This research was supported by the Department of Veterans Affairs Career Development Award 1IK2BX001701, CTSA award UL1TR000445 from the National Center for Advancing Translational Sciences, the National Science Foundation Award Numbers 1547757 and 1400969, and NIH grant GM05551. Its contents are solely the responsibility of the authors and do not necessarily represent official views of the National Center for Advancing Translational Sciences or the National Institutes of Health.

1. Expression of S100A12
<ol>
	<li>Transform competent BL21 DE3 cells with a pGEMEX-S100a12 plasmid using a standard heat shock protocol18. Add 1 to 5 &#181;L of plasmid to 50 &#181;L of bacteria in a microcentrifuge tube on ice. Incubate for 20 min.</li>
	<li>Heat shock the cells at 42 &#176;C for 30 s.</li>
	<li>Incubate the cells on ice for 2 min.</li>
	<li>Add 500 &#181;L of SOC media to the cells. Incubate at 37 &#176;C with shaking at 250 rpm on an orbital shaker for 1 h.</li>
	<li>Plate 150 &#181;L of the transformation reaction on LB-agar medium (supplemented with 100 &#181;g/mL ampicillin). Incubate for 12-16 h at 37 &#176;C.</li>
	<li>Pick one colony. Inoculate 2 mL of LB (supplemented with 100 &#181;g/mL ampicillin).</li>
	<li>Incubate for 4-6 h at 37 &#176;C on an orbital shaker (300 rpm). The OD600 should read between 1-3 absorbance units.</li>
	<li>Add 500 &#181;L of starter culture to 50 mL of ZYM-5052 autoinduction media26 supplemented with 100 &#181;g/mL of ampicillin. For best aeration and maximum expression, use a 250 mL baffled Erlenmeyer flask. Shake (300 rpm) for 24 h, at 37 &#176;C.</li>
	<li>Transfer bacterial suspension to a centrifuge tube. Pellet the cells by centrifugation (4,000 x g, 10 min) at 4 &#176;C.</li>
	<li>Decant the media, log sample, and store cell paste at -80 &#176;C. Sample is stable for years.</li>
</ol>
2. Purification of S100A12 Using Low Pressure Chromatography
<ol>
	<li>Resuspend cells in 30 mL of 20 mM Tris, pH 8.0.</li>
	<li>Sonicate the suspension on ice to lyse cells. Use ~20 W output, 5 s on and 5 s off cycle for 5 min.</li>
	<li>Transfer the solution to high-speed centrifuge tubes. Clarify the cell lysate by centrifugation, 20,000 x g for 30 min at 4 &#176;C.</li>
	<li>Decant the supernatant and transfer to a clean 100 mL polypropylene beaker. Cool the solution by placing the beaker on ice. Add a stir bar and slowly add 11.20 g of ammonium sulfate. Allow the solution to stir on ice for an additional 1 h. This will create a 60% solution of ammonium sulfate and precipitate most of the E. coli endogenous proteins. S100A12 will remain soluble.</li>
	<li>Centrifuge the solution at 4 &#176;C, 20,000 x g for 20 min to pellet the precipitated protein.</li>
	<li>Decant the supernatant and transfer to dialysis tubing (MWCO 3,500 kDa). Dialyze against 1 L of 20 mM Tris, pH 8.0 at 4 &#176;C. Change the dialysis buffer twice. Allow 4 h in between changes.</li>
	<li>Anion exchange chromatography
	<ol>
		<li>Perform chromatography on a low pressure system. Typical flow rate is 1 mL/min.</li>
		<li>Equilibrate a 5 mL Sepharose column with 10 mL of 20 mM Tris, pH 8.0.</li>
		<li>Load the ~40 mL of S100A12 solution using the sample pump (collect the flow through).</li>
		<li>Wash the column with 10 mL of 20 mM Tris, pH 8.</li>
		<li>Develop the column with a 0-30% gradient (Buffer B is 20 mM Tris, pH 8.0, 1 M NaCl) over 19 column volumes (CV, 95 mL). Collect 5 mL fractions.</li>
		<li>Take a 10 &#181;L aliquot of each fraction and analyze using MES SDS PAGE with Coomassie staining. Run gel using constant voltage (20 V/cm) for 30 min.</li>
		<li>Pool fractions containing S100A12. S100A12 runs at ~10 kDa protein on a denaturing gel.</li>
		<li>Concentrate fractions to 5 mL using an ultrafiltration device (MWCO 10 kDa). Centrifuge at 3,000 x g for ~8 min. Take the top fraction.</li>
	</ol>
	</li>
	<li>Size-exclusion chromatography
	<ol>
		<li>Equilibrate S75 column with 1 CV (120 mL) of 20 mM Tris pH 8, 100 mM NaCl.</li>
		<li>Inject &#60; 5 mL of concentrated S100A12 fractions (from the ion exchange chromatography).</li>
		<li>Develop the column at a flow rate of 1 mL/m over 120 mL. Collect 5 mL fractions.</li>
		<li>Take a 10 &#181;L aliquot of each fraction and analyze using SDS PAGE with Coomassie staining. Validate protein identity using western blot or mass spectrometry (calculated molecular mass of monomeric subunit 10,575.0 Da, measured 10575.4 Da).</li>
	</ol>
	</li>
	<li>Pool fractions
	<ol>
		<li>Measure the absorbance of the protein A280 using a spectrophotometer. Use the SEC buffer as a blank. The calculated extinction coefficient for S100A12 homodimer is 5960 M-1 cm-1. 
		NOTE: Typical yields are 35-45 mg of S100A12 per 50 mL of culture.</li>
		<li>Aliquot S100A12 into 1.5 mL microcentrifuge tubes (1 mg/tube), flash freeze in liquid nitrogen and store at -80 &#176;C.</li>
	</ol>
	</li>
</ol>
3. Antimicrobial Activity Assays
<ol>
	<li>Streak H. pylori strain G27 onto tryptic soy agar plates supplemented with 5% sheep blood (blood agar plates). Grow 2-3 days at 37 &#176;C in room air supplemented with 5% carbon dioxide.</li>
	<li>Inoculate H. pylori into Brucella broth supplemented with 1x cholesterol. Culture overnight shaking (250 rpm) at 37 &#176;C in room air supplemented with 5% carbon dioxide.</li>
	<li>Dilute H. pylori 1:10 into 50% Brucella broth, 50% calprotectin buffer plus 1x cholesterol and culture in medium alone or supplemented with 100 &#181;M zinc chloride plus 0, 100 or 1,000 &#181;g/mL of purified S100A12. Culture overnight shaking (250 rpm) at 37 &#176;C in room air supplemented with 5% carbon dioxide.</li>
	<li>The following day, perform serial dilutions and plate onto blood agar plates. Allow bacterial colonies to grow for 2-3 days at 37 &#176;C in room air supplemented with 5% carbon dioxide. Enumerate the colony forming units to calculate bacterial growth in the presence or absence of S100A12 and/or exogenous zinc.</li>
</ol>

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The authors declare that they have no competing financial interests.

An efficient protocol for both expression and purification of human S100A12 is presented. The E. coli expression system is the most common tool used for the production of recombinant proteins, particularly when mg quantities are required for biochemical and biophysical studies. A key enhancement of the procedure described here is the use of auto-induction media26 which increases the yield of purified protein by a factor of almost thirty as compared to expression with standard Luria-broth ...

S100 proteins are a class of the EF-hand family of calcium binding proteins with a diverse array of functions1. They are expressed in a tissue and cell specific manner, and regulate a broad spectrum of cellular functions2,3. Unique to calcium binding proteins, S100 proteins exhibit both intracellular and extracellular functions4,5. Within the cell, Ca2+ binding induces a conformational change that exposes a hydrophobic surface that specifically targets protein binding partners6. This intracellular mechanism regulates important processes such as cell proliferation, differentiation and energy metabolism. In the extracellular milieu, S100 proteins exhibit two functions7. In one, they act as damage associated molecular pattern (DAMP) proteins and initiate a pro-inflammatory immune response through interaction with pattern recognition receptors8,9. Additionally, several members of the S100 protein class sequester transition metals, a function that serves to starve microbial pathogens in a process termed nutritional immunity10,11.
S100A12 (also known as calgranulin C and EN-RAGE) is highly expressed in macrophages and neutrophils and has been identified as a potential biomarker for inflammatory diseases12,13. In addition to binding calcium at its EF-Hand sites, S100A12 has two high affinity transition metal binding sites located at opposite ends of the dimer interface14,15. Each binding site is comprised of three histidine residues and one aspartic acid residue and can chelate zinc or copper16,17. Recently, we reported that S100A12-dependent zinc starvation is important in regulating Helicobacter pylori growth and the activity of pro-inflammatory virulence factors18.
H. pylori infects the stomach of about half of the world&#39;s human population; making it arguably one of the most successful bacterial pathogens19. Infection with H. pylori can lead to significant gastric disease outcomes including gastritis, peptic and duodenal ulcer, mucosa associated lymphoid tissue (MALT) lymphoma, and invasive gastric adenocarcinoma (stomach cancer). Stomach cancer is the leading cause of non-cardia cancer-associated death in the world, and the single biggest associated risk factor for stomach cancer is infection with H. pylori.
H. pylori persists in the gastric niche despite a robust immune response to the pathogen, underscoring the need for a better understanding of immune mechanisms of controlling this bacterial infection20,21,22,23. H. pylori-associated inflammation is characterized by a profound infiltration of polymorphonuclear cells, or neutrophils, which deposit a repertoire of antimicrobial proteins, including S100A12, at the site of infection18,24,25. In an effort to understand the complex dialogue between host and pathogen, we sought to refine the technique to purify S100A12 and use it to study the antimicrobial affect it exerts upon this medically relevant pathogen. The protocol below outlines an improved technique for S100A12 purification in its biologically active state; capable of binding nutrient metals with high affinity and chelating them away from invading microorganisms. Furthermore, the methods below highlight the utility of this protein as a critical reagent to study the mechanism by which innate antimicrobial molecules restrict the growth of bacterial pathogens.
S100A-family proteins have gained appreciation as an important group of innate immune system molecules which participate in immune signaling as well as host defense27. The most well-studied of these is calprotectin (MRP-8/14, calgranulin A/B, S100A8/A9)28,29,30. Calprotectin is a neutrophil-associated protein which forms a heterodimer of the S100A8 and S100A9 subunits which binds transition metals at the dimer interface31. Calprotectin has been shown to possess two metal binding sites: Site 1 can bind Zn2+, Mn2+, or Fe2+, and Site 2 can bind Zn2+ 31,32. Numerous reports have demonstrated that calprotectin has antimicrobial activities against diverse pathogens including Staphylococcus aureus, Candida albicans, Acinetobacter baumannii, Klebsiella pneumoniae, Escherichia coli, and H. pylori, and that the inhibitory effects are due to the metal chelation activity of calprotectin25,28,29.
Previous work demonstrated calprotectin exerts numerous activities on H. pylori including altering the lipid A structure in the outer membrane, repressing the cag-Type IV secretion system (which is a major proinflammatory virulence factor within H. pylori), inducing biofilm formation, and repressing H. pylori growth and viability in a dose-dependent manner25,33. Furthermore, genetic and biochemical assays revealed the antibacterial activity of calprotectin against H. pylori was largely derived from its ability to bind nutrient zinc25. H. pylori requires zinc, as was determined by previous research which utilized a chemically defined medium to ascertain the micronutrient requirements for this pathogen to grow and proliferate34. Additionally, calprotectin was highly abundant within H. pylori-infected tissues, and associated with neutrophilic infiltrates, indicating the host may be employing calprotectin as an antimicrobial strategy during infection and subsequent inflammation25,35.
Recent evidence from unbiased proteomics screening techniques suggests that under conditions where reactive oxygen species are plentiful, calprotectin undergoes post-translational modifications which alter the hexa-histidine binding site, thereby inhibiting the metal-binding activity of the protein36. As such, we hypothesized that other S100A-family proteins among the wide repertoire of these molecules could potentially act as auxiliary metal-chelators. We selected S100A12 for further study because it was not identified in the aforementioned screen for post-translational modification, it has the capacity to bind zinc, and it is highly abundant in human tissues derived from H. pylori-infected individuals.
Our work indicates that S100A12 can inhibit H. pylori growth and viability in a dose-dependent manner in the G27 strain of H. pylori, and that the antimicrobial activity of this protein can be reversed by the addition of excess nutrient zinc. This work complements our previous work indicating S100A12 exerted antimicrobial activity against PMSS1 and 7.13 strains of H. pylori, demonstrating its broad antibacterial activity against numerous clinical isolates and laboratory-adapted strains of H. pylori18. Together, these results confirm the importance of S100A12 as a mechanism to control bacterial growth and proliferation via nutritional immunity. Future studies of this important host-bacterial interaction could include exploiting the activity of S100A12 to reduce bacterial burden within host tissues, or determining the contribution of this protein to immune signaling in the context of H. pylori infection.

<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

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 S100 proteins have the capacity to bind transition metals with high affinity and effectively sequester them away from invading microbial pathogens in a process that is termed "nutritional immunity". S100A12 (EN-RAGE) binds both zinc and copper and is highly abundant in innate immune cells such as macrophages and neutrophils. We report a refined method for the expression, enrichment and purification of S100A12 in its active, metal-binding configuration. Utilization of this protein in bacterial growth and viability analyses reveals that S100A12 has antimicrobial activity against the bacterial pathogen, Helicobacter pylori. The antimicrobial activity is predicated on the zinc-binding activity of S100A12, which chelates nutrient zinc, thereby starving H. pylori which requires zinc for growth and proliferation.

S100A12 expression and purification
A three-step purification produced ~40 mg of recombinant S100A12 from 50 mL of bacterial culture. The first step was an ammonium sulfate precipitation of endogenous E. coli proteins. This step was followed by anion-exchange chromatography (Figure1A). The protein is tracked by a SDS-PAGE stained with Coomassie Brilliant Blue (Figure 1B). ...

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

Expression, Purification, and Antimicrobial Activity of S100A12

Here, we present a method to express and purify S100A12 (calgranulin C). We describe a protocol to measure its antimicrobial activity against the human pathogen H. pylori.

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 조회수.  Fisk University. Here, we present a method to express and purify S100A12 (calgranulin C). We describe a protocol to measure its antimicrobial activity against the human pathogen H. pylori. 

비디오: 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.

항온, 발현, 정제, 인간 세로토닌 전달체 결정화 바운드<em&gt; S</em&gt; 시탈 로프 람

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

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생화학

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.

표현과 포유류 Bestrophin 이온 채널의 정화

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.

카페인 추출, 효소 활동 및 식물 세포 정지에서 카페인 Synthase의 유전자 발현

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.

혐 기성 단백질 정화 및 DesB Dioxygenase 활동을 연구 하 고 억제를 위한 산소 전극을 통해 운동 분석

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.

식 및 단일 입자 Cryo 전자 현미경 검사 법에 의하여 구조 결심에 대 한 인간의 지질 민감한 양이온 채널 TRPC3의 정화

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.

표현, 가용 화, 그리고 진 핵 Borate 전송기의 정화

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.

뉴클레아제 없는 산소 제거제 프로토카테의 발현 및 정제 3,4-디옥시게나아제

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.

Fumarylacetotate 하이드로 아세테이트 도메인 함유 단백질의 발현, 정제, 결정화 및 효소 어세포

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.

PCR 돌연변이 발생, 복제, 발현, 빠른 단백질 정화 프로토콜 및 트립토판 신타제의 야생 유형 및 돌연변이 형태의 결정화

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.

Ganglioside 추출, 정제 및 프로파일링

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