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Guan W, Zhang N, Bains A, Sadqi M, Dupureur CM, LiWang PJ. Efficient production of fluorophore-labeled CC chemokines for biophysical studies using recombinant enterokinase and recombinant sortase. Biopolymers 2024; 115:e23557. [PMID: 37341434 PMCID: PMC10733556 DOI: 10.1002/bip.23557] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 05/05/2023] [Accepted: 06/07/2023] [Indexed: 06/22/2023]
Abstract
Chemokines are important immune system proteins, many of which mediate inflammation due to their function to activate and cause chemotaxis of leukocytes. An important anti-inflammatory strategy is therefore to bind and inhibit chemokines, which leads to the need for biophysical studies of chemokines as they bind various possible partners. Because a successful anti-chemokine drug should bind at low concentrations, techniques such as fluorescence anisotropy that can provide nanomolar signal detection are required. To allow fluorescence experiments to be carried out on chemokines, a method is described for the production of fluorescently labeled chemokines. First, a fusion-tagged chemokine is produced in Escherichia coli, then efficient cleavage of the N-terminal fusion partner is carried out with lab-produced enterokinase, followed by covalent modification with a fluorophore, mediated by the lab-produced sortase enzyme. This overall process reduces the need for expensive commercial enzymatic reagents. Finally, we utilize the product, vMIP-fluor, in binding studies with the chemokine binding protein vCCI, which has great potential as an anti-inflammatory therapeutic, showing a binding constant for vCCI:vMIP-fluor of 0.37 ± 0.006 nM. We also show how a single modified chemokine homolog (vMIP-fluor) can be used in competition assays with other chemokines and we report a Kd for vCCI:CCL17 of 14 μM. This work demonstrates an efficient method of production and fluorescent labeling of chemokines for study across a broad range of concentrations.
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Affiliation(s)
- Wenyan Guan
- Materials and Biomaterials Science and Engineering, University of California Merced 5200 North Lake Rd. Merced, CA 95343
| | - Ning Zhang
- Current address: Qingdao Institute of Bioenergy and Bioprocess Technology, Chinese Academy of Sciences, Qingdao 266101, China
| | - Arjan Bains
- Chemistry and Biochemistry, University of California Merced 5200 North Lake Rd. Merced, CA 95343
| | - Mourad Sadqi
- Bioengineering, University of California Merced 5200 North Lake Rd. Merced, CA 95343
| | - Cynthia M. Dupureur
- Department of Chemistry and Biochemistry, University of Missouri St. Louis, St. Louis, MO 63043
| | - Patricia J. LiWang
- Molecular Cell Biology, Health Sciences Research Institute, University of California Merced 5200 North Lake Rd. Merced, CA 95343
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Akter S, Afrin S, Kim J, Kang J, Razzak MA, Berggren PO, Hwang I. Production of active Exendin-4 in Nicotiana benthamiana and its application in treatment of type-2 diabetics. Front Plant Sci 2022; 13:1062658. [PMID: 36618620 PMCID: PMC9812950 DOI: 10.3389/fpls.2022.1062658] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 10/06/2022] [Accepted: 12/05/2022] [Indexed: 06/17/2023]
Abstract
GLP-1 (Glucagon-like peptide-1) is a peptide that stimulates insulin secretion from the β-cell for glycemic control of the plasma blood glucose level. Its mimetic exenatide (synthetic Exendin-4) with a longer half-life of approximately 3.3-4 h is widely used in clinical application to treat diabetes. Currently, exenatide is chemically synthesized. In this study, we report that the GLP-1 analogue recombinant Exendin-4 (Exdn-4) can be produced at a high level in Nicotiana benthamiana, with an estimated yield of 50.0 µg/g fresh biomass. For high-level expression, we generated a recombinant gene, B:GB1:ddCBD1m:8xHis : Exendin-4 (BGC : Exdn-4), for the production of Exendin-4 using various domains such as the BiP signal peptide, the GB1 domain (B1 domain of streptococcal G protein), a double cellulose binding domain 1 (CBD1), and 8 His residues (8xHis) to the N-terminus of Exendin-4. GB1 was used to increase the expression, whereas double CBD1 and 8xHis were included as affinity tags for easy purification using MCC beads and Ni2+-NTA resin, respectively. BGC : Exdn-4 was purified by single-step purification to near homogeneity using both Ni2+-NTA resin and microcrystalline cellulose (MCC) beads. Moreover, Exdn-4 without any extra residues was produced from BGC : Exdn-4 bound onto MCC beads by treating with enterokinase. Plant-produced Exdn-4 (Exendin-4) was as effective as chemically synthesized Exendin-4 in glucose-induced insulin secretion (GIIS) from mouse MIN6m9 cells a pancreatic beta cell line.
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Affiliation(s)
- Shammi Akter
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Shajia Afrin
- Department of Research and Development, BioN Inc., Pohang, South Korea
| | - Jaeyoon Kim
- Department of Research and Development, BioN Inc., Pohang, South Korea
| | - Joohyun Kang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Md Abdur Razzak
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
| | - Per-Olof Berggren
- The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm, Sweden
| | - Inhwan Hwang
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, South Korea
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Freiburghaus AU, Roduner J, Hadorn HB. Activation of Human Pancreatic Proteolytic Enzymes: The Role of Enteropeptidase and Trypsin. JPGN Rep 2021; 2:e138. [PMID: 37206452 PMCID: PMC10191478 DOI: 10.1097/pg9.0000000000000138] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/18/2021] [Accepted: 10/08/2021] [Indexed: 05/21/2023]
Abstract
The role of enteropeptidase and trypsin in the process by which pancreatic proteolytic zymogens are converted into active enzymes has been investigated in the past, using purified enzymes and proenzymes of animal origin. In the present study, we wanted to study this process under conditions which come near to the physiological situation, which prevails in the human duodenum and upper small intestine. Patients and Methods Duodenal contents were collected from 2 patients with intestinal enteropeptidase deficiency. The samples expressed no tryptic activity and were used as the source of zymogens. Enteropeptidase or trypsin was added to these samples and the process of zymogen activation was followed by measuring trypsin and chymotrypsin activities. Results When exogenous trypsin was added to the duodenal contents of patients with enteropeptidase deficiency, having no tryptic activity, activation of intrinsic trypsinogen was not observed. When purified porcine or human enteropeptidase was added to the same samples of duodenal contents, this resulted in a rapid, dose-dependent activation of trypsinogen followed by the activation of chymotrypsinogen. Conclusion The study underlines the key role of enteropeptidase in the cascade process, which leads to the presence of active proteolytic enzymes in the human small intestine. The results also explain why patients with congenital deficiency of enteropeptidase are unable to activate trypsinogen by alternative pathways and therefore suffer from a severe disturbance of protein digestion with failure to thrive at young age, hypoproteinemia, and anemia.
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Affiliation(s)
| | | | - Hans Beat Hadorn
- Department of Paediatrics, University of Munich, München, Germany
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Liang Q, Shi J, Jin X, Du G, Kang Z. [Optimization of enterokinase secretion in Pichia pastoris]. Sheng Wu Gong Cheng Xue Bao 2020; 36:1689-1698. [PMID: 32924367 DOI: 10.13345/j.cjb.190577] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Enterokinase is a class of serine proteases that specifically recognize the cleavage DDDDK sequences. Therefore, enterokinase has been widely used as a tool enzyme in the field of biomedicine. Currently, the expression level of enterokinase in Pichia pastoris is low, which hinders related practical applications. In this study, the effects of six different signal peptides SP1, SP2, SP3, SP4, SP7 and SP8 on the secretory expression of enterokinase in Pichia pastoris were studied. Compared with α-factor, SP1 significantly increased the secretory expression of enterokinase (from 6.8 mg/L to 14.3 mg/L), and the enterokinase activity increased from (2 390±212) U/mL to (4 995±378) U/mL in shaking flask cultures. On this basis, the enterokinase activity was further enhanced to (7 219±489) U/mL by co-expressing the endogenous protein Kex2. Moreover, the activity that the mutant strain with N-terminal fusion of three amino acids of WLR was increased to (15 145±920) U/mL with a high specific activity of (1 174 600±53 100) U/mg. The efficient secretory expression of enterokinase laid a foundation for its applications in near future.
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Affiliation(s)
- Qixing Liang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.,Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Jingcheng Shi
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.,Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Xuerong Jin
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.,Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Guocheng Du
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.,Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
| | - Zhen Kang
- Key Laboratory of Industrial Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China.,Key Laboratory of Carbohydrate Chemistry and Biotechnology, Ministry of Education, School of Biotechnology, Jiangnan University, Wuxi 214122, Jiangsu, China
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Hayashi H, Kubo Y, Izumida M, Takahashi E, Kido H, Sato K, Yamaya M, Nishimura H, Nakayama K, Matsuyama T. Enterokinase Enhances Influenza A Virus Infection by Activating Trypsinogen in Human Cell Lines. Front Cell Infect Microbiol 2018; 8:91. [PMID: 29629340 PMCID: PMC5876233 DOI: 10.3389/fcimb.2018.00091] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 03/07/2018] [Indexed: 12/22/2022] Open
Abstract
Cleavage and activation of hemagglutinin (HA) by trypsin-like proteases in influenza A virus (IAV) are essential prerequisites for its successful infection and spread. In host cells, some transmembrane serine proteases such as TMPRSS2, TMPRSS4 and HAT, along with plasmin in the bloodstream, have been reported to cleave the HA precursor (HA0) molecule into its active forms, HA1 and HA2. Some trypsinogens can also enhance IAV proliferation in some cell types (e.g., rat cardiomyoblasts). However, the precise activation mechanism for this process is unclear, because the expression level of the physiological activator of the trypsinogens, the TMPRSS15 enterokinase, is expected to be very low in such cells, with the exception of duodenal cells. Here, we show that at least two variant enterokinases are expressed in various human cell lines, including A549 lung-derived cells. The exogenous expression of these enterokinases was able to enhance the proliferation of IAV in 293T human kidney cells, but the proliferation was reduced by knocking down the endogenous enterokinase in A549 cells. The enterokinase was able to enhance HA processing in the cells, which activated trypsinogen in vitro and in the IAV-infected cells also. Therefore, we conclude that enterokinase plays a role in IAV infection and proliferation by activating trypsinogen to process viral HA in human cell lines.
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Affiliation(s)
- Hideki Hayashi
- Medical University Research Administrator, Nagasaki University School of Medicine, Nagasaki, Japan
| | - Yoshinao Kubo
- Program for Nurturing Global Leaders in Tropical and Emerging Communicable Diseases, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
| | - Mai Izumida
- Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, Nagasaki, Japan
| | - Etsuhisa Takahashi
- Division of Enzyme Chemistry, Institute for Enzyme Research, Tokushima University, Tokushima, Japan
| | - Hiroshi Kido
- Division of Enzyme Chemistry, Institute for Enzyme Research, Tokushima University, Tokushima, Japan
| | - Ko Sato
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan
| | - Mutsuo Yamaya
- Department of Advanced Preventive Medicine for Infectious Disease, Tohoku University Graduate School of Medicine, Sendai, Japan
| | - Hidekazu Nishimura
- Virus Research Center, Clinical Research Division, Sendai Medical Center, Sendai, Japan
| | - Kou Nakayama
- Medical University Research Administrator, Nagasaki University School of Medicine, Nagasaki, Japan
| | - Toshifumi Matsuyama
- Department of Cancer Stem Cell Biology, Graduate School of Biomedical Sciences, Nagasaki University, Nagasaki, Japan
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Skala W, Goettig P, Brandstetter H. Do-it-yourself histidine-tagged bovine enterokinase: a handy member of the protein engineer's toolbox. J Biotechnol 2013; 168:421-5. [PMID: 24184090 PMCID: PMC3863954 DOI: 10.1016/j.jbiotec.2013.10.022] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2013] [Revised: 10/08/2013] [Accepted: 10/14/2013] [Indexed: 11/21/2022]
Abstract
Enterokinase, a two-chain duodenal serine protease, activates trypsinogen by removing its N-terminal propeptide. Due to a clean cut after the non-primed site recognition sequence, the enterokinase light chain is frequently employed in biotechnology to separate N-terminal affinity tags from target proteins with authentic N-termini. In order to obtain large quantities of this protease, we adapted an in vitro folding protocol for a pentahistidine-tagged triple mutant of the bovine enterokinase light chain. The purified, highly active enzyme successfully processed recombinant target proteins, while the pentahistidine-tag facilitated post-cleavage removal. Hence, we conclude that producing enterokinase in one's own laboratory is an efficient alternative to the commercial enzyme.
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Affiliation(s)
| | | | - Hans Brandstetter
- Division of Structural Biology, Department of Molecular Biology, University of Salzburg, Billrothstraße 11, 5020 Salzburg, Austria
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Ceppa EP, Lyo V, Grady EF, Knecht W, Grahn S, Peterson A, Bunnett NW, Kirkwood KS, Cattaruzza F. Serine proteases mediate inflammatory pain in acute pancreatitis. Am J Physiol Gastrointest Liver Physiol 2011; 300:G1033-42. [PMID: 21436316 PMCID: PMC3774216 DOI: 10.1152/ajpgi.00305.2010] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/31/2023]
Abstract
Acute pancreatitis is a life-threatening inflammatory disease characterized by abdominal pain of unknown etiology. Trypsin, a key mediator of pancreatitis, causes inflammation and pain by activating protease-activated receptor 2 (PAR(2)), but the isoforms of trypsin that cause pancreatitis and pancreatic pain are unknown. We hypothesized that human trypsin IV and rat P23, which activate PAR(2) and are resistant to pancreatic trypsin inhibitors, contribute to pancreatic inflammation and pain. Injections of a subinflammatory dose of exogenous trypsin increased c-Fos immunoreactivity, indicative of spinal nociceptive activation, but did not cause inflammation, as assessed by measuring serum amylase and myeloperoxidase activity and by histology. The same dose of trypsin IV and P23 increased some inflammatory end points and caused a more robust effect on nociception, which was blocked by melagatran, a trypsin inhibitor that also inhibits polypeptide-resistant trypsin isoforms. To determine the contribution of endogenous activation of trypsin and its minor isoforms, recombinant enterokinase (ENK), which activates trypsins in the duodenum, was administered into the pancreas. Intraductal ENK caused nociception and inflammation that were diminished by polypeptide inhibitors, including soybean trypsin inhibitor and a specific trypsin inhibitor (type I-P), and by melagatran. Finally, the secretagogue cerulein induced pancreatic nociceptive activation and nocifensive behavior that were reversed by melagatran. Thus trypsin and its minor isoforms mediate pancreatic pain and inflammation. In particular, the inhibitor-resistant isoforms trypsin IV and P23 may be important in mediating prolonged pancreatic inflammatory pain in pancreatitis. Our results suggest that inhibitors of these isoforms could be novel therapies for pancreatitis pain.
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Affiliation(s)
- Eugene P. Ceppa
- 1Department of Surgery, Duke University Medical Center, Durham, North Carolina;
| | | | | | - Wolfgang Knecht
- 4Molecular Pharmacology and Lead Generation, AstraZeneca Research and Development, Mölndal, Sweden
| | | | - Anders Peterson
- 4Molecular Pharmacology and Lead Generation, AstraZeneca Research and Development, Mölndal, Sweden
| | - Nigel W. Bunnett
- Departments of 2Surgery and ,3Physiology, University of California, San Francisco, San Francisco, California; and
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Das KM, Banerjee S, Shekhar N, Damodaran K, Nair R, Somani S, Raiker VP, Jain S, Padmanabhan S. Cloning, soluble expression and purification of high yield recombinant hGMCSF in Escherichia coli. Int J Mol Sci 2011; 12:2064-76. [PMID: 21673940 PMCID: PMC3111651 DOI: 10.3390/ijms12032064] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2011] [Revised: 02/17/2011] [Accepted: 03/20/2011] [Indexed: 11/29/2022] Open
Abstract
Expression of human granulocyte macrophage colony stimulating factor (hGMCSF), a cytokine of therapeutic importance, as a thioredoxin (TRX) fusion has been investigated in Escherichia coli BL21 (DE3) codon plus cells. The expression of this protein was low when cloned under the T7 promoter without any fusion tags. High yield of GMCSF was achieved (∼88 mg/L of fermentation broth) in the shake flask when the gene was fused to the E. coli TRX gene. The protein was purified using a single step Ni(2+)-NTA affinity chromatography and the column bound fusion tag was removed by on-column cleavage with enterokinase. The recombinant hGMCSF was expressed as a soluble and biologically active protein in E. coli, and upon purification, the final yield was ∼44 mg/L in shake flask with a specific activity of 2.3 × 10(8) U/mg. The results of Western blot and RP-HPLC analyses, along with biological activity using the TF-1 cell line, established the identity of the purified hGMCSF. In this paper, we report the highest yield of hGMCSF expressed in E. coli. The bioreactor study shows that the yield of hGMCSF could be easily scalable with a yield of ∼400 mg/L, opening up new opportunities for large scale production hGMCSF in E. coli.
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Affiliation(s)
- Krishna M.P. Das
- Clone Development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mails: (K.M.P.D.); (S.B.)
| | - Sampali Banerjee
- Clone Development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mails: (K.M.P.D.); (S.B.)
| | - Nivedita Shekhar
- Mammalian Bioassay Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mail:
| | - Karpagavalli Damodaran
- Analytical development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mails: (K.D.); (V.P.R.); (S.J.)
| | - Rahul Nair
- Upstream Development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mail:
| | - Sandeep Somani
- Downstream Development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mail:
| | - Veena P. Raiker
- Analytical development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mails: (K.D.); (V.P.R.); (S.J.)
| | - Shweta Jain
- Analytical development Team, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India; E-Mails: (K.D.); (V.P.R.); (S.J.)
| | - Sriram Padmanabhan
- Biotechnology R&D, Lupin Limited, Biotechnology R & D, Gat #1156, Ghotawade Village, Mulshi Taluka, Pune-411042, India
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Fonda I, Kenig M, Gaberc-Porekar V, Pristovaek P, Menart V. Attachment of histidine tags to recombinant tumor necrosis factor-alpha drastically changes its properties. ScientificWorldJournal 2002; 2:1312-25. [PMID: 12805914 PMCID: PMC6009408 DOI: 10.1100/tsw.2002.215] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
When studying two different histidine tags attached to the N-termini of the trimeric cytokine tumor necrosis factor alpha (TNF), the biological activity--measured as cytotoxicity on the L-929 cell line--of both tagged proteins was drastically reduced. The longer His10 tag reduced cytotoxicity to approximately 16% and the shorter His7 tag to 6% of the activity of their nontagged counterparts. After removal of the tags, biological activities reverted to the expected normal values, which clearly shows the key role of the attached histidine tags in diminishing biological activity. Studies on the mechanism of these effects revealed no specific interactions and showed that even the natural flexible N-terminus of TNF presents a steric hindrance for receptor binding, while any extension of the N-terminus increases this hindrance and consequently reduces biological activity. Also, in other proteins, the ligand or substrate binding sites may be hindered by histidine tags, leading to wrong conclusions about biological activity or other properties of the proteins. Thus caution is advised when using His-tagged proteins directly in screening procedures or in research.
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Affiliation(s)
- Irena Fonda
- National Institute of Chemistry, Hajdrihova 19, SI-1000, Ljubljana, Slovenia.
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