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Abstract
Western blotting (WB), also known as immunoblotting, is a well-known molecular biology method that biologists often use to investigate many features of the protein, ranging from basic protein analysis to disease detection. WB is simple, unique, rapid, widely used routine tool with easy interpretation and definite results. It is being used in various fields of science, research and development, diagnostic labs and hospitals. The principle of WB is to accomplish the separation of proteins based on molecular weight and charge. This review addresses in detail the individual steps involved in the WB technique, its troubleshooting, internal loading controls, total protein staining and its diverse applications in scientific research and clinical settings, along with its future perspectives.
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Xu WX, Wang J, Tang HP, Chen LH, Lian WB, Zhan JM, Gupta SK, Ji CN, Gu SH, Xie Y. A simpler and more cost-effective peptide biosynthetic method using the truncated GST as carrier for epitope mapping. PLoS One 2017; 12:e0186097. [PMID: 29023483 PMCID: PMC5638316 DOI: 10.1371/journal.pone.0186097] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2017] [Accepted: 09/25/2017] [Indexed: 11/19/2022] Open
Abstract
There is a need to develop better methods for epitope mapping and/or identification of antibody-recognizing motifs. Here, we describe improved biosynthetic peptide (BSP) method using a newly developed plasmid pXXGST-3 as vector, which has a viral E7 gene in the cloning sites of pXXGST-1. It is crucial to employ pXXGST-3 instead of pXXGST-1, since it makes use of the BSP method simpler and easier to perform, and more cost-effective for epitope mapping. These merits are embodied in two aspects: i) convenient recovery of double enzyme-digested product due to the existence of 315 bp inserted between BamH I and Sal I sites, and thus greatly reducing the production of self-ligation clones, and ii) no longer requiring control protein when screening recombinant (r-) clones expressing 8/18mer peptides by running polyacrylamide gel electrophoresis. The protocol involves the following core steps: (i) design of plus and minus strands of DNA fragments encoding overlapping 8/18mer peptides; (ii) chemical synthesis of the designed DNA fragments; (iii) development of r-clones using pXXGST-3 vector expressing each 8/18mer peptide fused with truncated GST188 protein; (iv) screening r-clones by running the cell pellets from each induced clone on SDS-PAGE gel followed by sequencing of inserted DNA fragments for each verified r-clone; and (v) Western blotting with either monoclonal antibodies or polyclonal antibodies. This improved GST188-BSP method provides a powerful alternative tool for epitope mapping.
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Affiliation(s)
- Wan-Xiang Xu
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
- * E-mail: (WXX); (SKG); (YX)
| | - Jian Wang
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
| | - Hai-Ping Tang
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
| | - Ling-Han Chen
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
| | - Wen-Bo Lian
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
| | - Jian-Min Zhan
- Division of Reproductive Immunology, Key Lab of Reproduction Regulation of NPFPC, Shanghai Institute of Planned Parenthood Research, Fudan University, Shanghai, P. R. China
| | - Satish K. Gupta
- Reproductive Cell Biology Laboratory, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
- * E-mail: (WXX); (SKG); (YX)
| | - Chao-Neng Ji
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, Shanghai, P. R. China
| | - Shao-Hua Gu
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, Shanghai, P. R. China
| | - Yi Xie
- State Key Laboratory of Genetic Engineering, Institute of Genetics, School of Life Science, Fudan University, Shanghai, P. R. China
- * E-mail: (WXX); (SKG); (YX)
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Hundsberger H, Önder K, Schuller-Götzburg P, Virok DP, Herzog J, Rid R. Assembly and use of high-density recombinant peptide chips for large-scale ligand screening is a practical alternative to synthetic peptide libraries. BMC Genomics 2017; 18:450. [PMID: 28595602 PMCID: PMC5463365 DOI: 10.1186/s12864-017-3814-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2017] [Accepted: 05/23/2017] [Indexed: 01/18/2023] Open
Abstract
Background Recombinant peptide chips could constitute a versatile complementation to state-of-the-art in situ (chemical on-chip) synthesis, particle-based printing, or pre-manufactured peptide spotting. Bottlenecks still impeding a routine implementation - from restricted peptide lengths, low diversity and low array densities to high costs - could so be overcome. Methods To assess overall performance, we assembled recombinant chips composed of 38,400 individual peptide spots on the area of a standard 96-well microtiter plate from comprehensive, highly diverse (>107 single clones) short random peptide libraries. Results Screening of altogether 476,160 clones against Streptavidin uncovered 2 discrete new binders: a characteristic HPQ-motif containing VSHPQAPF and a cyclic CSGSYGSC peptide. Interactions were technically confirmed by fluorescence polarization as well as biolayer-interferometry, and their potential suitability as novel detection tags evaluated by detection of a peptide-fused exemplary test protein. Conclusion From our data we conclude that the presented technical pipeline can reliably identify novel hits, useful as first-generation binders or templates for subsequent ligand design plus engineering.
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Affiliation(s)
- Harald Hundsberger
- Department of Medical and Pharmaceutical Biotechnology, University of Applied Sciences, 3500, Krems, Austria
| | - Kamil Önder
- Research Program for Rational Drug Design in Dermatology and Rheumatology, Department of Dermatology, Paracelsus Medical University of Salzburg, 5020, Salzburg, Austria. .,ProComCure Biotech, 5081, Anif, Austria.
| | - Peter Schuller-Götzburg
- Research Program in Prosthetics, Biomechanics and Biomaterials, Paracelsus Private Medical University, 5020, Salzburg, Austria
| | - Dezso P Virok
- Department of Medicinal Microbiology and Immunobiology, University of Szeged, Szeged, 6722, Hungary
| | - Julia Herzog
- Research Program for Rational Drug Design in Dermatology and Rheumatology, Department of Dermatology, Paracelsus Medical University of Salzburg, 5020, Salzburg, Austria
| | - Raphaela Rid
- Research Program for Rational Drug Design in Dermatology and Rheumatology, Department of Dermatology, Paracelsus Medical University of Salzburg, 5020, Salzburg, Austria
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Ahn SB, Mohamedali A, Anand S, Cheruku HR, Birch D, Sowmya G, Cantor D, Ranganathan S, Inglis DW, Frank R, Agrez M, Nice EC, Baker MS. Characterization of the Interaction between Heterodimeric αvβ6 Integrin and Urokinase Plasminogen Activator Receptor (uPAR) Using Functional Proteomics. J Proteome Res 2014; 13:5956-64. [DOI: 10.1021/pr500849x] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Affiliation(s)
| | | | | | | | | | | | | | | | | | - Ronald Frank
- Department
of Chemical Biology, Helmholtz Centre for Infection Research, Inhoffen
Strasse, 738124 Braunschweig, Germany
| | - Michael Agrez
- Division
of Surgery, John Hunter Hospital, Newcastle, NSW 2310, Australia
| | - Edouard C. Nice
- Department
of Biochemistry and Molecular Biology, Monash University, Melbourne, VIC 3800, Australia
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5
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Forsström B, Axnäs BB, Stengele KP, Bühler J, Albert TJ, Richmond TA, Hu FJ, Nilsson P, Hudson EP, Rockberg J, Uhlen M. Proteome-wide epitope mapping of antibodies using ultra-dense peptide arrays. Mol Cell Proteomics 2014; 13:1585-97. [PMID: 24705123 DOI: 10.1074/mcp.m113.033308] [Citation(s) in RCA: 100] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Antibodies are of importance for the field of proteomics, both as reagents for imaging cells, tissues, and organs and as capturing agents for affinity enrichment in mass-spectrometry-based techniques. It is important to gain basic insights regarding the binding sites (epitopes) of antibodies and potential cross-reactivity to nontarget proteins. Knowledge about an antibody's linear epitopes is also useful in, for instance, developing assays involving the capture of peptides obtained from trypsin cleavage of samples prior to mass spectrometry analysis. Here, we describe, for the first time, the design and use of peptide arrays covering all human proteins for the analysis of antibody specificity, based on parallel in situ photolithic synthesis of a total of 2.1 million overlapping peptides. This has allowed analysis of on- and off-target binding of both monoclonal and polyclonal antibodies, complemented with precise mapping of epitopes based on full amino acid substitution scans. The analysis suggests that linear epitopes are relatively short, confined to five to seven residues, resulting in apparent off-target binding to peptides corresponding to a large number of unrelated human proteins. However, subsequent analysis using recombinant proteins suggests that these linear epitopes have a strict conformational component, thus giving us new insights regarding how antibodies bind to their antigens.
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Affiliation(s)
- Björn Forsström
- From the ‡Science for Life Laboratory, KTH - Royal Institute of Technology, SE-171 21 Stockholm, Sweden
| | | | | | - Jochen Bühler
- ¶NimbleGen Systems GmbH, Roche, Beuthenerstr. 2, D-84478 Waldkraiburg, Germany
| | - Thomas J Albert
- ‖Nimblegen, Roche Applied Science, 500 S. Rosa Rd., Madison, Wisconsin 53719
| | - Todd A Richmond
- ‖Nimblegen, Roche Applied Science, 500 S. Rosa Rd., Madison, Wisconsin 53719
| | - Francis Jingxin Hu
- §Department of Proteomics, KTH - Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Peter Nilsson
- From the ‡Science for Life Laboratory, KTH - Royal Institute of Technology, SE-171 21 Stockholm, Sweden
| | - Elton P Hudson
- §Department of Proteomics, KTH - Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Johan Rockberg
- §Department of Proteomics, KTH - Royal Institute of Technology, SE-106 91 Stockholm, Sweden
| | - Mathias Uhlen
- From the ‡Science for Life Laboratory, KTH - Royal Institute of Technology, SE-171 21 Stockholm, Sweden; §Department of Proteomics, KTH - Royal Institute of Technology, SE-106 91 Stockholm, Sweden;
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Welner S, Trier NH, Houen G, Hansen PR. Identification and mapping of a linear epitope of centromere protein F using monoclonal antibodies. J Pept Sci 2013; 19:95-101. [DOI: 10.1002/psc.2478] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/14/2012] [Revised: 10/31/2012] [Accepted: 11/18/2012] [Indexed: 11/09/2022]
Affiliation(s)
- Simon Welner
- Department of Clinical Biochemistry, Immunology and Genetics; Statens Serum Institut; Artillerivej 5 2300 Copenhagen S Denmark
- IGM - Bioorganic Chemistry, Faculty of Life Sciences; University of Copenhagen; Thorvaldsensvej 40 1871 Frederiksberg C Denmark
- Present address: LEO Pharma A/S; Industriparken 55 2750 Ballerup Denmark
| | - Nicole H. Trier
- Department of Clinical Biochemistry, Immunology and Genetics; Statens Serum Institut; Artillerivej 5 2300 Copenhagen S Denmark
- IGM - Bioorganic Chemistry, Faculty of Life Sciences; University of Copenhagen; Thorvaldsensvej 40 1871 Frederiksberg C Denmark
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Universitetsparken 2 2100 Copenhagen Ø Denmark
| | - Gunnar Houen
- Department of Clinical Biochemistry, Immunology and Genetics; Statens Serum Institut; Artillerivej 5 2300 Copenhagen S Denmark
| | - Paul R. Hansen
- IGM - Bioorganic Chemistry, Faculty of Life Sciences; University of Copenhagen; Thorvaldsensvej 40 1871 Frederiksberg C Denmark
- Department of Drug Design and Pharmacology, Faculty of Health and Medical Sciences; University of Copenhagen; Universitetsparken 2 2100 Copenhagen Ø Denmark
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Cell-based arrays for the identification of interacting polypeptide domains or epitopes. Methods Mol Biol 2013; 1061:211-29. [PMID: 23963940 DOI: 10.1007/978-1-62703-589-7_13] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
The specific regions on proteins which are responsible for protein-protein interaction are called interacting domains, or epitopes in case of antigen-antibody binding. These domains are one feature to characterize proteins and are important in clinical diagnostics and research. For the mapping of such domains the use of protein/peptide arrays has become popular. Regardless of which kind of array, the major requirements are a high number of candidates arranged in the array, high quality, ease of use, and cost-effectiveness. Here, the authors describe a general protocol for mapping the interacting domains of proteins demonstrated by a high affinity protein interaction, the interaction of an antibody to an antigen. The chapter describes a stepwise protocol from library production to the verification of the domain by the use of an automated cell-based polypeptide array, which comprises the named requirements of a good array.
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Maier CJ, Maier RH, Virok DP, Maass M, Hintner H, Bauer JW, Onder K. Construction of a highly flexible and comprehensive gene collection representing the ORFeome of the human pathogen Chlamydia pneumoniae. BMC Genomics 2012; 13:632. [PMID: 23157390 PMCID: PMC3534531 DOI: 10.1186/1471-2164-13-632] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2012] [Accepted: 11/11/2012] [Indexed: 12/02/2022] Open
Abstract
Background The Gram-negative bacterium Chlamydia pneumoniae (Cpn) is the leading intracellular human pathogen responsible for respiratory infections such as pneumonia and bronchitis. Basic and applied research in pathogen biology, especially the elaboration of new mechanism-based anti-pathogen strategies, target discovery and drug development, rely heavily on the availability of the entire set of pathogen open reading frames, the ORFeome. The ORFeome of Cpn will enable genome- and proteome-wide systematic analysis of Cpn, which will improve our understanding of the molecular networks and mechanisms underlying and governing its pathogenesis. Results Here we report the construction of a comprehensive gene collection covering 98.5% of the 1052 predicted and verified ORFs of Cpn (Chlamydia pneumoniae strain CWL029) in Gateway® ‘entry’ vectors. Based on genomic DNA isolated from the vascular chlamydial strain CV-6, we constructed an ORFeome library that contains 869 unique Gateway® entry clones (83% coverage) and an additional 168 PCR-verified ‘pooled’ entry clones, reaching an overall coverage of ~98.5% of the predicted CWL029 ORFs. The high quality of the ORFeome library was verified by PCR-gel electrophoresis and DNA sequencing, and its functionality was demonstrated by expressing panels of recombinant proteins in Escherichia coli and by genome-wide protein interaction analysis for a test set of three Cpn virulence factors in a yeast 2-hybrid system. The ORFeome is available in different configurations of resource stocks, PCR-products, purified plasmid DNA, and living cultures of E. coli harboring the desired entry clone or pooled entry clones. All resources are available in 96-well microtiterplates. Conclusion This first ORFeome library for Cpn provides an essential new tool for this important pathogen. The high coverage of entry clones will enable a systems biology approach for Cpn or host–pathogen analysis. The high yield of recombinant proteins and the promising interactors for Cpn virulence factors described here demonstrate the possibilities for proteome-wide studies.
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Affiliation(s)
- Christina J Maier
- Department of Dermatology, Paracelsus Medical University, Salzburg, Austria
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Li Y, Yue W, Wang Y, Zhang L, Gu M, Xu S. [Detecting EGFR autoantibodies in serums of NSCLC patients with peptide array]. ZHONGGUO FEI AI ZA ZHI = CHINESE JOURNAL OF LUNG CANCER 2011; 13:727-30. [PMID: 20673491 PMCID: PMC6000384 DOI: 10.3779/j.issn.1009-3419.2010.07.13] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/18/2010] [Revised: 04/02/2010] [Indexed: 12/05/2022]
Abstract
背景与目的 自身抗体作为新的肿瘤标志物在肺癌的早期诊断和预后评价中可能发挥重要作用, 本研究利用多肽芯片检测非小细胞肺癌患者血清中表皮生长因子受体(epidermal growth factor receptor, EGFR)的自身抗体, 并筛选自身抗体识别的抗原表位。 方法 使用Intavis公司ASPSL多肽芯片合成仪合成EGFR多肽芯片, 利用多肽芯片检测非小细胞肺癌患者血清中EGFR自身抗体, 并筛选自身抗体识别的抗原表位。结果使用EGFR多肽芯片检测了20例非小细胞肺癌患者, 结果 有6例阳性, 阳性率为30%, 在该6例阳性患者中发现了9个高频位点, 并且有8个高频位点集中在EGFR胞外段的第Ⅲ和第Ⅳ结构域。 结论 本研究为我们进一步研究EGFR和EGFR自身抗体的功能提供了新的线索。
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Affiliation(s)
- Yuan Li
- Department of Cellular and Molecular Biology, Beijing TB and Thoracic Tumor Research Institute, Beijing 101149, China
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Karsunke XYZ, Pschenitza M, Rieger M, Weber E, Niessner R, Knopp D. Screening and characterization of new monoclonal anti-benzo[a]pyrene antibodies using automated flow-through microarray technology. J Immunol Methods 2011; 371:81-90. [PMID: 21723870 DOI: 10.1016/j.jim.2011.06.016] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2011] [Revised: 06/08/2011] [Accepted: 06/16/2011] [Indexed: 11/30/2022]
Abstract
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous environmental pollutants, which can cause cancer in humans. The maximum tolerable limit of benzo[a]pyrene (B[a]P) in drinking water was set to 10 ng/L by the European Commission (Council Directive 98/83/EC), because of its highly carcinogenic and mutagenic effect on humans. In the present investigation, mice were immunized with B[a]P-bovine serum albumin conjugates and 110 generated hybridoma cell lines screened by different techniques to identify clones that produce anti-B[a]P antibodies. Subsequently, a new automated flow-through biochip noncompetitive direct chemiluminescence immunoassay (CLEIA) was compared with conventional indirect and direct enzyme-linked immunosorbent assays (ELISAs). It was demonstrated that the microchip-based screening method compared to ELISA was fast and very sensitive with use of only nanoliter volumes of supernatant. Forty clones could be evaluated in less than 5 min. Six high affinity monoclonal antibodies with different cross-reactivities (CR) for individual PAHs were identified by the chip-based assay and indirect microtiter plate ELISA. In comparison, the direct ELISA in the microtiter plate failed to identify three of these clones. The four antibodies with the highest affinity had half maximum inhibitory concentrations (IC(50) values) between 0.31 and 0.92 μg/L for B[a]P. Affinity constants of these four antibodies were determined by surface plasmon resonance using a water soluble B[a]P-peptide. The observed CR pattern of the four monoclonal antibodies for 16 tested PAHs was quite different. Only one specific antibody for B[a]P was observed, while others were more suitable for class-specific PAH determination.
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Affiliation(s)
- Xaver Y Z Karsunke
- Institute of Hydrochemistry, Technische Universität München, Marchioninistr. 17, 81377 München, Germany
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11
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Van Damme P, Evjenth R, Foyn H, Demeyer K, De Bock PJ, Lillehaug JR, Vandekerckhove J, Arnesen T, Gevaert K. Proteome-derived peptide libraries allow detailed analysis of the substrate specificities of N(alpha)-acetyltransferases and point to hNaa10p as the post-translational actin N(alpha)-acetyltransferase. Mol Cell Proteomics 2011; 10:M110.004580. [PMID: 21383206 DOI: 10.1074/mcp.m110.004580] [Citation(s) in RCA: 108] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The impact of N(α)-terminal acetylation on protein stability and protein function in general recently acquired renewed and increasing attention. Although the substrate specificity profile of the conserved enzymes responsible for N(α)-terminal acetylation in yeast has been well documented, the lack of higher eukaryotic models has hampered the specificity profile determination of N(α)-acetyltransferases (NATs) of higher eukaryotes. The fact that several types of protein N termini are acetylated by so far unknown NATs stresses the importance of developing tools for analyzing NAT specificities. Here, we report on a method that implies the use of natural, proteome-derived modified peptide libraries, which, when used in combination with two strong cation exchange separation steps, allows for the delineation of the in vitro specificity profiles of NATs. The human NatA complex, composed of the auxiliary hNaa15p (NATH/hNat1) subunit and the catalytic hNaa10p (hArd1) and hNaa50p (hNat5) subunits, cotranslationally acetylates protein N termini initiating with Ser, Ala, Thr, Val, and Gly following the removal of the initial Met. In our studies, purified hNaa50p preferred Met-Xaa starting N termini (Xaa mainly being a hydrophobic amino acid) in agreement with previous data. Surprisingly, purified hNaa10p preferred acidic N termini, representing a group of in vivo acetylated proteins for which there are currently no NAT(s) identified. The most prominent representatives of the group of acidic N termini are γ- and β-actin. Indeed, by using an independent quantitative assay, hNaa10p strongly acetylated peptides representing the N termini of both γ- and β-actin, and only to a lesser extent, its previously characterized substrate motifs. The immunoprecipitated NatA complex also acetylated the actin N termini efficiently, though displaying a strong shift in specificity toward its known Ser-starting type of substrates. Thus, complex formation of NatA might alter the substrate specificity profile as compared with its isolated catalytic subunits, and, furthermore, NatA or hNaa10p may function as a post-translational actin N(α)-acetyltransferase.
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Affiliation(s)
- Petra Van Damme
- Department of Medical Protein Research, VIB, B-9000 Ghent, Belgium
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12
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Sedegah M, Kim Y, Peters B, McGrath S, Ganeshan H, Lejano J, Abot E, Banania G, Belmonte M, Sayo R, Farooq F, Doolan DL, Regis D, Tamminga C, Chuang I, Bruder JT, King CR, Ockenhouse CF, Faber B, Remarque E, Hollingdale MR, Richie TL, Sette A. Identification and localization of minimal MHC-restricted CD8+ T cell epitopes within the Plasmodium falciparum AMA1 protein. Malar J 2010; 9:241. [PMID: 20735847 PMCID: PMC2939619 DOI: 10.1186/1475-2875-9-241] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2010] [Accepted: 08/24/2010] [Indexed: 12/14/2022] Open
Abstract
Background Plasmodium falciparum apical membrane antigen-1 (AMA1) is a leading malaria vaccine candidate antigen that is expressed by sporozoite, liver and blood stage parasites. Since CD8+ T cell responses have been implicated in protection against pre-erythrocytic stage malaria, this study was designed to identify MHC class I-restricted epitopes within AMA1. Methods A recombinant adenovirus serotype 5 vector expressing P. falciparum AMA1 was highly immunogenic when administered to healthy, malaria-naive adult volunteers as determined by IFN-γ ELISpot responses to peptide pools containing overlapping 15-mer peptides spanning full-length AMA1. Computerized algorithms (NetMHC software) were used to predict minimal MHC-restricted 8-10-mer epitope sequences within AMA1 15-mer peptides active in ELISpot. A subset of epitopes was synthesized and tested for induction of CD8+ T cell IFN-γ responses by ELISpot depletion and ICS assays. A 3-dimensional model combining Domains I + II of P. falciparum AMA1 and Domain III of P. vivax AMA1 was used to map these epitopes. Results Fourteen 8-10-mer epitopes were predicted to bind to HLA supertypes A01 (3 epitopes), A02 (4 epitopes), B08 (2 epitopes) and B44 (5 epitopes). Nine of the 14 predicted epitopes were recognized in ELISpot or ELISpot and ICS assays by one or more volunteers. Depletion of T cell subsets confirmed that these epitopes were CD8+ T cell-dependent. A mixture of the 14 minimal epitopes was capable of recalling CD8+ T cell IFN-γ responses from PBMC of immunized volunteers. Thirteen of the 14 predicted epitopes were polymorphic and the majority localized to the more conserved front surface of the AMA1 model structure. Conclusions This study predicted 14 and confirmed nine MHC class I-restricted CD8+ T cell epitopes on AMA1 recognized in the context of seven HLA alleles. These HLA alleles belong to four HLA supertypes that have a phenotypic frequency between 23% - 100% in different human populations.
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Affiliation(s)
- Martha Sedegah
- USMMVP, Malaria Department, NMRC, Silver Spring, MD 20910, USA
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