Name: one-step negative chromatographic purification of helicobacter pylori neutrophil-activating protein overexpressed in escherichia coli in batch mode
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We thank Dr. Chao-Sheng Cheng at National Tsing Hua University, Taiwan, for performing the circular dichroism measurement. We also thank Drs. Evanthia Galanis and Ianko D. Iankov at Mayo Clinic, USA, for providing the anti-HP-NAP monoclonal antibody. We appreciate Drs. Han-Wen Chang and Chung-Chu Chen at Mackay Memorial Hospital, Hsinchu, Taiwan, for providing advice for IRB application, Mr. Te-Lung Tsai at the Mackay Memorial Hospital, Hsinchu, Taiwan, for supervising the analysis of isolated neutrophils, and Ms. Ju-Chen Weng at National Tsing Hua University, Taiwan, for her technical assistance. This work was supported by grants from the Ministry of Science and Technology of Taiwan (MOST 104-2311-B-007-003, NSC101-2311-B-007-007 and NSC98-2311-B-007-006-MY3), the Joint Research Program of National Tsing Hua University and Mackay Memorial Hospital (100N7727E1, 101N2727E1, 103N2773E1), and the research program of National Tsing Hua University (104N2052E1).

Human blood was collected from healthy volunteers with prior written informed consent and approval from the Institutional Review Board of the National Tsing Hua University, Hsinchu, Taiwan.
1. Expression of Recombinant HP-NAP in E. coli
<ol>
	<li>Prepare the plasmid pET42a-NAP containing the DNA sequence of HP-NAP from H. pylori 26695 strain as previously described16. Prepare the plasmids containing the DNA sequence of HP-NAP with the desired point mutations as described (see Protoco...

<ol>
	<li>Brunette, G. W., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Chapter+3,+Infectious+diseases+related+to+travel.">Chapter 3, Infectious diseases related to travel.</a> CDC Health Information for International Travel 2016. , (2015).</li><li>Bauer, B., Meyer, T. F. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+human+gastric+pathogen+Helicobacter+pylori+its+association+with+gastric+cancer+and+ulcer+disease.">The human gastric pathogen Helicobacter pylori its association with gastric cancer and ulcer disease.</a> Ulcers. 2011, 340157 (2011).</li><li>Malfertheiner, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Management+of+Helicobacter+pylori+infection--the+Maastricht+IV/+Florence+Consensus+Report.+Gut.">Management of Helicobacter pylori infection--the Maastricht IV/ Florence Consensus Report. Gut.</a> Gut. 61 (5), 646-664 (2012).</li><li>Evans, D. J., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Characterization+of+a+Helicobacter+pylori+neutrophil-activating+protein.">Characterization of a Helicobacter pylori neutrophil-activating protein.</a> Infect. Immun. 63 (6), 2213-2220 (1995).</li><li>Fu, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Helicobacter+pylori+neutrophil-activating+protein:+from+molecular+pathogenesis+to+clinical+applications.">Helicobacter pylori neutrophil-activating protein: from molecular pathogenesis to clinical applications.</a> World J. Gastroenterol. 20 (18), 5294-5301 (2014).</li><li>de Bernard, M., D'Elios, M. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+immune+modulating+activity+of+the+Helicobacter+pylori+HP-NAP:+Friend+or+foe?.">The immune modulating activity of the Helicobacter pylori HP-NAP: Friend or foe?.</a> Toxicon. 56 (7), 1186-1192 (2010).</li><li>Malfertheiner, P., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Safety+and+immunogenicity+of+an+intramuscular+Helicobacter+pylori+in+noninfected+volunteers:+a+phase+I+study.">Safety and immunogenicity of an intramuscular Helicobacter pylori in noninfected volunteers: a phase I study.</a> Gastroenterology. 135 (3), 787-795 (2008).</li><li>Codolo, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=HP-NAP+inhibits+the+growth+of+bladder+cancer+in+mice+by+activating+a+cytotoxic+Th1+response.">HP-NAP inhibits the growth of bladder cancer in mice by activating a cytotoxic Th1 response.</a> Cancer Immunol. Immunother. 61 (1), 31-40 (2012).</li><li>Codolo, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=The+neutrophil-activating+protein+of+Helicobacter+pylori+Th2+inflammation+in+ovalbumin-induced+allergic+asthma.">The neutrophil-activating protein of Helicobacter pylori Th2 inflammation in ovalbumin-induced allergic asthma.</a> Cell. Microbiol. 10 (11), 2355-2363 (2008).</li><li>Del Prete, ., G, , et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Immunosuppression+of+TH2+responses+in+Trichinella+spiralis+by+Helicobacter+pylori+neutrophil-activating+protein.">Immunosuppression of TH2 responses in Trichinella spiralis by Helicobacter pylori neutrophil-activating protein.</a> J. Allergy Clin. Immunol. 122 (5), 908-913.e5 (2008).</li><li>Tang, R. X., Luo, D. J., Sun, A. H., Yan, J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Diversity+of+Helicobacter+pylori+in+expression+of+antigens+and+induction+of+antibodies.">Diversity of Helicobacter pylori in expression of antigens and induction of antibodies.</a> World J. Gastroenterol. 14 (30), 4816-4822 (2008).</li><li>Long, M., Luo, J., Li, Y., Zeng, F. Y., Li, M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Detection+and+evaluation+of+antibodies+against+neutrophil-activating+protein+of+Helicobacter+pylori+in+patients+with+gastric+cancer.">Detection and evaluation of antibodies against neutrophil-activating protein of Helicobacter pylori in patients with gastric cancer.</a> World J. Gastroenterol. 15 (19), 2381-2388 (2009).</li><li>Song, H., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=A+CagA-independent+cluster+of+antigens+related+to+the+risk+of+noncardia+gastric+cancer:+associations+between+Helicobacter+pylori+and+gastric+adenocarcinoma+explored+by+multiplex+serology.">A CagA-independent cluster of antigens related to the risk of noncardia gastric cancer: associations between Helicobacter pylori and gastric adenocarcinoma explored by multiplex serology.</a> Int. J. Cancer. 134 (12), 2942-2950 (2014).</li><li>Kottakis, F., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Helicobacter+pylori+neutrophil-activating+protein+activates+neutrophils+by+its+C-terminal+region+even+without+dodecamer+formation,+which+is+a+prerequisite+for+DNA+protection--novel+approaches+against+Helicobacter+pylori+inflammation.">Helicobacter pylori neutrophil-activating protein activates neutrophils by its C-terminal region even without dodecamer formation, which is a prerequisite for DNA protection--novel approaches against Helicobacter pylori inflammation.</a> FEBS J. 275 (2), 302-317 (2008).</li><li>Thoreson, A. C., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Differences+in+surface-exposed+antigen+expression+between+Helicobacter+pylori+isolated+from+duodenal+ulcer+patients+and+from+asymptomatic+subjects.">Differences in surface-exposed antigen expression between Helicobacter pylori isolated from duodenal ulcer patients and from asymptomatic subjects.</a> J. Clin. Microbiol. 38 (9), 3436-3441 (2000).</li><li>Wang, C. A., Liu, Y. C., Du, S. Y., Lin, C. W., Fu, H. W. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Helicobacter+pylori+neutrophil-activating+protein+promotes+myeloperoxidase+release+from+human+neutrophils.">Helicobacter pylori neutrophil-activating protein promotes myeloperoxidase release from human neutrophils.</a> Biochem. Biophys. Res. Commun. 377 (1), 52-56 (2008).</li><li>Iyer, G., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Reduced+surface+area+chromatography+for+flow-through+purification+of+viruses+and+virus+like+particles.">Reduced surface area chromatography for flow-through purification of viruses and virus like particles.</a> J. Chromatogr. A. 1218 (26), 3973-3981 (2011).</li><li>Wongchuphan, R., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+rabbit+polyclonal+immunoglobulin+G+using+anion+exchangers.">Purification of rabbit polyclonal immunoglobulin G using anion exchangers.</a> Process Biochem. 46 (1), 101-107 (2011).</li><li>Lu, X., Zhao, D., Su, Z. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+of+hemoglobin+by+ion+exchange+chromatography+in+flow-through+mode+with+PEG+as+an+escort.">Purification of hemoglobin by ion exchange chromatography in flow-through mode with PEG as an escort.</a> Artif. Cells Blood Substit. Immobil. Biotechnol. 32 (2), 209-227 (2004).</li><li>Brooks, S. P., Storey, K. B. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Purification+and+characterization+of+a+protein+phosphatase+that+dephosphorylates+pyruvate+kinase+in+an+anoxia+tolerant+animal.">Purification and characterization of a protein phosphatase that dephosphorylates pyruvate kinase in an anoxia tolerant animal.</a> Biochem. Mol. Biol. Int. 38 (6), 1223-1234 (1996).</li><li>Gewirtz, A. T., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=PubMed&cmd=Search&doptcmdl=Citation&defaultField=Title+Word&term=Salmonella+typhimurium+translocates+flagellin+across+intestinal+epithelia,+inducing+a+proinflammatory+response.">Salmonella typhimurium translocates flagellin across intestinal epithelia, inducing a proinflammatory response.</a> J. Clin. Invest. 107 (1), 99-109 (2001).</li><li>Levison, P. 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The negative mode batch chromatography with DEAE anion-exchange resins presented here is suitable for purification of recombinant HP-NAP overexpressed in E coli. The pH values of the buffers used in the steps of cell lysis and purification are very critical to ensure the solubility of HP-NAP in E. coli lysates and efficient separation of recombinant HP-NAP from host cell impurities, respectively. Bacterial cells should be lysed at pH 9.0, and the negative purification should be performed at pH 8.0 to ob...

Helicobacter pylori (H. pylori) is a major cause of gastritis and peptic ulcer. This bacterium has also been classified as a carcinogen in humans by the International Agency for Research on Cancer, part of the World Health Organization, in 1994. It has been estimated that the prevalence of H. pylori infection is 70% in the developing countries and 30-40% in the industrialized countries1. Even though the infection rate of H. pylori is decreasing in the industrialized countries, the infection rate of H. pylori in the developing countries is still high2. The standard treatment to eradicate H. pylori infection consists of the administration of a proton pump inhibitor, PPI, and two antibiotics, clarithromycin plus amoxicillin or metronidazole3. However, the rise of antibiotic resistance in H. pylori-related ulcer therapy urges the development of new strategies to prevent or cure the infection. Development of preventive and/or therapeutic vaccination against H. pylori could provide an alternative approach to control H. pylori infection.
Helicobacter pylori neutrophil-activating protein (HP-NAP), a major virulence factor of H pylori, was first identified in water extracts of H. pylori with the ability to activate neutrophils to adhere to endothelial cells and produce reactive oxygen species (ROS)4. Neutrophil infiltration of gastric mucosa found in H. pylori-infected patients with active gastritis may result in inflammation and tissue damage of the stomach. Thus, HP-NAP may play a pathological role by activating neutrophils to induce gastric inflammation, which further causes ulcer or H. pylori-associated gastric diseases. Nevertheless, HP-NAP is a potential candidate for clinical applications5,6. Due to the immunogenic and immunomodulatory properties of HP-NAP, this protein could be used to develop vaccines, therapeutic agents, and diagnostic tools. A clinical trial has been conducted for using recombinant HP-NAP as one of the components of a protein vaccine against H. pylori. This vaccine consists of recombinant HP-NAP, cytotoxin-associated gene A (CagA), and vacuolating cytotoxin A (VacA) proteins formulated with aluminum hydroxide and has further been demonstrated to be safe and immunogenic in humans7. Also, HP-NAP acts as a potent immunomodulator to trigger T helper type 1 (Th1)-polarized immune responses for cancer therapy8 and to down regulate Th2-mediated immune responses elicited by allergic reactions and parasitic infections9,10. As for diagnostics, recombinant HP-NAP-based ELISA has been applied to detect serum antibodies against HP-NAP in H. pylori-infected patients11. One study showed that the level of HP-NAP-specific antibodies in sera from H. pylori-infected patients with gastric cancer was significantly higher than that from patients with chronic gastritis12. Another study also showed that serum antibodies against HP-NAP are associated with the presence of non-cardia gastric adenocarcinoma13. Thus, recombinant HP-NAP-based ELISA may be applied to detect serum antibodies against HP-NAP for prognosis of gastric cancer in H. pylori-infected patients. Taken together, the purified HP-NAP could be further utilized for the prevention, treatment, and prognosis of H. pylori-associated diseases as well as cancer therapy.
Among the several methods used for purification of recombinant HP-NAP expressed in Escherichia coli (E. coli) in its native form reported so far, a second purification step involving gel-filtration chromatography is needed to obtain highly pure HP-NAP14-16. Here, a method using negative mode batch chromatography with diethylaminoethyl (DEAE) ion-exchange resins is described for purification of HP-NAP overexpressed in E. coli with high yield and high purity. This purification technique was based on the binding of host cell proteins and/or impurities other than HP-NAP to the resin. At pH 8.0, almost no other proteins except HP-NAP are recovered from the unbound fraction. This purification approach using DEAE ion-exchange chromatography in negative mode is simple and time saving by allowing purification of recombinant HP-NAP via one-step chromatography through the collection of the unbound fraction. In addition to HP-NAP, several other biomolecules, such as viruses17, Immunoglobulin G (IgG)18, hemoglobin19, protein phosphatase20, and virulence factor flagellin21, have also been reported to be purified by ion-exchange chromatography in negative mode. The negative mode is preferred for ion-exchange chromatography if impurities are the minor components present in the sample subjected to be purified22. The application of negative chromatography in purification of natural or recombinant biomolecules has been recently reviewed23.
The present report provides a step by step protocol for expression of recombinant HP-NAP in E. coli, lysis of the cells, and purification of HP-NAP using negative mode batch chromatography with DEAE ion-exchange resins. If a protein desired for purification is suitable for ion-exchange chromatography in negative mode, the described protocol could also be adapted as a starting point for development of a purification process.

<table border="1" fo:keep-together.within-page="1" fo:keep-with-next.within-page="always">
	<tbody>
		<tr>
			<td>Material</td>
			<td></td>
			<td></td>
			<td></td>
		</tr>
		<tr>
			<td>pET42a-NAP&#160;</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>prepared as described in Supplementary data of Refernce 15&#160; 
			http://www.sciencedirect.com/science/article/pii/S0006291X08018317</td>
		</tr>
		<tr>
			<td>E. coli BL21 (DE3)</td>
			<td>Thermo Fisher Scientific Inc</td>
			<td>C6000-03</td>
			<td>https://www.thermofisher.com/order/catalog/product/C600003</td>
		</tr>
		<tr>
			<td>Kanamycin</td>
			<td>Amresco</td>
			<td>25389-94-0</td>
			<td>http://www.amresco-inc.com/KANAMYCIN-SULFATE-0408.cmsx</td>
		</tr>
		<tr>
			<td>Isopropyl &#946;-D-1-thiogalactopyranoside (IPTG)</td>
			<td>MD Biomedical Inc</td>
			<td>101-367-93-1</td>
			<td>http://www.antibody-antibodies.com/product_det.php?id=238064&#38;supplier=search&#38;name =IPTG%20</td>
		</tr>
		<tr>
			<td>phenylmethylsulfonyl fluoride (PMSF)</td>
			<td>Sigma-Aldrich</td>
			<td>10837091001</td>
			<td>protease inhibitor 
			http://www.sigmaaldrich.com/catalog/product/roche/PMSFRO?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>N-alpha-tosyl-L-lysinyl-chloromethylketone (TLCK)</td>
			<td>Sigma-Aldrich</td>
			<td>T7254</td>
			<td>protease inhibitor 
			http://www.sigmaaldrich.com/catalog/product/sigma/t7254?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>N-tosyl-L-phenylalaninyl-chloromethylketone (TPCK)</td>
			<td>Sigma-Aldrich</td>
			<td>T4376</td>
			<td>protease inhibitor 
			http://www.sigmaaldrich.com/catalog/product/sigma/t4376?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>Bio-Rad protein assay dye reagent concentrate</td>
			<td>Bio&#8208;Rad</td>
			<td>500-0006</td>
			<td>for protein quantitation 
			http://www.bio-rad.com/en-us/sku/5000006-bio-rad-protein-assay-dye-reagent-concentrate</td>
		</tr>
		<tr>
			<td>Protein standard (bovine serum albumin)</td>
			<td>Sigma-Aldrich</td>
			<td>P5619&#160;</td>
			<td>a standard protein for Bio-Rad Protein Assay 
			http://www.sigmaaldrich.com/catalog/product/fluka/p5619?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>DEAE&#8211;Sephadex &#160;A-25 chloride form</td>
			<td>Sigma-Aldrich</td>
			<td>A25120</td>
			<td>http://www.sigmaaldrich.com/catalog/product/sigma/a25120?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>Spectrum/Por dialysis tubing</td>
			<td>Spectrum Laboratories</td>
			<td>132720</td>
			<td>with molecular weight cutoff of 14 kDa 
			http://www.spectrumlabs.com/dialysis/RCtubing.html?Pn=132720;</td>
		</tr>
		<tr>
			<td>Acrodisc&#174; units with Mustang&#174; E membrane</td>
			<td>Pall</td>
			<td>MSTG25E3</td>
			<td>for endotoxin removal; operated at flow rates ranging from 1 to 4 ml/min 
			http://www.pall.com/main/laboratory/product.page?id=19992</td>
		</tr>
		<tr>
			<td>mouse monoclonal antibody MAb 16F4</td>
			<td>N/A</td>
			<td>N/A</td>
			<td>raised against the purified HP-NAP of H. pylori strain NCTC 11637 as described in Refernce 23;&#160; A gift from Drs. Evanthia Galanis and Ianko D. Iankov at Mayo Clinic, USA 
			http://www.sciencedirect.com/science/article/pii/S0264410X10017585</td>
		</tr>
		<tr>
			<td>HiLoad 16/600 Superdex 200 pg</td>
			<td>GE Healthcare Life Sciences</td>
			<td>28989335</td>
			<td>for gel filtration chromatography 
			http://www.gelifesciences.com/webapp/wcs/stores/servlet/productById/en/GELifeSciences-tw/28989335</td>
		</tr>
		<tr>
			<td>PlusOne silver staining kit, protein</td>
			<td>GE Healthcare Life Sciences</td>
			<td>17-1150-01</td>
			<td>http://www.gelifesciences.com/webapp/wcs/stores/servlet/productById/en/GELifeSciences-tw/17115001</td>
		</tr>
		<tr>
			<td>Ficoll-Paque PLUS</td>
			<td>GE Healthcare Life Sciences</td>
			<td>17-1440-02</td>
			<td>for density gradient centrifugation to purify human neutrophils 
			http://www.gelifesciences.com/webapp/wcs/stores/servlet/catalog/en/GELifeSciences-tw/products/AlternativeProductStructure _16963/17144002</td>
		</tr>
		<tr>
			<td>Flat bottom 96-well white plate</td>
			<td>Thermo Fisher Scientific Inc</td>
			<td>236108</td>
			<td>http://www.thermoscientific.com/en/product/nunc-f96-microwell-black-white-polystyrene-plate.html</td>
		</tr>
		<tr>
			<td>Luminol</td>
			<td>Sigma-Aldrich</td>
			<td>A8511</td>
			<td>protected from light 
			http://www.sigmaaldrich.com/catalog/product/sigma/a8511?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>Expand &#160;long template PCR system</td>
			<td>Sigma-Aldrich</td>
			<td>11681834001</td>
			<td>source of High Fidelity PCR enzyme mix 
			http://www.sigmaaldrich.com/catalog/product/roche/elongro?lang=en&#38;region=TW</td>
		</tr>
		<tr>
			<td>Dpn I</td>
			<td>New England Biolabs</td>
			<td>R0176S</td>
			<td>https://www.neb.com/products/r0176-dpni</td>
		</tr>
		<tr>
			<td>Xho I</td>
			<td>New England Biolabs</td>
			<td>R0146S</td>
			<td>https://www.neb.com/products/r0146-xhoi</td>
		</tr>
		<tr>
			<td>E. coli DH5&#945;</td>
			<td>Thermo Fisher Scientific Inc</td>
			<td>18265-017</td>
			<td>https://www.thermofisher.com/order/catalog/product/18265017</td>
		</tr>
		<tr>
			<td>Name</td>
			<td>Company</td>
			<td>Product Number</td>
			<td>Comments</td>
		</tr>
		<tr>
			<td>Equipment</td>
			<td></td>
			<td></td>
			<td> 
			&#160;</td>
		</tr>
		<tr>
			<td>U-2800 double beam UV/VIS spectrophotometer</td>
			<td>Hitachi&#160;</td>
			<td>N/A</td>
			<td>out of market and upgraded to a new model 
			http://hitachi-hta.com/products/life-sciences-chemical-analysis/uvvisible-spectrophotometers</td>
		</tr>
		<tr>
			<td>EmulsiFlex-C3 high pressure homogenizer</td>
			<td>Avestin Inc</td>
			<td>C315320</td>
			<td>http://www.avestin.com/English/c3page.html</td>
		</tr>
		<tr>
			<td>Hitachi Koki himac CP80WX general ultracentrifuge</td>
			<td>Hitachi Koki Co</td>
			<td>90106401</td>
			<td>for separation of the soluble and insoluble protein fractions from E. coli lysates 
			http://centrifuges.hitachi-koki.com/products/ultra/cp_wx/cp_wx.html</td>
		</tr>
		<tr>
			<td>&#196;KTA FPLC</td>
			<td>GE Healthcare Life Sciences</td>
			<td>18-1900-26</td>
			<td>for gel filtration chromatography 
			http://www.gelifesciences.com/webapp/wcs/stores/servlet/productById/en/GELifeSciences-tw/18190026</td>
		</tr>
		<tr>
			<td>Aviv model 62ADS CD spectrophotometer</td>
			<td>Aviv Biomedical</td>
			<td>N/A</td>
			<td>out of market and upgraded to a new model 
			http://www.avivbiomedical.com/circular.php</td>
		</tr>
		<tr>
			<td>LAS-3000 imaging system</td>
			<td>Fujifilm</td>
			<td>N/A</td>
			<td>discontinued and replaced 
			http://www.gelifesciences.com/webapp/wcs/stores/servlet/productById/en/GELifeSciences-tw/28955810</td>
		</tr>
		<tr>
			<td>Wallac 1420 (Victor2) multilabel counter</td>
			<td>Perkin-Elmer</td>
			<td>1420-018</td>
			<td>for chemiluminescence detection 
			http://www.perkinelmer.com/catalog/product/id/1420-018</td>
		</tr>
	</tbody>
</table>

one-step negative chromatographic purification of helicobacter pylori neutrophil-activating protein overexpressed in escherichia coli in batch mode

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor of Helicobacter pylori (H. pylori). It plays a critical role in H. pylori-induced gastric inflammation by activating several innate leukocytes including neutrophils, monocytes, and mast cells. The immunogenic and immunomodulatory properties of HP-NAP make it a potential diagnostic and vaccine candidate for H. pylori and a new drug candidate for cancer therapy. In order to obtain substantial quantities of purified HP-NAP used for its clinical applications, an efficient method to purify this protein with high yield and purity needs to be established.
In this protocol, we have described a method for one-step negative chromatographic purification of recombinant HP-NAP overexpressed in Escherichia coli (E. coli) by using diethylaminoethyl (DEAE) ion-exchange resins (e.g., Sephadex) in batch mode. Recombinant HP-NAP constitutes nearly 70% of the total protein in E. coli and is almost fully recovered in the soluble fraction upon cell lysis at pH 9.0. Under the optimal condition at pH 8.0, the majority of HP-NAP is recovered in the unbound fraction while the endogenous proteins from E. coli are efficiently removed by the resin.
This purification method using negative mode batch chromatography with DEAE ion-exchange resins yields functional HP-NAP from E. coli in its native form with high yield and purity. The purified HP-NAP could be further utilized for the prevention, treatment, and prognosis of H. pylori-associated diseases as well as cancer therapy.

The schematic diagram of the experimental procedure of negative purification of recombinant HP-NAP expressed in E. coli by using DEAE ion-exchange resins in batch mode is shown in Figure 1. This purification technique is based on the binding of host cell proteins and/or impurities other than HP-NAP to the resin. At pH 8.0, almost no other proteins except HP-NAP in its native form are recovered from the unbound fraction (Figure 2A and B</s...

Watch this Scientific Journal Video about One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode at JoVE.co

One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode

A high yield method for one-step negative purification of recombinant Helicobacter pylori neutrophil-activating protein (HP-NAP) overexpressed in Escherichia coli by using diethylaminoethyl resins in batch mode is described. HP-NAP purified by this method is beneficial for the development of vaccines, drugs, or diagnostics for H. pylori-associated diseases.

One-step Negative Chromatographic Purification of Helicobacter pylori Neutrophil-activating Protein Overexpressed in Escherichia coli in Batch Mode

Helicobacter pylori neutrophil-activating protein (HP-NAP) is a major virulence factor of Helicobacter pylori (H. pylori). It plays a critical role in H. ...

The overall goal of this purification is to yield functional Helicobacter pylori Neutrophil-activating protein or HP-NAP in its native form with high purity and high yield using negative mode batch chromatography with di-ethyl amino-ethyl ion exchange resin. The main advantage of this technique is that HP-NAP can be purified in its native form in one step with high purity and high yield. Negative purification of HP-NAP starts with a batch binding procedure in which the soluble protein fraction from bacterial lysates is added to DEAE resin.The mixture is incubated to allow wholesale proteins to bind to the resin. HP-NAP present in the unbound fraction is then obtained by centrifugation of gravity flow. The implications of this technique is 10:1 prevention treatment and prognostic of Helicobacter pylori associated diseases as well as cancer therapy.Because of the immunogenic and immunomodulatory properties of HP-NAP. Generally, individuals new to this method will struggle. Because HP-NAP easily aggregates during the sterilization.Demonstrating the procedure will be Zhi-Wei Hong, a graduate student from our lab. Working at four degrees Celsius, we suspend 50 milliliters of the cell palate prepared as described in the text protocol in 20 milliliters of low salt, tris-buffer at pH 9.0 with protease inhibitor mixture. It's critical to keep sample at the four degrees Celsius to allow the procedure to prevent the protein aggregation.Disrupt the bacterial cells by passing the bacterial suspension through a high-pressure homogenizer operated at a range of 15, 000 to 20, 000 PSI for seven times at four degrees Celsius. After lysates baterializes, it should be centrifuged immediately. Transfer homogenized samples to a centrifuge tube.Immediately centrifuge the cell-lysate at 30, 000 times G at four degrees Celsius for one hour to separate the soluble and insoluble protein fractions by using an ultra-centrifuge. Following centrifugation, transfer the supernatant as the soluble protein fraction to a beaker. Measure the protein concentration of the soluble protein fraction by the Bradford method using a commercial kit with bovine serum albumin as the standard according to the manufacturer's instructions.Then add 177.6 microliters of one normal HCl into 20 milliliters of the soluble protein fraction to adjust its pH value from pH 9.0 to pH 8.0. Add 20 millimeter Tris-HCl, pH 8.0, 50 milliliter sodium chloride to the protein solution to result in a final protein concentration of 0.5 milligrams per milliliter. To prepare 15 milliliters of DEAE resin, suspend 0.6 grams of DEAE resin dry powder in 30 milliliters of Tris-HCl buffer at room temperature for at least one day.Centrifuge the resin at 10, 000 times G at four degrees Celsius for one minute and then remove and discard the supernatant. Then add 15 milliliters of Tris-HCl buffer. After repeating the centrifugation resuspension steps four more times, store the 15 milliliters of settled resin at four degrees Celsius for subsequent use.Working at four degrees Celsius, add 45 milliliters of the prepared soluble proteins to milliliters of the resin and transfer to a 100 milliliter beaker with stir bar. Stir the protein resin slurry using a stir plate at four degrees Celsius for one hour. Next, pour the protein resin slurry into a plastic or a glass column fitted with a stopcock and allow the resin to settle under gravity.Open the stopcock to allow the protein solution to run through the column by gravity flow until the liquid level in the column is just above the resin. Collect the flow through as the unbound fraction which contains the purified neutrophil-activating protein. Add 15 milliliters of the ice-cold Tris-HCl buffer into the column.Open the stopcock again to allow the wash buffer to run through the column by gravity flow until the liquid level in the column is just above the resin. Collect the flow through as the wash fraction. Repeat washing with ice-cold buffer four more times to collect the additional wash fractions.Then add 15 milliliters of ice-cold 20 millimeter Tris-HCl pH 8.0, one molar sodium chloride into the column. Collect the flow through as the elution fractions as before. Repeat the elution steps four more times to collect the additional elution fractions.The effect of pH on solubility of HP-NAP in E.coli lysate are shown here. The amount of HP-NAP detected in this soluble fraction was markedly increased at pH 7.5 to 9.5. Recombinant HP-NAP was almost fully recovered in the soluble fraction upon cell lysis at pH 9.0.Here, the effect of pH on negative purification of recombinant HP-NAP expressed in E.coli by DEAE resins in batch mode are shown. At pH 8.0, only a little amount of HP-NAP was present in the elution fraction. The amount of HP-NAP present in the unbound fractions was the highest at pH 8.0.The optimized amount of proteins loaded onto the DEAE resin is 1.5 milligrams of protein per milliliter of resin for achieving maximum capacity of the resin to absorb the impurities from E.coli. At pH 8.0, very few proteins other than HP-NAP in its native form are recovered in the unbound fraction using DEAE resins in batch mode. The purity of HP-NAP was higher than 95 percent.The purified HP-NAP folds into a multimer with a secondary structure of alpha-helix as revealed by the gelifiltration chromotogram and the far UV circular dichroism spectrum. A luminal dependent chemiluminescence assay reveals that the purified HP-NAP is able to trigger the production of reactive oxygen species by neutrophiles. Once mastered, these techniques can be done within five hours if it is performed properly.After watching this video you should have a good understanding of how to purify functional HP-NAP in its native form with high yield and purity using negative mode batch chromotography with DEAE and exchange resin. While attempting this procedure, it's important to remember to use buffers at the appropriate pH in the step of sterilizes in the batch chromotography. We first had the idea for this method when we tried to apply other chromotographic approaches instead of filtration to purify HP-NAP in its native form.Though this method is designed to appeal by recombinant HP-NAP expressed in E.coli. It can also be applied to other bacterial expression systems such as per-sida sep-tidas. Visual demonstration of this measure is quick code.Plus the step of sterilizes and batch chromotography are difficult to learn. Because these steps must be carried out at the four degrees Celsius without any time delay. If a protein designed for purification is suitable for our exchange chromotography in negative mode, this procedure could also be adapted as a starting point for the development of purification process.After its development, this technique paved the way for researchers in the field of clinical research to explore the possibility of using HP-NAP in cancer therapy as well as the development of vaccines, drugs, and the diagnostics for Helicobacter pylori associated disease.

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Research

JoVE Journal

Immunology and Infection

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal features of the natural infection. This protocol describes procedures for the establishment and evaluation of systemic infection due to neuropathogenic Escherichia coli K1 in the neonatal rat. Colonization of the gastrointestinal tract leads to dissemination of the pathogen along the gut-lymph-blood-brain course of infection and the model displays strong age dependency. A strain of E. coli O18:K1 with enhanced virulence for the neonatal rat produces exceptionally high rates of colonization, translocation to the blood compartment and invasion of the meninges following transit through the choroid plexus. As in the human host, penetration of the central nervous system is accompanied by local inflammation and an invariably lethal outcome. The model is of proven utility for studies of the mechanism of pathogenesis, for evaluation of therapeutic interventions and for assessment of bacterial virulence.

Non-Invasive Model of Neuropathogenic Escherichia coli Infection in the Neonatal Rat

Here, a procedure is described for the establishment of systemic infection in the neonatal rat with cultures of Escherichia coli K1. This non-invasive procedure permits colonization of the gastrointestinal tract, translocation of the pathogen to the systemic circulation, and invasion of the central nervous system at the choroid plexus.

Investigation of the interactions between animal host and bacterial pathogen is only meaningful if the infection model employed replicates the principal ...

High Resolution Electron Microscopy of the Helicobacter pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability

Helicobacter pylori is a helical-shaped, gram negative bacterium that colonizes the human gastric niche of half of the human population1,2. H. pylori is the primary cause of gastric cancer, the second leading cause of cancer-related deaths worldwide3. One virulence factor that has been associated with increased risk of gastric disease is the Cag-pathogenicity island, a 40-kb region within the chromosome of H. pylori that encodes a type IV secretion system and the cognate effector molecule, CagA4,5. The Cag-T4SS is responsible for translocating CagA and peptidoglycan into host epithelial cells5,6. The activity of the Cag-T4SS results in numerous changes in host cell biology including upregulation of cytokine expression, activation of proinflammatory pathways, cytoskeletal remodeling, and induction of oncogenic cell-signaling networks5-8. The Cag-T4SS is a macromolecular machine comprised of sub-assembly components spanning the inner and outer membrane and extending outward from the cell into the extracellular space. The extracellular portion of the Cag-T4SS is referred to as the &#8220;pilus&#8221;5. Numerous studies have demonstrated that the Cag-T4SS pili are formed at the host-pathogen interface9,10. However, the environmental features that regulate the biogenesis of this important organelle remain largely obscure. Recently, we reported that conditions of low iron availability increased the Cag-T4SS activity and pilus biogenesis. Here we present an optimized protocol to grow H. pylori in varying conditions of iron availability prior to co-culture with human gastric epithelial cells. Further, we present the comprehensive protocol for visualization of the hyper-piliated phenotype exhibited in iron restricted conditions by high resolution scanning electron microscopy analyses.

High Resolution Electron Microscopy of the Helicobacter pylori Cag Type IV Secretion System Pili Produced in Varying Conditions of Iron Availability

Here we describe a method to visualize the oncogenic bacterial organelle known as the Cag Type IV Secretion System (Cag-T4SS). We find that the Cag-T4SS is differentially produced on the surface of H. pylori in response to varying conditions of iron availability.

Helicobacter pylori is a helical-shaped, gram negative bacterium that colonizes the human gastric niche of half of the human population1,2.  H. pylori is ...

Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System

Enterohemorrhagic E. coli (EHEC) O157:H7, which is a foodborne pathogen that causesdiarrhea, hemorrhagic colitis (HS), and hemolytic uremic syndrome (HUS), colonize to the intestinal tract of humans. To study the detailed mechanism of EHEC colonization in vivo, it is essential to have animal models to monitor and quantify EHEC colonization. We demonstrate here a mouse-EHEC colonization model by transforming the bioluminescent expressing plasmid to EHEC to monitor and quantify EHEC colonization in living hosts. Animals inoculated with bioluminescence-labeled EHEC show intense bioluminescent signals in mice by detection with a non-invasive in vivo imaging system. After 1 and 2 days post infection, bioluminescent signals could still be detected in infected animals, which suggests that EHEC colonize in hosts for at least 2 days. We also demonstrate that these bioluminescent EHEC locate to mouse intestine, specifically in the cecum and colon, from ex vivo images. This mouse-EHEC colonization model may serve as a tool to advance the current knowledge of the EHEC colonization mechanism.

Detection of Enterohemorrhagic Escherichia Coli Colonization in Murine Host by Non-invasive In Vivo Bioluminescence System

A detailed protocol of a mouse model for enterohemorrhagic E. coli (EHEC) colonization by using bioluminescence-labeled bacteria is presented. The detection of these bioluminescent bacteria by a non-invasive in vivo imaging system in live animals can advance our current understanding of EHEC colonization.

Enterohemorrhagic E. coli (EHEC) O157:H7, which is a foodborne pathogen that causesdiarrhea, hemorrhagic colitis (HS), and hemolytic uremic syndrome ...

Creation of a Dense Transposon Insertion Library Using Bacterial Conjugation in Enterobacterial Strains Such As Escherichia Coli or Shigella flexneri

Transposon mutagenesis is a method that allows gene disruption via the random genomic insertion of a piece of DNA called a transposon. The protocol below outlines a method for high efficiency transfer between bacterial strains of a plasmid harboring a transposon containing a kanamycin resistance marker. The plasmid-borne transposase is encoded by a variant tnp gene that inserts the transposon into the genome of the recipient strain with very low insertional bias. This method thus allows the creation of large mutant libraries in which transposons have been inserted into unique genomic positions in a recipient strain of either Escherichia coli or Shigella flexneri bacteria. By using bacterial conjugation, as opposed to other methods such as electroporation or chemical transformation, large libraries with hundreds of thousands of unique clones can be created. This yields high-density insertion libraries, with insertions occurring as frequently as every 4-6 base pairs in non-essential genes. This method is superior to other methods as it allows for an inexpensive, easy to use, and high efficiency method for the creation of a dense transposon insertion library. The transposon library can be used in downstream applications such as transposon sequencing (Tn-Seq), to infer genetic interaction networks, or more simply, in mutational (forward genetic) screens.

Creation of a Dense Transposon Insertion Library Using Bacterial Conjugation in Enterobacterial Strains Such As Escherichia Coli or Shigella flexneri

Presented here is a simple method for creating a high-density transposon insertion library in Escherichia coli or Shigella flexneri using bacterial conjugation. This protocol allows the creation of a collection of hundreds of thousands of unique mutants in bacteria by the random genomic insertion of a transposon.

Transposon mutagenesis is a method that allows gene disruption via the random genomic insertion of a piece of DNA called a transposon. The protocol below ...

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli

Prenyltransferases (PT) are a group of enzymes that catalyze chain elongation of allylic diphosphate using isopentenyl diphosphate (IPP) via multiple condensation reactions. DHDDS (dehydrodolichyl diphosphate synthase) is a eukaryotic long-chain cis-PT (forming cis double bonds from the condensation reaction) that catalyzes chain elongation of farnesyl diphosphate (FPP, an allylic diphosphate) via multiple condensations with isopentenyl diphosphate (IPP). DHDDS is of biomedical importance, as a non-conservative mutation (K42E) in the enzyme results in retinitis pigmentosa, ultimately leading to blindness. Therefore, the present protocol was developed in order to acquire large quantities of purified DHDDS, suitable for mechanistic studies. Here, the usage of protein fusion, optimized culture conditions and codon-optimization were used to allow the overexpression and purification of functionally active human DHDDS in E. coli. The described protocol is simple, cost-effective and time sparing. The homology of cis-PT among different species suggests that this protocol may be applied for other eukaryotic cis-PT as well, such as those involved in natural rubber synthesis.

Overexpression and Purification of Human Cis-prenyltransferase in Escherichia coli

A simple protocol for overexpression and purification of codon-optimized, human cis-prenyltransferase, under non-denaturing conditions, from Escherichia coli, is described, along with an enzymatic activity assay. This protocol can be generalized for production of other cis- prenyltransferase proteins in quantity and quality suitable for mechanistic studies.

Prenyltransferases (PT) are a group of enzymes that catalyze chain elongation of allylic diphosphate using isopentenyl diphosphate (IPP) via multiple ...

A Facile Protocol to Generate Site-Specifically Acetylated Proteins in Escherichia Coli

Post-translational modifications that occur at specific positions of proteins have been shown to play important roles in a variety of cellular processes. Among them, reversible lysine acetylation is one of the most widely distributed in all domains of life. Although numerous mass spectrometry-based acetylome studies have been performed, further characterization of these putative acetylation targets has been limited. One possible reason is that it is difficult to generate purely acetylated proteins at desired positions by most classic biochemical approaches. To overcome this challenge, the genetic code expansion technique has been applied to use the pair of an engineered pyrrolysyl-tRNA synthetase variant, and its cognate tRNA from Methanosarcinaceae species, to direct the cotranslational incorporation of acetyllysine at the specific site in the protein of interest. After first application in the study of histone acetylation, this approach has facilitated acetylation studies on a variety of proteins. In this work, we demonstrated a facile protocol to produce site-specifically acetylated proteins by using the model bacterium Escherichia coli as the host. Malate dehydrogenase was used as a demonstration example in this work.

A Facile Protocol to Generate Site-Specifically Acetylated Proteins in Escherichia Coli

Genetic code expansion serves as a powerful tool to study a wide range of biological processes, including protein acetylation. Here we demonstrate a facile protocol to exploit this technique for generating homogeneously acetylated proteins at specific sites in Escherichia coli cells.

Post-translational modifications that occur at specific positions of proteins have been shown to play important roles in a variety of cellular processes. ...

Dissecting Multi-protein Signaling Complexes by Bimolecular Complementation Affinity Purification (BiCAP)

The assembly of protein complexes is a central mechanism underlying the regulation of many cell signaling pathways. A major focus of biomedical research is deciphering how these dynamic protein complexes act to integrate signals from multiple sources in order to direct a specific biological response, and how this becomes deregulated in many disease settings. Despite the importance of this key biochemical mechanism, there is a lack of experimental techniques that can facilitate the specific and sensitive deconvolution of these multi-molecular signaling complexes.
Here this shortcoming is addressed through the combination of a protein complementation assay with a conformation-specific nanobody, which we have termed Bimolecular Complementation Affinity Purification (BiCAP). This novel technique facilitates the specific isolation and downstream proteomic characterization of any pair of interacting proteins, to the exclusion of un-complexed individual proteins and complexes formed with competing binding partners. 
The BiCAP technique is adaptable to a wide array of downstream experimental assays, and the high degree of specificity afforded by this technique allows more nuanced investigations into the mechanics of protein complex assembly than is currently possible using standard affinity purification techniques.

Dissecting Multi-protein Signaling Complexes by Bimolecular Complementation Affinity Purification BiCAP

This manuscript describes the protocol for Bimolecular Complementation Affinity Purification (BiCAP). This novel method facilitates the specific isolation and downstream proteomic characterization of any two interacting proteins, while excluding un-complexed individual proteins as well as complexes formed with competing binding partners.

The assembly of protein complexes is a central mechanism underlying the regulation of many cell signaling pathways. A major focus of biomedical research ...

Using Enhanced Green Fluorescence Protein-expressing Escherichia Coli to Assess Mouse Peritoneal Macrophage Phagocytosis

This manuscript describes a simple and reproducible method to perform a phagocytosis assay. The first part of this method involves building a pET-SUMO-EGFP vector (SUMO = small ubiquitin-like modifier) and expressing enhanced green fluorescence protein (EGFP) in Escherichia coli (BL21DE). EGFP-expressing E. coli is coincubated with macrophages for 1 h at 37 &#176;C; the negative control group is incubated on ice for the same amount of time. Then, the macrophages are ready for assessment. The advantages of this technique include its simple and straightforward steps, and phagocytosis can be measured by both flow cytometer and fluorescence microscope. The EGFP-expressing E. coli are stable and display a strong fluorescence signal even after the macrophages are fixed with paraformaldehyde. This method is not only suitable for the assessment of macrophage cell lines or primary macrophages in vitro but also suitable for the evaluation of granulocyte and monocyte phagocytosis in peripheral blood mononuclear cells. The results show that the phagocytic capability of peritoneal macrophages from young (eight-week-old) mice is higher than that of macrophages from aged (16-month-old) mice. In summary, this method measures macrophage phagocytosis and is suitable for studying the innate immune system function.

Using Enhanced Green Fluorescence Protein-expressing Escherichia Coli to Assess Mouse Peritoneal Macrophage Phagocytosis

Here, we present a protocol to assess mouse peritoneal macrophage phagocytosis using enhanced green fluorescence protein-expressing Escherichia coli.

This manuscript describes a simple and reproducible method to perform a phagocytosis assay. The first part of this method involves building a ...

Purification of a High Molecular Mass Protein in Streptococcus mutans

Elucidation of a gene&#39;s function typically involves comparison of phenotypic traits of wild-type strains and strains in which the gene of interest has been disrupted. Loss of function following gene disruption is subsequently restored by exogenous addition of the product of the disrupted gene. This helps to determine the function of the gene. A method previously described involves generating a gtfC gene-disrupted Streptococcus mutans strain. Here, an undemanding method is described for purifying the gtfC gene product from the newly generated S. mutans strain following the gene disruption. It involves the addition of a polyhistidine-coding sequence at the 3&#8242; end of the gene of interest, which allows simple purification of the gene product using immobilized metal affinity chromatography. No enzymatic reactions other than PCR are required for the genetic modification in this method. The restoration of the gene product by exogenous addition after gene disruption is an efficient method for determining gene function, which may also be adapted to different species.

Purification of a High Molecular Mass Protein in Streptococcus mutans

Described here is a simple method for the purification of a gene product in Streptococcus mutans. This technique may be advantageous in the purification of proteins, especially membrane proteins and high molecular mass proteins, and can be used with various other bacterial species.

Elucidation of a gene&#39;s function typically involves comparison of phenotypic traits of wild-type strains and strains in which the gene of interest has ...

Recurrent Escherichia coli Urinary Tract Infection Triggered by Gardnerella vaginalis Bladder Exposure in Mice

Recurrent urinary tract infections (rUTI) caused by uropathogenic Escherichia coli (UPEC) are common and costly. Previous articles describing models of UTI in male and female mice have illustrated the procedures for bacterial inoculation and enumeration in urine and tissues. During an initial bladder infection in C57BL/6 mice, UPEC establish latent reservoirs inside bladder epithelial cells that persist following clearance of UPEC bacteriuria. This model builds on these studies to examine rUTI caused by the emergence of UPEC from within latent bladder reservoirs. The urogenital bacterium Gardnerella vaginalis is used as the trigger of rUTI in this model because it is frequently present in the urogenital tracts of women, especially in the context of vaginal dysbiosis that has been associated with UTI. In addition, a method for in situ bladder fixation followed by scanning electron microscopy (SEM) analysis of bladder tissue is also described, with potential application to other studies involving the bladder.

Recurrent Escherichia coli Urinary Tract Infection Triggered by Gardnerella vaginalis Bladder Exposure in Mice

A mouse model of uropathogenic E. coli (UPEC) transurethral inoculation to establish latent intracellular bladder reservoirs and subsequent bladder exposure to G. vaginalis to induce recurrent UPEC UTI is demonstrated. Also demonstrated are the enumeration of bacteria, urine cytology, and in situ bladder fixation and processing for scanning electron microscopy.

Recurrent urinary tract infections (rUTI) caused by uropathogenic Escherichia coli (UPEC) are common and costly. Previous articles describing models of ...