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Matsubara T. Peptide mimotopes to emulate carbohydrates. Chem Soc Rev 2022; 51:8160-8173. [PMID: 36128765 DOI: 10.1039/d2cs00470d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Glycoconjugates on animal cell surfaces are involved in numerous biological functions and diseases, especially the adhesion/metastasis of cancer cells, infection, and the onset of glycan-related diseases. In addition to glycoantigen detection, the regulation of glycan (carbohydrate)-protein interactions is needed to develop therapeutic strategies for glycan-related diseases. Preparation of a diverse range of glycan derivatives requires a massive effort, but the preparation and identification of alternative glycan-mimetic peptide mimotopes may provide a solution to this issue. Peptide mimotopes are recognized by glycan-binding proteins, such as lectins, enzymes, and antibodies, alternative to glycan ligands. Phage-display technology is the first choice in the selection of "glycan (carbohydrate)-mimetic peptide mimotopes" from a large repertoire of library sequences. This tutorial review describes the advantages of peptide mimotopes in comparison to glycan ligands, as well as their structural and functional mimicry. The detailed library design is followed by a description of the strategy used to improve affinity, and finally, an outline of the vaccine application of glycan-mimetic peptides is provided.
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Affiliation(s)
- Teruhiko Matsubara
- Department of Biosciences and Informatics, Keio University, 3-14-1 Hiyoshi, Kouhoku-ku, Yokohama 223-8522, Japan.
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2
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Antibody specificity and promiscuity. Biochem J 2019; 476:433-447. [PMID: 30723137 DOI: 10.1042/bcj20180670] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2018] [Revised: 01/06/2019] [Accepted: 01/07/2019] [Indexed: 12/16/2022]
Abstract
The immune system is capable of making antibodies against anything that is foreign, yet it does not react against components of self. In that sense, a fundamental requirement of the body's immune defense is specificity. Remarkably, this ability to specifically attack foreign antigens is directed even against antigens that have not been encountered a priori by the immune system. The specificity of an antibody for the foreign antigen evolves through an iterative process of somatic mutations followed by selection. There is, however, accumulating evidence that the antibodies are often functionally promiscuous or multi-specific which can lead to their binding to more than one antigen. An important cause of antibody cross-reactivity is molecular mimicry. Molecular mimicry has been implicated in the generation of autoimmune response. When foreign antigen shares similarity with the component of self, the antibodies generated could result in an autoimmune response. The focus of this review is to capture the contrast between specificity and promiscuity and the structural mechanisms employed by the antibodies to accomplish promiscuity, at the molecular level. The conundrum between the specificity of the immune system for foreign antigens on the one hand and the multi-reactivity of the antibody on the other has been addressed. Antibody specificity in the context of the rapid evolution of the antigenic determinants and molecular mimicry displayed by antigens are also discussed.
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Schmidt R, Krizsan A, Volke D, Knappe D, Hoffmann R. Identification of New Resistance Mechanisms in Escherichia coli against Apidaecin 1b Using Quantitative Gel- and LC–MS-Based Proteomics. J Proteome Res 2016; 15:2607-17. [DOI: 10.1021/acs.jproteome.6b00169] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Rico Schmidt
- Institute
of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103 Leipzig, Germany
- Center
for Biotechnology and Biomedicine (BBZ), Universität Leipzig, 04103 Leipzig, Germany
| | - Andor Krizsan
- Institute
of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103 Leipzig, Germany
- Center
for Biotechnology and Biomedicine (BBZ), Universität Leipzig, 04103 Leipzig, Germany
| | - Daniela Volke
- Institute
of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103 Leipzig, Germany
- Center
for Biotechnology and Biomedicine (BBZ), Universität Leipzig, 04103 Leipzig, Germany
| | - Daniel Knappe
- Institute
of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103 Leipzig, Germany
- Center
for Biotechnology and Biomedicine (BBZ), Universität Leipzig, 04103 Leipzig, Germany
| | - Ralf Hoffmann
- Institute
of Bioanalytical Chemistry, Faculty of Chemistry and Mineralogy, Universität Leipzig, 04103 Leipzig, Germany
- Center
for Biotechnology and Biomedicine (BBZ), Universität Leipzig, 04103 Leipzig, Germany
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Kell DB, Kenny LC. A Dormant Microbial Component in the Development of Preeclampsia. Front Med (Lausanne) 2016; 3:60. [PMID: 27965958 PMCID: PMC5126693 DOI: 10.3389/fmed.2016.00060] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2016] [Accepted: 11/04/2016] [Indexed: 12/12/2022] Open
Abstract
Preeclampsia (PE) is a complex, multisystem disorder that remains a leading cause of morbidity and mortality in pregnancy. Four main classes of dysregulation accompany PE and are widely considered to contribute to its severity. These are abnormal trophoblast invasion of the placenta, anti-angiogenic responses, oxidative stress, and inflammation. What is lacking, however, is an explanation of how these themselves are caused. We here develop the unifying idea, and the considerable evidence for it, that the originating cause of PE (and of the four classes of dysregulation) is, in fact, microbial infection, that most such microbes are dormant and hence resist detection by conventional (replication-dependent) microbiology, and that by occasional resuscitation and growth it is they that are responsible for all the observable sequelae, including the continuing, chronic inflammation. In particular, bacterial products such as lipopolysaccharide (LPS), also known as endotoxin, are well known as highly inflammagenic and stimulate an innate (and possibly trained) immune response that exacerbates the inflammation further. The known need of microbes for free iron can explain the iron dysregulation that accompanies PE. We describe the main routes of infection (gut, oral, and urinary tract infection) and the regularly observed presence of microbes in placental and other tissues in PE. Every known proteomic biomarker of "preeclampsia" that we assessed has, in fact, also been shown to be raised in response to infection. An infectious component to PE fulfills the Bradford Hill criteria for ascribing a disease to an environmental cause and suggests a number of treatments, some of which have, in fact, been shown to be successful. PE was classically referred to as endotoxemia or toxemia of pregnancy, and it is ironic that it seems that LPS and other microbial endotoxins really are involved. Overall, the recognition of an infectious component in the etiology of PE mirrors that for ulcers and other diseases that were previously considered to lack one.
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Affiliation(s)
- Douglas B. Kell
- School of Chemistry, The University of Manchester, Manchester, UK
- The Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
- Centre for Synthetic Biology of Fine and Speciality Chemicals, The University of Manchester, Manchester, UK
- *Correspondence: Douglas B. Kell,
| | - Louise C. Kenny
- The Irish Centre for Fetal and Neonatal Translational Research (INFANT), University College Cork, Cork, Ireland
- Department of Obstetrics and Gynecology, University College Cork, Cork, Ireland
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Tapryal S, Gaur V, Kaur KJ, Salunke DM. Structural evaluation of a mimicry-recognizing paratope: plasticity in antigen-antibody interactions manifests in molecular mimicry. THE JOURNAL OF IMMUNOLOGY 2013; 191:456-63. [PMID: 23733869 DOI: 10.4049/jimmunol.1203260] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Molecular mimicry manifests antagonistically with respect to the specificity of immune recognition. However, it often occurs because different Ags share surface topologies in terms of shape or chemical nature. It also occurs when a flexible paratope accommodates dissimilar Ags by adjusting structural features according to the antigenic epitopes or differential positioning in the Ag combining site. Toward deciphering the structural basis of molecular mimicry, mAb 2D10 was isolated from a maturing immune response elicited against methyl α-d-mannopyranoside and also bound equivalently to a dodecapeptide. The physicochemical evidence of this carbohydrate-peptide mimicry in the case of mAb 2D10 had been established earlier. These studies had strongly suggested direct involvement of a flexible paratope in the observed mimicry. Surprisingly, comparison of the Ag-free structure of single-chain variable fragment 2D10 with those bound to sugar and peptide Ags revealed a conformationally invariant state of the Ab while binding to chemically and structurally disparate Ags. This equivalent binding of the two dissimilar Ags was through mutually independent interactions, demonstrating functional equivalence in the absence of structural correlation. Thus, existence of a multispecific, mature Ab in the secondary immune response was evident, as was the plasticity in the interactions while accommodating topologically diverse Ags. Although our data highlight the structural basis of receptor multispecificity, they also illustrate mechanisms adopted by the immune system to neutralize the escape mutants generated during pathogenic insult.
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Affiliation(s)
- Suman Tapryal
- National Institute of Immunology, New Delhi 110067, India
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Agostino M, Sandrin MS, Thompson PE, Ramsland PA, Yuriev E. Peptide inhibitors of xenoreactive antibodies mimic the interaction profile of the native carbohydrate antigens. Biopolymers 2011; 96:193-206. [PMID: 20564023 DOI: 10.1002/bip.21427] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Carbohydrate-antibody interactions mediate many cellular processes and immune responses. Carbohydrates expressed on the surface of cells serve as recognition elements for particular cell types, for example, in the ABO(H) blood group system. Antibodies that recognize host-incompatible ABO(H) system antigens exist in the bloodstream of all individuals (except AB individuals), preventing blood transfusion and organ transplantation between incompatible donors and recipients. A similar barrier exists for cross-species transplantation (xenotransplantation), in particular for pig-to-human transplantation. All humans express antibodies against the major carbohydrate xenoantigen, Galalpha (1,3)Gal (alphaGal), preventing successful xenotransplantation. Although antibody binding sites are precisely organized so as to selectively bind a specific antigen, many antibodies recognize molecules other than their native antigen. A range of peptides have been identified that can mimic carbohydrates and inhibit anti-alphaGal antibodies. However, the structural basis of how the peptides achieved this was not known. Previously, we developed an in silico method which we used to investigate carbohydrate recognition by a panel of anti-alphaGal antibodies. The method involves molecular docking of carbohydrates to antibodies and uses the docked carbohydrate poses to generate maps of th antibody binding sites in terms of prevalent hydrogen bonding and van der Waals interactions. We have applied this method to investigate peptide recognition by the anti-alphaGal antibodies. It was found that the site maps of the peptides and the carbohydrates were similar, indicating that the peptides interact with the same residues as those involved in carbohydrate recognition. This study demonstrates the potential for "design by mapping" of anti-carbohydrate antibody inhibitors.
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Affiliation(s)
- Mark Agostino
- Medicinal Chemistry and Drug Action, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC 3052, Australia
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Agostino M, Sandrin MS, Thompson PE, Farrugia W, Ramsland PA, Yuriev E. Carbohydrate-mimetic peptides: structural aspects of mimicry and therapeutic implications. Expert Opin Biol Ther 2011; 11:211-24. [DOI: 10.1517/14712598.2011.542140] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
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Tapryal S, Krishnan L, Batra JK, Kaur KJ, Salunke DM. Cloning, expression and efficient refolding of carbohydrate-peptide mimicry recognizing single chain antibody 2D10. Protein Expr Purif 2010; 72:162-8. [PMID: 20363331 DOI: 10.1016/j.pep.2010.03.024] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2009] [Revised: 03/25/2010] [Accepted: 03/29/2010] [Indexed: 11/24/2022]
Abstract
Carbohydrate-peptide mimicry was found to be manifested through the cross-reactivity of an anti-mannopyranoside monoclonal antibody 2D10 (mAb-2D10) with YPY motif containing 12-mer peptide (DVFYPYPYASGS). Such multiple binding options for a monoclonal antibody could emanate from the possible flexibility of the antigen combining site. To address the molecular details of this phenomenon, single chain antibody (scFv) containing the antigen combining variable domain of mAb-2D10 was constructed. The present work describes the cloning, expression, purification and efficient refolding of scFv-2D10 and its His(6) tag fusion variants. The scFv expressed poorly in soluble/active form in the periplasmic compartment and concurrently exhibited higher tendency towards accumulation in inclusion bodies inside the Escherichia coli cytoplasm. The scFv was refolded from the inclusion bodies with approximately 68% yield using a previously described protocol which employed concomitant removal of the chaotropic and oxidizing reagents along with the additives. However, their differential removal, as described in the present report resulted in approximately 97% effective yield of the soluble scFv-2D10, an increase of 42%. The binding kinetics of the refolded scFv for both the mimicking ligands was examined using surface plasmon resonance experiments. The scFv-2D10 exhibited binding affinities similar to those reported for mAb-2D10 (IgG) showing that the modifications introduced in the refolding protocol have facilitated efficient preparation of active 2D10 scFv.
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Affiliation(s)
- Suman Tapryal
- National Institute of Immunology, Aruna Asaf Ali Road, New Delhi 110067, India
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Pandey G, Fatma T, Komath SS. Specific Interaction of the Legume Lectins, Concanavalin A and Peanut Agglutinin, with Phycocyanin. Photochem Photobiol 2009; 85:1126-33. [DOI: 10.1111/j.1751-1097.2009.00571.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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10
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Yu L, Yu PS, Yee Yen Mui E, McKelvie JC, Pham TPT, Yap YW, Wong WQ, Wu J, Deng W, Orner BP. Phage display screening against a set of targets to establish peptide-based sugar mimetics and molecular docking to predict binding site. Bioorg Med Chem 2009; 17:4825-32. [DOI: 10.1016/j.bmc.2009.03.054] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2008] [Revised: 03/24/2009] [Accepted: 03/25/2009] [Indexed: 10/21/2022]
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Johnson MA, Pinto BM. Structural and functional studies of Peptide-carbohydrate mimicry. Top Curr Chem (Cham) 2008; 273:55-116. [PMID: 23605459 DOI: 10.1007/128_2007_18] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Certain peptides act as molecular mimics of carbohydrates in that they are specifically recognizedby carbohydrate-binding proteins. Peptides that bind to anti-carbohydrate antibodies, carbohydrate-processingenzymes, and lectins have been identified. These peptides are potentially useful as vaccines andtherapeutics; for example, immunologically functional peptide molecular mimics (mimotopes) can strengthenor modify immune responses induced by carbohydrate antigens. However, peptides that bind specificallyto carbohydrate-binding proteins may not necessarily show the corresponding biological activity, andfurther selection based on biochemical studies is always required. The degree of structural mimicryrequired to generate the desired biological activity is therefore an interesting question. This reviewwill discuss recent structural studies of peptide-carbohydrate mimicry employing NMR spectroscopy,X-ray crystallography, and molecular modeling, as well as relevant biochemical data. These studiesprovide insights into the basis of mimicry at the molecular level. Comparisons with other carbohydrate-mimeticcompounds, namely proteins and glycopeptides, will be drawn. Finally, implications for the designof new therapeutic compounds will also be presented.
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Affiliation(s)
- Margaret A Johnson
- Department of Molecular Biology, The Scripps Research Institute, 10550 North Torrey Pines Rd., MB-44, 92037, La Jolla, CA, USA,
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12
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Role of antibody paratope conformational flexibility in the manifestation of molecular mimicry. Biophys J 2007; 94:1367-76. [PMID: 18032557 DOI: 10.1529/biophysj.107.108654] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Molecular mimicry is a recurrent theme in host defense processes. The correlation of functional mimicry with the structural features of the antibody paratope has been investigated, addressing the consequences of mimicry in host immune mechanisms. Two anti-mannopyranoside antibodies, 1H7 and 2D10, representing the possible extremes of the recognition spectrum with regard to peptide-carbohydrate mimicry were examined. Crystallographic and molecular dynamics simulation analyses established correlation between the antibody flexibility and the manifestation of mimicry. It was evident that monoclonal antibody (mAb) 1H7, which has a narrow specificity in favor of the immunizing antigen, exhibited structural invariance. On the other hand, the antigen-combining site of 2D10, the mimicry-recognizing antibody, showed substantial divergence in the complementarity determining region loops. The docking of mannopyranoside within the antibody paratope revealed multiple modes of binding of the carbohydrate antigen in mAb 2D10 vis à vis single docking mode in mAb 1H7, which overlapped with the common monosaccharide binding site defined in anti-carbohydrate antibodies. The presence of additional antigen binding modes is perhaps reflective of the utilization of conformational flexibility in molecular mimicry. A relatively broader recognition repertoire--attributable to paratope flexibility--may facilitate the recognition of altered antigens of invading pathogens while the antibodies with narrow recognition specificity maintain the fidelity of the response.
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Krishnan L, Lomash S, Raj BPJ, Kaur KJ, Salunke DM. Paratope plasticity in diverse modes facilitates molecular mimicry in antibody response. THE JOURNAL OF IMMUNOLOGY 2007; 178:7923-31. [PMID: 17548630 DOI: 10.4049/jimmunol.178.12.7923] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The immune response against methyl-alpha-D-mannopyranoside mimicking 12-mer peptide (DVFYPYPYASGS) was analyzed at the molecular level towards understanding the equivalence of these otherwise disparate Ags. The Ab 7C4 recognized the immunizing peptide and its mimicking carbohydrate Ag with comparable affinities. Thermodynamic analyses of the binding interactions of both molecules suggested that the mAb 7C4 paratope lacks substantial conformational flexibility, an obvious possibility for facilitating binding to chemically dissimilar Ags. Favorable changes in entropy during binding indicated the importance of hydrophobic interactions in recognition of the mimicking carbohydrate Ag. Indeed, the topology of the Ag-combining site was dominated by a cluster of aromatic residues, contributed primarily by the specificity defining CDR H3. Epitope-mapping analysis demonstrated the critical role of three aromatic residues of the 12-mer in binding to the Ab. Our studies delineate a mechanism by which mimicry is manifested in the absence of either structural similarity of the epitopes or conformational flexibility in the paratope. An alternate mode of recognition of dissimilar yet mimicking Ags by the anti-peptide Ab involves plasticity associated with aromatic/hydrophobic and van der Waals interactions. Thus, antigenic mimicry may be a consequence of paratope-specific modulations rather than being dependent only on the properties of the epitope. Such modulations may have evolved toward minimizing the consequences of antigenic variation by invading pathogens.
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Affiliation(s)
- Lavanya Krishnan
- National Institute of Immunology, Aruna Asaf Ali Road, New Delhi-100067, India
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Kaur KJ, Pandey S, Salunke DM. Design of a functionally equivalent nonglycosylated analog of the glycopeptide antibiotic formaecin I. Protein Sci 2007; 16:309-15. [PMID: 17242433 PMCID: PMC2203295 DOI: 10.1110/ps.062581707] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Abstract
Various nonglycosylated analogs were designed in order to explore the role of glycosylation in formaecin I, an antibacterial glycopeptide of insect origin. The functional behavior of a designed nonglycosylated analog (P(7),endo P(8a),DeltaT(11))formaecin I was found to be similar to that of native glycosylated peptide. Both the peptides showed similar antibacterial activities against Escherichia coli and Salmonella strains. The designed nonglycosylated analog (P(7),endo P(8a),DeltaT(11))formaecin I has low binding affinity to LPS identical to that of native glycopeptide, formaecin I. Both the peptides have similar killing kinetics and are nontoxic to erythrocytes. Formaecin I and designed nonglycosylated (P(7),endo P(8a),DeltaT(11))formaecin I have no definite conformational features associated with them. The glycosylated residue of threonine in formaecin I and proline residues in designed peptide [(P(7),endo P(8a),DeltaT(11))formaecin I], possibly help in stabilizing the correct conformation that facilitates presentation of the peptide to its receptor. It is evident that a functionally equivalent nonglycosylated analog of native glycosylated antibacterial peptide can be designed by strategically modifying the sequence.
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Affiliation(s)
- Kanwal J Kaur
- Structural Biology Unit, National Institute of Immunology, Aruna Asal Ali Marg, New Delhi 110-067, India.
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Pashov AD, Plaxco J, Kaveri SV, Monzavi-Karbassi B, Harn D, Kieber-Emmons T. Multiple antigenic mimotopes of HIV carbohydrate antigens: relating structure and antigenicity. J Biol Chem 2006; 281:29675-83. [PMID: 16899462 DOI: 10.1074/jbc.m604137200] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carbohydrate mimetic peptides are designable, and they can carry T-cell epitopes and circumvent tolerance. A mimic-based human immunodeficiency virus (HIV) vaccine can be a viable alternative to carbohydrate-based antigens if the diversity of epitopes found on gp120 can be recapitulated. To improve existing mimics, an attempt was made to study the structural correlates of the observed polyspecificity of carbohydrate mimetic peptides based on the Y(P/R)Y motif in more detail. A carbohydrate mimetic peptide, D002 (RGGLCYCRYRYCVCVGR), bound a number of lectins with different specificities. Although this peptide reacted strongly with both lotus and concanavalin A (ConA) lectins, it bound to lotus stronger than ConA. By varying the central motif RYRY, five versions were produced in multiple antigen peptide format, and their avidity for lotus and ConA lectins was tested by surface plasmon resonance. Although the kinetic parameters were similar, the version based on the sequence YPYRY had an optimal affinity for both lectins as well as improved avidity for wheat germ agglutinin and phytohemagglutinin. Thus, as far as lectin specificity is concerned, YPYRY had improved multiple antigenic properties. Both RYRY and YPYRY precipitated antibodies from human IgG for intravenous use that bound to gp120 in vitro and immunoprecipitated gp120 from transfected CHO-PI cells. Thus, Y(P/R)Y motifs mimic multiple carbohydrate epitopes, many of which are found on HIV, and preimmune human IgG antibodies that bind to HIV carbohydrates cross-react to a comparable extent with both RYRY and YPYRY carbohydrate mimetic peptides.
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Affiliation(s)
- Anastas D Pashov
- Department of Pathology, University of Arkansas for Medical Sciences, Little Rock, Arkansas 72205, USA
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Buchwald UK, Lees A, Steinitz M, Pirofski LA. A peptide mimotope of type 8 pneumococcal capsular polysaccharide induces a protective immune response in mice. Infect Immun 2005; 73:325-33. [PMID: 15618169 PMCID: PMC538987 DOI: 10.1128/iai.73.1.325-333.2005] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Increasing antibiotic resistance and a rising patient population at risk for infection due to impaired immunity underscore the importance of vaccination against pneumococci. However, available capsular polysaccharide vaccines are often poorly immunogenic in patients at risk for pneumococcal disease. The goal of this study was to explore the potential of peptide mimotopes to function as alternative vaccine antigens to elicit a type-specific antibody response to pneumococci. We used a human monoclonal immunoglobulin A (IgA) antibody (NAD) to type 8 Streptococcus pneumoniae capsular polysaccharide (type 8 PS) to screen a phage display library, and the phage PUB1 displaying the peptide FHLPYNHNWFAL was selected after three rounds of biopanning. Inhibition studies with phage-displayed peptide or the peptide PUB1 and type 8 PS showed that PUB1 is a mimetic of type 8 PS. PUB1 conjugated to tetanus toxoid (PUB1-TT) induced a type 8 PS-specific antibody response in BALB/c mice, further defining it as a mimotope of type 8 PS. The administration of immune sera obtained from PUB1-TT-immunized mice earlier (days 14 and 21) and later (days 87 and 100) after primary and reimmunization resulted in a highly significant prolongation of the survival of naive mice after pneumococcal challenge compared to controls. The survival of PUB1-TT-immunized mice was also prolonged after pneumococcal challenge nearly 4 months after primary immunization. The efficacy of PUB1-TT-induced immune sera provides proof of principle that a mimotope-induced antibody response can protect against pneumococci and suggests that peptide mimotopes selected by type-specific human antibodies could hold promise as immunogens for pneumococci.
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Affiliation(s)
- Ulrike K Buchwald
- Albert Einstein College of Medicine, Division of Infectious Diseases, Room 709 Forchheimer Bldg., 1300 Morris Park Ave., Bronx, NY 10461, USA
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Goel M, Krishnan L, Kaur S, Kaur KJ, Salunke DM. Plasticity within the Antigen-Combining Site May Manifest as Molecular Mimicry in the Humoral Immune Response. THE JOURNAL OF IMMUNOLOGY 2004; 173:7358-67. [PMID: 15585860 DOI: 10.4049/jimmunol.173.12.7358] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Structural and physiological facets of carbohydrate-peptide mimicry were addressed by analyzing the Ab response to alpha-d-mannopyranoside. mAbs against alpha-d-mannopyranoside were generated and screened with the carbohydrate-mimicking 12 mer (DVFYPYPYASGS) peptide. Three mAbs, 2D10, 1H11, and 1H7, which were subjected to detailed analysis, exhibit diverse V gene usage, indicating their independent germline origins. Although the mAb 1H7 was specific in binding only to the immunizing Ag, the Abs 2D10 and 1H11 recognize the 12 mer peptide as well as the immunogen, alpha-d-mannopyranoside. The Abs that recognize mimicry appear to bind to a common epitope on the peptide and do not share the mode of peptide binding with Con A. Binding kinetics and thermodynamics of Ag recognition suggest that the Ab that does not recognize peptide-carbohydrate mimicry probably has a predesigned mannopyranoside-complementing site. In contrast, the mimicry-recognizing Abs adopt the Ag-combining site only on exposure to the sugar, exploiting the conformational flexibility in the CDRs. Although the mAb 1H7 showed unique specificity toward mannopyranoside, the mimicry-recognizing Abs 2D10 and 1H11 exhibited degenerate specificities with regard to other sugar moieties. It is proposed that the degeneracy of specificity arising from the plasticity at the Ag-combining site in a subset of the Ab clones may be responsible for exhibiting molecular mimicry in the context of Ab response.
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Affiliation(s)
- Manisha Goel
- National Institute of Immunology, New Delhi, India
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Olson LJ, Zhang J, Dahms NM, Kim JJP. Twists and turns of the cation-dependent mannose 6-phosphate receptor. Ligand-bound versus ligand-free receptor. J Biol Chem 2002; 277:10156-61. [PMID: 11786557 DOI: 10.1074/jbc.m112230200] [Citation(s) in RCA: 40] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Mannose 6-phosphate receptors (MPRs) participate in the biogenesis of lysosomes in higher eukaryotes by transporting soluble acid hydrolases from the trans-Golgi network to late endosomal compartments. The receptors release their ligands into the acidic environment of the late endosome and then return to the trans-Golgi network to repeat the process. However, the mechanism that facilitates ligand binding and dissociation upon changes in pH is not known. We report the crystal structure of the extracytoplasmic domain of the homodimeric cation-dependent MPR in a ligand-free form at pH 6.5. A comparison of the ligand-bound and ligand-free structures reveals a significant change in quaternary structure as well as a reorganization of the binding pocket, with the most prominent change being the relocation of a loop (residues Glu(134)-Cys(141)). The movements involved in the bound-to-free transition of the cation-dependent MPR are reminiscent of those of the oxy-to-deoxy hemoglobin transition. These results allow us to propose a mechanism by which the receptor regulates its ligand binding upon changes in pH; the pK(a) of Glu(133) appears to be responsible for ligand release in the acidic environment of the late endosomal compartment, and the pK(a) values of the sugar phosphate and His(105) are accountable for its inability to bind ligand at the cell surface where the pH is about 7.4.
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Affiliation(s)
- Linda J Olson
- Department of Biochemistry, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA
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Goel M, Jain D, Kaur KJ, Kenoth R, Maiya BG, Swamy MJ, Salunke DM. Functional equality in the absence of structural similarity: an added dimension to molecular mimicry. J Biol Chem 2001; 276:39277-81. [PMID: 11504727 DOI: 10.1074/jbc.m105387200] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
The crystal structure of meso-tetrasulfonatophenylporphyrin complexed with concanavalin A (ConA) was determined at 1.9 A resolution. Comparison of this structure with that of ConA bound to methyl alpha-d-mannopyranoside provided direct structural evidence of molecular mimicry in the context of ligand receptor binding. The sulfonatophenyl group of meso-tetrasulfonatophenylporphyrin occupies the same binding site on ConA as that of methyl alpha-d-mannopyranoside, a natural ligand. A pair of stacked porphyrin molecules stabilizes the crystal structure by end-to-end cross-linking with ConA resulting in a network similar to that observed upon agglutination of cells by lectins. The porphyrin binds to ConA predominantly through hydrogen bonds and water-mediated interactions. The sandwiched water molecules in the complex play a cementing role, facilitating favorable binding of porphyrin. Seven of the eight hydrogen bonds observed between methyl alpha-d-mannopyranoside and ConA are mimicked by the sulfonatophenyl group of porphyrin after incorporating two water molecules. Thus, the similarity in chemical interactions was manifested in terms of functional mimicry despite the obvious structural dissimilarity between the sugar and the porphyrin.
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Affiliation(s)
- M Goel
- Structural Biology Unit, National Institute of Immunology, New Delhi 110067, India
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20
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Abstract
We have compiled a comprehensive list of the articles published in the year 2000 that describe work employing commercial optical biosensors. Selected reviews of interest for the general biosensor user are highlighted. Emerging applications in areas of drug discovery, clinical support, food and environment monitoring, and cell membrane biology are emphasized. In addition, the experimental design and data processing steps necessary to achieve high-quality biosensor data are described and examples of well-performed kinetic analysis are provided.
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Affiliation(s)
- R L Rich
- Center for Biomolecular Interaction Analysis, University of Utah, Salt Lake City, UT 84132, USA
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Jain D, Kaur KJ, Salunke DM. Plasticity in protein-peptide recognition: crystal structures of two different peptides bound to concanavalin A. Biophys J 2001; 80:2912-21. [PMID: 11371463 PMCID: PMC1301474 DOI: 10.1016/s0006-3495(01)76256-x] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
The structures of concanavalin A (ConA) in complex with two carbohydrate-mimicking peptides, 10-mer (MYWYPYASGS) and 15-mer (RVWYPYGSYLTASGS) have been determined at 2.75 A resolution. In both crystal structures four independent peptide molecules bind to each of the crystallographically independent subunits of ConA tetramer. The peptides exhibit small but significant variability in conformations and interactions while binding to ConA. The crystal structure of another similar peptide, 12-mer (DVFYPYPYASGS), in complex with ConA has been determined (Jain, D., K. J. Kaur, B. Sundaravadivel, and D. M. Salunke. 2000. Structural and functional consequences of peptide-carbohydrate mimicry. J. Biol. Chem. 275:16098-16102). Comparison of the three complexes shows that the peptides bind to ConA at a common binding site, using different contacting residues and interactions depending on their sequence and the local environment at the binding site. The binding is also optimized by corresponding plasticity of the peptide binding site on ConA. The diversity in conformation and interactions observed here are in agreement with the structural leeway concerning plasticity of specific molecular recognition in biological processes. The adaptability of peptide-ConA interactions may also be correlated with the carbohydrate-mimicking property of these peptides.
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Affiliation(s)
- D Jain
- Structural Biology Unit, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi 110 067, India
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Cunto-Amesty G, Dam TK, Luo P, Monzavi-Karbassi B, Brewer CF, Van Cott TC, Kieber-Emmons T. Directing the immune response to carbohydrate antigens. J Biol Chem 2001; 276:30490-8. [PMID: 11384987 DOI: 10.1074/jbc.m103257200] [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: 11/06/2022] Open
Abstract
Peptide mimetics may substitute for carbohydrate antigens in vaccine design applications. At present, the structural and immunological aspects of antigenic mimicry, which translate into immunologic mimicry, as well as the functional correlates of each, are unknown. In contrast to screening peptide display libraries, we demonstrate the feasibility of a structure-assisted vaccine design approach to identify functional mimeotopes. By using concanavalin A (ConA), as a recognition template, peptide mimetics reactive with ConA were identified. Designed peptides were observed to compete with synthetic carbohydrate probes for ConA binding, as demonstrated by enzyme-linked immunosorbent assay and isothermal titration calorimetry (ITC) analysis. ITC measurements indicate that a multivalent form of one particular mimetic binds to ConA with similar affinity as does trimannoside. Splenocytes from mimeotope-immunized mice display a peptide-specific cellular response, confirming a T-cell-dependent nature for the mimetic. As ConA binds to the Envelope protein of the human immunodeficiency virus, type 1 (HIV-1), we observed that mimeotope-induced serum also binds to HIV-1-infected cells, as assessed by flow cytometry, and could neutralize T-cell line adapted HIV-1 isolates in vitro, albeit at low titers. These studies emphasize that mimicry is based more upon functional rather than structural determinants that regulate mimeotope-induced T-dependent antibody responses to polysaccharide and emphasize that rational approaches can be employed to develop further vaccine candidates.
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Affiliation(s)
- G Cunto-Amesty
- Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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Kaur KJ, Jain D, Goel M, Salunke DM. Immunological implications of structural mimicry between a dodecapeptide and a carbohydrate moiety. Vaccine 2001; 19:3124-30. [PMID: 11312007 DOI: 10.1016/s0264-410x(01)00027-5] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
The immunogenicity and antibody cross-reactivity of two chemically different but structurally equivalent molecular mimics were analyzed by presenting them to the immune system in different modes. The observed differences in IgM and IgG responses in terms of cross-reactivity with the mimicking antigen could reflect the differential proliferative abilities of the corresponding B-cells. Modification of the T-cell help, either by using a promiscuous T-cell epitope or by prepriming, led to the shift in the antibody response towards the mimicking epitope. Also, the anti-sugar antibodies could be boosted using a carbohydrate mimicking peptide on cross-immunization. Thus, the carbohydrate-peptide mimicry appears to be a topological quasi-equivalence reflected differently in terms of antibody response during maturation.
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Affiliation(s)
- K J Kaur
- Structural Biology Unit, National Institute of Immunology, Aruna Asaf Ali Marg, New Delhi, India
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Gabius HJ. Glycohistochemistry: the why and how of detection and localization of endogenous lectins. Anat Histol Embryol 2001; 30:3-31. [PMID: 11284160 DOI: 10.1046/j.1439-0264.2001.00305.x] [Citation(s) in RCA: 72] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
The central dogma of molecular biology limits the downstream flow of genetic information to proteins. Progress from the last two decades of research on cellular glycoconjugates justifies adding the enzymatic production of glycan antennae with information-bearing determinants to this famous and basic pathway. An impressive variety of regulatory processes including cell growth and apoptosis, folding and routing of glycoproteins and cell adhesion/migration have been unravelled and found to be mediated or modulated by specific protein (lectin)-carbohydrate interactions. The conclusion has emerged that it would have meant missing manifold opportunities not to recruit the sugar code to cellular information transfer. Currently, the potential for medical applications in anti-adhesion therapy or drug targeting is one of the major driving forces fuelling progress in glycosciences. In histochemistry, this concept has prompted the introduction of carrier-immobilized carbohydrate ligands (neoglycoconjugates) to visualize the cells' capacity to be engaged in oligosaccharide recognition. After their isolation these tissue lectins will be tested for ligand analysis. Since fine specificities of different lectins can differ despite identical monosaccharide binding, the tissue lectins will eventually replace plant agglutinins to move from glycan profiling and localization to functional considerations. Namely, these two marker types, i.e. neoglycoconjugates and tissue lectins, track down accessible binding sites with relevance for involvement in interactions in situ. The documented interplay of synthetic organic chemistry and biochemistry with cyto- and histochemistry nourishes the optimism that the application of this set of innovative custom-prepared tools will provide important insights into the ways in which glycans can act as hardware in transmitting information during normal tissue development and pathological situations.
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Affiliation(s)
- H J Gabius
- Institut für Physiologische Chemie, Tierärztliche Fakultät, Ludwig-Maximilians-Universität München, Veterinärstr. 13, D-80539 München, Germany.
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