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Stern AM, Liu L, Jin S, Liu W, Meunier AL, Ericsson M, Miller MB, Batson M, Sun T, Kathuria S, Reczek D, Pradier L, Selkoe DJ. OUP accepted manuscript. Brain 2022; 145:2528-2540. [PMID: 35084489 PMCID: PMC9337809 DOI: 10.1093/brain/awac023] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 12/01/2021] [Accepted: 12/20/2021] [Indexed: 11/26/2022] Open
Abstract
Aqueously soluble oligomers of amyloid-β peptide may be the principal neurotoxic forms of amyloid-β in Alzheimer’s disease, initiating downstream events that include tau hyperphosphorylation, neuritic/synaptic injury, microgliosis and neuron loss. Synthetic oligomeric amyloid-β has been studied extensively, but little is known about the biochemistry of natural oligomeric amyloid-β in human brain, even though it is more potent than simple synthetic peptides and comprises truncated and modified amyloid-β monomers. We hypothesized that monoclonal antibodies specific to neurotoxic oligomeric amyloid-β could be used to isolate it for further study. Here we report a unique human monoclonal antibody (B24) raised against synthetic oligomeric amyloid-β that potently prevents Alzheimer’s disease brain oligomeric amyloid-β-induced impairment of hippocampal long-term potentiation. B24 binds natural and synthetic oligomeric amyloid-β and a subset of amyloid plaques, but only in the presence of Ca2+. The amyloid-β N terminus is required for B24 binding. Hydroxyapatite chromatography revealed that natural oligomeric amyloid-β is highly avid for Ca2+. We took advantage of the reversible Ca2+-dependence of B24 binding to perform non-denaturing immunoaffinity isolation of oligomeric amyloid-β from Alzheimer’s disease brain-soluble extracts. Unexpectedly, the immunopurified material contained amyloid fibrils visualized by electron microscopy and amenable to further structural characterization. B24-purified human oligomeric amyloid-β inhibited mouse hippocampal long-term potentiation. These findings identify a calcium-dependent method for purifying bioactive brain oligomeric amyloid-β, at least some of which appears fibrillar.
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Affiliation(s)
- Andrew M Stern
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, 60 Fenwood Road Rm 10002Q, Boston, MA 02115, USA
| | - Lei Liu
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, 60 Fenwood Road Rm 10002Q, Boston, MA 02115, USA
| | - Shanxue Jin
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, 60 Fenwood Road Rm 10002Q, Boston, MA 02115, USA
| | - Wen Liu
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, 60 Fenwood Road Rm 10002Q, Boston, MA 02115, USA
| | - Angela L Meunier
- Ann Romney Center for Neurologic Diseases, Department of Neurology, Brigham and Women’s Hospital, 60 Fenwood Road Rm 10002Q, Boston, MA 02115, USA
| | - Maria Ericsson
- Harvard Medical School Electron Microscopy Facility, Goldenson Building 323, 220 Longwood Avenue, Boston, MA 02115, USA
| | - Michael B Miller
- Division of Neuropathology, Department of Pathology, Brigham and Women’s Hospital, 75 Francis St, Boston, MA 02115, USA
| | - Megan Batson
- Sanofi Corporation, 49 New York Avenue, Framingham, MA 01701, USA
| | - Tingwan Sun
- Sanofi Corporation, 49 New York Avenue, Framingham, MA 01701, USA
| | - Sagar Kathuria
- Sanofi Corporation, 49 New York Avenue, Framingham, MA 01701, USA
| | - David Reczek
- Sanofi Corporation, 49 New York Avenue, Framingham, MA 01701, USA
| | - Laurent Pradier
- Sanofi Corporation, 49 New York Avenue, Framingham, MA 01701, USA
| | - Dennis J Selkoe
- Correspondence to: Dennis J. Selkoe Ann Romney Center for Neurologic Diseases Department of Neurology, Brigham and Women’s Hospital 60 Fenwood Road Rm 10002Q Boston, MA 02115, USA E-mail:
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Osterbaan LJ, Hoyle V, Curtis M, DeBlasio S, Rivera KD, Heck M, Fuchs M. Identification of protein interactions of grapevine fanleaf virus RNA-dependent RNA polymerase during infection of Nicotiana benthamiana by affinity purification and tandem mass spectrometry. J Gen Virol 2021; 102:001607. [PMID: 34043500 PMCID: PMC8295916 DOI: 10.1099/jgv.0.001607] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 05/07/2021] [Indexed: 11/24/2022] Open
Abstract
The RNA-dependent RNA polymerase (1EPol) is involved in replication of grapevine fanleaf virus (GFLV, Nepovirus, Secoviridae) and causes vein clearing symptoms in Nicotiana benthamiana. Information on protein 1EPol interaction with other viral and host proteins is scarce. To study protein 1EPol biology, three GFLV infectious clones, i.e. GHu (a symptomatic wild-type strain), GHu-1EK802G (an asymptomatic GHu mutant) and F13 (an asymptomatic wild-type strain), were engineered with protein 1EPol fused to a V5 epitope tag at the C-terminus. Following Agrobacterium tumefaciens-mediated delivery of GFLV clones in N. benthamiana and protein extraction at seven dpi, when optimal 1EPol:V5 accumulation was detected, two viral and six plant putative interaction partners of V5-tagged protein 1EPol were identified for the three GFLV clones by affinity purification and tandem mass spectrometry. This study provides insights into the protein interactome of 1EPol during GFLV systemic infection in N. benthamiana and lays the foundation for validation work.
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Affiliation(s)
- Larissa J. Osterbaan
- Cornell University, Plant Pathology and Plant Microbe-Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Geneva, NY 14456, USA
- Present address: Department of Biology, Utica College, Utica, NY 13502, USA
| | - Victoria Hoyle
- Cornell University, Plant Pathology and Plant Microbe-Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Geneva, NY 14456, USA
| | - Michelle Curtis
- Cornell University, Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Ithaca, NY 14853, USA
| | - Stacy DeBlasio
- Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY 14853, USA
| | - Keith D. Rivera
- Cold Spring Harbor Laboratory, Cold Spring Harbor, NY 11724, USA
- Present address: The Broad Institute of Massachusetts Institute of Technology and Harvard, Cambridge, MA 02142, USA
| | - Michelle Heck
- Cornell University, Plant Pathology and Plant-Microbe Biology Section, School of Integrative Plant Science, Ithaca, NY 14853, USA
- Emerging Pests and Pathogens Research Unit, USDA Agricultural Research Service, Robert W. Holley Center for Agriculture and Health, Ithaca, NY 14853, USA
| | - Marc Fuchs
- Cornell University, Plant Pathology and Plant Microbe-Biology Section, School of Integrative Plant Science, Cornell AgriTech at the New York State Agricultural Experiment Station, Geneva, NY 14456, USA
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Uchibori A, Gyohda A, Chiba A. Ca(2+)-dependent anti-GQ1b antibody in GQ1b-seronegative Fisher syndrome and related disorders. J Neuroimmunol 2016; 298:172-7. [PMID: 27609292 DOI: 10.1016/j.jneuroim.2016.07.021] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2016] [Revised: 07/29/2016] [Accepted: 07/30/2016] [Indexed: 11/29/2022]
Abstract
Although serum IgG anti-ganglioside GQ1b antibody is the most specific biomarker for Fisher syndrome and its related disorders (FS-RD), 10%-30% of the patients are still negative in conventional assays ("GQ1b-seronegative") and the relationship between GQ1b-seropositive and -seronegative patients has been unclear. Some molecules require Ca(2+) cations to interact with their ligands (Ca(2+)-dependency). Here we have investigated whether Ca(2+)-dependency is also present in anti-GQ1b antibodies in FS-RD, especially in the GQ1b-seronegative patients and show that IgG antibodies against GQ1b-related antigens (isolated GQ1b and GQ1b-containing complexes) are detected Ca(2+)-dependently in the majority of GQ1b-seronegative patients with FS-RD. The Ca(2+)-dependent antibodies might react specifically with GQ1b-Ca(2+) conformation. This is the first demonstration of disease-related Ca(2+)-dependent antibodies in neurological field. GQ1b-related pathology would be involved in FS-RD more extensively than previously revealed.
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Affiliation(s)
- Ayumi Uchibori
- Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan
| | - Atsuko Gyohda
- Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan
| | - Atsuro Chiba
- Department of Neurology, Faculty of Medicine, Kyorin University, 6-20-2 Shinkawa, Mitaka, Tokyo 181-8611, Japan.
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Young NM, Watson DC, Cunningham AM, MacKenzie CR. The intrinsic cysteine and histidine residues of the anti-Salmonella antibody Se155-4: a model for the introduction of new functions into antibody-binding sites. Protein Eng Des Sel 2014; 27:383-90. [DOI: 10.1093/protein/gzu018] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Several affinity tags commonly used in chromatographic purification. JOURNAL OF ANALYTICAL METHODS IN CHEMISTRY 2013; 2013:581093. [PMID: 24490106 PMCID: PMC3893739 DOI: 10.1155/2013/581093] [Citation(s) in RCA: 121] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/12/2013] [Revised: 11/11/2013] [Accepted: 12/02/2013] [Indexed: 02/05/2023]
Abstract
Affinity tags have become powerful tools from basic biological research to structural and functional proteomics. They were widely used to facilitate the purification and detection of proteins of interest, as well as the separation of protein complexes. Here, we mainly discuss the benefits and drawbacks of several affinity or epitope tags frequently used, including hexahistidine tag, FLAG tag, Strep II tag, streptavidin-binding peptide (SBP) tag, calmodulin-binding peptide (CBP), glutathione S-transferase (GST), maltose-binding protein (MBP), S-tag, HA tag, and c-Myc tag. In some cases, a large-size affinity tag, such as GST or MBP, can significantly impact on the structure and biological activity of the fusion partner protein. So it is usually necessary to excise the tag by protease. The most commonly used endopeptidases are enterokinase, factor Xa, thrombin, tobacco etch virus, and human rhinovirus 3C protease. The proteolysis features of these proteases are described in order to provide a general guidance on the proteolytic removal of the affinity tags.
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Schmidt PM, Sparrow LG, Attwood RM, Xiao X, Adams TE, McKimm-Breschkin JL. Taking down the FLAG! How insect cell expression challenges an established tag-system. PLoS One 2012; 7:e37779. [PMID: 22701579 PMCID: PMC3368911 DOI: 10.1371/journal.pone.0037779] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2011] [Accepted: 04/27/2012] [Indexed: 02/05/2023] Open
Abstract
In 1988 the preceding journal of Nature Biotechnology, Bio/Technology, reported a work by Hopp and co-workers about a new tag system for the identification and purification of recombinant proteins: the FLAG-tag. Beside the extensively used hexa-his tag system the FLAG-tag has gained broad popularity due to its small size, its high solubility, the presence of an internal Enterokinase cleavage site, and the commercial availability of high-affinity anti-FLAG antibodies. Surprisingly, considering the heavy use of FLAG in numerous laboratories world-wide, we identified in insect cells a post-translational modification (PTM) that abolishes the FLAG-anti-FLAG interaction rendering this tag system ineffectual for secreted proteins. The present publication shows that the tyrosine that is part of the crucial FLAG epitope DYK is highly susceptible to sulfation, a PTM catalysed by the enzyme family of Tyrosylprotein-Sulfo-transferases (TPSTs). We showed that this modification can result in less than 20% of secreted FLAG-tagged protein being accessible for purification questioning the universal applicability of this established tag system.
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Affiliation(s)
- Peter M Schmidt
- CSIRO Materials Science and Engineering, Parkville, Victoria, Australia.
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Young CL, Britton ZT, Robinson AS. Recombinant protein expression and purification: A comprehensive review of affinity tags and microbial applications. Biotechnol J 2012; 7:620-34. [DOI: 10.1002/biot.201100155] [Citation(s) in RCA: 312] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2011] [Revised: 11/23/2011] [Accepted: 11/29/2011] [Indexed: 12/27/2022]
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Parisot J, Kurz K, Hilbrig F, Freitag R. Use of azobenzene amino acids as photo-responsive conformational switches to regulate antibody-antigen interaction. J Sep Sci 2009; 32:1613-24. [DOI: 10.1002/jssc.200800698] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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Mersich C, Jungbauer A. Generic method for quantification of FLAG-tagged fusion proteins by a real time biosensor. ACTA ACUST UNITED AC 2007; 70:555-63. [PMID: 17321594 DOI: 10.1016/j.jbbm.2007.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2006] [Revised: 01/02/2007] [Accepted: 01/05/2007] [Indexed: 11/25/2022]
Abstract
Availability of rapid quantitative protein-expression analysis is often the bottleneck in high throughput screening applications. A real time biosensor was employed to establish a quantitative assay for FLAG fusion proteins using FLAG-tagged bacterial alkaline phosphatase as standard. A range of FLAG-tagged bacterial alkaline phosphatase concentrations were injected over the anti-FLAG M2 antibody surface of the biosensor and used as standards to determine the concentration of different FLAG-tagged proteins with a molecular mass of 18.1 kDa respectively 49.3 kDa from yeast culture supernatants. The M2 immobilized chip was found to retain binding capacity following regeneration for at least 120 cycles. This real time biosensor method allows the quantitation of proteins from culture supernatants using a calibration curve obtained with a different protein. Further benefits include the short assay time of approximately 5 min, the small amount of sample required (35 microl per injection) and the ability to monitor the binding event in real time.
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Affiliation(s)
- Christa Mersich
- Department of Biotechnology, University of Natural Resources and Applied Life Sciences Vienna, Muthgasse 18, Vienna, Austria
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McLean GR, Cho CW, Trotter B, Schrader JW. RIVETS: The recombinant immunoglobulin and viral epitope tag system. J Immunol Methods 2006; 315:208-13. [PMID: 16919678 DOI: 10.1016/j.jim.2006.07.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Revised: 06/08/2006] [Accepted: 07/10/2006] [Indexed: 11/29/2022]
Abstract
The human monoclonal antibody 8F9 binds to a linear 10 amino acid epitope that is present within the N-terminal region of the gB envelope glycoprotein of HCMV. Here we show that this short sequence (ETIYNTTLKY) can function as a tag for the detection of recombinant proteins using antibody 8F9. The AD-2S1 tag was recognized by 8F9 whether present at the N- or C-terminus of recombinant proteins and tagged recombinant proteins could be quantified with multiple analytical techniques such as ELISA, western blotting, immunofluorescence and flow cytometry. Production of 8F9 using different constant regions or constant regions from different species enhances the convenience and range of use of this system which we term the Recombinant Immunoglobulin and Viral Epitope Tag System or RIVETS.
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Affiliation(s)
- Gary R McLean
- The Biomedical Research Centre, University of British Columbia, 2222 Health Sciences Mall, Vancouver, BC, Canada V6T 1Z3.
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Ethier M, Lambert JP, Vasilescu J, Figeys D. Analysis of protein interaction networks using mass spectrometry compatible techniques. Anal Chim Acta 2006; 564:10-8. [PMID: 17723357 DOI: 10.1016/j.aca.2005.12.046] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2005] [Revised: 12/07/2005] [Accepted: 12/12/2005] [Indexed: 11/23/2022]
Abstract
The ability to map protein-protein interactions has grown tremendously over the last few years, making it possible to envision the mapping of whole or targeted protein interaction networks and to elucidate their temporal dynamics. The use of mass spectrometry for the study of protein complexes has proven to be an invaluable tool due to its ability to unambiguously identify proteins from a variety of biological samples. Furthermore, when affinity purification is combined with mass spectrometry analysis, the identification of multimeric protein complexes is greatly facilitated. Here, we review recent developments for the analysis of protein interaction networks by mass spectrometry and discuss the integration of different bioinformatic tools for predicting, validating, and managing interaction datasets.
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Affiliation(s)
- Martin Ethier
- The Ottawa Institute of Systems Biology, University of Ottawa, 451 Smyth Road, Ottawa, Ont., Canada K1H 8M5
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Einhauer A, Jungbauer A. Complex formation of a calcium-dependent antibody: A thermodynamical consideration. J Chromatogr A 2003; 1009:81-7. [PMID: 13677647 DOI: 10.1016/s0021-9673(03)00444-8] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
The elution of FLAG-fusions (an octapeptide with the sequence DYKDDDDK) from immobilized anti-FLAG antibody M1 cannot be explained by a switch of the equilibrium binding constant to a lower value. To get a further insight into thermodynamics, the binding of anti-FLAG antibody M1 to the FLAG peptide was studied by real-time biosensor technology at seven different temperatures in the range from 5 to 35 degrees C. Binding studies were performed in the presence and absence of calcium. Thermodynamic parameters such as change in Gibbs free energy (deltaG), enthalpy (deltaH) and entropy (deltaS) were evaluated from the corresponding equilibrium data applying the integrated Van't Hoff equation. In contrast to similar kinetic data obtained, the contribution of deltaH and deltaS to deltaG in the presence or absence of calcium results in a different conformation of the antibody-antigen complex under binding and non-binding conditions. Therefore, complex dissociation with EDTA must be effected during a transition state of complex formation and dissociation.
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Affiliation(s)
- Adelheid Einhauer
- Institute for Applied Microbiology, University of Natural Resources and Applied Life Sciences, Muthgasse 18, 1190 Vienna, Austria
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Einhauer A, Schuster M, Wasserbauer E, Jungbauer A. Expression and purification of homogenous proteins in Saccharomyces cerevisiae based on ubiquitin-FLAG fusion. Protein Expr Purif 2002; 24:497-504. [PMID: 11922767 DOI: 10.1006/prep.2001.1595] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The construction of an expression vector for increased expression of cytoplasmic proteins in Saccharomyces cerevisiae is described. To enhance the yield of expressed proteins, fusion of ubiquitin to an octapeptide (a FLAG tag) upstream of the respective model genes was applied. During protein maturation ubiquitin is efficiently removed by yeast autologous hydrolases, generating the FLAG octapeptide at the N-terminus. Fusion proteins were recognized by the specific monoclonal antibody M1 directed against the FLAG tag. The FLAG-tagged proteins were purified to homogeneity by immunoaffinity chromatography using an anti-FLAG M1 agarose. Different model proteins, green fluorescent protein, green fluorescent protein-human lysozyme, green fluorescent protein elongation-initiahon factor 5a, green fluorescent protein-rapamycin-selective 25-kDa immunophilin, and green fluorescent protein-heat shock protein 90 beta have been selected to demonstrate the efficiency of the new vector construct.
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Affiliation(s)
- A Einhauer
- Institute for Applied Microbiology, University of Agricultural Sciences, Muthgasse 18, 1190 Vienna, Austria
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Buranda T, Lopez GP, Simons P, Pastuszyn A, Sklar LA. Detection of epitope-tagged proteins in flow cytometry: fluorescence resonance energy transfer-based assays on beads with femtomole resolution. Anal Biochem 2001; 298:151-62. [PMID: 11700971 DOI: 10.1006/abio.2001.5363] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Epitope tagging of expressed proteins is a versatile tool for the detection and purification of the proteins. This approach has been used in protein-protein interaction studies, protein localization, and immunoprecipitation. Among the most popular tag systems is the FLAG epitope tag, which is recognized by three monoclonal antibodies M1, M2, and M5. We describe novel approaches to the detection of epitope-tagged proteins via fluorescence resonance energy transfer on beads. We have synthesized and characterized biotinylated and fluorescein-labeled FLAG peptides and examined the binding of FLAG peptides to commercial streptavidin beads using flow cytometric analysis. A requirement of assay development is the elucidation of parameters that characterize the binding interactions between component systems. We have thus compiled a set of Kd values determined from a series of equilibrium binding experiments with beads, peptides, and antibodies. We have defined conditions for binding biotinylated and fluoresceinated FLAG peptides to beads. Site occupancies of the peptides were determined to be on the order of several million sites per bead and Kd values in the 0.3-2.0 nM range. The affinity for antibody attachment to peptides was determined to be in the low nanomolar range (less than 10 nM) for measurements on beads and solution. We demonstrate the applicability of this methodology to assay development, by detecting femtomole amounts of N-terminal FLAG-bacteria alkaline phosphatase fusion protein. These characterizations form the basis of generalizable and high throughput assays for proteins with known epitopes, for research, proteomic, or clinical applications.
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Affiliation(s)
- T Buranda
- Department of Pathology, University of New Mexico School of Medicine, Albuquerque 87131, USA.
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Einhauer A, Jungbauer A. The FLAG peptide, a versatile fusion tag for the purification of recombinant proteins. JOURNAL OF BIOCHEMICAL AND BIOPHYSICAL METHODS 2001; 49:455-65. [PMID: 11694294 DOI: 10.1016/s0165-022x(01)00213-5] [Citation(s) in RCA: 295] [Impact Index Per Article: 12.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A fusion tag, called FLAG and consisting of eight amino acids (AspTyrLysAspAspAspAspLys) including an enterokinase-cleavage site, was specifically designed for immunoaffinity chromatography. It allows elution under non-denaturing conditions [Bio/Technology, 6 (1988) 1204]. Several antibodies against this peptide have been developed. One antibody, denoted as M1, binds the peptide in the presence of bivalent metal cations, preferably Ca(+). Elution is effected by chelating agents. Another strategy is competitive elution with excess of free FLAG peptide. Antibodies M2 and M5 are applied in this procedure. Examples demonstrating the versatility, practicability and limitations of this technology are given.
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Affiliation(s)
- A Einhauer
- Institute for Applied Microbiology, University of Agriculture and Forestry, Muthgasse 18, 1190 Vienna, Austria.
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16
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Abstract
The FLAG (Sigma, St. Louis, MO, USA) peptide is a frequently used hydrophilic and immunogenic fusion tag which was specifically designed to facilitate rapid purification by immunoaffinity chromatography. The monoclonal antibody M1 recognizes the free N-terminus of the peptide tag in a calcium dependent manner. Dissociation of the complex can be performed by the addition of chelating agents such as EDTA. This effect can be exploited for immunoaffinity purification of FLAG-tagged fusion proteins. Kinetic information obtained from monitoring interactions in real-time measurement (Biacore 2000) using surface plasmon resonance as detection principle did not show any difference for association and dissociation rate constants in the presence (k(a) = 3.03 x 10(3) M(-1) k(d) = 1.25 x 10(-3) s(-1)) and in the absence of Ca2+ (k(a) = 3.59 x 10(3) M(-1) s(-1), k(d) = 1.16 x 10(-3) s(-1)). These findings corroborate the reports from Mol. Immunol. 33 (1996) 601-608 describing similar binding analyzed by enzyme-linked immunosorbent assay experiments. These investigations are in contrast to the observations in immunoaffinity chromatography with immobilized anti-FLAG antibody M1.
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Affiliation(s)
- A Einhauer
- Institute of Applied Microbiology, University of Agricultural Sciences, Vienna, Austria
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17
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Vijesurier RM, Carlock L, Blumenthal RM, Dunbar JC. Role and mechanism of action of C. PvuII, a regulatory protein conserved among restriction-modification systems. J Bacteriol 2000; 182:477-87. [PMID: 10629196 PMCID: PMC94299 DOI: 10.1128/jb.182.2.477-487.2000] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/1999] [Accepted: 10/27/1999] [Indexed: 11/20/2022] Open
Abstract
The PvuII restriction-modification system is a type II system, which means that its restriction endonuclease and modification methyltransferase are independently active proteins. The PvuII system is carried on a plasmid, and its movement into a new host cell is expected to be followed initially by expression of the methyltransferase gene alone so that the new host's DNA is protected before endonuclease activity appears. Previous studies have identified a regulatory gene (pvuIIC) between the divergently oriented genes for the restriction endonuclease (pvuIIR) and modification methyltransferase (pvuIIM), with pvuIIC in the same orientation as and partially overlapping pvuIIR. The product of pvuIIC, C. PvuII, was found to act in trans and to be required for expression of pvuIIR. In this study we demonstrate that premature expression of pvuIIC prevents establishment of the PvuII genes, consistent with the model that requiring C. PvuII for pvuIIR expression provides a timing delay essential for protection of the new host's DNA. We find that the opposing pvuIIC and pvuIIM transcripts overlap by over 60 nucleotides at their 5' ends, raising the possibility that their hybridization might play a regulatory role. We furthermore characterize the action of C. PvuII, demonstrating that it is a sequence-specific DNA-binding protein that binds to the pvuIIC promoter and stimulates transcription of both pvuIIC and pvuIIR into a polycistronic mRNA. The apparent location of C. PvuII binding, overlapping the -10 promoter hexamer and the pvuIICR transcriptional starting points, is highly unusual for transcriptional activators.
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Affiliation(s)
- R M Vijesurier
- Center for Molecular Medicine, Wayne State University School of Medicine, Detroit, Michigan 48201, USA
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