1
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Erramilli SK, Dominik PK, Ogbu CP, Kossiakoff AA, Vecchio AJ. Structural and biophysical insights into targeting of claudin-4 by a synthetic antibody fragment. Commun Biol 2024; 7:733. [PMID: 38886509 PMCID: PMC11183071 DOI: 10.1038/s42003-024-06437-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 06/11/2024] [Indexed: 06/20/2024] Open
Abstract
Claudins are a 27-member family of ~25 kDa membrane proteins that integrate into tight junctions to form molecular barriers at the paracellular spaces between endothelial and epithelial cells. As the backbone of tight junction structure and function, claudins are attractive targets for modulating tissue permeability to deliver drugs or treat disease. However, structures of claudins are limited due to their small sizes and physicochemical properties-these traits also make therapy development a challenge. Here we report the development of a synthetic antibody fragment (sFab) that binds human claudin-4 and the determination of a high-resolution structure of it bound to claudin-4/enterotoxin complexes using cryogenic electron microscopy. Structural and biophysical results reveal this sFabs mechanism of select binding to human claudin-4 over other homologous claudins and establish the ability of sFabs to bind hard-to-target claudins to probe tight junction structure and function. The findings provide a framework for tight junction modulation by sFabs for tissue-selective therapies.
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Affiliation(s)
- Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Pawel K Dominik
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
- Pfizer, San Diego, CA, 92121, USA
| | - Chinemerem P Ogbu
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA
- Department of Structural Biology, University at Buffalo, Buffalo, NY, 14203, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637, USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588, USA.
- Department of Structural Biology, University at Buffalo, Buffalo, NY, 14203, USA.
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2
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Kordon SP, Cechova K, Bandekar SJ, Leon K, Dutka P, Siffer G, Kossiakoff AA, Vafabakhsh R, Araç D. Structural analysis and conformational dynamics of a holo-adhesion GPCR reveal interplay between extracellular and transmembrane domains. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.02.25.581807. [PMID: 38464178 PMCID: PMC10925191 DOI: 10.1101/2024.02.25.581807] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/12/2024]
Abstract
Adhesion G Protein-Coupled Receptors (aGPCRs) are key cell-adhesion molecules involved in numerous physiological functions. aGPCRs have large multi-domain extracellular regions (ECR) containing a conserved GAIN domain that precedes their seven-pass transmembrane domain (7TM). Ligand binding and mechanical force applied on the ECR regulate receptor function. However, how the ECR communicates with the 7TM remains elusive, because the relative orientation and dynamics of the ECR and 7TM within a holoreceptor is unclear. Here, we describe the cryo-EM reconstruction of an aGPCR, Latrophilin3/ADGRL3, and reveal that the GAIN domain adopts a parallel orientation to the membrane and has constrained movement. Single-molecule FRET experiments unveil three slow-exchanging FRET states of the ECR relative to the 7TM within the holoreceptor. GAIN-targeted antibodies, and cancer-associated mutations at the GAIN-7TM interface, alter FRET states, cryo-EM conformations, and receptor signaling. Altogether, this data demonstrates conformational and functional coupling between the ECR and 7TM, suggesting an ECR-mediated mechanism of aGPCR activation.
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3
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Olson KM, Campbell A, Alt A, Traynor JR. Finding the Perfect Fit: Conformational Biosensors to Determine the Efficacy of GPCR Ligands. ACS Pharmacol Transl Sci 2022; 5:694-709. [PMID: 36110374 PMCID: PMC9469492 DOI: 10.1021/acsptsci.1c00256] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
G protein-coupled receptors (GPCRs) are highly druggable targets that adopt numerous conformations. A ligand's ability to stabilize specific conformation(s) of its cognate receptor determines its efficacy or ability to produce a biological response. Identifying ligands that produce different receptor conformations and potentially discrete pharmacological effects (e.g., biased agonists, partial agonists, antagonists, allosteric modulators) is a major goal in drug discovery and necessary to develop drugs with better effectiveness and fewer side effects. Fortunately, direct measurements of ligand efficacy, via receptor conformational changes are possible with the recent development of conformational biosensors. In this review, we discuss classical efficacy models, including the two-state model, the ternary-complex model, and multistate models. We describe how nanobody-, transducer-, and receptor-based conformational biosensors detect and/or stabilize specific GPCR conformations to identify ligands with different levels of efficacy. In particular, conformational biosensors provide the potential to identify and/or characterize therapeutically desirable but often difficult to measure conformations of receptors faster and better than current methods. For drug discovery/development, several recent proof-of-principle studies have optimized conformational biosensors for high-throughput screening (HTS) platforms. However, their widespread use is limited by the fact that few sensors are reliably capable of detecting low-frequency conformations and technically demanding assay conditions. Nonetheless, conformational biosensors do help identify desirable ligands such as allosteric modulators, biased ligands, or partial agonists in a single assay, representing a distinct advantage over classical methods.
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Affiliation(s)
- Keith M. Olson
- Department
of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, Michigan 48109, United States
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Andra Campbell
- Department
of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, Michigan 48109, United States
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - Andrew Alt
- Department
of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, Michigan 48109, United States
- Life
Sciences Institute, University of Michigan, Ann Arbor, Michigan 48109, United States
| | - John R. Traynor
- Department
of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, Michigan 48109, United States
- Department
of Medicinal Chemistry, College of Pharmacy, University of Michigan, 428 Church Street, Ann Arbor, Michigan 48109, United
States
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4
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Wingler LM, Feld AP. Nanobodies as Probes and Modulators of Cardiovascular G Protein-Coupled Receptors. J Cardiovasc Pharmacol 2022; 80:342-353. [PMID: 34840268 DOI: 10.1097/fjc.0000000000001185] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/30/2021] [Accepted: 11/06/2021] [Indexed: 01/31/2023]
Abstract
ABSTRACT Understanding the activation of G protein-coupled receptors (GPCRs) is of paramount importance to the field of cardiovascular medicine due to the critical physiological roles of these receptors and their prominence as drug targets. Although many cardiovascular GPCRs have been extensively studied as model receptors for decades, new complexities in their regulation continue to emerge. As a result, there is an ongoing need to develop novel approaches to monitor and to modulate GPCR activation. In less than a decade, nanobodies, or recombinant single-domain antibody fragments from camelids, have become indispensable tools for interrogating GPCRs both in purified systems and in living cells. Nanobodies have gained traction rapidly due to their biochemical tractability and their ability to recognize defined states of native proteins. Here, we review how nanobodies have been adopted to elucidate the structure, pharmacology, and signaling of cardiovascular GPCRs, resolving long-standing mysteries and revealing unexpected mechanisms. We also discuss how advancing technologies to discover nanobodies with tailored specificities may expand the impact of these tools for both basic science and therapeutic applications.
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Affiliation(s)
- Laura M Wingler
- Department of Pharmacology and Cancer Biology, Duke University, Durham, NC
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5
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Orlando BJ, Dominik PK, Roy S, Ogbu CP, Erramilli SK, Kossiakoff AA, Vecchio AJ. Development, structure, and mechanism of synthetic antibodies that target claudin and Clostridium perfringens enterotoxin complexes. J Biol Chem 2022; 298:102357. [PMID: 35952760 PMCID: PMC9463536 DOI: 10.1016/j.jbc.2022.102357] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2022] [Revised: 08/01/2022] [Accepted: 08/03/2022] [Indexed: 11/15/2022] Open
Abstract
Strains of Clostridium perfringens produce a two-domain enterotoxin (CpE) that afflicts humans and domesticated animals, causing prevalent gastrointestinal illnesses. CpE’s C-terminal domain (cCpE) binds cell surface receptors, followed by a restructuring of its N-terminal domain to form a membrane-penetrating β-barrel pore, which is toxic to epithelial cells of the gut. The claudin family of membrane proteins are known receptors for CpE and also control the architecture and function of cell-cell contacts (tight junctions) that create barriers to intercellular molecular transport. CpE binding and assembly disables claudin barrier function and induces cytotoxicity via β-pore formation, disrupting gut homeostasis; however, a structural basis of this process and strategies to inhibit the claudin–CpE interactions that trigger it are both lacking. Here, we used a synthetic antigen-binding fragment (sFab) library to discover two sFabs that bind claudin-4 and cCpE complexes. We established these sFabs’ mode of molecular recognition and binding properties and determined structures of each sFab bound to claudin-4–cCpE complexes using cryo-EM. The structures reveal that the sFabs bind a shared epitope, but conform distinctly, which explains their unique binding equilibria. Mutagenesis of antigen/sFab interfaces observed therein result in binding changes, validating the structures, and uncovering the sFab’s targeting mechanism. From these insights, we generated a model for CpE’s claudin-bound β-pore that predicted sFabs would not prevent cytotoxicity, which we then verified in vivo. Taken together, this work demonstrates the development and mechanism of claudin/cCpE-binding sFabs that provide a framework and strategy for obstructing claudin/CpE assembly to treat CpE-linked gastrointestinal diseases.
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Affiliation(s)
- Benjamin J Orlando
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, MI, 48824 USA
| | - Pawel K Dominik
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Sourav Roy
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA
| | - Chinemerem P Ogbu
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, 60637 USA
| | - Alex J Vecchio
- Department of Biochemistry, University of Nebraska-Lincoln, Lincoln, NE, 68588 USA.
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6
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Rohaim A, Slezak T, Koh YH, Blachowicz L, Kossiakoff AA, Roux B. Engineering of a synthetic antibody fragment for structural and functional studies of K+ channels. J Gen Physiol 2022; 154:e202112965. [PMID: 35234830 PMCID: PMC8924934 DOI: 10.1085/jgp.202112965] [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: 05/14/2021] [Accepted: 01/28/2022] [Indexed: 11/20/2022] Open
Abstract
Engineered antibody fragments (Fabs) have made major impacts on structural biology research, particularly to aid structural determination of membrane proteins. Nonetheless, Fabs generated by traditional monoclonal technology suffer from challenges of routine production and storage. Starting from the known IgG paratopes of an antibody that binds to the "turret loop" of the KcsA K+ channel, we engineered a synthetic Fab (sFab) based upon the highly stable Herceptin Fab scaffold, which can be recombinantly expressed in Escherichia coli and purified with single-step affinity chromatography. This synthetic Fab was used as a crystallization chaperone to obtain crystals of the KcsA channel that diffracted to a resolution comparable to that from the parent Fab. Furthermore, we show that the turret loop can be grafted into the unrelated voltage-gated Kv1.2-Kv2.1 channel and still strongly bind the engineered sFab, in support of the loop grafting strategy. Macroscopic electrophysiology recordings show that the sFab affects the activation and conductance of the chimeric voltage-gated channel. These results suggest that straightforward engineering of antibodies using recombinant formats can facilitate the rapid and scalable production of Fabs as structural biology tools and functional probes. The impact of this approach is expanded significantly based on the potential portability of the turret loop to a myriad of other K+ channels.
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Affiliation(s)
- Ahmed Rohaim
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
- Department of Biophysics, Faculty of Science, Cairo University, Giza, Egypt
| | - Tomasz Slezak
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
| | - Young Hoon Koh
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
| | - Lydia Blachowicz
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
| | - Anthony A. Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL
| | - Benoît Roux
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL
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7
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Kermani AA, Burata OE, Koff BB, Koide A, Koide S, Stockbridge RB. Crystal structures of bacterial small multidrug resistance transporter EmrE in complex with structurally diverse substrates. eLife 2022; 11:76766. [PMID: 35254261 PMCID: PMC9000954 DOI: 10.7554/elife.76766] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2022] [Accepted: 03/06/2022] [Indexed: 11/13/2022] Open
Abstract
Proteins from the bacterial small multidrug resistance (SMR) family are proton-coupled exporters of diverse antiseptics and antimicrobials, including polyaromatic cations and quaternary ammonium compounds. The transport mechanism of the Escherichia coli transporter, EmrE, has been studied extensively, but a lack of high-resolution structural information has impeded a structural description of its molecular mechanism. Here, we apply a novel approach, multipurpose crystallization chaperones, to solve several structures of EmrE, including a 2.9 Å structure at low pH without substrate. We report five additional structures in complex with structurally diverse transported substrates, including quaternary phosphonium, quaternary ammonium, and planar polyaromatic compounds. These structures show that binding site tryptophan and glutamate residues adopt different rotamers to conform to disparate structures without requiring major rearrangements of the backbone structure. Structural and functional comparison to Gdx-Clo, an SMR protein that transports a much narrower spectrum of substrates, suggests that in EmrE, a relatively sparse hydrogen bond network among binding site residues permits increased sidechain flexibility.
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Affiliation(s)
- Ali A Kermani
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Olive E Burata
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - B Ben Koff
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
| | - Akiko Koide
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, United States
| | - Shohei Koide
- Laura and Isaac Perlmutter Cancer Center, New York University Langone Medical Center, New York, United States
| | - Randy B Stockbridge
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, United States
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8
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Davydova EK. Protein Engineering: Advances in Phage Display for Basic Science and Medical Research. BIOCHEMISTRY. BIOKHIMIIA 2022; 87:S146-S110. [PMID: 35501993 PMCID: PMC8802281 DOI: 10.1134/s0006297922140127] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/26/2021] [Revised: 10/28/2021] [Accepted: 11/02/2021] [Indexed: 12/03/2022]
Abstract
Functional Protein Engineering became the hallmark in biomolecule manipulation in the new millennium, building on and surpassing the underlying structural DNA manipulation and recombination techniques developed and employed in the last decades of 20th century. Because of their prominence in almost all biological processes, proteins represent extremely important targets for engineering enhanced or altered properties that can lead to improvements exploitable in healthcare, medicine, research, biotechnology, and industry. Synthetic protein structures and functions can now be designed on a computer and/or evolved using molecular display or directed evolution methods in the laboratory. This review will focus on the recent trends in protein engineering and the impact of this technology on recent progress in science, cancer- and immunotherapies, with the emphasis on the current achievements in basic protein research using synthetic antibody (sABs) produced by phage display pipeline in the Kossiakoff laboratory at the University of Chicago (KossLab). Finally, engineering of the highly specific binding modules, such as variants of Streptococcal protein G with ultra-high orthogonal affinity for natural and engineered antibody scaffolds, and their possible applications as a plug-and-play platform for research and immunotherapy will be described.
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Affiliation(s)
- Elena K Davydova
- The University of Chicago, Department of Biochemistry and Molecular Biology, Chicago, IL 60637, USA.
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9
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Abstract
Cryogenic electron microscopy (cryo-EM) has revolutionized the field of structural biology, particularly in solving the structures of large protein complexes or cellular machineries that play important biological functions. This review focuses on the contribution and future potential of cryo-EM in related emerging applications-enzymatic mechanisms and dynamic processes. Work on these subjects can benefit greatly from the capability of cryo-EM to solve the structures of specific protein complexes in multiple conditions, including variations in the buffer condition, ligands, and temperature, and to capture multiple conformational states, conformational change intermediates, and reaction intermediates. These studies can expand the structural landscape of specific proteins or protein complexes in multiple dimensions and drive new advances in the fields of enzymology and dynamic processes. The advantages and complementarity of cryo-EM relative to X-ray crystallography and nuclear magnetic resonance with regard to these applications are also addressed. Expected final online publication date for the Annual Review of Biophysics, Volume 51 is May 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Ming-Daw Tsai
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; .,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
| | - Wen-Jin Wu
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan;
| | - Meng-Chiao Ho
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; .,Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan
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10
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Bloch JS, Mukherjee S, Kowal J, Filippova EV, Niederer M, Pardon E, Steyaert J, Kossiakoff AA, Locher KP. Development of a universal nanobody-binding Fab module for fiducial-assisted cryo-EM studies of membrane proteins. Proc Natl Acad Sci U S A 2021; 118:e2115435118. [PMID: 34782475 PMCID: PMC8617411 DOI: 10.1073/pnas.2115435118] [Citation(s) in RCA: 36] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2021] [Accepted: 10/11/2021] [Indexed: 11/18/2022] Open
Abstract
With conformation-specific nanobodies being used for a wide range of structural, biochemical, and cell biological applications, there is a demand for antigen-binding fragments (Fabs) that specifically and tightly bind these nanobodies without disturbing the nanobody-target protein interaction. Here, we describe the development of a synthetic Fab (termed NabFab) that binds the scaffold of an alpaca-derived nanobody with picomolar affinity. We demonstrate that upon complementary-determining region grafting onto this parent nanobody scaffold, nanobodies recognizing diverse target proteins and derived from llama or camel can cross-react with NabFab without loss of affinity. Using NabFab as a fiducial and size enhancer (50 kDa), we determined the high-resolution cryogenic electron microscopy (cryo-EM) structures of nanobody-bound VcNorM and ScaDMT, both small membrane proteins of ∼50 kDa. Using an additional anti-Fab nanobody further facilitated reliable initial three-dimensional structure determination from small cryo-EM test datasets. Given that NabFab is of synthetic origin, is humanized, and can be conveniently expressed in Escherichia coli in large amounts, it may be useful not only for structural biology but also for biomedical applications.
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Affiliation(s)
- Joël S Bloch
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| | - Julia Kowal
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Ekaterina V Filippova
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637
| | - Martina Niederer
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel, B-1050 Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, B-1050 Brussels, Belgium
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL 60637;
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637
| | - Kaspar P Locher
- Institute of Molecular Biology and Biophysics, ETH Zürich, 8093 Zürich, Switzerland;
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11
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Olson KM, Traynor JR, Alt A. Allosteric Modulator Leads Hiding in Plain Site: Developing Peptide and Peptidomimetics as GPCR Allosteric Modulators. Front Chem 2021; 9:671483. [PMID: 34692635 PMCID: PMC8529114 DOI: 10.3389/fchem.2021.671483] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2021] [Accepted: 08/02/2021] [Indexed: 12/17/2022] Open
Abstract
Allosteric modulators (AMs) of G-protein coupled receptors (GPCRs) are desirable drug targets because they can produce fewer on-target side effects, improved selectivity, and better biological specificity (e.g., biased signaling or probe dependence) than orthosteric drugs. An underappreciated source for identifying AM leads are peptides and proteins-many of which were evolutionarily selected as AMs-derived from endogenous protein-protein interactions (e.g., transducer/accessory proteins), intramolecular receptor contacts (e.g., pepducins or extracellular domains), endogenous peptides, and exogenous libraries (e.g., nanobodies or conotoxins). Peptides offer distinct advantages over small molecules, including high affinity, good tolerability, and good bioactivity, and specific disadvantages, including relatively poor metabolic stability and bioavailability. Peptidomimetics are molecules that combine the advantages of both peptides and small molecules by mimicking the peptide's chemical features responsible for bioactivity while improving its druggability. This review 1) discusses sources and strategies to identify peptide/peptidomimetic AMs, 2) overviews strategies to convert a peptide lead into more drug-like "peptidomimetic," and 3) critically analyzes the advantages, disadvantages, and future directions of peptidomimetic AMs. While small molecules will and should play a vital role in AM drug discovery, peptidomimetics can complement and even exceed the advantages of small molecules, depending on the target, site, lead, and associated factors.
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Affiliation(s)
- Keith M. Olson
- Department of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, MI, United States
| | - John R. Traynor
- Department of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, MI, United States
- Department of Medicinal Chemistry, College of Pharmacy, University of Michigan, Ann Arbor, MI, United States
| | - Andrew Alt
- Department of Pharmacology and Edward F Domino Research Center, University of Michigan, Ann Arbor, MI, United States
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, United States
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12
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McIlwain BC, Erwin AL, Davis AR, Ben Koff B, Chang L, Bylund T, Chuang GY, Kwong PD, Ohi MD, Lai YT, Stockbridge RB. N-terminal Transmembrane-Helix Epitope Tag for X-ray Crystallography and Electron Microscopy of Small Membrane Proteins. J Mol Biol 2021; 433:166909. [PMID: 33676924 PMCID: PMC8292168 DOI: 10.1016/j.jmb.2021.166909] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 02/19/2021] [Accepted: 02/23/2021] [Indexed: 12/21/2022]
Abstract
Structural studies of membrane proteins, especially small membrane proteins, are associated with well-known experimental challenges. Complexation with monoclonal antibody fragments is a common strategy to augment such proteins; however, generating antibody fragments that specifically bind a target protein is not trivial. Here we identify a helical epitope, from the membrane-proximal external region (MPER) of the gp41-transmembrane subunit of the HIV envelope protein, that is recognized by several well-characterized antibodies and that can be fused as a contiguous extension of the N-terminal transmembrane helix of a broad range of membrane proteins. To analyze whether this MPER-epitope tag might aid structural studies of small membrane proteins, we determined an X-ray crystal structure of a membrane protein target that does not crystallize without the aid of crystallization chaperones, the Fluc fluoride channel, fused to the MPER epitope and in complex with antibody. We also demonstrate the utility of this approach for single particle electron microscopy with Fluc and two additional small membrane proteins that represent different membrane protein folds, AdiC and GlpF. These studies show that the MPER epitope provides a structurally defined, rigid docking site for antibody fragments that is transferable among diverse membrane proteins and can be engineered without prior structural information. Antibodies that bind to the MPER epitope serve as effective crystallization chaperones and electron microscopy fiducial markers, enabling structural studies of challenging small membrane proteins.
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Affiliation(s)
- Benjamin C McIlwain
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Amanda L Erwin
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48019, United States
| | - Alexander R Davis
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, United States
| | - B Ben Koff
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, United States
| | - Louise Chang
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States
| | - Tatsiana Bylund
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States
| | - Gwo-Yu Chuang
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States
| | - Peter D Kwong
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States
| | - Melanie D Ohi
- Life Sciences Institute, University of Michigan, Ann Arbor, MI 48109, United States; Department of Cell and Developmental Biology, University of Michigan, Ann Arbor, MI 48019, United States.
| | - Yen-Ting Lai
- Vaccine Research Center, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, MD 20892, United States; Moderna Therapeutics, 200 Technology Square, Cambridge, MA 02139, United States.
| | - Randy B Stockbridge
- Department of Molecular, Cellular and Developmental Biology, University of Michigan, Ann Arbor, MI 48109, United States; Program in Biophysics, University of Michigan, Ann Arbor, MI 48109, United States.
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13
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Wakasa A, Kaneko MK, Kato Y, Takagi J, Arimori T. Site-specific epitope insertion into recombinant proteins using the MAP tag system. J Biochem 2021; 168:375-384. [PMID: 32386302 PMCID: PMC7585734 DOI: 10.1093/jb/mvaa054] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2020] [Accepted: 04/24/2020] [Indexed: 01/17/2023] Open
Abstract
The MAP tag system comprises a 14-residue peptide derived from mouse podoplanin and its high-affinity monoclonal antibody PMab-1. We determined the crystal structure of PMab-1 complexed with the MAP tag peptide and found that the recognition required only the N-terminal 8 residues of MAP tag sequence, enabling the shortening of the tag length without losing the affinity for PMab-1. Furthermore, the structure illustrated that the MAP tag adopts a U-shaped conformation when bound by PMab-1, suggesting that loop-inserted MAP tag would assume conformation compatible with the PMab-1 binding. We inserted the 8-residue MAP tag into multiple loop regions in various proteins including fibronectin type III domain and G-protein-coupled receptors and tested if they maintain PMab-1 reactivity. Despite the conformational restraints forced by the insertion position, all MAP-inserted mutants were expressed well in mammalian cells at levels comparable to the non-tagged proteins. Furthermore, the binding by PMab-1 was fully maintained even for the mutant where MAP tag was inserted at a structurally restricted β-hairpin, indicating that the MAP tag system has unique feature that allows placement in the middle of protein domain at desired locations. Our results indicate the versatile utility of the MAP tag system in 'site-specific epitope insertion' application.
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Affiliation(s)
- Ayami Wakasa
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Mika K Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine.,New Industry Creation Hatchery Center, Tohoku University, 2-1 Seiryo-machi, Aoba-ku, Sendai, Miyagi 980-8575, Japan
| | - Junichi Takagi
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
| | - Takao Arimori
- Laboratory of Protein Synthesis and Expression, Institute for Protein Research, Osaka University, 3-2 Yamadaoka, Suita, Osaka 565-0871, Japan
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14
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Uchański T, Masiulis S, Fischer B, Kalichuk V, López-Sánchez U, Zarkadas E, Weckener M, Sente A, Ward P, Wohlkönig A, Zögg T, Remaut H, Naismith JH, Nury H, Vranken W, Aricescu AR, Pardon E, Steyaert J. Megabodies expand the nanobody toolkit for protein structure determination by single-particle cryo-EM. Nat Methods 2021; 18:60-68. [PMID: 33408403 PMCID: PMC7611088 DOI: 10.1038/s41592-020-01001-6] [Citation(s) in RCA: 68] [Impact Index Per Article: 22.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2019] [Accepted: 10/22/2020] [Indexed: 01/28/2023]
Abstract
Nanobodies are popular and versatile tools for structural biology. They have a compact single immunoglobulin domain organization, bind target proteins with high affinities while reducing their conformational heterogeneity and stabilize multi-protein complexes. Here we demonstrate that engineered nanobodies can also help overcome two major obstacles that limit the resolution of single-particle cryo-electron microscopy reconstructions: particle size and preferential orientation at the water-air interfaces. We have developed and characterized constructs, termed megabodies, by grafting nanobodies onto selected protein scaffolds to increase their molecular weight while retaining the full antigen-binding specificity and affinity. We show that the megabody design principles are applicable to different scaffold proteins and recognition domains of compatible geometries and are amenable for efficient selection from yeast display libraries. Moreover, we demonstrate that megabodies can be used to obtain three-dimensional reconstructions for membrane proteins that suffer from severe preferential orientation or are otherwise too small to allow accurate particle alignment.
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Affiliation(s)
- Tomasz Uchański
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Simonas Masiulis
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Baptiste Fischer
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Valentina Kalichuk
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Uriel López-Sánchez
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Eleftherios Zarkadas
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Miriam Weckener
- Rosalind Franklin Institute, Rutherford Appleton Laboratory, Didcot, UK
| | - Andrija Sente
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK
| | - Philip Ward
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Alexandre Wohlkönig
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Thomas Zögg
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Han Remaut
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - James H Naismith
- Rosalind Franklin Institute, Rutherford Appleton Laboratory, Didcot, UK
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Hugues Nury
- CNRS, Université Grenoble Alpes, CEA, Institut de Biologie Structurale, Grenoble, France
| | - Wim Vranken
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
- Interuniversity Institute of Bioinformatics in Brussels, ULB-VUB, Brussels, Belgium
| | - A Radu Aricescu
- MRC Laboratory of Molecular Biology, Cambridge Biomedical Campus, Cambridge, UK.
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, UK.
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium.
- VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium.
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15
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Thompson MC, Yeates TO, Rodriguez JA. Advances in methods for atomic resolution macromolecular structure determination. F1000Res 2020; 9:F1000 Faculty Rev-667. [PMID: 32676184 PMCID: PMC7333361 DOI: 10.12688/f1000research.25097.1] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 06/25/2020] [Indexed: 12/13/2022] Open
Abstract
Recent technical advances have dramatically increased the power and scope of structural biology. New developments in high-resolution cryo-electron microscopy, serial X-ray crystallography, and electron diffraction have been especially transformative. Here we highlight some of the latest advances and current challenges at the frontiers of atomic resolution methods for elucidating the structures and dynamical properties of macromolecules and their complexes.
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Affiliation(s)
- Michael C. Thompson
- Department of Chemistry and Chemical Biology, University of California, Merced, CA, USA
| | - Todd O. Yeates
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
- UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, CA, USA
| | - Jose A. Rodriguez
- Department of Chemistry and Biochemistry, University of California Los Angeles, Los Angeles, CA, USA
- UCLA-DOE Institute for Genomics and Proteomics, Los Angeles, CA, USA
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16
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Daniels MJ, Jagielnicki M, Yeager M. Structure/Function Analysis of human ZnT8 (SLC30A8): A Diabetes Risk Factor and Zinc Transporter. Curr Res Struct Biol 2020; 2:144-155. [PMID: 34235474 PMCID: PMC8244513 DOI: 10.1016/j.crstbi.2020.06.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2020] [Revised: 06/15/2020] [Accepted: 06/22/2020] [Indexed: 12/17/2022] Open
Abstract
The human zinc transporter ZnT8 (SLC30A8) is expressed primarily in pancreatic β-cells and plays a key function in maintaining the concentration of blood glucose through its role in insulin storage, maturation and secretion. ZnT8 is an autoantigen for Type 1 diabetes (T1D) and is associated with Type 2 diabetes (T2D) through its risk allele that encodes a major non-synonymous single nucleotide polymorphism (SNP) at Arg325. Loss of function mutations improve insulin secretion and are protective against diabetes. Despite its role in diabetes and concomitant potential as a drug target, little is known about the structure or mechanism of ZnT8. To this end, we expressed ZnT8 in Pichia pastoris yeast and Sf9 insect cells. Guided by a rational screen of 96 detergents, we developed a method to solubilize and purify recombinant ZnT8. An in vivo transport assay in Pichia and a liposome-based uptake assay for insect-cell derived ZnT8 showed that the protein is functionally active in both systems. No significant difference in activity was observed between full-length ZnT8 (ZnT8A) and the amino-terminally truncated ZnT8B isoform. A fluorescence-based in vitro transport assay using proteoliposomes indicated that human ZnT8 functions as a Zn2+/H+ antiporter. We also purified E. coli-expressed amino- and carboxy-terminal cytoplasmic domains of ZnT8A. Circular dichroism spectrometry suggested that the amino-terminal domain contains predominantly α-helical structure, and indicated that the carboxy-terminal domain has a mixed α/β structure. Negative-stain electron microscopy and single-particle image analysis yielded a density map of ZnT8B at 20 Å resolution, which revealed that ZnT8 forms a dimer in detergent micelles. Two prominent lobes are ascribed to the transmembrane domains, and the molecular envelope recapitulates that of the bacterial zinc transporter YiiP. These results provide a foundation for higher resolution structural studies and screening experiments to identify compounds that modulate ZnT8 activity.
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Affiliation(s)
- Mark J. Daniels
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
| | - Maciej Jagielnicki
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Biochemistry, University of Toronto, Toronto, ON, M5G 1M1, Canada
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
- Department of Medicine, Division of Cardiovascular Medicine, University of Virginia Health System, Charlottesville, VA, 22908, USA
- Center for Membrane and Cell Physiology, University of Virginia School of Medicine, Charlottesville, VA, 22908, USA
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17
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Mukherjee S, Erramilli SK, Ammirati M, Alvarez FJD, Fennell KF, Purdy MD, Skrobek BM, Radziwon K, Coukos J, Kang Y, Dutka P, Gao X, Qiu X, Yeager M, Eric Xu H, Han S, Kossiakoff AA. Synthetic antibodies against BRIL as universal fiducial marks for single-particle cryoEM structure determination of membrane proteins. Nat Commun 2020; 11:1598. [PMID: 32221310 PMCID: PMC7101349 DOI: 10.1038/s41467-020-15363-0] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2019] [Accepted: 03/03/2020] [Indexed: 12/22/2022] Open
Abstract
We propose the concept of universal fiducials based on a set of pre-made semi-synthetic antibodies (sABs) generated by customized phage display selections against the fusion protein BRIL, an engineered variant of apocytochrome b562a. These sABs can bind to BRIL fused either into the loops or termini of different GPCRs, ion channels, receptors and transporters without disrupting their structure. A crystal structure of BRIL in complex with an affinity-matured sAB (BAG2) that bound to all systems tested delineates the footprint of interaction. Negative stain and cryoEM data of several examples of BRIL-membrane protein chimera highlight the effectiveness of the sABs as universal fiducial marks. Taken together with a cryoEM structure of sAB bound human nicotinic acetylcholine receptor, this work demonstrates that these anti-BRIL sABs can greatly enhance the particle properties leading to improved cryoEM outcomes, especially for challenging membrane proteins.
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Affiliation(s)
- Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Mark Ammirati
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Frances J D Alvarez
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Kimberly F Fennell
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Michael D Purdy
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - Blazej M Skrobek
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Gene Center and Department of Biochemistry, Ludwig Maximilian University of Munich, Munich, Germany
| | - Katarzyna Radziwon
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Department of Biochemistry, University of Wisconsin Madison, Madison, WI, USA
| | - John Coukos
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Yanyong Kang
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
- Takeda San Diego Inc., San Diego, CA, USA
| | - Przemysław Dutka
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
- Division of Chemistry and Chemical Engineering, California Institute of Technology, Pasadena, CA, USA
| | - Xiang Gao
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
| | - Xiayang Qiu
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Mark Yeager
- Department of Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA, USA
| | - H Eric Xu
- Center for Cancer and Cell Biology, Structural Biology Program, Van Andel Research Institute, Grand Rapids, MI, USA
- Key Laboratory of Receptor Research, VARI-SIMM Center, Center for Structure and Function of Drug Targets, Shanghai Institute of Materia Medica, Chinese Academy of Sciences, Shanghai, China
| | - Seungil Han
- Medicine Design, Worldwide Research and Development, Pfizer Inc., Eastern Point Road, Groton, CT, 06340, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA.
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA.
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