Questa ricerca è stata sostenuta dal Dipartimento per i Premi Veterans Affairs Award di sviluppo professionale 1IK2BX001701, il premio CTSA UL1TR000445 dal Centro Nazionale per l&#39;Avanzamento delle Scienze Traslazionali, il National Science Foundation Award Numbers 1547757 e 1400969 e NIH concede GM05551. Il suo contenuto è esclusivamente responsabile degli autori e non rappresenta necessariamente una visione ufficiale del Centro Nazionale per l&#39;Avanzamento delle Scienze Traslazionali o degli Istituti Nazionali di Salute.

1. Espressione di S100A12 <ol><li> Trasformare le competenti BL21 DE3 con un plasmide pGEMEX-S100a12 utilizzando un protocollo di scossa termica standard 18 . Aggiungere 1 a 5 μL di plasmide a 50 μL di batteri in un tubo di microcentrifuga sul ghiaccio. Incubare per 20 min. </li><li> Scoppio di calore le cellule a 42 ° C per 30 s. </li><li> Incubare le celle sul ghiaccio per 2 min. </li><li> Aggiungere 500 μL di supporti SOC alle cellule. Incubare a 37 ° C con agitazione a 250 giri / min su un agitatore orbitale per 1 h. </li><li> Piastra 150 μL della reazione di trasformazione sul supporto LB-agar (integrato con 100 μg / mL ampicillina). Incubare per 12-16 h a 37 ° C. </li><li> Scegli una colonia. Inoculare 2 mL di LB (integrato con 100 μg / mL ampicillina). </li><li> Incubare per 4-6 h a 37 ° C su un agitatore orbitale (300 rpm). L&#39;OD 600 dovrebbe leggere tra 1-3 unità di assorbanza. </li><li> Aggiungere 500 μl di coltura d&#39;avviamento a 50 ml di autoinduzione ZYM-5052Cazione media 26 integrata con 100 μg / mL di ampicillina. Per una migliore aerazione e massima espressione, utilizzare un pallone Erlenmeyer confuso da 250 mL. Agitare (300 giri / min) per 24 h, a 37 ° C. </li><li> Trasferire la sospensione batterica in un tubo di centrifuga. Pellet le cellule per centrifugazione (4.000 xg, 10 min) a 4 ° C. </li><li> Decantare il supporto, il campione di registro e memorizzare la pasta cellulare a -80 ° C. Il campione è stabile per anni. </li></ol> 2. Purificazione di S100A12 utilizzando la cromatografia a bassa pressione <ol><li> Riposizionare le cellule in 30 mL di 20 mM Tris, pH 8,0. </li><li> Sonicare la sospensione sul ghiaccio per lire le cellule. Usare ~ 20 W uscita, 5 s su e 5 s fuori ciclo per 5 min. </li><li> Trasferire la soluzione ai tubi centrifughi ad alta velocità. Chiarire il lisato cellulare per centrifugazione, 20.000 xg per 30 minuti a 4 ° C. </li><li> Decantare il surnatante e trasferire in un bicchiere da 100 ml di polipropilene pulito. Raffreddare la soluzione posando il bicchiere sul ghiaccio. Aggiungete un agitatoreR e aggiungere lentamente 11,20 g di solfato di ammonio. Lasciare agire la soluzione su ghiaccio per altri 1 h. Questo creerà una soluzione al 60% di solfato di ammonio e precipita la maggior parte delle proteine ​​endogene di E. coli . S100A12 resterà solubile. </li><li> Centrifugare la soluzione a 4 ° C, 20.000 xg per 20 minuti per far pelliccare la proteina precipitata. </li><li> Decantare il surnatante e trasferire in tubo di dialisi (MWCO 3.500 kDa). Dializzare contro 1 L di 20 mM Tris, pH 8,0 a 4 ° C. Cambiare due volte il buffer di dialisi. Permettono 4 ore tra le modifiche. </li><li> Cianografia cromatica anionica <ol><li> Eseguire la cromatografia su un sistema a bassa pressione. La portata tipica è di 1 mL / min. </li><li> Equilibrare una colonna di Sepharose da 5 ml con 10 mi di 20 mM Tris, pH 8,0. </li><li> Caricare la ~ 40 mL di soluzione S100A12 utilizzando la pompa di campionamento (raccogliere il flusso attraverso). </li><li> Lavare la colonna con 10 ml di 20 mM Tris, pH 8. </li><li> Sviluppare la colonna con una gradiente 0-30% (BuFfer B è 20 mM Tris, pH 8,0, 1 M NaCl) su 19 volumi di colonna (CV, 95 mL). Raccogliere 5 ml di frazioni. </li><li> Prendere un&#39; aliquota di 10 μl di ciascuna frazione e analizzare utilizzando MES SDS PAGE con la colorazione di Coomassie. Eseguire il gel con tensione costante (20 V / cm) per 30 min. </li><li> Frazioni di pool contenenti S100A12. S100A12 funziona a ~ 10 kDa proteina su un gel di denaturazione. </li><li> Frazioni concentrate a 5 mL utilizzando un dispositivo di ultrasuono (MWCO 10 kDa). Centrifugare a 3.000 xg per ~ 8 min. Prendi la frazione superiore. </li></ol></li><li> Cromatografia di esclusione di dimensioni <ol><li> Equilibrare la colonna S75 con 1 CV (120 mL) di 20 mM Tris pH 8, 100 mM NaCl. </li><li> Iniettare &lt;5 mL di frazioni concentrate S100A12 (dalla cromatografia di scambio ionico). </li><li> Sviluppare la colonna con una portata di 1 mL / m su 120 mL. Raccogliere 5 ml di frazioni. </li><li> Prendere un&#39; aliquota di 10 μl di ciascuna frazione e analizzare usando SDS PAGE con la colorazione di Coomassie. Convalida l&#39;identità di proteine ​​utilizzandoWestern blot o spettrometria di massa (massa molecolare calcolata di subunità monomerica 10.575.0 Da, misurata 10575.4 Da). </li></ol></li><li> Frazioni di pool <ol><li> Misurare l&#39;assorbanza della proteina A 280 utilizzando uno spettrofotometro. Utilizzare il buffer SEC come un vuoto. Il coefficiente di estinzione calcolato per l&#39;omodimero S100A12 è di 5960 M -1 cm -1 . NOTA: Le rese tipiche sono 35-45 mg di S100A12 per 50 ml di coltura. </li><li> Aliquot S100A12 in 1,5 mL di microcentrifuga (1 mg / tubo), congelare in azoto liquido e conservare a -80 ° C. </li></ol></li></ol> 3. Analisi di attività antimicrobiche <ol><li> Streak H. pylori ceppo G27 su piatti triplici di agar di soia integrati con 5% di sangue di pecora (piastre agarico di sangue). Crescere 2-3 giorni a 37 ° C in aria ambiente integrata con 5% di anidride carbonica. </li><li> Inoculare H. pylori nel brodo Brucella integrato con 1x colesterolo. Cultura oltreScuotendo la notte (250 rpm) a 37 ° C in aria ambiente integrata con 5% di anidride carbonica. </li><li> Diluire H. pylori 1:10 in brodo Brucella al 50%, 50% tampone di calprotectina più 1x colesterolo e coltura in mezzo solo o integrato con 100 μM cloruro di zinco più 0, 100 o 1.000 μg / mL di S100A12 purificato. La cultura si scuota durante la notte (250 rpm) a 37 ° C in aria ambiente integrata con il 5% di anidride carbonica. </li><li> Il giorno successivo, eseguire le diluizioni e la piastra seriali sulle piastre di agar sangue. Lasciare colonie batteriche a crescere per 2-3 giorni a 37 ° C in aria ambiente integrata con 5% di anidride carbonica. Enumerare le unità formanti colonia per calcolare la crescita batterica in presenza o in assenza di S100A12 e / o di zinco esogeno. </li></ol>

<ol>
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Gli autori dichiarano di non avere interessi finanziari concorrenti.

Viene presentato un protocollo efficiente sia per l&#39;espressione che per la purificazione dell&#39;uomo S100A12. Il sistema di espressione E. coli è lo strumento più comune per la produzione di proteine ​​ricombinanti, in particolare quando sono necessari quantitativi di mg per studi biochimici e biofisici. Un valorizzazione chiave della procedura qui descritta è l&#39;uso di mezzi autoinduttivi 26 che aumentano la resa della proteina purificata di un fattore di quasi trenta ri...

Le proteine ​​S100 sono una classe della famiglia EF di proteine ​​legate al calcio con una varietà di funzioni 1 . Essi vengono espressi in maniera specifica per tessuti e cellule e regolano un ampio spettro di funzioni cellulari 2 , 3 . Uniche alle proteine ​​legate al calcio, le proteine ​​S100 presentano sia funzioni intracellulari che extracellulari 4 , 5 . All&#39;interno della cellula, il legame Ca 2+ induce un cambiamento conformazionale che espone una superficie idrofobica che specifica targeting partner legati alla proteina 6 . Questo meccanismo intracellulare regola processi importanti come la proliferazione cellulare, la differenziazione e il metabolismo energetico. Nell&#39;ambiente extracellulare, le proteine ​​S100 presentano due funzioni 7 . In uno, agiscono come proteine ​​del modello molecolare associate a danni (DAMP) e iniziano un pro-inflammRisposta immunitaria atorica attraverso l&#39;interazione con i recettori di riconoscimento del pattern 8 , 9 . Inoltre, diversi membri dei metalli di transizione sequenziali delle proteine ​​S100, una funzione che serve a morire di fame gli agenti patogeni microbiali in un processo chiamato immunità nutrizionale 10 , 11 . S100A12 (noto anche come calgranulina C e EN-RAGE) è altamente espresso in macrofagi e neutrofili ed è stato identificato come potenziale biomarker per le malattie infiammatorie 12 , 13 . Oltre a legare il calcio nei suoi siti EF-Hand, S100A12 presenta due siti di rilascio di metallo di transizione ad alta affinità situati alle estremità opposte dell&#39;interfaccia dimerica 14 , 15 . Ogni sito di legame è costituito da tre residui di istidina e un residuo di acido aspartico e può chelare zinco o rameSup class = &quot;xref&quot;&gt; 16 , 17 . Recentemente, abbiamo riportato che la fame di zinco dipendente da S100A12 è importante per la regolazione della crescita di Helicobacter pylori e l&#39;attività dei fattori di virulenza pro-infiammatoria 18 . H. pylori infetta lo stomaco di circa la metà della popolazione umana del mondo; Rendendo probabilmente uno dei patogeni batterici più riusciti 19 . L&#39;infezione con H. pylori può portare a risultati significativi della malattia gastrica, tra cui gastrite, ulcera peptica e duodenale, linfoma associato a linfoma associata alla mucosa (MALT) e adenocarcinoma gastrico invasivo (tumore dello stomaco). Il cancro allo stomaco è la causa principale della morte associata a cancro non cardiaca nel mondo e il più grande fattore di rischio associato per il cancro allo stomaco è l&#39;infezione da H. pylori . H. pylori persiste nella nicchia gastrica nonostante un robuSt rispondendo alla risposta immunitaria al patogeno sottolineando la necessità di una migliore comprensione dei meccanismi immunitari di controllo di questa infezione batterica 20 , 21 , 22 , 23 . L&#39; infiammazione associata a H. pylori è caratterizzata da una profonda infiltrazione di cellule polimorfonucleari, o neutrofili, che depositano un repertorio di proteine ​​antimicrobiche, tra cui S100A12, nel sito dell&#39;infezione 18 , 24 , 25 . Nel tentativo di comprendere il complesso dialogo tra host e agenti patogeni, abbiamo cercato di perfezionare la tecnica per purificare S100A12 e utilizzarlo per studiare l&#39;effetto antimicrobico che esercita su questo patogeno medico rilevante. Il protocollo sottostante descrive una tecnica migliorata per la purificazione del S100A12 nel suo stato biologicamente attivo; Capace di legare metalli nutrienti ad alta affiniChe li ha allontanati dai microrganismi invasori. Inoltre, i metodi sottostanti evidenziano l&#39;utilità di questa proteina come reagente critico per studiare il meccanismo in base alle quali le innate molecole antimicrobiche restringono la crescita di patogeni batterici. Le proteine ​​della famiglia S100A hanno guadagnato l&#39;apprezzamento come un importante gruppo di molecole innate del sistema immunitario che partecipano al segnalamento immunitario e alla difesa dell&#39;ospite 27 . Il più ben studiato di questi è la calprotectina (MRP-8/14, calgranulina A / B, S100A8 / A9) 28 , 29 , 30 . La calprotectina è una proteina associata a neutrofili che forma un eterodimero delle sottounità S100A8 e S100A9 che lega i metalli di transizione all&#39;interfaccia dimerica 31 . La calprotectina ha dimostrato di possedere due siti di legame metallico: il sito 1 può legare Zn 2+ , Mn 2+ o Fe 2+ e il sito 2 può<html> Lega Zn 2+ 31 , 32 . Numerose relazioni hanno dimostrato che la calprotectina ha attività antimicrobiche contro diversi agenti patogeni tra cui Staphylococcus aureus , Candida albicans , Acinetobacter baumannii , Klebsiella pneumoniae , Escherichia coli e H. pylori e che gli effetti inibitori sono dovuti all&#39;attività di chelazione metallica della calprotectina 25,28 , 29 . Il lavoro precedente ha dimostrato che la calprotectina esercita numerose attività su H. pylori, tra cui alterare la struttura lipidica A nella membrana esterna, reprimendo il sistema di secrezione cag -Type IV (che è un fattore importante della virulenza di proinfiammazione all&#39;interno di H. pylori ), inducendo la formazione del biofilm e reprimendo La crescita e la vitalità di H. pylori in modo dose-dipendenteClass = &quot;xref&quot;&gt; 25 , 33 . Inoltre, i test genetici e biochimici hanno rivelato l&#39;attività antibatterica della calprotectina contro H. pylori è stata in gran parte derivata dalla sua capacità di legare lo zinco nutrizionale 25 . H. pylori richiede lo zinco, come è stato determinato dalla ricerca precedente che ha utilizzato un mezzo chimicamente definito per accertare i requisiti micronutrienti per questo patogeno per crescere e proliferare 34 . Inoltre, la calprotectina era altamente abbondante nei tessuti H. pylori- infettati e associata a infiltrati neutrofili, indicando che l&#39;ospite può impiegare calprotectina come strategia antimicrobica durante l&#39;infezione e successiva infiammazione 25 , 35 . Recenti evidenze da tecniche di screening proteomiche impareggiabili suggeriscono che in condizioni in cui le specie reattive di ossigeno sono abbondanti, calprotecLa stagna subisce modificazioni post-traslazionali che alterano il sito di legame ad esa-istidina, inibendo così l&#39;attività legante del metallo della proteina 36 . Come tale, abbiamo ipotizzato che altre proteine ​​della famiglia S100A tra l&#39;ampio repertorio di queste molecole potrebbero potenzialmente agire come chelatori metallici ausiliari. Abbiamo selezionato S100A12 per ulteriori studi perché non è stato identificato nello schermo di cui sopra per la modifica post-traslatoria, ha la capacità di legare lo zinco ed è altamente abbondante nei tessuti umani derivanti da individui infetti da H. pylori . Il nostro lavoro indica che S100A12 può inibire la crescita e la vitalità di H. pylori in maniera dose-dipendente nel ceppo G27 di H. pylori e che l&#39;attività antimicrobica di questa proteina può essere invertita con l&#39;aggiunta di zinco in eccesso di nutrienti. Questo lavoro completa il nostro precedente lavoro che indica l&#39;attività antimicrobica S100A12 contro PMSS1 e 7.13 ceppi di H. pylori , dimostrando la sua vasta attività antibatterica contro numerosi isolati clinici e ceppi adattati al laboratorio di H. pylori 18 . Insieme, questi risultati confermano l&#39;importanza di S100A12 come meccanismo di controllo della crescita batterica e della proliferazione attraverso l&#39;immunità nutrizionale. Studi futuri di questa importante interazione batterica possono includere lo sfruttamento dell&#39;attività di S100A12 per ridurre il carico batterico nei tessuti dell&#39;host, o determinare il contributo di questa proteina alla segnalazione immunitaria nel contesto dell&#39;infezione da H. pylori .

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>S100A12 Expression</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Expression cells</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>BL 21 (DE3) competent cells</td>
			<td>New England Biolabs</td>
			<td>C25271</td>
		</tr>
		<tr>
			<td>Autoinduction medium components</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Yeast Extract</td>
			<td>Research Products International</td>
			<td>Y20020-250.0</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Research Products International</td>
			<td>S23020-500.0</td>
		</tr>
		<tr>
			<td>Tryptone</td>
			<td>Research Products International</td>
			<td>T60060-250.0</td>
		</tr>
		<tr>
			<td>FeCl3</td>
			<td>Sigma-Aldrich</td>
			<td>F2877</td>
		</tr>
		<tr>
			<td>MgSO4</td>
			<td>Research Products International</td>
			<td>M65240-100.0</td>
		</tr>
		<tr>
			<td>Na2HPO4</td>
			<td>Research Products International</td>
			<td>S23100-500.0</td>
		</tr>
		<tr>
			<td>KH2PO4</td>
			<td>Research Products International</td>
			<td>P41200-500.0</td>
		</tr>
		<tr>
			<td>NH4Cl</td>
			<td>Research Products International</td>
			<td>A20424-500.0</td>
		</tr>
		<tr>
			<td>Na2SO4</td>
			<td>Research Products International</td>
			<td>S25150-500.0</td>
		</tr>
		<tr>
			<td>Glycerol</td>
			<td>Research Products International</td>
			<td>G22020-1.0</td>
		</tr>
		<tr>
			<td>D-glucose</td>
			<td>Research Products International</td>
			<td>G32040-500.0</td>
		</tr>
		<tr>
			<td>lactose</td>
			<td>Sigma-Aldrich</td>
			<td>L2643</td>
		</tr>
		<tr>
			<td>Selection agent</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>ampicillin</td>
			<td>Research Products International</td>
			<td>A40040-5.0</td>
		</tr>
		<tr>
			<td>S100A12 Purification</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>AKTA Start Chromatography System</td>
			<td>GE</td>
			<td>29-220-94</td>
		</tr>
		<tr>
			<td>HiTrap Q Sepharaose Fast Flow</td>
			<td>GE</td>
			<td>17-5156-01</td>
		</tr>
		<tr>
			<td>HiPrep 16/60 S-200 HR</td>
			<td>GE</td>
			<td>17-1166-01</td>
		</tr>
		<tr>
			<td>Nanodrop lite spectrophotometer</td>
			<td>Thermo Fisher Scientific</td>
			<td>ND-LITE</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Research Products International</td>
			<td>T60040-1000.0</td>
		</tr>
		<tr>
			<td>H. pylori Culture</td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>Blood agar plates</td>
			<td>Lab Supply Company</td>
			<td>BBL221261</td>
		</tr>
		<tr>
			<td>Brucella broth</td>
			<td>Sigma-Aldrich</td>
			<td>B3051</td>
		</tr>
		<tr>
			<td>Cholesterol (250X)</td>
			<td>Thermo Fisher Scientific</td>
			<td>12531018</td>
		</tr>
		<tr>
			<td>NaCl</td>
			<td>Sigma-Aldrich</td>
			<td>793566</td>
		</tr>
		<tr>
			<td>CaCl2</td>
			<td>Sigma-Aldrich</td>
			<td>C4901</td>
		</tr>
		<tr>
			<td>&#946;-mercaptoethanol</td>
			<td>Sigma-Aldrich</td>
			<td>M6250</td>
		</tr>
		<tr>
			<td>Tris Base</td>
			<td>Sigma-Aldrich</td>
			<td>T1503</td>
		</tr>
		<tr>
			<td>Zinc Chloride</td>
			<td>Sigma-Aldrich</td>
			<td>229997</td>
		</tr>
	</tbody>
</table>

expression, purification, and antimicrobial activity of s100a12

Le proteine ​​di Calgranulina sono importanti mediatori dell&#39;immunità innata e sono membri della classe S100 della famiglia EF di proteine ​​legate al calcio. Alcune proteine ​​S100 hanno la capacità di legare i metalli di transizione con elevata affinità e di bloccarli in modo efficace dagli invasori di patogeni microbici in un processo chiamato &quot;immunitario nutrizionale&quot;. S100A12 (EN-RAGE) lega sia lo zinco che il rame ed è altamente abbondante nelle cellule immunitarie innate come macrofagi e neutrofili. Riconosciamo un metodo raffinato per l&#39;espressione, l&#39;arricchimento e la purificazione di S100A12 nella sua attiva configurazione metallica. L&#39;utilizzo di questa proteina in analisi della crescita batterica e della vitalità rivela che S100A12 ha un&#39;attività antimicrobica contro il patogeno batterico , Helicobacter pylori . L&#39;attività antimicrobica è basata sull&#39;attività di legame di zinco di S100A12, cheelato lo zinco nutritivo, affamando così H. pylori che richiede zinco per la crescita e proliferation.

S100A12 espressione e purificazione Una depurazione a tre fasi ha prodotto ~ 40 mg di S100A12 ricombinante da 50 ml di coltura batterica. Il primo passo era una precipitazione di solfato di ammonio di proteine ​​endogene di E. coli . Questa fase è stata seguita da una cromatografia di anion-exchange ( figura 1A ). La proteina è tracciata da una SDS-PAGE macchiata con Coomassie Bril...

Watch this Scientific Journal Video about Expression, Purification, and Antimicrobial Activity of S100A12 at JoVE.com

Expression, Purification, and Antimicrobial Activity of S100A12

Qui, presentiamo un metodo per esprimere e purificare S100A12 (calgranulina C). Descriviamo un protocollo per misurare la sua attività antimicrobica contro il patogeno umano H. pylori .

Espressione, purificazione e attività antimicrobica di S100A12

Calgranulin proteins are important mediators of innate immunity and are members of the S100 class of the EF-hand family of calcium binding proteins. Some ...

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8.3K Views.  Fisk University.  Qui, presentiamo un metodo per esprimere e purificare S100A12 (calgranulina C). Descriviamo un protocollo per misurare la sua attività antimicrobica contro il patogeno umano H. pylori . 

Video: Expression, Purification, and Antimicrobial Activity of S100A12

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug used to treat depression and anxiety by binding to the serotonin transporter with high-affinity, blocking serotonin reuptake. Here we report an efficient procedure and a set of tools to stabilize, express, purify, and crystallize serotonin transporter-antibody complexes bound to S-citalopram and other antidepressants. Mutations which stabilize the serotonin transporter were identified using an S-citalopram binding assay. Serotonin transporter expressed in baculovirus-transduced HEK293S GnTI- cells, was reconstituted into proteoliposomes and used to raise high-affinity antibodies. We have developed a strategy to discover antibodies that are useful for structural studies. A straightforward approach for the expression of antibody fragments in Sf9 cells has also been established. Transporter-antibody complexes purified using this procedure are well-behaved and readily crystallize, producing complexes with S-citalopram that diffract X-rays to 3-4 &#197; resolution. The strategies developed here can be utilized to determine the structure of other challenging membrane proteins.

Thermostabilization, Expression, Purification, and Crystallization of the Human Serotonin Transporter Bound to S-citalopram

This manuscript describes how to screen for thermostabilizing mutations, purify the human serotonin transporter, generate high affinity antibodies, and crystallize the serotonin transporter-antibody complex bound to the antidepressant drug S-citalopram. This protocol can be adapted to the study of other challenging membrane transporters, receptors, and channels.

Thermostabilization, Espressione, purificazione e cristallizzazione della umana trasportatore della serotonina associato a<em&gt; S</em&gt; -citalopram

The serotonin transporter is a sodium and chloride-coupled transporter that &#34;pumps&#34; extracellular serotonin into cells. S-citalopram is a drug ...

Ricerca

Biochimica

Expression and Purification of Mammalian Bestrophin Ion Channels

The human genome encodes four bestrophin paralogs, namely BEST1, BEST2, BEST3, and BEST4. BEST1, encoded by the BEST1 gene, is a Ca2+-activated Cl- channel (CaCC) predominantly expressed in retinal pigment epithelium (RPE). The physiological and pathological significance of BEST1 is highlighted by the fact that over 200 distinct mutations in the BEST1 gene have been genetically linked to a spectrum of at least five retinal degenerative disorders, such as Best vitelliform macular dystrophy (Best disease). Therefore, understanding the biophysics of bestrophin channels at the single-molecule level holds tremendous significance. However, obtaining purified mammalian ion channels is often a challenging task. Here, we report a protocol for the expression of mammalian bestrophin proteins with the BacMam baculovirus gene transfer system and their purification by affinity and size-exclusion chromatography. The purified proteins have the potential to be utilized in subsequent functional and structural analyses, such as electrophysiological recording in lipid bilayers and crystallography. Importantly, this pipeline can be adapted to study the functions and structures of other ion channels.

The purification of ion channels is often challenging, but once achieved, it can potentially allow in vitro investigations of the functions and structures of the channels. Here, we describe the stepwise procedures for the expression and purification of mammalian bestrophin proteins, a family of Ca2+-activated Cl- channels.

Espressione e purificazione dei canali ionici di mammiferi Bestrophin

The human genome encodes four bestrophin paralogs, namely BEST1, BEST2, BEST3, and BEST4. BEST1, encoded by the BEST1 gene, is a Ca2+-activated Cl- ...

Caffeine Extraction, Enzymatic Activity and Gene Expression of Caffeine Synthase from Plant Cell Suspensions

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in popular drinks such as coffee and tea. This secondary metabolite is regarded as a chemical defense because it has antimicrobial activity and is considered a natural insecticide. Caffeine can also produce negative allelopathic effects that prevent the growth of surrounding plants. In addition, people around the world consume caffeine for its analgesic and stimulatory effects. Due to interest in the technological applications of caffeine, research on the biosynthetic pathway of this compound has grown. These studies have primarily focused on understanding the biochemical and molecular mechanisms that regulate the biosynthesis of caffeine. In vitro tissue culture has become a useful system for studying this biosynthetic pathway. This article will describe a step-by-step protocol for the quantification of caffeine and for measuring the transcript levels of the gene (CCS1) encoding caffeine synthase (CS) in cell suspensions of C. arabica L. as well as its activity.

This protocol describes an efficient methodology for the extraction and quantification of caffeine in cell suspensions of C. arabica L. and an experimental process for evaluating the enzymatic activity of caffeine synthase with the expression level of the gene that encodes this enzyme.

Estrazione di caffeina, l'attività enzimatica e l'espressione genica della sintasi di caffeina da sospensioni di cellule vegetali

Caffeine (1,3,7-trimethylxanthine) is a purine alkaloid present in popular drinks such as coffee and tea. This secondary metabolite is regarded as a ...

Anaerobic Protein Purification and Kinetic Analysis via Oxygen Electrode for Studying DesB Dioxygenase Activity and Inhibition

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic purification methods. This manuscript illustrates the technical details involved in the anaerobic purification process, including the preparation of buffers and reagents, the methods for column chromatography in a glove box, and the desalting of the protein prior to kinetics. Also described are the methods for preparing and using an oxygen electrode to perform kinetic characterization of an oxygen-utilizing enzyme. These methods are illustrated using the dioxygenase enzyme DesB, a gallate dioxygenase from the bacterium Sphingobium sp. strain SYK-6.

Here we present a protocol for anaerobic protein purification, anaerobic protein concentration, and subsequent kinetic characterization using an oxygen electrode system. The method is illustrated using the enzyme DesB, a dioxygenase enzyme which is more stable and active when purified and stored in an anaerobic environment.

Purificazione della proteina anaerobica e analisi cinetica tramite elettrodo di ossigeno per lo studio di inibizione e attività di Dioxygenase di Giuroma90

Oxygen-sensitive proteins, including those enzymes which utilize oxygen as a substrate, can have reduced stability when purified using traditional aerobic ...

Expression and Purification of the Human Lipid-sensitive Cation Channel TRPC3 for Structural Determination by Single-particle Cryo-electron Microscopy

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium homeostasis, particularly store-operated calcium entry, which is critical to maintaining proper function of synaptic vesicle release and intracellular signaling pathways. Accordingly, TRPC channels have been implicated in a variety of human diseases including cardiovascular disorders such as cardiac hypertrophy, neurodegenerative disorders such as Parkinson&#39;s disease, and neurologic disorders such as spinocerebellar ataxia. Therefore, TRPC channels represent a potential pharmacologic target in human diseases. However, the molecular mechanisms of gating in these channels are still unclear. The difficulty in obtaining large quantities of stable, homogeneous, and purified protein has been a limiting factor in structure determination studies, particularly for mammalian membrane proteins such as the TRPC ion channels. Here, we present a protocol for the large-scale expression of mammalian ion channel membrane proteins using a modified baculovirus gene transfer system and the purification of these proteins by affinity and size-exclusion chromatography. We further present a protocol to collect single-particle cryo-electron microscopy images from purified protein and to use these images to determine the protein structure. Structure determination is a powerful method for understanding the mechanisms of gating and function in ion channels.

This protocol describes techniques used to determine ion channel structures by cryo-electron microscopy, including a baculovirus system used to efficiently express genes in mammalian cells with minimum effort and toxicity, protein extraction, purification, and quality checking, sample grid preparation and screening, as well as data collection and processing.

Espressione e purificazione di TRPC3 la scanalatura del catione del lipido sensibili umani per determinazione strutturale di singola particella cRIO-microscopia elettronica

Transient receptor potential channels (TRPCs) of the canonical TRP subfamily are nonselective cation channels that play an essential role in calcium ...

Expression, Solubilization, and Purification of Eukaryotic Borate Transporters

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also known as Band 3), the most abundant membrane protein in the red blood cells. The SLC4 family is homologous with borate transporters, which have been characterized in plants and fungi. It remains a significant technical challenge to express and purify membrane transport proteins to homogeneity in quantities suitable for&#160;structural or functional studies. Here we describe detailed procedures for the overexpression of borate transporters in Saccharomyces cerevisiae, isolation of yeast membranes, solubilization of protein by detergent, and purification of borate transporter homologs from S. cerevisiae, Arabidopsis thaliana, and Oryza sativa. We also detail a glutaraldehyde cross-linking experiment to assay multimerization of homomeric transporters. Our generalized procedures can be applied to all three proteins and have been optimized for efficacy. Many of the strategies developed here can be utilized for the study of other challenging membrane proteins.

Here we present a protocol to express, solubilize, and purify several eukaryotic borate transporters with homology to the SLC4 transporter family using yeast. We also describe a chemical cross-linking assay to assess the purified homomeric proteins for multimeric assembly. These protocols can be adapted for other challenging membrane proteins.

Espressione, solubilizzazione e purificazione dei trasportatori eucariotiche borato

The Solute Carrier 4 (SLC4) family of proteins is called the bicarbonate transporters and includes the archetypal protein Anion Exchanger 1 (AE1, also ...

Expression and Purification of Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Dioxygenase

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, fluorophores are prone to loss of signal via photobleaching by dissolved oxygen (O2). To prevent photobleaching and extend the fluorophore lifetime, oxygen scavenging systems (OSS) are employed to reduce O2. Commercially available OSS may be contaminated by nucleases that damage or degrade nucleic acids, confounding interpretation of experimental results. Here we detail a protocol for the expression and purification of highly active Pseudomonas putida protocatechuate-3,4-dioxygenase (PCD) with no detectable nuclease contamination. PCD can efficiently remove reactive O2 species by conversion of the substrate protocatechuic acid (PCA) to 3-carboxy-cis,cis-muconic acid. This method can be used in any aqueous system where O2 plays a detrimental role in data acquisition. This method is effective in producing highly active, nuclease free PCD in comparison with commercially available PCD.

Protocatechuate 3,4-dioxygenase (PCD) can enzymatically remove free diatomic oxygen from an aqueous system using its substrate protocatechuic acid (PCA). This protocol describes the expression, purification, and activity analysis of this oxygen scavenging enzyme.

Espressione e purificazione di Nuclease-Free Oxygen Scavenger Protocatechuate 3,4-Diossigenasi

Single molecule (SM) microscopy is used in the study of dynamic molecular interactions of fluorophore labeled biomolecules in real time. However, ...

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

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this superfamily generally display multi-functionality, involving mainly hydrolase and decarboxylase mechanisms. This article presents a series of consecutive methods for the expression and purification of FAHD proteins, mainly FAHD protein 1 (FAHD1) orthologues among species (human, mouse, nematodes, plants, etc.). Covered methods are protein expression in E. coli, affinity chromatography, ion exchange chromatography, preparative and analytical gel filtration, crystallization, X-ray diffraction, and photometric assays. Concentrated protein of high levels of purity (&#62;98%) may be employed for crystallization or antibody production. Proteins of similar or lower quality may be employed in enzyme assays or used as antigens in detection systems (Western-Blot, ELISA). In the discussion of this work, the identified enzymatic mechanisms of FAHD1 are outlined to describe its hydrolase and decarboxylase bi-functionality in more detail.

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

Espressione, purificazione, cristallizzazione e saggi enzimatici di Fumarylacetoacetate Hydrolase Domain-Containing Proteins

Fumarylacetoacetate hydrolase (FAH) domain-containing proteins (FAHD) are identified members of the FAH superfamily in eukaryotes. Enzymes of this ...

PCR Mutagenesis, Cloning, Expression, Fast Protein Purification Protocols and Crystallization of the Wild Type and Mutant Forms of Tryptophan Synthase

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand its catalytic mechanism, allosteric behavior, and details of the enzymatic transformation of substrate to product in PLP-dependent enzymes. In this work, a novel expression system to produce the isolated &#945;- and isolated &#946;-subunit allowed the purification of high amounts of pure subunits and &#945;2&#946;2 StTS complex from the isolated subunits within 2 days. Purification was carried out by affinity chromatography followed by cleavage of the affinity tag, ammonium sulfate precipitation, and size exclusion chromatography (SEC). To better understand the role of key residues at the enzyme &#946;-site, site-direct mutagenesis was performed in prior structural studies. Another protocol was created to purify the wild type and mutant &#945;2&#946;2 StTS complexes. A simple, fast and efficient protocol using ammonium sulfate fractionation and SEC allowed purification of &#945;2&#946;2 StTS complex in a single day. Both purification protocols described in this work have considerable advantages when compared with previous protocols to purify the same complex using PEG 8000 and spermine to crystalize the &#945;2&#946;2 StTS complex along the purification protocol. Crystallization of wild type and some mutant forms occurs under slightly different conditions, impairing the purification of some mutants using PEG 8000 and spermine. To prepare crystals suitable for x-ray crystallographic studies several efforts were made to optimize crystallization, crystal quality and cryoprotection. The methods presented here should be generally applicable for purification of tryptophan synthase subunits and wild type and mutant &#945;2&#946;2 StTS complexes.

This article presents a series of consecutive methods for the expression and purification of Salmonella typhimurium tryptophan synthase comp this protocol a rapid system to purify the protein complex in a day. Covered methods are site-directed mutagenesis, protein expression in Escherichia coli, affinity chromatography, gel filtration chromatography, and crystallization.

Mutagenesi PCR, clonazione, espressione, protocolli di purificazione rapida delle proteine e cristallizzazione del tipo selvatico e delle forme mutanti di triptofano sintasi

Structural studies with tryptophan synthase (TS) bienzyme complex (&#945;2&#946;2 TS) from Salmonella typhimurium have been performed to better understand ...

Ganglioside Extraction, Purification and Profiling

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially abundant in the brain. Expressed primarily on the outer leaflet of the plasma membranes of cells, they modulate the activities of cell surface proteins via lateral association, act as receptors in cell-cell interactions and are targets for pathogens and toxins. Genetic dysregulation of ganglioside biosynthesis in humans results in severe congenital nervous system disorders. Because of their amphipathic nature, extraction, purification, and analysis of gangliosides require techniques that have been optimized by many investigators in the 80 years since their discovery. Here, we describe bench-level methods for the extraction, purification, and preliminary qualitative and quantitative analyses of major gangliosides from tissues and cells that can be completed in a few hours. We also describe methods for larger scale isolation and purification of major ganglioside species from brain. Together, these methods provide analytical and preparative scale access to this class of bioactive molecules.

Gangliosides are sialic acid-bearing glycosphingolipids that are particularly abundant in the brain. Their amphipathic nature requires organic/aqueous extraction and purification techniques to ensure optimal recovery and accurate analyses. This article provides overviews of analytic and preparative scale ganglioside extraction, purification, and thin layer chromatography analysis.

Estrazione, purificazione e profilatura del ganglioside

Gangliosides are glycosphingolipids that contain one or more sialic acid residues. They are found on all vertebrate cells and tissues but are especially ...