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Kabir KL, Ma B, Nussinov R, Shehu A. Fewer Dimensions, More Structures for Improved Discrete Models of Dynamics of Free versus Antigen-Bound Antibody. Biomolecules 2022; 12:biom12071011. [PMID: 35883567 PMCID: PMC9313177 DOI: 10.3390/biom12071011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 07/12/2022] [Accepted: 07/19/2022] [Indexed: 12/10/2022] Open
Abstract
Over the past decade, Markov State Models (MSM) have emerged as powerful methodologies to build discrete models of dynamics over structures obtained from Molecular Dynamics trajectories. The identification of macrostates for the MSM is a central decision that impacts the quality of the MSM but depends on both the selected representation of a structure and the clustering algorithm utilized over the featurized structures. Motivated by a large molecular system in its free and bound state, this paper investigates two directions of research, further reducing the representation dimensionality in a non-parametric, data-driven manner and including more structures in the computation. Rigorous evaluation of the quality of obtained MSMs via various statistical tests in a comparative setting firmly shows that fewer dimensions and more structures result in a better MSM. Many interesting findings emerge from the best MSM, advancing our understanding of the relationship between antibody dynamics and antibody–antigen recognition.
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Affiliation(s)
- Kazi Lutful Kabir
- Department of Computer Science, George Mason University, Fairfax, VA 22030, USA;
- Correspondence: ; Tel.: +1-571-201-5070
| | - Buyong Ma
- Engineering Research Center of Cell & Therapeutic Antibody School of Pharmacy, Shanghai Jiaotong University, Shanghai 200240, China;
| | - Ruth Nussinov
- Computational Structural Biology Section, Cancer Innovation Laboratory, Frederick National Laboratory for Cancer Research, National Cancer Institute, Frederick, MD 21702, USA;
| | - Amarda Shehu
- Department of Computer Science, George Mason University, Fairfax, VA 22030, USA;
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2
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Yoshikawa M, Nakamura H, Oda-Ueda N, Ueda T, Ohkuri T. Effect of an intermolecular disulfide bond introduced into the first loop of CH1 domain of Adalimumab Fab on thermal stability and antigen-binding activity. J Biochem 2022; 172:49-56. [PMID: 35476872 DOI: 10.1093/jb/mvac040] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2022] [Accepted: 04/08/2022] [Indexed: 11/14/2022] Open
Abstract
The introduction of intermolecular disulfide bonds by amino acid mutations is an effective method for stabilizing dimeric proteins. X-ray crystal structure of Fab of a therapeutic antibody, adalimumab, revealed the first loop of the CH1 domain to be partially unsolved at position 135-141. To find new sites for the introduction of intermolecular disulfide bonds in adalimumab Fab, Fab mutants targeting the unsolved region were predicted using molecular simulation software. Four Fab mutants, H:K137C-L:I117C, H:K137C-L:F209C, H:S138C-L:F116C, and H:S140C-L:S114C, were expressed in the methylotrophic yeast Pichia pastoris. SDS-PAGE analysis of these mutants indicated that H:K137C-L:F209C, H:S138C-L:F116C, and H:S140C-L:S114C mutants mostly formed intermolecular disulfide bonds, whereas some H:K137C-L:I117C mutants formed intermolecular disulfide bonds and some did not. DSC measurements showed increased thermal stability in all Fab mutants with engineered disulfide bonds. The bio-layer interferometry measurements, for binding of the antigen tumor necrotic factor α, indicated that Fab mutants had less antigen-binding activity than wild-type Fab. In particular, the KD value of H:K137C-L:F209C was approximately 17-times higher than that of wild-type Fab. Thus, we successfully introduced intermolecular disulfide bonds between the first loop region of the CH1 and CL domains and observed that it increases the thermostability of Fab and affects the antigen-binding activity.
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Affiliation(s)
| | | | | | - Tadashi Ueda
- Graduate School of Pharmaceutical Sciences, Kyushu University
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3
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Schulz S, Boyer S, Smerlak M, Cocco S, Monasson R, Nizak C, Rivoire O. Parameters and determinants of responses to selection in antibody libraries. PLoS Comput Biol 2021; 17:e1008751. [PMID: 33765014 PMCID: PMC7993935 DOI: 10.1371/journal.pcbi.1008751] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Accepted: 01/31/2021] [Indexed: 12/01/2022] Open
Abstract
The sequences of antibodies from a given repertoire are highly diverse at few sites located on the surface of a genome-encoded larger scaffold. The scaffold is often considered to play a lesser role than highly diverse, non-genome-encoded sites in controlling binding affinity and specificity. To gauge the impact of the scaffold, we carried out quantitative phage display experiments where we compare the response to selection for binding to four different targets of three different antibody libraries based on distinct scaffolds but harboring the same diversity at randomized sites. We first show that the response to selection of an antibody library may be captured by two measurable parameters. Second, we provide evidence that one of these parameters is determined by the degree of affinity maturation of the scaffold, affinity maturation being the process by which antibodies accumulate somatic mutations to evolve towards higher affinities during the natural immune response. In all cases, we find that libraries of antibodies built around maturated scaffolds have a lower response to selection to other arbitrary targets than libraries built around germline-based scaffolds. We thus propose that germline-encoded scaffolds have a higher selective potential than maturated ones as a consequence of a selection for this potential over the long-term evolution of germline antibody genes. Our results are a first step towards quantifying the evolutionary potential of biomolecules. Antibodies in the immune system consist of a genetically encoded scaffold that exposes a few highly diverse, non-genetically encoded sites. This focused diversity is sufficient to produce antibodies that bind to any target molecule. To understand the role of the scaffold, which acquires hypermutations during the immune response, over the selective response, we analyze quantitative in vitro experiments where large antibody populations based on different scaffolds are selected against different targets. We show that selective responses are described statistically by two parameters, one of which depends on prior evolution of the scaffold as part of a previous response. Our work provides methods to assay whether naïve antibody scaffolds are endowed with a distinctively high selective potential.
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Affiliation(s)
- Steven Schulz
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, PSL University, Paris, France
| | - Sébastien Boyer
- Département de biochimie, Faculté de Médecine, Université de Montréal, Montréal, Canada
| | - Matteo Smerlak
- Max Planck Institute for Mathematics in the Sciences, Leipzig, Germany
| | - Simona Cocco
- Laboratory of Physics of École Normale Supérieure, UMR 8023, CNRS & PSL University, Paris, France
| | - Rémi Monasson
- Laboratory of Physics of École Normale Supérieure, UMR 8023, CNRS & PSL University, Paris, France
| | - Clément Nizak
- Laboratory of Biochemistry, CBI, UMR 8231, ESPCI Paris, PSL University, CNRS, Paris, France
- * E-mail: (CN); (OR)
| | - Olivier Rivoire
- Center for Interdisciplinary Research in Biology (CIRB), Collège de France, CNRS UMR 7241, INSERM U1050, PSL University, Paris, France
- * E-mail: (CN); (OR)
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4
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Beveridge R, Calabrese AN. Structural Proteomics Methods to Interrogate the Conformations and Dynamics of Intrinsically Disordered Proteins. Front Chem 2021; 9:603639. [PMID: 33791275 PMCID: PMC8006314 DOI: 10.3389/fchem.2021.603639] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2020] [Accepted: 01/19/2021] [Indexed: 12/21/2022] Open
Abstract
Intrinsically disordered proteins (IDPs) and regions of intrinsic disorder (IDRs) are abundant in proteomes and are essential for many biological processes. Thus, they are often implicated in disease mechanisms, including neurodegeneration and cancer. The flexible nature of IDPs and IDRs provides many advantages, including (but not limited to) overcoming steric restrictions in binding, facilitating posttranslational modifications, and achieving high binding specificity with low affinity. IDPs adopt a heterogeneous structural ensemble, in contrast to typical folded proteins, making it challenging to interrogate their structure using conventional tools. Structural mass spectrometry (MS) methods are playing an increasingly important role in characterizing the structure and function of IDPs and IDRs, enabled by advances in the design of instrumentation and the development of new workflows, including in native MS, ion mobility MS, top-down MS, hydrogen-deuterium exchange MS, crosslinking MS, and covalent labeling. Here, we describe the advantages of these methods that make them ideal to study IDPs and highlight recent applications where these tools have underpinned new insights into IDP structure and function that would be difficult to elucidate using other methods.
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Affiliation(s)
- Rebecca Beveridge
- Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, United Kingdom
| | - Antonio N. Calabrese
- Astbury Centre for Structural Molecular Biology, School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds, United Kingdom
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5
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Monoclonal antibody stability can be usefully monitored using the excitation-energy-dependent fluorescence edge-shift. Biochem J 2021; 477:3599-3612. [PMID: 32869839 PMCID: PMC7527260 DOI: 10.1042/bcj20200580] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2020] [Revised: 08/27/2020] [Accepted: 09/01/2020] [Indexed: 11/17/2022]
Abstract
Among the major challenges in the development of biopharmaceuticals are structural heterogeneity and aggregation. The development of a successful therapeutic monoclonal antibody (mAb) requires both a highly active and also stable molecule. Whilst a range of experimental (biophysical) approaches exist to track changes in stability of proteins, routine prediction of stability remains challenging. The fluorescence red edge excitation shift (REES) phenomenon is sensitive to a range of changes in protein structure. Based on recent work, we have found that quantifying the REES effect is extremely sensitive to changes in protein conformational state and dynamics. Given the extreme sensitivity, potentially this tool could provide a ‘fingerprint’ of the structure and stability of a protein. Such a tool would be useful in the discovery and development of biopharamceuticals and so we have explored our hypothesis with a panel of therapeutic mAbs. We demonstrate that the quantified REES data show remarkable sensitivity, being able to discern between structurally identical antibodies and showing sensitivity to unfolding and aggregation. The approach works across a broad concentration range (µg–mg/ml) and is highly consistent. We show that the approach can be applied alongside traditional characterisation testing within the context of a forced degradation study (FDS). Most importantly, we demonstrate the approach is able to predict the stability of mAbs both in the short (hours), medium (days) and long-term (months). The quantified REES data will find immediate use in the biopharmaceutical industry in quality assurance, formulation and development. The approach benefits from low technical complexity, is rapid and uses instrumentation which exists in most biochemistry laboratories without modification.
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Abstract
We studied the molecular details of the recognition of antigens by the variable domain of their cognate antibodies in as well as those elicited by the constant domains, which do not directly interact with antigens. Such effects are difficult to study experimentally; however, molecular dynamics simulations and subsequent residue interaction network analysis provide insight into the allosteric communication between the antigen-binding CDR region and the constant domain. We performed MD simulations of the complex of Fab and prion-associated peptide in the apo and bound forms and follow the conformational changes in the antibody and cross-talk between its subunits and with antigens. These protocols could be generally applied for studies of other antigens-antibody recognition systems.
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Affiliation(s)
- Jun Zhao
- Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA
- Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA.
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7
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Fernández-Quintero ML, Loeffler JR, Bacher LM, Waibl F, Seidler CA, Liedl KR. Local and Global Rigidification Upon Antibody Affinity Maturation. Front Mol Biosci 2020; 7:182. [PMID: 32850970 PMCID: PMC7426445 DOI: 10.3389/fmolb.2020.00182] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 07/13/2020] [Indexed: 01/03/2023] Open
Abstract
During the affinity maturation process the immune system produces antibodies with higher specificity and activity through various rounds of somatic hypermutations in response to an antigen. Elucidating the affinity maturation process is fundamental in understanding immunity and in the development of biotherapeutics. Therefore, we analyzed 10 pairs of antibody fragments differing in their specificity and in distinct stages of affinity maturation using metadynamics in combination with molecular dynamics (MD) simulations. We investigated differences in flexibility of the CDR-H3 loop and global changes in plasticity upon affinity maturation. Among all antibody pairs we observed a substantial rigidification in flexibility and plasticity reflected in a substantial decrease of conformational diversity. To visualize and characterize these findings we used Markov-states models to reconstruct the kinetics of CDR-H3 loop dynamics and for the first time provide a method to define and localize surface plasticity upon affinity maturation.
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Affiliation(s)
- Monica L Fernández-Quintero
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Johannes R Loeffler
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Lisa M Bacher
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Franz Waibl
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Clarissa A Seidler
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
| | - Klaus R Liedl
- Center for Molecular Biosciences Innsbruck, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innsbruck, Austria
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8
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Prigent J, Jarossay A, Planchais C, Eden C, Dufloo J, Kök A, Lorin V, Vratskikh O, Couderc T, Bruel T, Schwartz O, Seaman MS, Ohlenschläger O, Dimitrov JD, Mouquet H. Conformational Plasticity in Broadly Neutralizing HIV-1 Antibodies Triggers Polyreactivity. Cell Rep 2019; 23:2568-2581. [PMID: 29847789 PMCID: PMC5990490 DOI: 10.1016/j.celrep.2018.04.101] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2018] [Revised: 03/26/2018] [Accepted: 04/25/2018] [Indexed: 12/18/2022] Open
Abstract
Human high-affinity antibodies to pathogens often recognize unrelated ligands. The molecular origin and the role of this polyreactivity are largely unknown. Here, we report that HIV-1 broadly neutralizing antibodies (bNAbs) are frequently polyreactive, cross-reacting with non-HIV-1 molecules, including self-antigens. Mutating bNAb genes to increase HIV-1 binding and neutralization also results in de novo polyreactivity. Unliganded paratopes of polyreactive bNAbs with improved HIV-1 neutralization exhibit a conformational flexibility, which contributes to enhanced affinity of bNAbs to various HIV-1 envelope glycoproteins and non-HIV antigens. Binding adaptation of polyreactive bNAbs to the divergent ligands mainly involves hydrophophic interactions. Plasticity of bNAbs' paratopes may, therefore, facilitate accommodating divergent viral variants, but it simultaneously triggers promiscuous binding to non-HIV-1 antigens. Thus, a certain level of polyreactivity can be a mark of adaptable antibodies displaying optimal pathogens' recognition.
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Affiliation(s)
- Julie Prigent
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France
| | - Annaëlle Jarossay
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France; INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France; Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France
| | - Cyril Planchais
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France
| | - Caroline Eden
- Laboratory of Molecular Immunology, The Rockefeller University, New York, NY 10065, USA; Icahn School of Medicine at Mount Sinai, New York, NY 10029, USA
| | - Jérémy Dufloo
- Virus & Immunity Unit, Department of Virology, Institut Pasteur, Paris 75015, France; CNRS URA3015, Paris 75015, France
| | - Ayrin Kök
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France
| | - Valérie Lorin
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France
| | - Oxana Vratskikh
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France
| | - Thérèse Couderc
- Biology of Infection Unit, INSERM U1117, Department of Cell Biology and Infection, Institut Pasteur, Paris 75015, France
| | - Timothée Bruel
- Virus & Immunity Unit, Department of Virology, Institut Pasteur, Paris 75015, France; CNRS URA3015, Paris 75015, France
| | - Olivier Schwartz
- Virus & Immunity Unit, Department of Virology, Institut Pasteur, Paris 75015, France; CNRS URA3015, Paris 75015, France
| | | | | | - Jordan D Dimitrov
- Sorbonne Universités, UPMC Univ Paris 06, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France; INSERM, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France; Université Paris Descartes, Sorbonne Paris Cité, UMR_S 1138, Centre de Recherche des Cordeliers, Paris 75006, France.
| | - Hugo Mouquet
- Laboratory of Humoral Response to Pathogens, Department of Immunology, Institut Pasteur, Paris 75015, France; INSERM U1222, Paris 75015, France.
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Varese M, Guardiola S, García J, Giralt E. Enthalpy‐ versus Entropy‐Driven Molecular Recognition in the Era of Biologics. Chembiochem 2019; 20:2981-2986. [DOI: 10.1002/cbic.201900270] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Indexed: 12/15/2022]
Affiliation(s)
- Monica Varese
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST) Baldiri Reixac, 10 08028 Barcelona Spain
| | - Salvador Guardiola
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST) Baldiri Reixac, 10 08028 Barcelona Spain
| | - Jesús García
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST) Baldiri Reixac, 10 08028 Barcelona Spain
| | - Ernest Giralt
- Institute for Research in Biomedicine (IRB Barcelona)Barcelona Institute of Science and Technology (BIST) Baldiri Reixac, 10 08028 Barcelona Spain
- Department of Inorganic and Organic ChemistryUniversity of Barcelona Martí i Franquès 1–11 08028 Barcelona Spain
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10
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Adhikary R, Zimmermann J, Stanfield RL, Wilson IA, Yu W, Oda M, Romesberg FE. Structure and Dynamics of Stacking Interactions in an Antibody Binding Site. Biochemistry 2019; 58:2987-2995. [PMID: 31243995 DOI: 10.1021/acs.biochem.9b00119] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
For years, antibodies (Abs) have been used as a paradigm for understanding how protein structure contributes to molecular recognition. However, with the ability to evolve Abs that recognize specific chromophores, they also have great potential as models for how protein dynamics contribute to molecular recognition. We previously raised murine Abs to different chromophores and, with the use of three-pulse photon echo peak shift spectroscopy, demonstrated that the immune system is capable of producing Abs with widely varying flexibility. We now report the characterization of the complexes formed between two Abs, 5D11 and 10A6, and the chromophoric ligand that they were evolved to recognize, 8-methoxypyrene-1,3,6-trisulfonic acid (MPTS). The sequences of the Ab genes indicate that they evolved from a common precursor. We also used a variety of spectroscopic methods to probe the photophysics and dynamics of the Ab-MPTS complexes and found that they are similar to each other but distinct from previously characterized anti-MPTS Abs. Structural studies revealed that this difference likely results from a unique mode of binding in which MPTS is sandwiched between the side chain of PheH98, which interacts with the chromophore via T-stacking, and the side chain of TrpL91, which interacts with the chromophore via parallel stacking. The T-stacking interaction appears to mediate relaxation on the picosecond time scale, while the parallel stacking appears to mediate relaxation on an ultrafast, femtosecond time scale, which dominates the response. The anti-MPTS Abs thus not only demonstrate the simultaneous use of the two limiting modes of stacking for molecular recognition, but also provide a unique opportunity to characterize how dynamics might contribute to molecular recognition. Both types of stacking are common in proteins and protein complexes where they may similarly contribute to dynamics and molecular recognition.
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Affiliation(s)
| | | | | | | | | | - Masayuki Oda
- Graduate School of Life and Environmental Sciences , Kyoto Prefectural University , 1-5, Hangi-cho , Shimogamo, Sakyo-ku, Kyoto 606-8522 , Japan
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11
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Zhao J, Nussinov R, Ma B. Antigen binding allosterically promotes Fc receptor recognition. MAbs 2019; 11:58-74. [PMID: 30212263 PMCID: PMC6343797 DOI: 10.1080/19420862.2018.1522178] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2018] [Revised: 08/10/2018] [Accepted: 09/04/2018] [Indexed: 12/11/2022] Open
Abstract
A key question in immunology is whether antigen recognition and Fc receptor (FcR) binding are allosterically linked. This question is also relevant for therapeutic antibody design. Antibody Fab and Fc domains are connected by flexible unstructured hinge region. Fc chains have conserved glycosylation sites at Asn297, with each conjugated to a core heptasaccharide and forming biantennary Fc glycan. The glycans modulate the Fc conformations and functions. It is well known that the antibody Fab and Fc domains and glycan affect antibody activity, but whether these elements act independently or synergistically is still uncertain. We simulated four antibody complexes: free antibody, antigen-bound antibody, FcR-bound antibody, and an antigen-antibody-FcR complex. We found that, in the antibody's "T/Y" conformation, the glycans, and the Fc domain all respond to antigen binding, with the antibody population shifting to two dominant clusters, both with the Fc-receptor binding site open. The simulations reveal that the Fc-glycan-receptor complexes also segregate into two conformational clusters, one corresponding to the antigen-free antibody-FcR baseline binding, and the other with an antigen-enhanced antibody-FcR interaction. Our study confirmed allosteric communications in antibody-antigen recognition and following FcR activation. Even though we observed allosteric communications through the IgG domains, the most important mechanism that we observed is the communication via population shift, stimulated by antigen binding and propagating to influence FcR recognition.
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Affiliation(s)
- Jun Zhao
- Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland, USA
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland, USA
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, Maryland, USA
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12
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Kaur H, Sain N, Mohanty D, Salunke DM. Deciphering evolution of immune recognition in antibodies. BMC STRUCTURAL BIOLOGY 2018; 18:19. [PMID: 30563492 PMCID: PMC6299584 DOI: 10.1186/s12900-018-0096-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/17/2018] [Accepted: 11/14/2018] [Indexed: 11/29/2022]
Abstract
Background Antibody, the primary effector molecule of the immune system, evolves after initial encounter with the antigen from a precursor form to a mature one to effectively deal with the antigen. Antibodies of a lineage diverge through antigen-directed isolated pathways of maturation to exhibit distinct recognition potential. In the context of evolution in immune recognition, diversity of antigen cannot be ignored. While there are reports on antibody lineage, structural perspective with respect to diverse recognition potential in a lineage has never been studied. Hence, it is crucial to evaluate how maturation leads to topological tailoring within a lineage enabling them to interact with significantly distinct antigens. Results A data-driven approach was undertaken for the study. Global experimental mouse and human antibody-antigen complex structures from PDB were compiled into a coherent database of germline-linked antibodies bound with distinct antigens. Structural analysis of all lineages showed variations in CDRs of both H and L chains. Observations of conformational adaptation made from analysis of static structures were further evaluated by characterizing dynamics of interaction in two lineages, mouse VH1–84 and human VH5–51. Sequence and structure analysis of the lineages explained that somatic mutations altered the geometries of individual antibodies with common structural constraints in some CDRs. Additionally, conformational landscape obtained from molecular dynamics simulations revealed that incoming pathogen led to further conformational divergence in the paratope (as observed across datasets) even while maintaining similar overall backbone topology. MM-GB/SA analysis showed binding energies to be in physiological range. Results of the study are coherent with experimental observations. Conclusions The findings of this study highlight basic structural principles shaping the molecular evolution of a lineage for significantly diverse antigens. Antibodies of a lineage follow different developmental pathways while preserving the imprint of the germline. From the study, it can be generalized that structural diversification of the paratope is an outcome of natural selection of a conformation from an available ensemble, which is further optimized for antigen interaction. The study establishes that starting from a common lineage, antibodies can mature to recognize a wide range of antigens. This hypothesis can be further tested and validated experimentally. Electronic supplementary material The online version of this article (10.1186/s12900-018-0096-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Harmeet Kaur
- Regional Centre for Biotechnology, Biotech Science Cluster, Faridabad, Haryana, 121001, India.,Manipal Academy of Higher Education, Manipal, Karnataka, 576104, India
| | - Neetu Sain
- National Institute of Immunology, New Delhi, Delhi, 110067, India
| | - Debasisa Mohanty
- National Institute of Immunology, New Delhi, Delhi, 110067, India
| | - Dinakar M Salunke
- Regional Centre for Biotechnology, Biotech Science Cluster, Faridabad, Haryana, 121001, India. .,International Centre for Genetic Engineering and Biotechnology, New Delhi, Delhi, 110067, India.
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Nguyen TH, Rustenburg AS, Krimmer SG, Zhang H, Clark JD, Novick PA, Branson K, Pande VS, Chodera JD, Minh DDL. Bayesian analysis of isothermal titration calorimetry for binding thermodynamics. PLoS One 2018; 13:e0203224. [PMID: 30212471 PMCID: PMC6136728 DOI: 10.1371/journal.pone.0203224] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/16/2018] [Indexed: 12/04/2022] Open
Abstract
Isothermal titration calorimetry (ITC) is the only technique able to determine both the enthalpy and entropy of noncovalent association in a single experiment. The standard data analysis method based on nonlinear regression, however, provides unrealistically small uncertainty estimates due to its neglect of dominant sources of error. Here, we present a Bayesian framework for sampling from the posterior distribution of all thermodynamic parameters and other quantities of interest from one or more ITC experiments, allowing uncertainties and correlations to be quantitatively assessed. For a series of ITC measurements on metal:chelator and protein:ligand systems, the Bayesian approach yields uncertainties which represent the variability from experiment to experiment more accurately than the standard data analysis. In some datasets, the median enthalpy of binding is shifted by as much as 1.5 kcal/mol. A Python implementation suitable for analysis of data generated by MicroCal instruments (and adaptable to other calorimeters) is freely available online.
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Affiliation(s)
- Trung Hai Nguyen
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL, United States of America
| | - Ariën S. Rustenburg
- Computational and Systems Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
- Graduate Program in Physiology, Biophysics, and Systems Biology, Weill Cornell Medical College, New York, NY, United States of America
| | - Stefan G. Krimmer
- Department of Pharmaceutical Chemistry, University of Marburg, Marbacher Weg 6, Marburg, Germany
| | - Hexi Zhang
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL, United States of America
| | - John D. Clark
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL, United States of America
| | - Paul A. Novick
- Department of Chemistry, Stanford University, Stanford, CA, United States of America
| | - Kim Branson
- Department of Chemistry, Stanford University, Stanford, CA, United States of America
| | - Vijay S. Pande
- Department of Chemistry, Stanford University, Stanford, CA, United States of America
| | - John D. Chodera
- Computational and Systems Biology Program, Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, United States of America
- * E-mail: (JDC); (DDLM)
| | - David D. L. Minh
- Department of Chemistry, Illinois Institute of Technology, Chicago, IL, United States of America
- * E-mail: (JDC); (DDLM)
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14
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Zhao J, Nussinov R, Wu WJ, Ma B. In Silico Methods in Antibody Design. Antibodies (Basel) 2018; 7:E22. [PMID: 31544874 PMCID: PMC6640671 DOI: 10.3390/antib7030022] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2018] [Revised: 06/28/2018] [Accepted: 06/28/2018] [Indexed: 01/10/2023] Open
Abstract
Antibody therapies with high efficiency and low toxicity are becoming one of the major approaches in antibody therapeutics. Based on high-throughput sequencing and increasing experimental structures of antibodies/antibody-antigen complexes, computational approaches can predict antibody/antigen structures, engineering the function of antibodies and design antibody-antigen complexes with improved properties. This review summarizes recent progress in the field of in silico design of antibodies, including antibody structure modeling, antibody-antigen complex prediction, antibody stability evaluation, and allosteric effects in antibodies and functions. We listed the cases in which these methods have helped experimental studies to improve the affinities and physicochemical properties of antibodies. We emphasized how the molecular dynamics unveiled the allosteric effects during antibody-antigen recognition and antibody-effector recognition.
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Affiliation(s)
- Jun Zhao
- Division of Biotechnology Review and Research I, Office of Biotechnology Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA.
- Interagency Oncology Task Force (IOTF) Fellowship: Oncology Product Research/Review Fellow, National Cancer Institute, Bethesda, MD 20892, USA.
- Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.
- Sackler Inst. of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel.
| | - Wen-Jin Wu
- Division of Biotechnology Review and Research I, Office of Biotechnology Products, Office of Pharmaceutical Quality, Center for Drug Evaluation and Research, US Food and Drug Administration, 10903 New Hampshire Avenue, Silver Spring, MD 20993, USA.
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA.
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15
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Jeliazkov JR, Sljoka A, Kuroda D, Tsuchimura N, Katoh N, Tsumoto K, Gray JJ. Repertoire Analysis of Antibody CDR-H3 Loops Suggests Affinity Maturation Does Not Typically Result in Rigidification. Front Immunol 2018; 9:413. [PMID: 29545810 PMCID: PMC5840193 DOI: 10.3389/fimmu.2018.00413] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2017] [Accepted: 02/14/2018] [Indexed: 12/18/2022] Open
Abstract
Antibodies can rapidly evolve in specific response to antigens. Affinity maturation drives this evolution through cycles of mutation and selection leading to enhanced antibody specificity and affinity. Elucidating the biophysical mechanisms that underlie affinity maturation is fundamental to understanding B-cell immunity. An emergent hypothesis is that affinity maturation reduces the conformational flexibility of the antibody's antigen-binding paratope to minimize entropic losses incurred upon binding. In recent years, computational and experimental approaches have tested this hypothesis on a small number of antibodies, often observing a decrease in the flexibility of the complementarity determining region (CDR) loops that typically comprise the paratope and in particular the CDR-H3 loop, which contributes a plurality of antigen contacts. However, there were a few exceptions and previous studies were limited to a small handful of cases. Here, we determined the structural flexibility of the CDR-H3 loop for thousands of recent homology models of the human peripheral blood cell antibody repertoire using rigidity theory. We found no clear delineation in the flexibility of naïve and antigen-experienced antibodies. To account for possible sources of error, we additionally analyzed hundreds of human and mouse antibodies in the Protein Data Bank through both rigidity theory and B-factor analysis. By both metrics, we observed only a slight decrease in the CDR-H3 loop flexibility when comparing affinity matured antibodies to naïve antibodies, and the decrease was not as drastic as previously reported. Further analysis, incorporating molecular dynamics simulations, revealed a spectrum of changes in flexibility. Our results suggest that rigidification may be just one of many biophysical mechanisms for increasing affinity.
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Affiliation(s)
- Jeliazko R Jeliazkov
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, United States
| | - Adnan Sljoka
- Department of Informatics, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Daisuke Kuroda
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan.,Medical Device Development and Regulation Research Center, School of Engineering, The University of Tokyo, Tokyo, Japan
| | - Nobuyuki Tsuchimura
- Department of Informatics, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Naoki Katoh
- Department of Informatics, School of Science and Technology, Kwansei Gakuin University, Sanda, Hyogo, Japan
| | - Kouhei Tsumoto
- Department of Bioengineering, School of Engineering, The University of Tokyo, Tokyo, Japan.,Laboratory of Medical Proteomics, The Institute of Medical Science, The University of Tokyo, Tokyo, Japan
| | - Jeffrey J Gray
- Program in Molecular Biophysics, Johns Hopkins University, Baltimore, MD, United States.,Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD, United States.,Institute for NanoBioTechnology, Johns Hopkins University, Baltimore, MD, United States.,Sidney Kimmel Comprehensive Cancer Center, Johns Hopkins University, Baltimore, MD, United States
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16
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Stanfield RL, Haakenson J, Deiss TC, Criscitiello MF, Wilson IA, Smider VV. The Unusual Genetics and Biochemistry of Bovine Immunoglobulins. Adv Immunol 2018; 137:135-164. [PMID: 29455846 DOI: 10.1016/bs.ai.2017.12.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Antibodies are the key circulating molecules that have evolved to fight infection by the adaptive immune system of vertebrates. Typical antibodies of most species contain six complementarity-determining regions (CDRs), where the third CDR of the heavy chain (CDR H3) has the greatest diversity and often makes the most significant contact with antigen. Generally, the process of V(D)J recombination produces a vast repertoire of antibodies; multiple V, D, and J gene segments recombine with additional junctional diversity at the V-D and D-J joints, and additional combinatorial possibilities occur through heavy- and light-chain pairing. Despite these processes, the overall structure of the resulting antibody is largely conserved, and binding to antigen occurs predominantly through the CDR loops of the immunoglobulin V domains. Bovines have deviated from this general paradigm by having few VH regions and thus little germline combinatorial diversity, but their antibodies contain long CDR H3 regions, with substantial diversity generated through somatic hypermutation. A subset of the repertoire comprises antibodies with ultralong CDR H3s, which can reach over 70 amino acids in length. Structurally, these unusual antibodies form a β-ribbon "stalk" and disulfide-bonded "knob" that protrude far from the antibody surface. These long CDR H3s allow cows to mount a particularly robust immune response when immunized with viral antigens, particularly to broadly neutralizing epitopes on a stabilized HIV gp140 trimer, which has been a challenge for other species. The unusual genetics and structural biology of cows provide for a unique paradigm for creation of immune diversity and could enable generation of antibodies against especially challenging targets and epitopes.
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Affiliation(s)
| | | | - Thaddeus C Deiss
- College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Michael F Criscitiello
- College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX, United States
| | - Ian A Wilson
- The Scripps Research Institute, La Jolla, CA, United States
| | - Vaughn V Smider
- The Scripps Research Institute, La Jolla, CA, United States.
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17
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Wang M, Zhu D, Zhu J, Nussinov R, Ma B. Local and global anatomy of antibody-protein antigen recognition. J Mol Recognit 2017; 31:e2693. [PMID: 29218757 DOI: 10.1002/jmr.2693] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Revised: 09/13/2017] [Accepted: 11/08/2017] [Indexed: 12/15/2022]
Abstract
Deciphering antibody-protein antigen recognition is of fundamental and practical significance. We constructed an antibody structural dataset, partitioned it into human and murine subgroups, and compared it with nonantibody protein-protein complexes. We investigated the physicochemical properties of regions on and away from the antibody-antigen interfaces, including net charge, overall antibody charge distributions, and their potential role in antigen interaction. We observed that amino acid preference in antibody-protein antigen recognition is entropy driven, with residues having low side-chain entropy appearing to compensate for the high backbone entropy in interaction with protein antigens. Antibodies prefer charged and polar antigen residues and bridging water molecules. They also prefer positive net charge, presumably to promote interaction with negatively charged protein antigens, which are common in proteomes. Antibody-antigen interfaces have large percentages of Tyr, Ser, and Asp, but little Lys. Electrostatic and hydrophobic interactions in the Ag binding sites might be coupled with Fab domains through organized charge and residue distributions away from the binding interfaces. Here we describe some features of antibody-antigen interfaces and of Fab domains as compared with nonantibody protein-protein interactions. The distributions of interface residues in human and murine antibodies do not differ significantly. Overall, our results provide not only a local but also a global anatomy of antibody structures.
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Affiliation(s)
- Meryl Wang
- Basic Science Program, Leidos Biomedical Research, Inc, Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA
| | - David Zhu
- Basic Science Program, Leidos Biomedical Research, Inc, Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA
| | - Jianwei Zhu
- School of Pharmacy, Shanghai Jiao Tong University, Shanghai, China
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc, Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA.,Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc, Cancer and Inflammation Program, National Cancer Institute, Frederick, MD, USA
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18
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Vargas-Lara F, Starr FW, Douglas JF. Molecular rigidity and enthalpy-entropy compensation in DNA melting. SOFT MATTER 2017; 13:8309-8330. [PMID: 29057399 DOI: 10.1039/c7sm01220a] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Enthalpy-entropy compensation (EEC) is observed in diverse molecular binding processes of importance to living systems and manufacturing applications, but this widely occurring phenomenon is not sufficiently understood from a molecular physics standpoint. To gain insight into this fundamental problem, we focus on the melting of double-stranded DNA (dsDNA) since measurements exhibiting EEC are extensive for nucleic acid complexes and existing coarse-grained models of DNA allow us to explore the influence of changes in molecular parameters on the energetic parameters by using molecular dynamics simulations. Previous experimental and computational studies have indicated a correlation between EEC and changes in molecular rigidity in certain binding-unbinding processes, and, correspondingly, we estimate measures of DNA molecular rigidity under a wide range of conditions, along with resultant changes in the enthalpy and entropy of binding. In particular, we consider variations in dsDNA rigidity that arise from changes of intrinsic molecular rigidity such as varying the associative interaction strength between the DNA bases, the length of the DNA chains, and the bending stiffness of the individual DNA chains. We also consider extrinsic changes of molecular rigidity arising from the addition of polymer additives and geometrical confinement of DNA between parallel plates. All our computations confirm EEC and indicate that this phenomenon is indeed highly correlated with changes in molecular rigidity. However, two distinct patterns relating to how DNA rigidity influences the entropy of association emerge from our analysis. Increasing the intrinsic DNA rigidity increases the entropy of binding, but increases in molecular rigidity from external constraints decreases the entropy of binding. EEC arises in numerous synthetic and biological binding processes and we suggest that changes in molecular rigidity might provide a common origin of this ubiquitous phenomenon in the mutual binding and unbinding of complex molecules.
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Affiliation(s)
- Fernando Vargas-Lara
- Materials Science and Engineering Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA.
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19
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Zhao J, Nussinov R, Ma B. Mechanisms of recognition of amyloid-β (Aβ) monomer, oligomer, and fibril by homologous antibodies. J Biol Chem 2017; 292:18325-18343. [PMID: 28924036 DOI: 10.1074/jbc.m117.801514] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 08/26/2017] [Indexed: 12/31/2022] Open
Abstract
Alzheimer's disease is one of the most devastating neurodegenerative diseases without effective therapies. Immunotherapy is a promising approach, but amyloid antibody structural information is limited. Here we simulate the recognition of monomeric, oligomeric, and fibril amyloid-β (Aβ) by three homologous antibodies (solanezumab, crenezumab, and their chimera, CreneFab). Solanezumab only binds the monomer, whereas crenezumab and CreneFab can recognize different oligomerization states; however, the structural basis for this observation is not understood. We successfully identified stable complexes of crenezumab with Aβ pentamer (oligomer model) and 16-mer (fibril model). It is noteworthy that solanezumab targets Aβ residues 16-26 preferentially in the monomeric state; conversely, crenezumab consistently targets residues 13-16 in different oligomeric states. Unlike the buried monomeric peptide in solanezumab's complementarity-determining region, crenezumab binds the oligomer's lateral and edge residues. Surprisingly, crenezumab's complementarity-determining region loops can effectively bind the Aβ fibril lateral surface around the same 13-16 region. The constant domain influences antigen recognition through entropy redistribution. Different constant domain residues in solanezumab/crenezumab/chimera influence the binding of Aβ aggregates. Collectively, we provide molecular insight into the recognition mechanisms facilitating antibody design.
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Affiliation(s)
- Jun Zhao
- From the Cancer and Inflammation Program, NCI-Frederick, Frederick, Maryland 21702
| | - Ruth Nussinov
- the Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, NCI-Frederick, Frederick, Maryland 21702, and.,the Sackler Institute of Molecular Medicine, Department of Human Genetics and Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- the Basic Science Program, Leidos Biomedical Research, Inc. Cancer and Inflammation Program, NCI-Frederick, Frederick, Maryland 21702, and
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20
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Stevenson P, Tokmakoff A. Ultrafast Fluctuations of High Amplitude Electric Fields in Lipid Membranes. J Am Chem Soc 2017; 139:4743-4752. [DOI: 10.1021/jacs.6b12412] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Paul Stevenson
- Department
of Chemistry, Massachusetts Institute of Technology, 77 Massachusetts
Ave., Cambridge, Massachusetts 02139, United States
- Department
of Chemistry, James Frank Institute, and The Institute
for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
| | - Andrei Tokmakoff
- Department
of Chemistry, James Frank Institute, and The Institute
for Biophysical Dynamics, The University of Chicago, 929 E 57th Street, Chicago, Illinois 60637, United States
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21
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Adhikary R, Zimmermann J, Romesberg FE. Transparent Window Vibrational Probes for the Characterization of Proteins With High Structural and Temporal Resolution. Chem Rev 2017; 117:1927-1969. [DOI: 10.1021/acs.chemrev.6b00625] [Citation(s) in RCA: 83] [Impact Index Per Article: 11.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Ramkrishna Adhikary
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Jörg Zimmermann
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
| | - Floyd E. Romesberg
- Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037, United States
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22
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Frappier V, Chartier M, Najmanovich R. Applications of Normal Mode Analysis Methods in Computational Protein Design. Methods Mol Biol 2017; 1529:203-214. [PMID: 27914052 DOI: 10.1007/978-1-4939-6637-0_9] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Recent advances in coarse-grained normal mode analysis methods make possible the large-scale prediction of the effect of mutations on protein stability and dynamics as well as the generation of biologically relevant conformational ensembles. Given the interplay between flexibility and enzymatic activity, the combined analysis of stability and dynamics using the Elastic Network Contact Model (ENCoM) method has ample applications in protein engineering in industrial and medical applications such as in computational antibody design. Here, we present a detailed tutorial on how to perform such calculations using ENCoM.
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Affiliation(s)
- Vincent Frappier
- Department of Biology, Massachusetts Institute of Technology, 77 Massachusetts avenue, Cambridge, MA, 02139, USA
- Faculty of Medicine and Health Sciences, Department of Biochemistry, University of Sherbrooke, 3001, 12 Av., NordSherbrooke, QCJ1H 5N4, Canada
| | - Matthieu Chartier
- Faculty of Medicine and Health Sciences, Department of Biochemistry, University of Sherbrooke, 3001, 12 Av., NordSherbrooke, QCJ1H 5N4, Canada
| | - Rafael Najmanovich
- Department of Pharmacology and Physiology, Faculty of Medicine, Université de Montreal, Montreal, H3C 3J7, QC, Canada.
- Faculty of Medicine and Health Sciences, Department of Biochemistry, University of Sherbrooke, 3001, 12 Av., NordSherbrooke, QCJ1H 5N4, Canada.
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23
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Zhao J, Nussinov R, Ma B. Allosteric control of antibody-prion recognition through oxidation of a disulfide bond between the CH and CL chains. Protein Eng Des Sel 2017; 30:67-76. [PMID: 27899437 PMCID: PMC5157118 DOI: 10.1093/protein/gzw065] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Revised: 10/05/2016] [Accepted: 11/14/2016] [Indexed: 12/12/2022] Open
Abstract
Molecular details of the recognition of disordered antigens by their cognate antibodies have not been studied as extensively as folded protein antigens and much is still unknown. To follow the conformational changes in the antibody and cross-talk between its subunits and with antigens, we performed molecular dynamics (MD) simulations of the complex of Fab and prion-associated peptide in the apo and bound forms. We observed that the inter-chain disulfide bond in constant domains restrains the conformational changes of Fab, especially the loops in the CH1 domain, resulting in inhibition of the cross-talk between Fab subdomains that thereby may prevent prion peptide binding. We further identified several negative and positive correlations of motions between the peptide and Fab constant domains, which suggested structural cross-talks between the constant domains and the antigen. The cross-talk was influenced by the inter-chain disulfide bond, which reduced the number of paths between them. Importantly, network analysis of the complex and its bound water molecules observed that those water molecules form an integral part of the Fab/peptide complex network and potential allosteric pathways. On-going work focuses on developing strategies aimed to incorporate these new network communications-including the associated water molecules-toward the grand challenge of antibody design.
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Affiliation(s)
- Jun Zhao
- Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA
| | - Ruth Nussinov
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA
- Department of Human Genetics and Molecular Medicine, Sackler Institute of Molecular Medicine, Sackler School of Medicine, Tel Aviv University, Tel Aviv 69978, Israel
| | - Buyong Ma
- Basic Science Program, Leidos Biomedical Research, Inc., Cancer and Inflammation Program, National Cancer Institute, Frederick, MD 21702, USA
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24
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VanPatten S, Sun S, He M, Cheng KF, Altiti A, Papatheodorou A, Kowal C, Jeganathan V, Crawford JM, Bloom O, Volpe BT, Grant C, Meurice N, Coleman TR, Diamond B, Al-Abed Y. Amending HIV Drugs: A Novel Small-Molecule Approach To Target Lupus Anti-DNA Antibodies. J Med Chem 2016; 59:8859-8867. [PMID: 27603688 DOI: 10.1021/acs.jmedchem.6b00694] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Systemic lupus erythematosus is an autoimmune disease that can affect numerous tissues and is characterized by the production of nuclear antigen-directed autoantibodies (e.g., anti-dsDNA). Using a combination of virtual and ELISA-based screens, we made the intriguing discovery that several HIV-protease inhibitors can function as decoy antigens to specifically inhibit the binding of anti-dsDNA antibodies to target antigens such as dsDNA and pentapeptide DWEYS. Computational modeling revealed that HIV-protease inhibitors comprised structural features present in DWEYS and predicted that analogues containing more flexible backbones would possess preferred binding characteristics. To address this, we reduced the internal amide backbone to improve flexibility, producing new small-molecule decoy antigens, which neutralize anti-dsDNA antibodies in vitro, in situ, and in vivo. Pharmacokinetic and SLE model studies demonstrated that peptidomimetic FISLE-412,1 a reduced HIV protease inhibitor analogue, was well-tolerated, altered serum reactivity to DWEYS, reduced glomeruli IgG deposition, preserved kidney histology, and delayed SLE onset in NZB/W F1 mice.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Christian Grant
- BioMedical Research Models, Inc. , 67 Millbrook Street, Worcester, Massachusetts 01606, United States
| | - Nathalie Meurice
- Department of Research, Mayo Clinic , 13400 East Shea Boulevard, Scottsdale, Arizona 85259, United States
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25
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Kaur H, Salunke DM. Antibody promiscuity: Understanding the paradigm shift in antigen recognition. IUBMB Life 2015; 67:498-505. [DOI: 10.1002/iub.1397] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2015] [Accepted: 06/16/2015] [Indexed: 11/06/2022]
Affiliation(s)
- Harmeet Kaur
- Regional Centre for Biotechnology, Biotech Science Cluster; Faridabad 121001 Haryana India
- Manipal University; 576104 Karnataka India
| | - Dinakar M. Salunke
- Regional Centre for Biotechnology, Biotech Science Cluster; Faridabad 121001 Haryana India
- National Institute of Immunology; New Delhi 110067 India
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26
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Adhikary R, Yu W, Oda M, Walker RC, Chen T, Stanfield RL, Wilson IA, Zimmermann J, Romesberg FE. Adaptive mutations alter antibody structure and dynamics during affinity maturation. Biochemistry 2015; 54:2085-93. [PMID: 25756188 DOI: 10.1021/bi501417q] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
While adaptive mutations can bestow new functions on proteins via the introduction or optimization of reactive centers, or other structural changes, a role for the optimization of protein dynamics also seems likely but has been more difficult to evaluate. Antibody (Ab) affinity maturation is an example of adaptive evolution wherein the adaptive mutations may be identified and Abs may be raised to specific targets that facilitate the characterization of protein dynamics. Here, we report the characterization of three affinity matured Abs that evolved from a common germline precursor to bind the chromophoric antigen (Ag), 8-methoxypyrene-1,3,6-trisulfonate (MPTS). In addition to characterizing the sequence, molecular recognition, and structure of each Ab, we characterized the dynamics of each complex by determining their mechanical response to an applied force via three-pulse photon echo peak shift (3PEPS) spectroscopy and deconvoluting the response into elastic, anelastic, and plastic components. We find that for one Ab, affinity maturation was accomplished via the introduction of a single functional group that mediates a direct contact with MPTS and results in a complex with little anelasticity or plasticity. In the other two cases, more mutations were introduced but none directly contact MPTS, and while their effects on structure are subtle, their effects on anelasticity and plasticity are significant, with the level of plasticity correlated with specificity, suggesting that the optimization of protein dynamics may have contributed to affinity maturation. A similar optimization of structure and dynamics may contribute to the evolution of other proteins.
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Affiliation(s)
| | | | - Masayuki Oda
- §Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, 1-5, Hangi-cho, Shimogamo, Sakyo-ku, Kyoto 606-8522, Japan
| | - Ross C Walker
- ∥Department of Chemistry and Biochemistry and San Diego Supercomputer Center, University of California, San Diego, La Jolla, California 92093, United States
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27
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Wolynes PG. Evolution, energy landscapes and the paradoxes of protein folding. Biochimie 2014; 119:218-30. [PMID: 25530262 DOI: 10.1016/j.biochi.2014.12.007] [Citation(s) in RCA: 110] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 12/11/2014] [Indexed: 01/25/2023]
Abstract
Protein folding has been viewed as a difficult problem of molecular self-organization. The search problem involved in folding however has been simplified through the evolution of folding energy landscapes that are funneled. The funnel hypothesis can be quantified using energy landscape theory based on the minimal frustration principle. Strong quantitative predictions that follow from energy landscape theory have been widely confirmed both through laboratory folding experiments and from detailed simulations. Energy landscape ideas also have allowed successful protein structure prediction algorithms to be developed. The selection constraint of having funneled folding landscapes has left its imprint on the sequences of existing protein structural families. Quantitative analysis of co-evolution patterns allows us to infer the statistical characteristics of the folding landscape. These turn out to be consistent with what has been obtained from laboratory physicochemical folding experiments signaling a beautiful confluence of genomics and chemical physics.
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Affiliation(s)
- Peter G Wolynes
- Department of Chemistry and Center for Theoretical Biological Physics, Rice University, Houston, TX 77005, USA.
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28
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Alemany A, Sanvicens N, de Lorenzo S, Marco MP, Ritort F. Bond elasticity controls molecular recognition specificity in antibody-antigen binding. NANO LETTERS 2013; 13:5197-5202. [PMID: 24074342 DOI: 10.1021/nl402617f] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Force-spectroscopy experiments make it possible to characterize single ligand-receptor pairs. Here we measure the spectrum of bond strengths and flexibilities in antibody-antigen interactions using optical tweezers. We characterize the mechanical evolution of polyclonal antibodies generated under infection and the ability of a monoclonal antibody to cross-react against different antigens. Our results suggest that bond flexibility plays a major role in remodeling antibody-antigen bonds in order to improve recognition during the maturation of the humoral immune system.
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Affiliation(s)
- Anna Alemany
- Small Biosystems Lab, Department Física Fonamental, Universitat de Barcelona , C/Martí i Franquès 1, 08028 Barcelona, Spain
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29
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Corrada D, Colombo G. Energetic and dynamic aspects of the affinity maturation process: characterizing improved variants from the bevacizumab antibody with molecular simulations. J Chem Inf Model 2013; 53:2937-50. [PMID: 24168661 DOI: 10.1021/ci400416e] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Antibody affinity maturation is one of the fundamental processes of immune defense against invading pathogens. From the biological point of view, the clonal selection hypothesis represents the most accepted mechanism to explain how mutations increasing the affinity for target antigens are introduced and selected in antibody molecules. However, understanding at the molecular level how protein modifications, such as point mutation, can modify and modulate the affinity of an antibody for its antigen is still a major open issue in molecular biology. In this paper, we address various aspects of this problem by analyzing and comparing atomistic simulations of 17 variants of the bevacizumab antibody, all directed against the common target protein VEGF-A. In particular, we examine MD-based descriptors of the internal energetics and dynamics of mutated antibodies and their possible correlations with experimentally determined affinities for the antigens. Our results show that affinity improvement is correlated with a variation of the internal stabilization energy of the antibody molecule when bound to the antigen, compensated by the variation in the interaction energy between the antigen and the antibody, paralleled by an overall modulation of internal coordination within the antibody molecular structure. A possible model of the mechanism of rigidification and of the main residues involved is proposed. Overall, our results can help in understanding the molecular determinants of antigen recognition and have implications in the rational design of new antibodies with optimized affinities.
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Affiliation(s)
- Dario Corrada
- Istituto di Chimica del Riconoscimento Molecolare - Consiglio Nazionale delle Ricerche (CNR-ICRM) , via Mario Bianco 9, 20131 Milano, Italy
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30
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Khalili H, Godwin A, Choi JW, Lever R, Khaw PT, Brocchini S. Fab-PEG-Fab as a Potential Antibody Mimetic. Bioconjug Chem 2013; 24:1870-82. [DOI: 10.1021/bc400246z] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Hanieh Khalili
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
- NIHR
Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, EC1 V 9EL, United Kingdom
| | - Antony Godwin
- PolyTherics
Ltd, The London Bioscience Innovation Centre, 2 Royal College Street, London NW1 0NH, United Kingdom
| | - Ji-won Choi
- PolyTherics
Ltd, The London Bioscience Innovation Centre, 2 Royal College Street, London NW1 0NH, United Kingdom
| | - Rebecca Lever
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
| | - Peng T. Khaw
- NIHR
Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, EC1 V 9EL, United Kingdom
| | - Steve Brocchini
- UCL
School of Pharmacy, University College London, 29-39 Brunswick Square, London WC1N 1AX, United Kingdom
- NIHR
Biomedical Research Centre, Moorfields Eye Hospital and UCL Institute of Ophthalmology, London, EC1 V 9EL, United Kingdom
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31
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Doerrbecker J, Meuleman P, Kang J, Riebesehl N, Wilhelm C, Friesland M, Pfaender S, Steinmann J, Pietschmann T, Steinmann E. Thermostability of seven hepatitis C virus genotypes in vitro and in vivo. J Viral Hepat 2013; 20:478-85. [PMID: 23730841 DOI: 10.1111/jvh.12055] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2012] [Accepted: 12/01/2012] [Indexed: 01/06/2023]
Abstract
Hepatitis C virus (HCV) is transmitted primarily through percutaneous exposure to contaminated blood especially in healthcare settings and among people who inject drugs. The environmental stability of HCV has been extrapolated from studies with the bovine viral diarrhoea virus or was so far only addressed with HCV genotype 2a viruses. The aim of this study was to compare the environmental and thermostability of all so far known seven HCV genotypes in vitro and in vivo. Incubation experiments at room temperature revealed that all HCV genotypes showed similar environmental stabilities in suspension with viral infectivity detectable for up to 28 days. The risk of HCV infection may not accurately be reflected by determination of HCV RNA levels. However, viral stability and transmission risks assessed from in vitro experiments correlated with viral infectivity in transgenic mice containing human liver xenografts. A reduced viral stability for up to 2 days was observed at 37 °C with comparable decays for all HCV genotypes confirmed by thermodynamic analysis. These results demonstrate that different HCV genotypes possess comparable stability in the environment and that noninfectious particles after incubation in vitro do not cause infection in an HCV in vivo model. These findings are important for estimation of HCV cross-transmission in the environment and indicate that different HCV genotypes do not display an altered stability or resistance at certain temperatures.
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Affiliation(s)
- J Doerrbecker
- Division of Experimental Virology, Twincore Center for Experimental and Clinical Infection Research, Feodor-Lynen-Straße 7-9, 30625 Hannover, Germany
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32
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Mock AJ, Kang J. Comment on degradation of ascorbic acid in ethanolic solutions. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2013; 61:2580-2582. [PMID: 23452173 DOI: 10.1021/jf304890b] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Affiliation(s)
- Andrew J Mock
- Department of Biology, Valdosta State University , Valdosta, Georgia 31698, United States
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33
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Kuroda D, Shirai H, Jacobson MP, Nakamura H. Computer-aided antibody design. Protein Eng Des Sel 2012; 25:507-21. [PMID: 22661385 PMCID: PMC3449398 DOI: 10.1093/protein/gzs024] [Citation(s) in RCA: 168] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2012] [Revised: 04/14/2012] [Accepted: 04/19/2012] [Indexed: 11/12/2022] Open
Abstract
Recent clinical trials using antibodies with low toxicity and high efficiency have raised expectations for the development of next-generation protein therapeutics. However, the process of obtaining therapeutic antibodies remains time consuming and empirical. This review summarizes recent progresses in the field of computer-aided antibody development mainly focusing on antibody modeling, which is divided essentially into two parts: (i) modeling the antigen-binding site, also called the complementarity determining regions (CDRs), and (ii) predicting the relative orientations of the variable heavy (V(H)) and light (V(L)) chains. Among the six CDR loops, the greatest challenge is predicting the conformation of CDR-H3, which is the most important in antigen recognition. Further computational methods could be used in drug development based on crystal structures or homology models, including antibody-antigen dockings and energy calculations with approximate potential functions. These methods should guide experimental studies to improve the affinities and physicochemical properties of antibodies. Finally, several successful examples of in silico structure-based antibody designs are reviewed. We also briefly review structure-based antigen or immunogen design, with application to rational vaccine development.
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Affiliation(s)
- Daisuke Kuroda
- Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka, Japan.
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34
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Fukunishi H. Influence of ionization states of antigen on anti-fluorescein antibodies. Chem Phys Lett 2012. [DOI: 10.1016/j.cplett.2012.08.049] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
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35
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Bax HJ, Keeble AH, Gould HJ. Cytokinergic IgE Action in Mast Cell Activation. Front Immunol 2012; 3:229. [PMID: 22888332 PMCID: PMC3412263 DOI: 10.3389/fimmu.2012.00229] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2012] [Accepted: 07/14/2012] [Indexed: 12/20/2022] Open
Abstract
Some 10 years ago it emerged that at sufficiently high concentrations certain monoclonal mouse IgEs exert previously unsuspected effects on mast cells. Thus they can both promote survival and induce activation of mast cells without the requirement for antigens. This was a wake up call that appears to have been missed (or dismissed) by the majority of immunologists. The structural attributes responsible for the potency of the so-called “highly cytokinergic” or HC IgEs have not yet been determined, but the events that ensue when such IgEs bind to the high-affinity receptor, FcεRI, on mast cells have been thoroughly studied, and are strikingly similar to those engendered by antigens when they form cross-linked complexes with the receptors. We review the evidence for the cytokinergic activity of IgE, and the structural features and known properties of immunoglobulins, and of IgE in particular, most likely to be implicated in the phenomenon. We suggest that IgEs with cytokinergic activity may be generated by local germinal center reactions in the target organs of allergy. We consider also the important implications that the existence of cytokinergic IgE may have for a fuller understanding of adaptive immunity and of the action of IgE in asthma and other diseases.
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Affiliation(s)
- Heather J Bax
- Randall Division of Cell and Molecular Biophysics, King's College London London, UK
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36
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Adhikary R, Yu W, Oda M, Zimmermann J, Romesberg FE. Protein dynamics and the diversity of an antibody response. J Biol Chem 2012; 287:27139-47. [PMID: 22685303 PMCID: PMC3411056 DOI: 10.1074/jbc.m112.372698] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2012] [Revised: 05/25/2012] [Indexed: 01/08/2023] Open
Abstract
The immune system is remarkable in its ability to produce antibodies (Abs) with virtually any specificity from a limited repertoire of germ line precursors. Although the contribution of sequence diversity to this molecular recognition has been studied for decades, recent models suggest that protein dynamics may also broaden the range of targets recognized. To characterize the contribution of protein dynamics to immunological molecular recognition, we report the sequence, thermodynamic, and time-resolved spectroscopic characterization of a panel of eight Abs elicited to the chromophoric antigen 8-methoxypyrene-1,3,6-trisulfonate (MPTS). Based on the sequence data, three of the Abs arose from unique germ line Abs, whereas the remaining five comprise two sets of siblings that arose by somatic mutation of a common precursor. The thermodynamic data indicate that the Abs recognize MPTS via a variety of mechanisms. Although the spectroscopic data reveal small differences in protein dynamics, the anti-MPTS Abs generally show similar levels of flexibility and conformational heterogeneity, possibly representing the convergent evolution of the dynamics necessary for function. However, one Ab is significantly more rigid and conformationally homogeneous than the others, including a sibling Ab from which it differs by only five somatic mutations. This example of divergent evolution demonstrates that point mutations are capable of fixing significant differences in protein dynamics. The results provide unique insight into how high affinity Abs may be produced that bind virtually any target and possibly, from a more general perspective, how new protein functions are evolved.
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Affiliation(s)
- Ramkrishna Adhikary
- From the Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037 and
| | - Wayne Yu
- From the Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037 and
| | - Masayuki Oda
- the Graduate School of Life and Environmental Sciences, Kyoto Prefectural University, Kyoto 606-8522, Japan
| | - Jörg Zimmermann
- From the Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037 and
| | - Floyd E. Romesberg
- From the Department of Chemistry, The Scripps Research Institute, La Jolla, California 92037 and
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37
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Viqar B, Gopinath A, Dimitrov JD, Kang J. Comment on Enhancement of the catalytic activity of a 27 kDa subtilisin-like enzyme from Bacillus amyloliquefaciens CH51 by in vitro mutagenesis. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2012; 60:4170-4172. [PMID: 22475247 DOI: 10.1021/jf2050729] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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38
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Antibody recognition of cancer-related gangliosides and their mimics investigated using in silico site mapping. PLoS One 2012; 7:e35457. [PMID: 22536387 PMCID: PMC3334985 DOI: 10.1371/journal.pone.0035457] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2012] [Accepted: 03/19/2012] [Indexed: 11/27/2022] Open
Abstract
Modified gangliosides may be overexpressed in certain types of cancer, thus, they are considered a valuable target in cancer immunotherapy. Structural knowledge of their interaction with antibodies is currently limited, due to the large size and high flexibility of these ligands. In this study, we apply our previously developed site mapping technique to investigate the recognition of cancer-related gangliosides by anti-ganglioside antibodies. The results reveal a potential ganglioside-binding motif in the four antibodies studied, suggesting the possibility of structural convergence in the anti-ganglioside immune response. The structural basis of the recognition of ganglioside-mimetic peptides is also investigated using site mapping and compared to ganglioside recognition. The peptides are shown to act as structural mimics of gangliosides by interacting with many of the same binding site residues as the cognate carbohydrate epitopes. These studies provide important clues as to the structural basis of immunological mimicry of carbohydrates.
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39
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Fukunishi H, Shimada J, Shiraishi K. Antigen-antibody interactions and structural flexibility of a femtomolar-affinity antibody. Biochemistry 2012; 51:2597-605. [PMID: 22390639 DOI: 10.1021/bi3000319] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The femtomolar-affinity mutant antibody (4M5.3) generated by directed evolution is interesting because of the potential of antibody engineering. In this study, the mutant and its wild type (4-4-20) were compared in terms of antigen-antibody interactions and structural flexibility to elucidate the effects of directed evolution. For this purpose, multiple steered molecular dynamics (SMD) simulations were performed. The pulling forces of SMD simulations elucidated the regions that form strong attractive interactions in the binding pocket. Structural analysis in these regions showed two important mutations for improving attractive interactions. First, mutation of Tyr102(H) to Ser (sequence numbering of Protein Data Bank entry 1FLR ) played a role in resolving the steric hindrance on the pathway of the antigen in the binding pocket. Second, mutation of Asp31(H) to His played a role in resolving electrostatic repulsion. Potentials of mean force (PMFs) of both the wild type and the mutant showed landscapes that do not include obvious intermediate states and go directly to the bound state. These landscapes were regarded as funnel-like binding free energy landscapes. Furthermore, the structural flexibility based on the fluctuations of the positions of atoms was analyzed. It was shown that the fluctuations in the positions of the antigen and residues in contact with antigen tend to be smaller in the mutant than in the wild type. This result suggested that structural flexibility decreases as affinity is improved by directed evolution. This suggestion is similar to the relationship between affinity and flexibility for in vivo affinity maturation, which was suggested by Romesberg and co-workers [Jimenez, R., et al. (2003) Proc. Natl. Acad. Sci. U.S.A.100, 92-97]. Consequently, the relationship was found to be applicable up to femotomolar affinity levels.
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Affiliation(s)
- Hiroaki Fukunishi
- Green Innovation Research Laboratories, NEC Corporation, 34, Miyukigaoka, Tsukuba, Ibaraki 305-8501, Japan.
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40
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Costa G, Danz H, Kataria P, Bromage E. A holistic view of the dynamisms of teleost IgM: a case study of Streptococcus iniae vaccinated rainbow trout (Oncorhynchus mykiss). DEVELOPMENTAL AND COMPARATIVE IMMUNOLOGY 2012; 36:298-305. [PMID: 21641928 DOI: 10.1016/j.dci.2011.04.011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/06/2011] [Revised: 04/26/2011] [Accepted: 04/27/2011] [Indexed: 05/30/2023]
Abstract
To date, little is known about how trout IgM, the primary antibody of fish, varies in titer, specificity, disulfide cross-linking, and affinity following immunization with a pathogen. Work using defined antigens has demonstrated that the disulfide cross-linking structure of IgM becomes increasingly more polymerized during an immune response, coinciding with an increase in affinity, but it is unknown if this has relevance to aquatic pathogens. Understanding how IgM varies following vaccination with an aquatic pathogen is of considerable importance as effector functions allocated to multiple antibody isotypes in mammals are essentially relegated to this single molecule. To gain insights into the dynamism of IgM, rainbow trout were immunized with Streptococcus iniae and individual serum titers, their specificity and affinity to S. iniae, and the disulfide cross-linking pattern of both total-serum and specific Ig were analyzed over a period of 37 weeks. We found that in vaccinated animals titer increased by a factor of ≈100 from starting levels, affinity increased 10-fold, and diversity of S. iniae proteins recognized by trout antibody increased at least 5-fold. Most intriguing, though less cross-linked IgM predominated early in response, by week 5, the fully tetramerized antibody comprised 50% of total specific protein. We propose that this is a mechanism to optimize efficacy of carrying out effector functions and recognizing a wide array of epitopes with higher affinity.
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Affiliation(s)
- Gregory Costa
- Department of Biology, University of Massachusetts Dartmouth, Dartmouth, MA 02747, United States
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41
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Brock JR, Rosa BQ, Kang J. Comment on color loss in ethanolic solutions of chlorophyll a. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2011; 59:9045-9047. [PMID: 21786782 DOI: 10.1021/jf2001469] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
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42
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Bumbaca D, Wong A, Drake E, Reyes AE, Lin BC, Stephan JP, Desnoyers L, Shen BQ, Dennis MS. Highly specific off-target binding identified and eliminated during the humanization of an antibody against FGF receptor 4. MAbs 2011; 3:376-86. [PMID: 21540647 DOI: 10.4161/mabs.3.4.15786] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Off-target binding can significantly affect the pharmacokinetics (PK), tissue distribution, efficacy and toxicity of a therapeutic antibody. Herein we describe the development of a humanized anti- fibroblast growth factor receptor 4 (FGFR4) antibody as a potential therapeutic for hepatocellular carcinoma (HCC). A chimeric anti FGFR4 monoclonal antibody (chLD1) was previously shown to block ligand binding and to inhibit FGFR4 mediated signaling as well as tumor growth in vivo. A humanized version of chLD1, hLD1.vB, had similar binding affinity and in vitro blocking activity, but it exhibited rapid clearance, poor target tissue biodistribution and limited efficacy when compared to chLD1 in a HUH7 human HCC xenograft mouse model. These problems were traced to instability of the molecule in rodent serum. Size exclusion high performance liquid chromatography, immunoprecipitation and mass spectral sequencing identified a specific interaction between hLD1.vB and mouse complement component 3 (C3). A PK study in C3 knock-out mice further confirmed this specific interaction. Subsequently, an affinity-matured variant derived from hLD1.vB (hLD1.v22), specifically selected for its lack of binding to mouse C3 was demonstrated to have a PK profile and in vivo efficacy similar to that of chLD1 in mice. Although reports of non-specific off-target binding have been observed for other antibodies, this represents the first report identifying a specific off-target interaction that affected disposition and biological activity. Screens developed to identify general non-specific interactions are likely to miss the rare and highly specific cross-reactivity identified in this study, thus highlighting the importance of animal models as a proxy for avoiding unexpected clinical outcomes.
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Affiliation(s)
- Daniela Bumbaca
- Early Development PKPD, Genentech, Inc., South San Francisco, CA, USA
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43
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Bostrom J, Haber L, Koenig P, Kelley RF, Fuh G. High affinity antigen recognition of the dual specific variants of herceptin is entropy-driven in spite of structural plasticity. PLoS One 2011; 6:e17887. [PMID: 21526167 PMCID: PMC3081289 DOI: 10.1371/journal.pone.0017887] [Citation(s) in RCA: 60] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2010] [Accepted: 02/16/2011] [Indexed: 12/25/2022] Open
Abstract
The antigen-binding site of Herceptin, an anti-human Epidermal Growth Factor Receptor 2 (HER2) antibody, was engineered to add a second specificity toward Vascular Endothelial Growth Factor (VEGF) to create a high affinity two-in-one antibody bH1. Crystal structures of bH1 in complex with either antigen showed that, in comparison to Herceptin, this antibody exhibited greater conformational variability, also called "structural plasticity". Here, we analyzed the biophysical and thermodynamic properties of the dual specific variants of Herceptin to understand how a single antibody binds two unrelated protein antigens. We showed that while bH1 and the affinity-improved bH1-44, in particular, maintained many properties of Herceptin including binding affinity, kinetics and the use of residues for antigen recognition, they differed in the binding thermodynamics. The interactions of bH1 and its variants with both antigens were characterized by large favorable entropy changes whereas the Herceptin/HER2 interaction involved a large favorable enthalpy change. By dissecting the total entropy change and the energy barrier for dual interaction, we determined that the significant structural plasticity of the bH1 antibodies demanded by the dual specificity did not translate into the expected increase of entropic penalty relative to Herceptin. Clearly, dual antigen recognition of the Herceptin variants involves divergent antibody conformations of nearly equivalent energetic states. Hence, increasing the structural plasticity of an antigen-binding site without increasing the entropic cost may play a role for antibodies to evolve multi-specificity. Our report represents the first comprehensive biophysical analysis of a high affinity dual specific antibody binding two unrelated protein antigens, furthering our understanding of the thermodynamics that drive the vast antigen recognition capacity of the antibody repertoire.
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Affiliation(s)
- Jenny Bostrom
- Department of Antibody Engineering, Genentech Inc., South San Francisco, California, United States of America
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
| | - Lauric Haber
- Department of Antibody Engineering, Genentech Inc., South San Francisco, California, United States of America
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
| | - Patrick Koenig
- Department of Antibody Engineering, Genentech Inc., South San Francisco, California, United States of America
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
| | - Robert F. Kelley
- Department of Antibody Engineering, Genentech Inc., South San Francisco, California, United States of America
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
| | - Germaine Fuh
- Department of Antibody Engineering, Genentech Inc., South San Francisco, California, United States of America
- Department of Protein Engineering, Genentech, Inc., South San Francisco, California, United States of America
- * E-mail:
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44
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Rational design of T cell receptors with enhanced sensitivity for antigen. PLoS One 2011; 6:e18027. [PMID: 21455495 PMCID: PMC3063236 DOI: 10.1371/journal.pone.0018027] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2010] [Accepted: 02/18/2011] [Indexed: 11/20/2022] Open
Abstract
Enhancing the affinity of therapeutic T cell receptors (TCR) without altering their specificity is a significant challenge for adoptive immunotherapy. Current efforts have primarily relied on empirical approaches. Here, we used structural analyses to identify a glycine-serine variation in the TCR that modulates antigen sensitivity. A G at position 107 within the CDR3β stalk is encoded within a single mouse and human TCR, TRBV13-2 and TRBV12-5 respectively. Most TCR bear a S107. The S hydroxymethyl side chain intercalates into the core of the CDR3β loop, stabilizing it. G107 TRBV possess a gap in their CDR3β where this S hydroxymethyl moiety would fit. We predicted based on modeling and molecular dynamics simulations that a G107S substitution would increase CDR3β stability and thereby augment receptor sensitivity. Experimentally, a G107S replacement led to an ∼10–1000 fold enhanced antigen sensitivity in 3 of 4 TRBV13-2+ TCR tested. Analysis of fine specificity indicated a preserved binding orientation. These results support the feasibility of developing high affinity antigen specific TCR for therapeutic purposes through the identification and manipulation of critical framework residues. They further indicate that amino acid variations within TRBV not directly involved in ligand contact can program TCR sensitivity, and suggest a role for CDR3 stability in this programming.
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45
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Fisher NR, Purnell CB, Kang J. Comment on effect of heating on the stability of quinolones in milk. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2010; 58:13020-13021. [PMID: 21090650 DOI: 10.1021/jf1034724] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/30/2023]
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46
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Mao H, Graziano JJ, Chase TMA, Bentley CA, Bazirgan OA, Reddy NP, Song BD, Smider VV. Spatially addressed combinatorial protein libraries for recombinant antibody discovery and optimization. Nat Biotechnol 2010; 28:1195-202. [PMID: 20972421 DOI: 10.1038/nbt.1694] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2010] [Accepted: 09/27/2010] [Indexed: 12/21/2022]
Abstract
Antibody discovery typically uses hybridoma- or display-based selection approaches, which lack the advantages of directly screening spatially addressed compound libraries as in small-molecule discovery. Here we apply the latter strategy to antibody discovery, using a library of ∼10,000 human germline antibody Fabs created by de novo DNA synthesis and automated protein expression and purification. In multiplexed screening assays, we obtained specific hits against seven of nine antigens. Using sequence-activity relationships and iterative mutagenesis, we optimized the binding affinities of two hits to the low nanomolar range. The matured Fabs showed full and partial antagonism activities in cell-based assays. Thus, protein drug leads can be discovered using surprisingly small libraries of proteins with known sequences, questioning the requirement for billions of members in an antibody discovery library. This methodology also provides sequence, expression and specificity information at the first step of the discovery process, and could enable novel antibody discovery in functional screens.
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47
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Protein functional landscapes, dynamics, allostery: a tortuous path towards a universal theoretical framework. Q Rev Biophys 2010; 43:295-332. [DOI: 10.1017/s0033583510000119] [Citation(s) in RCA: 123] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
AbstractEnergy landscape theories have provided a common ground for understanding the protein folding problem, which once seemed to be overwhelmingly complicated. At the same time, the native state was found to be an ensemble of interconverting states with frustration playing a more important role compared to the folding problem. The landscape of the folded protein – the native landscape – is glassier than the folding landscape; hence, a general description analogous to the folding theories is difficult to achieve. On the other hand, the native basin phase volume is much smaller, allowing a protein to fully sample its native energy landscape on the biological timescales. Current computational resources may also be used to perform this sampling for smaller proteins, to build a ‘topographical map’ of the native landscape that can be used for subsequent analysis. Several major approaches to representing this topographical map are highlighted in this review, including the construction of kinetic networks, hierarchical trees and free energy surfaces with subsequent structural and kinetic analyses. In this review, we extensively discuss the important question of choosing proper collective coordinates characterizing functional motions. In many cases, the substates on the native energy landscape, which represent different functional states, can be used to obtain variables that are well suited for building free energy surfaces and analyzing the protein's functional dynamics. Normal mode analysis can provide such variables in cases where functional motions are dictated by the molecule's architecture. Principal component analysis is a more expensive way of inferring the essential variables from the protein's motions, one that requires a long molecular dynamics simulation. Finally, the two popular models for the allosteric switching mechanism, ‘preexisting equilibrium’ and ‘induced fit’, are interpreted within the energy landscape paradigm as extreme points of a continuum of transition mechanisms. Some experimental evidence illustrating each of these two models, as well as intermediate mechanisms, is presented and discussed.
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Zhou J, Battig MR, Wang Y. Aptamer-based molecular recognition for biosensor development. Anal Bioanal Chem 2010; 398:2471-80. [PMID: 20644915 DOI: 10.1007/s00216-010-3987-y] [Citation(s) in RCA: 109] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2010] [Revised: 06/21/2010] [Accepted: 06/29/2010] [Indexed: 11/30/2022]
Abstract
Nucleic acid aptamers are an emerging class of synthetic ligands and have recently attracted significant attention in numerous fields. One is in biosensor development. In principle, nucleic acid aptamers can be discovered to recognize any molecule of interest with high affinity and specificity. In addition, unlike most ligands evolved in nature, synthetic nucleic acid aptamers are usually tolerant of harsh chemical, physical, and biological conditions. These distinguished characteristics make aptamers attractive molecular recognition ligands for biosensing applications. This review first concisely introduces methods for aptamer discovery including upstream selection and downstream truncation, then discusses aptamer-based biosensor development from the viewpoint of signal production.
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Affiliation(s)
- Jing Zhou
- Department of Chemical, Materials and Biomolecular Engineering, University of Connecticut, 191 Auditorium Road, Storrs, CT 06269-3222, USA
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Zimmermann J, Romesberg FE, Brooks CL, Thorpe IF. Molecular description of flexibility in an antibody combining site. J Phys Chem B 2010; 114:7359-70. [PMID: 20455589 PMCID: PMC2892760 DOI: 10.1021/jp906421v] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Mature antibodies (Abs) that are exquisitely specific for virtually any foreign molecule may be produced by affinity maturation of naïve (or germline) Abs. However, the finite number of germline Abs available suggests that, in contrast to mature Abs, germline Abs must be broadly polyspecific so that they are able to recognize a wide range of ligands. Thus, affinity maturation must play a role in mediating Ab specificity. One biophysical property that distinguishes polyspecificity from specificity is protein flexibility; a flexible combining site is able to adopt different conformations that recognize different foreign molecules (or antigens), while a rigid combining site is locked into a conformation that is specific for a given antigen. Recent studies (Proc. Natl. Acad. Sci. U.S.A. 2007, 104, 8821-8826) have examined, at the atomic level, the structural properties that mediate changes in flexibility at four stages of affinity maturation in the 4-4-20 Ab. These studies employed molecular dynamics simulations to reveal a network of residue interactions that mediate the flexibility changes accompanying maturation. The flexibility of the Ab combining sites in these molecular systems was originally measured using three-pulse photon echo spectroscopy (3PEPS). The present investigation extends this work by providing a concrete link between structural properties of the Ab molecules and features of the spectroscopic measurements used to characterize their flexibility. Results obtained from the simulations are in good qualitative agreement with the experimental measurements and indicate that the spectroscopic signal is sensitive to protein dynamics distributed throughout the entire combining site. Thus, the simulations provide a molecular-level interpretation of the changes induced by affinity maturation of the Ab. The results suggest that 3PEPS spectroscopy in combination with molecular dynamics simulations can provide a detailed description of protein dynamics and, in this case, how it is evolved for biological function.
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Affiliation(s)
- Jörg Zimmermann
- Corresponding author. , Phone : (858) 784-7335, Fax : (858) 784-7472. , Phone: (410) 455-5728, Fax: (410) 455-2608
| | | | | | - Ian F. Thorpe
- Corresponding author. , Phone : (858) 784-7335, Fax : (858) 784-7472. , Phone: (410) 455-5728, Fax: (410) 455-2608
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Kobayashi N, Oyama H, Kato Y, Goto J, Söderlind E, Borrebaeck CAK. Two-step in vitro antibody affinity maturation enables estradiol-17beta assays with more than 10-fold higher sensitivity. Anal Chem 2010; 82:1027-38. [PMID: 20047279 DOI: 10.1021/ac902283n] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Immunoassays for haptens depend on competitive hapten-anti-hapten reactions, and consequently their sensitivities are significantly influenced by the affinities of anti-hapten antibodies. Thus, genetically engineered antibodies, which have much higher affinities than native antibodies, should increase assay sensitivities. Here, we created a mutated single-chain Fv fragment (scFv) against estradiol-17beta (E(2)) that allowed immunoassays with a much improved sensitivity. Two steps of affinity maturation were performed on a "wild-type" scFv (scFv#E4-4) composed of V(H) and V(L) domains from a mouse anti-E(2) antibody (Ab#E4-4). First, we conducted complementarity-determining region (CDR)-targeted mutagenesis by "CDR-shuffling". Gene fragments encoding CDRs H2, H3, L1, and L3, each of which contained random point mutations, were combined by "shuffling" into the gene encoding the scFv#E4-4 scaffold. After phage display and repeated panning, we isolated a mutated scFv clone [scFv#m1-e7; Ile(L29)Val] that had 5-fold higher affinity (K(a) = 2.6 x 10(8) M(-1)) compared to the Ab#E4-4 Fab fragment (Fab#E4-4). Next, the entire V(H) and V(L) of this clone were randomly mutated by error-prone polymerase chain reaction (PCR). From this library, we found an improved clone, scFv#m2-c4 (K(a) = 6.3 x 10(8) M(-1); Lys(H19)Arg, Tyr(H56)Phe, Ser(H84)Pro, Glu(H85)Gly, Gln(L27)Arg, Leu(L36)Met, Ser(L63)Gly, and Ser(L77)Gly). ScFv#m2-c4 had more than 10-fold higher sensitivity (the midpoint of its dose-response curve was 0.56 ng) than Fab#E4-4 (midpoint 9.0 ng/assay) in a competitive E(2) radioimmunoassay, and even higher sensitivity [midpoint 21 pg/assay, and a limit of detection of 0.47 pg (1.7 fmol)/assay] in a competitive enzyme-linked immunosorbent assay. Cross-reactivity with selected E(2)-related endogenous steroids strongly suggested that scFv#m2-c4 has improved specificity compared to conventional antibodies.
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Affiliation(s)
- Norihiro Kobayashi
- Kobe Pharmaceutical University, 4-19-1, Motoyama-Kitamachi, Higashinada-ku, Kobe 658-8558, Japan.
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