procedure to pull down protein complexes. Finally, we precipitate the protein sample, which is ready for analysis by high-performance liquid chromatography/ tandem mass spectrometry. Most importantly, proteins in the control strain are labeled by the heavy isotope and will produce a mass/ charge shift that can be quantified against the unlabeled proteins in the bait strain. Therefore, contaminants, or unspecific binding can be easily eliminated. By using this approach, we have identified several novel proteins that localize to ER-PM MCSs. Here we present a detailed description of our approach. 

Here we describe a new quantitative proteomics technique for identifying protein complexes in Saccharomyces cerevisiae. In this study, we have used the SILAC method together with affinity purification followed by tandem mass spectrometry to identify with high specificity the binding partners of an ER protein, Scs2p.

L&#39;identificazione di complessi proteici con la proteomica quantitativa in S. cerevisiae

Lipids are the building blocks of cellular membranes that function as barriers and in compartmentalization of cellular processes, and recently, as ...

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.

La colorazione delle proteine ​​in gel con Coomassie G-250, senza solventi organici acido acetico e

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

Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System 

Understanding the roles of human DNA repair proteins in genetic pathways is a formidable challenge to many researchers. Genetic studies in mammalian systems have been limited due to the lack of readily available tools including defined mutant genetic cell lines, regulatory expression systems, and appropriate selectable markers. To circumvent these difficulties, model genetic systems in lower eukaryotes have become an attractive choice for the study of functionally conserved DNA repair proteins and pathways. We have developed a model yeast system to study the poorly defined genetic functions of the Werner syndrome helicase-nuclease (WRN) in nucleic acid metabolism. Cellular phenotypes associated with defined genetic mutant backgrounds can be investigated to clarify the cellular and molecular functions of WRN through its catalytic activities and protein interactions. The human WRN gene and associated variants, cloned into DNA plasmids for expression in yeast, can be placed under the control of a regulatory plasmid element. The expression construct can then be transformed into the appropriate yeast mutant background, and genetic function assayed by a variety of methodologies. Using this approach, we determined that WRN, like its related RecQ family members BLM and Sgs1, operates in a Top3-dependent pathway that is likely to be important for genomic stability. This is described in our recent publication [1] at <a href="http://www.impactaging.com">www.impactaging.com</a>. Detailed methods of specific assays for genetic complementation studies in yeast are provided in this paper.

Genetic Studies of Human DNA Repair Proteins Using Yeast as a Model System

Genetic studies in yeast can be employed to investigate the molecular and cellular functions of human genes in cellular DNA metabolism. Methods are described for the genetic characterization of the human WRN gene product defective in the premature aging disorder Werner syndrome in functionally conserved pathways using yeast as a tractable model system.

Studi genetici di proteine ​​umane di riparazione del DNA Utilizzando lievito come sistema modello

Understanding the roles of human DNA repair proteins in genetic pathways is a formidable challenge to many researchers.  Genetic studies in mammalian ...

One-step Metabolomics: Carbohydrates, Organic and Amino Acids Quantified in a Single Procedure

Every infant born in the US is now screened for up to 42 rare genetic disorders called "inborn errors of metabolism". The screening method is based on tandem mass spectrometry and quantifies acylcarnitines as a screen for organic acidemias and also measures amino acids. All states also perform enzymatic testing for carbohydrate disorders such as galactosemia. Because the results can be non-specific, follow-up testing of positive results is required using a more definitive method. The present report describes the "urease" method of sample preparation for inborn error screening. Crystalline urease enzyme is used to remove urea from body fluids which permits most other water-soluble metabolites to be dehydrated and derivatized for gas chromatography in a single procedure. Dehydration by evaporation in a nitrogen stream is facilitated by adding acetonitrile and methylene chloride. Then, trimethylsilylation takes place in the presence of a unique catalyst, triethylammonium trifluoroacetate. Automated injection and chromatography is followed by macro-driven custom quantification of 192 metabolites and semi-quantification of every major component using specialized libraries of mass spectra of TMS derivatized biological compounds. The analysis may be performed on the widely-used Chemstation platform using the macros and libraries available from the author. In our laboratory, over 16,000 patient samples have been analyzed using the method with a diagnostic yield of about 17%--that is, 17% of the samples results reveal findings that should be acted upon by the ordering physician. Included in these are over 180 confirmed inborn errors, of which about 38% could not have been diagnosed using previous methods.

The urease method of sample preparation for GC/MS analysis of intermediary metabolites is presented by its inventor. The method allows one-step follow-up of newborn screening for inborn errors by tandem mass spectrometry by quantifying carbohydrates, organic and amino acids all in a single process.

One-step Metabolomica: carboidrati, acidi organici e aminoacidi quantificati in una procedura unica

Every infant born in the US is now screened for up to 42 rare genetic disorders called "inborn errors of metabolism". The screening method is based on ...

Preparation, Purification, and Characterization of Lanthanide Complexes for Use as Contrast Agents for Magnetic Resonance Imaging

Polyaminopolycarboxylate-based ligands are commonly used to chelate lanthanide ions, and the resulting complexes are 
useful as contrast agents for magnetic resonance imaging (MRI). Many commercially available ligands are especially useful because they contain 
functional groups that allow for fast, high-purity, and high-yielding conjugation to macromolecules and biomolecules via amine-reactive 
activated esters and isothiocyanate groups or thiol-reactive maleimides. While metalation of these ligands is considered common 
knowledge in the field of bioconjugation chemistry, subtle differences in metalation procedures must be taken into account when 
selecting metal starting materials. Furthermore, multiple options for purification and characterization exist, and selection of the most 
effective procedure partially depends on the selection of starting materials. These subtle differences are often neglected in published 
protocols. Here, our goal is to demonstrate common methods for metalation, purification, and characterization of lanthanide complexes 
that can be used as contrast agents for MRI (Figure 1). We expect that this publication will enable biomedical scientists to incorporate 
lanthanide complexation reactions into their repertoire of commonly used reactions by easing the selection of starting materials and 
purification methods.

We demonstrate the metalation, purification, and characterization of lanthanide complexes. The complexes described here can be conjugated to macromolecules to enable tracking of these molecules using magnetic resonance imaging.

Preparazione, purificazione e caratterizzazione di complessi lantanidi per l&#39;uso di agenti di contrasto per Risonanza Magnetica

Polyaminopolycarboxylate-based ligands are commonly used to chelate lanthanide ions, and the resulting complexes are 
useful as contrast agents for ...

Identification of Protein Complexes in Escherichia coli using Sequential Peptide Affinity Purification in Combination with Tandem Mass Spectrometry

Since most cellular processes are mediated by macromolecular assemblies, the systematic identification of protein-protein interactions (PPI) and the identification of the subunit composition of multi-protein complexes can provide insight into gene function and enhance understanding of biological systems1, 2. Physical interactions can be mapped with high confidence vialarge-scale isolation and characterization of endogenous protein complexes under near-physiological conditions based on affinity purification of chromosomally-tagged proteins in combination with mass spectrometry (APMS). This approach has been successfully applied in evolutionarily diverse organisms, including yeast, flies, worms, mammalian cells, and bacteria1-6. In particular, we have generated a carboxy-terminal Sequential Peptide Affinity (SPA) dual tagging system for affinity-purifying native protein complexes from cultured gram-negative Escherichia coli, using genetically-tractable host laboratory strains that are well-suited for genome-wide investigations of the fundamental biology and conserved processes of prokaryotes1, 2, 7. Our SPA-tagging system is analogous to the tandem affinity purification method developed originally for yeast8, 9, and consists of a calmodulin binding peptide (CBP) followed by the cleavage site for the highly specific tobacco etch virus (TEV) protease and three copies of the FLAG epitope (3X FLAG), allowing for two consecutive rounds of affinity enrichment. After cassette amplification, sequence-specific linear PCR products encoding the SPA-tag and a selectable marker are integrated and expressed in frame as carboxy-terminal fusions in a DY330 background that is induced to transiently express a highly efficient heterologous bacteriophage lambda recombination system10. Subsequent dual-step purification using calmodulin and anti-FLAG affinity beads enables the highly selective and efficient recovery of even low abundance protein complexes from large-scale cultures. Tandem mass spectrometry is then used to identify the stably co-purifying proteins with high sensitivity (low nanogram detection limits).
Here, we describe detailed step-by-step procedures we commonly use for systematic protein tagging, purification and mass spectrometry-based analysis of soluble protein complexes from E. coli, which can be scaled up and potentially tailored to other bacterial species, including certain opportunistic pathogens that are amenable to recombineering. The resulting physical interactions can often reveal interesting unexpected components and connections suggesting novel mechanistic links. Integration of the PPI data with alternate molecular association data such as genetic (gene-gene) interactions and genomic-context (GC) predictions can facilitate elucidation of the global molecular organization of multi-protein complexes within biological pathways. The networks generated for E. coli can be used to gain insight into the functional architecture of orthologous gene products in other microbes for which functional annotations are currently lacking.

Identification of Protein Complexes in Escherichia coli using Sequential Peptide Affinity Purification in Combination with Tandem Mass Spectrometry

Affinity purification of tagged proteins in combination with mass spectrometry (APMS) is a powerful method for the systematic mapping of protein interaction networks and for investigating the mechanistic basis of biological processes. Here, we describe an optimized sequential peptide affinity (SPA) APMS procedure developed for the bacterium Escherichia coli that can be used to isolate and characterize stable multi-protein complexes to near homogeneity even starting from low copy numbers per cell.

Identificazione di complessi proteici in<em&gt; Escherichia coli</em&gt; Con sequenziale purificazione per affinità Peptide in combinazione con Tandem Mass Spectrometry

Since most cellular processes are mediated by macromolecular assemblies, the systematic identification of protein-protein interactions (PPI) and the ...

Formulations for Freeze-drying of Bacteria and Their Influence on Cell Survival

Cellular water can be removed to reversibly inactivate microorganisms to facilitate storage. One such method of removal is freeze-drying, which is considered a gentle dehydration method. To facilitate cell survival during drying, the cells are often formulated beforehand. The formulation forms a matrix that embeds the cells and protects them from various harmful stresses imposed on the cells during freezing and drying. We present here a general method to evaluate the survival rate of cells after freeze-drying and we illustrate it by comparing the results obtained with four different formulations: the disaccharide sucrose, the sucrose derived polymer Ficoll PM400, and the respective polysaccharides hydroxyethyl cellulose (HEC) and hydroxypropyl methyl cellulose (HPMC), on two strains of bacteria, P. putida KT2440 and A. chlorophenolicus A6. In this work we illustrate how to prepare formulations for freeze-drying and how to investigate the mechanisms of cell survival after rehydration by characterizing the formulation using of differential scanning calorimetry (DSC), surface tension measurements, X-ray analysis, and electron microscopy and relating those data to survival rates. The polymers were chosen to get a monomeric structure of the respective polysaccharide resembling sucrose to a varying degrees. Using this method setup we showed that polymers can support cell survival as effectively as disaccharides if certain physical properties of the formulation are controlled1.

Freeze-drying is often an easy and convenient way to obtain dry products of viable bacterial cells. An issue of the process is cell survival. We detail here a procedure to investigate how cell survival during freeze-drying is influenced by the properties of the formulation used.

Formulazioni per la liofilizzazione di batteri e la loro influenza sulla sopravvivenza cellulare

Cellular water can be removed to reversibly inactivate microorganisms to facilitate storage. One such method of removal is freeze-drying, which is ...

High-throughput Purification of Affinity-tagged Recombinant Proteins

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further biochemical analyses to obtain detailed insights into structure/function relationships. Advances in oligonucleotide- and gene synthesis technology make large-scale mutagenesis strategies increasingly feasible, including the substitution of target residues by all 19 other amino acids. Gain- or loss-of-function phenotypes then allow systematic conclusions to be drawn, such as the contribution of particular residues to catalytic activity, protein stability and/or protein-protein interaction specificity.
In order to attribute the different phenotypes to the nature of the mutation - rather than to fluctuating experimental conditions - it is vital to purify and analyse the proteins in a controlled and reproducible manner. High-throughput strategies and the automation of manual protocols on robotic liquid-handling platforms have created opportunities to perform such complex molecular biological procedures with little human intervention and minimal error rates1-5.
Here, we present a general method for the purification of His-tagged recombinant proteins in a high-throughput manner. In a recent study, we applied this method to a detailed structure-function investigation of TFIIB, a component of the basal transcription machinery. TFIIB is indispensable for promoter-directed transcription in vitro and is essential for the recruitment of RNA polymerase into a preinitiation complex6-8. TFIIB contains a flexible linker domain that penetrates the active site cleft of RNA polymerase9-11. This linker domain confers two biochemically quantifiable activities on TFIIB, namely (i) the stimulation of the catalytic activity during the 'abortive' stage of transcript initiation, and (ii) an additional contribution to the specific recruitment of RNA polymerase into the preinitiation complex4,5,12 . We exploited the high-throughput purification method to generate single, double and triple substitution and deletions mutations within the TFIIB linker and to subsequently analyse them in functional assays for their stimulation effect on the catalytic activity of RNA polymerase4. Altogether, we generated, purified and analysed 381 mutants - a task which would have been time-consuming and laborious to perform manually. We produced and assayed the proteins in multiplicates which allowed us to appreciate any experimental variations and gave us a clear idea of the reproducibility of our results.
This method serves as a generic protocol for the purification of His-tagged proteins and has been successfully used to purify other recombinant proteins. It is currently optimised for the purification of 24 proteins but can be adapted to purify up to 96 proteins.

We describe a method for the affinity-tagged purification of recombinant proteins using liquid-handling robotics. This method is generally applicable to the small-scale purification of soluble His-tagged proteins in a high-throughput format.

High-throughput Purificazione di affinità-tagged proteine ​​ricombinanti

X-ray crystallography is the method of choice for obtaining a detailed view of the structure of proteins. Such studies need to be complemented by further ...

Purification of Transcripts and Metabolites from Drosophila Heads

For the last decade, we have tried to understand the molecular and cellular mechanisms of neuronal degeneration using Drosophila as a model organism. Although fruit flies provide obvious experimental advantages, research on neurodegenerative diseases has mostly relied on traditional techniques, including genetic interaction, histology, immunofluorescence, and protein biochemistry. These techniques are effective for mechanistic, hypothesis-driven studies, which lead to a detailed understanding of the role of single genes in well-defined biological problems. However, neurodegenerative diseases are highly complex and affect multiple cellular organelles and processes over time. The advent of new technologies and the omics age provides a unique opportunity to understand the global cellular perturbations underlying complex diseases. Flexible model organisms such as Drosophila are ideal for adapting these new technologies because of their strong annotation and high tractability. One challenge with these small animals, though, is the purification of enough informational molecules (DNA, mRNA, protein, metabolites) from highly relevant tissues such as fly brains. Other challenges consist of collecting large numbers of flies for experimental replicates (critical for statistical robustness) and developing consistent procedures for the purification of high-quality biological material. Here, we describe the procedures for collecting thousands of fly heads and the extraction of transcripts and metabolites to understand how global changes in gene expression and metabolism contribute to neurodegenerative diseases. These procedures are easily scalable and can be applied to the study of proteomic and epigenomic contributions to disease.

Purification of Transcripts and Metabolites from Drosophila Heads

We describe here the procedures for the extraction and purification of mRNA and metabolites from Drosophila heads. We are applying these techniques to better understand the cellular perturbations underlying neuronal degeneration. These methodologies can be easily scaled and adapted for other "omic" projects.

Purificazione di Trascrizioni e metaboliti<em&gt; Drosophila</em&gt; Teste

For the last decade, we have tried to understand the molecular and cellular mechanisms of neuronal degeneration using Drosophila as a model organism. ...

One-step purificazione di proteine ​​Twin-Strep-taggate e dei loro complessi su Strep-Tactin resina reticolato con Bis (Sulfosuccinimidil) suberato (BS3)

One-step purificazione di proteine Twin-Strep-taggate e dei loro complessi su Strep-Tactin resina reticolato con Bis (Sulfosuccinimidil) suberato (BS3)