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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Stover L, Bahramimoghaddam H, Wang L, Schrecke S, Yadav GP, Zhou M, Laganowsky A. Grafting the ALFA tag for structural studies of aquaporin Z. J Struct Biol X 2024; 9:100097. [PMID: 38361954 PMCID: PMC10867769 DOI: 10.1016/j.yjsbx.2024.100097] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2023] [Revised: 01/29/2024] [Accepted: 01/30/2024] [Indexed: 02/17/2024] Open
Abstract
Aquaporin Z (AqpZ), a bacterial water channel, forms a tetrameric complex and, like many other membrane proteins, activity is regulated by lipids. Various methods have been developed to facilitate structure determination of membrane proteins, such as the use of antibodies. Here, we graft onto AqpZ the ALFA tag (AqpZ-ALFA), an alpha helical epitope, to make use of the high-affinity anti-ALFA nanobody (nB). Native mass spectrometry reveals the AqpZ-ALFA fusion forms a stable, 1:1 complex with nB. Single-particle cryogenic electron microscopy studies reveal the octameric (AqpZ-ALFA)4(nB)4 complex forms a dimeric assembly and the structure was determined to 1.9 Å resolution. Dimerization of the octamer is mediated through stacking of the symmetrically bound nBs. Tube-like density is also observed, revealing a potential cardiolipin binding site. Grafting of the ALFA tag, or other epitope, along with binding and association of nBs to promote larger complexes will have applications in structural studies and protein engineering.
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Affiliation(s)
- Lauren Stover
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | | | - Lie Wang
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
| | - Samantha Schrecke
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
| | - Gaya P. Yadav
- Laboratory for Biomolecular Structure and Dynamics (LBSD), Department of Biochemistry and Biophysics, Texas A&M University, College Station, TX 77843, United States
| | - Ming Zhou
- Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, Houston, TX 77030, United States
| | - Arthur Laganowsky
- Department of Chemistry, Texas A&M University, College Station, TX 77843, United States
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3
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Skiba MA, Sterling SM, Rawson S, Zhang S, Xu H, Jiang H, Nemeth GR, Gilman MSA, Hurley JD, Shen P, Staus DP, Kim J, McMahon C, Lehtinen MK, Rockman HA, Barth P, Wingler LM, Kruse AC. Antibodies expand the scope of angiotensin receptor pharmacology. Nat Chem Biol 2024:10.1038/s41589-024-01620-6. [PMID: 38744986 DOI: 10.1038/s41589-024-01620-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Accepted: 04/12/2024] [Indexed: 05/16/2024]
Abstract
G-protein-coupled receptors (GPCRs) are key regulators of human physiology and are the targets of many small-molecule research compounds and therapeutic drugs. While most of these ligands bind to their target GPCR with high affinity, selectivity is often limited at the receptor, tissue and cellular levels. Antibodies have the potential to address these limitations but their properties as GPCR ligands remain poorly characterized. Here, using protein engineering, pharmacological assays and structural studies, we develop maternally selective heavy-chain-only antibody ('nanobody') antagonists against the angiotensin II type I receptor and uncover the unusual molecular basis of their receptor antagonism. We further show that our nanobodies can simultaneously bind to angiotensin II type I receptor with specific small-molecule antagonists and demonstrate that ligand selectivity can be readily tuned. Our work illustrates that antibody fragments can exhibit rich and evolvable pharmacology, attesting to their potential as next-generation GPCR modulators.
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Affiliation(s)
- Meredith A Skiba
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Sarah M Sterling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Cryo-EM Facility at MIT.nano, Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Shuhao Zhang
- Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
| | - Huixin Xu
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Haoran Jiang
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
| | - Genevieve R Nemeth
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Morgan S A Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Joseph D Hurley
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Pengxiang Shen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Dean P Staus
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA
- Septerna, South San Francisco, CA, USA
| | - Jihee Kim
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC, USA
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
- Sanofi, Large Molecule Research, Cambridge, MA, USA
| | - Maria K Lehtinen
- Department of Pathology, Boston Children's Hospital, Boston, MA, USA
| | - Howard A Rockman
- Department of Medicine, Duke University Medical Center, Durham, NC, USA
- Department of Cell Biology, Duke University Medical Center, Durham, NC, USA
| | - Patrick Barth
- Interfaculty Institute of Bioengineering, École Polytechnique Fédérale de Lausanne, Lausanne, Switzerland
- Ludwig Institute for Cancer Research Lausanne, Epalinges, Switzerland
| | - Laura M Wingler
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC, USA
| | - Andrew C Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA.
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4
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Gao R, Jia Y, Xu X, Fu P, Zhou J, Yang G. Structural insights into the Oryza sativa cation transporters HKTs in salt tolerance. JOURNAL OF INTEGRATIVE PLANT BIOLOGY 2024; 66:700-708. [PMID: 38409933 DOI: 10.1111/jipb.13632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 02/28/2024]
Abstract
The high-affinity potassium transporters (HKTs), selectively permeable to either Na+ alone or Na+/K+, play pivotal roles in maintaining plant Na+/K+ homeostasis. Although their involvement in salt tolerance is widely reported, the molecular underpinnings of Oryza sativa HKTs remain elusive. In this study, we elucidate the structures of OsHKT1;1 and OsHKT2;1, representing two distinct classes of rice HKTs. The dimeric assembled OsHKTs can be structurally divided into four domains. At the dimer interface, a half-helix or a loop in the third domain is coordinated by the C-terminal region of the opposite subunit. Additionally, we present the structures of OsHKT1;5 salt-tolerant and salt-sensitive variants, a key quantitative trait locus associated with salt tolerance. The salt-tolerant variant of OsHKT1;5 exhibits enhanced Na+ transport capability and displays a more flexible conformation. These findings shed light on the molecular basis of rice HKTs and provide insights into their role in salt tolerance.
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Affiliation(s)
- Ran Gao
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Yutian Jia
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Xia Xu
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Peng Fu
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Jiaqi Zhou
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
| | - Guanghui Yang
- State Key Laboratory of Plant Environmental Resilience, Frontiers Science Center for Molecular Design Breeding, College of Biological Sciences, China Agricultural University, Beijing, 100193, China
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5
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Abstract
The vesicular monoamine transporter 2 (VMAT2) is a proton-dependent antiporter responsible for loading monoamine neurotransmitters into synaptic vesicles. Dysregulation of VMAT2 can lead to several neuropsychiatric disorders including Parkinson's disease and schizophrenia. Furthermore, drugs such as amphetamine and MDMA are known to act on VMAT2, exemplifying its role in the mechanisms of actions for drugs of abuse. Despite VMAT2's importance, there remains a critical lack of mechanistic understanding, largely driven by a lack of structural information. Here, we report a 3.1 Å resolution cryo-electron microscopy (cryo-EM) structure of VMAT2 complexed with tetrabenazine (TBZ), a non-competitive inhibitor used in the treatment of Huntington's chorea. We find TBZ interacts with residues in a central binding site, locking VMAT2 in an occluded conformation and providing a mechanistic basis for non-competitive inhibition. We further identify residues critical for cytosolic and lumenal gating, including a cluster of hydrophobic residues which are involved in a lumenal gating strategy. Our structure also highlights three distinct polar networks that may determine VMAT2 conformational dynamics and play a role in proton transduction. The structure elucidates mechanisms of VMAT2 inhibition and transport, providing insights into VMAT2 architecture, function, and the design of small-molecule therapeutics.
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Affiliation(s)
- Michael P Dalton
- Department of Structural Biology, University of PittsburghPittsburghUnited States
| | - Mary Hongying Cheng
- Laufer Center for Physical and Quantitative Biology, and Department of Biochemistry and Cell Biology, School of Medicine, Stony Brook UniversityStony BrookUnited States
| | - Ivet Bahar
- Laufer Center for Physical and Quantitative Biology, and Department of Biochemistry and Cell Biology, School of Medicine, Stony Brook UniversityStony BrookUnited States
| | - Jonathan A Coleman
- Department of Structural Biology, University of PittsburghPittsburghUnited States
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6
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Zhang K, Chen L, Chen J, Huang H, Liu K, Zhang Y, Yang J, Wu S. Mutation V65I in the β1 Subunit of the Nicotinic Acetylcholine Receptor Confers Neonicotinoid and Sulfoxaflor Resistance in Insects. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2024; 72:5671-5681. [PMID: 38442746 DOI: 10.1021/acs.jafc.3c09456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/07/2024]
Abstract
Neonicotinoids have been widely used to control pests with remarkable effectiveness. Excessive insecticides have led to serious insect resistance. Mutations of the nicotinic acetylcholine receptor (nAChR) are one of the reasons for neonicotinoid resistance conferred in various agricultural pests. Two mutations, V65I and V104I, were found in the nAChR β1 subunit of two neonicotinoid-resistant aphid populations. However, the specific functions of the two mutations remain unclear. In this study, we cloned and identified four nAChR subunits (α1, α2, α8, and β1) of thrips and found them to be highly homologous to the nAChR subunits of other insects. Subsequently, we successfully expressed two subtypes nAChR (α1/α2/α8/β1 and α1/α8/β1) by coinjecting three cofactors for the first time in thrips, and α1/α8/β1 showed abundant current rapidly. Acetylcholine, neonicotinoids, and sulfoxaflor exhibited different activation capacities for the two subtypes of nAChRs. Finally, V65I was found to significantly reduce the binding ability of nAChR to neonicotinoids and sulfoxaflor through electrophysiology and computer simulations. V104I caused a decrease in agonist affinity (pEC50) but an increase in the efficacy (Imax) of nAChR against neonicotinoids and reduced the binding ability of nAChR to sulfoxaflor. This study provides theoretical and technical support for studying the molecular mechanisms of neonicotinoid resistance in pests.
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Affiliation(s)
- Kun Zhang
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Longwei Chen
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Jianwen Chen
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Huixiu Huang
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Kaiyang Liu
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Yi Zhang
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
| | - Jingfang Yang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing 100193, China
- National Nanfan Research Institute, Chinese Academy of Agricultural Sciences, Sanya 572024, China
| | - Shaoying Wu
- School of Breeding and Multiplication (Sanya Institute of Breeding and Multiplication), Hainan University, Sanya 572024, China
- School of Tropical Agriculture and Forestry (School of Agricultural and Rural Affairs, School of Rural Revitalization), Hainan University, Danzhou 571700, China
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7
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Cebi E, Lee J, Subramani VK, Bak N, Oh C, Kim KK. Cryo-electron microscopy-based drug design. Front Mol Biosci 2024; 11:1342179. [PMID: 38501110 PMCID: PMC10945328 DOI: 10.3389/fmolb.2024.1342179] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 01/31/2024] [Indexed: 03/20/2024] Open
Abstract
Structure-based drug design (SBDD) has gained popularity owing to its ability to develop more potent drugs compared to conventional drug-discovery methods. The success of SBDD relies heavily on obtaining the three-dimensional structures of drug targets. X-ray crystallography is the primary method used for solving structures and aiding the SBDD workflow; however, it is not suitable for all targets. With the resolution revolution, enabling routine high-resolution reconstruction of structures, cryogenic electron microscopy (cryo-EM) has emerged as a promising alternative and has attracted increasing attention in SBDD. Cryo-EM offers various advantages over X-ray crystallography and can potentially replace X-ray crystallography in SBDD. To fully utilize cryo-EM in drug discovery, understanding the strengths and weaknesses of this technique and noting the key advancements in the field are crucial. This review provides an overview of the general workflow of cryo-EM in SBDD and highlights technical innovations that enable its application in drug design. Furthermore, the most recent achievements in the cryo-EM methodology for drug discovery are discussed, demonstrating the potential of this technique for advancing drug development. By understanding the capabilities and advancements of cryo-EM, researchers can leverage the benefits of designing more effective drugs. This review concludes with a discussion of the future perspectives of cryo-EM-based SBDD, emphasizing the role of this technique in driving innovations in drug discovery and development. The integration of cryo-EM into the drug design process holds great promise for accelerating the discovery of new and improved therapeutic agents to combat various diseases.
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Affiliation(s)
| | | | | | | | - Changsuk Oh
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
| | - Kyeong Kyu Kim
- Department of Precision Medicine, Sungkyunkwan University School of Medicine, Suwon, Republic of Korea
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8
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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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9
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Addis P, Bali U, Baron F, Campbell A, Harborne S, Jagger L, Milne G, Pearce M, Rosethorne EM, Satchell R, Swift D, Young B, Unitt JF. Key aspects of modern GPCR drug discovery. SLAS DISCOVERY : ADVANCING LIFE SCIENCES R & D 2024; 29:1-22. [PMID: 37625784 DOI: 10.1016/j.slasd.2023.08.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/13/2023] [Revised: 08/07/2023] [Accepted: 08/22/2023] [Indexed: 08/27/2023]
Abstract
G-protein-coupled receptors (GPCRs) are the largest and most versatile cell surface receptor family with a broad repertoire of ligands and functions. We've learned an enormous amount about discovering drugs of this receptor class since the first GPCR was cloned and expressed in 1986, such that it's now well-recognized that GPCRs are the most successful target class for approved drugs. Here we take the reader through a GPCR drug discovery journey from target to the clinic, highlighting the key learnings, best practices, challenges, trends and insights on discovering drugs that ultimately modulate GPCR function therapeutically in patients. The future of GPCR drug discovery is inspiring, with more desirable drug mechanisms and new technologies enabling the delivery of better and more successful drugs.
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Affiliation(s)
- Phil Addis
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Utsav Bali
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Frank Baron
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Adrian Campbell
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Steven Harborne
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Liz Jagger
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Gavin Milne
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Martin Pearce
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Elizabeth M Rosethorne
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Rupert Satchell
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Denise Swift
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - Barbara Young
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK
| | - John F Unitt
- Bioscience, Medicinal Chemistry, Pharmacology and Protein Science Departments, Sygnature Discovery Ltd, BioCity, Pennyfoot Street, Nottingham NG1 1GR, UK.
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10
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Guo Q, He B, Zhong Y, Jiao H, Ren Y, Wang Q, Ge Q, Gao Y, Liu X, Du Y, Hu H, Tao Y. A method for structure determination of GPCRs in various states. Nat Chem Biol 2024; 20:74-82. [PMID: 37580554 DOI: 10.1038/s41589-023-01389-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2023] [Accepted: 06/28/2023] [Indexed: 08/16/2023]
Abstract
G-protein-coupled receptors (GPCRs) are a class of integral membrane proteins that detect environmental cues and trigger cellular responses. Deciphering the functional states of GPCRs induced by various ligands has been one of the primary goals in the field. Here we developed an effective universal method for GPCR cryo-electron microscopy structure determination without the need to prepare GPCR-signaling protein complexes. Using this method, we successfully solved the structures of the β2-adrenergic receptor (β2AR) bound to antagonistic and agonistic ligands and the adhesion GPCR ADGRL3 in the apo state. For β2AR, an intermediate state stabilized by the partial agonist was captured. For ADGRL3, the structure revealed that inactive ADGRL3 adopts a compact fold and that large unusual conformational changes on both the extracellular and intracellular sides are required for activation of adhesion GPCRs. We anticipate that this method will open a new avenue for understanding GPCR structure‒function relationships and drug development.
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Affiliation(s)
- Qiong Guo
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Binbin He
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yixuan Zhong
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Haizhan Jiao
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China
| | - Yinhang Ren
- Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Qinggong Wang
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Qiangqiang Ge
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Yongxiang Gao
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China
| | - Xiangyu Liu
- Beijing Frontier Research Center for Biological Structure, Beijing Advanced Innovation Center for Structural Biology, Tsinghua-Peking Center for Life Sciences, School of Pharmaceutical Sciences, Tsinghua University, Beijing, China
| | - Yang Du
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China
| | - Hongli Hu
- Kobilka Institute of Innovative Drug Discovery, School of Medicine, The Chinese University of Hong Kong, Shenzhen, China.
| | - Yuyong Tao
- Department of Laboratory Medicine, The First Affiliated Hospital of USTC, MOE Key Laboratory for Membraneless Organelles and Cellular Dynamics, Hefei National Center for Cross-Disciplinary Sciences, Biomedical Sciences and Health Laboratory of Anhui Province, Center for Advanced Interdisciplinary Science and Biomedicine of IHM, Division of Life Sciences and Medicine, University of Science and Technology of China, Hefei, China.
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11
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Erramilli SK, Dominik PK, Deneka D, Tokarz P, Kim SS, Reddy BG, Skrobek BM, Dalmas O, Perozo E, Kossiakoff AA. Conformation-specific Synthetic Antibodies Discriminate Multiple Functional States of the Ion Channel CorA. J Mol Biol 2023; 435:168192. [PMID: 37394032 PMCID: PMC10529903 DOI: 10.1016/j.jmb.2023.168192] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/20/2023] [Accepted: 06/26/2023] [Indexed: 07/04/2023]
Abstract
CorA, the primary magnesium ion channel in prokaryotes and archaea, is a prototypical homopentameric ion channel that undergoes ion-dependent conformational transitions. CorA adopts five-fold symmetric non-conductive states in the presence of high concentrations of Mg2+, and highly asymmetric flexible states in its complete absence. However, the latter were of insufficient resolution to be thoroughly characterized. In order to gain additional insights into the relationship between asymmetry and channel activation, we exploited phage display selection strategies to generate conformation-specific synthetic antibodies (sABs) against CorA in the absence of Mg2+. Two sABs from these selections, C12 and C18, showed different degrees of Mg2+-sensitivity. Through structural, biochemical, and biophysical characterization, we found the sABs are both conformation-specific but probe different features of the channel under open-like conditions. C18 is highly specific to the Mg2+-depleted state of CorA and through negative-stain electron microscopy (ns-EM), we show sAB binding reflects the asymmetric arrangement of CorA protomers in Mg2+-depleted conditions. We used X-ray crystallography to determine a structure at 2.0 Å resolution of sAB C12 bound to the soluble N-terminal regulatory domain of CorA. The structure shows C12 is a competitive inhibitor of regulatory magnesium binding through its interaction with the divalent cation sensing site. We subsequently exploited this relationship to capture and visualize asymmetric CorA states in different [Mg2+] using ns-EM. We additionally utilized these sABs to provide insights into the energy landscape that governs the ion-dependent conformational transitions of CorA.
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Affiliation(s)
- Satchal K Erramilli
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Pawel K Dominik
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Dawid Deneka
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Piotr Tokarz
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Sangwoo S Kim
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Bharat G Reddy
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Blazej M Skrobek
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA; Intercollegiate Faculty of Biotechnology of University of Gdansk and Medical University of Gdansk, Gdansk, Poland
| | - Olivier Dalmas
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA
| | - Eduardo Perozo
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA; Grossman Institute for Neuroscience, Quantitative Biology and Human Behavior, The University of Chicago, Chicago, IL, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL, USA; Institute for Biophysical Dynamics, The University of Chicago, Chicago, IL, USA.
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12
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Skiba MA, Sterling SM, Rawson S, Gilman MS, Xu H, Nemeth GR, Hurley JD, Shen P, Staus DP, Kim J, McMahon C, Lehtinen MK, Wingler LM, Kruse AC. Antibodies Expand the Scope of Angiotensin Receptor Pharmacology. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.23.554128. [PMID: 37662341 PMCID: PMC10473732 DOI: 10.1101/2023.08.23.554128] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/05/2023]
Abstract
G protein-coupled receptors (GPCRs) are key regulators of human physiology and are the targets of many small molecule research compounds and therapeutic drugs. While most of these ligands bind to their target GPCR with high affinity, selectivity is often limited at the receptor, tissue, and cellular level. Antibodies have the potential to address these limitations but their properties as GPCR ligands remain poorly characterized. Here, using protein engineering, pharmacological assays, and structural studies, we develop maternally selective heavy chain-only antibody ("nanobody") antagonists against the angiotensin II type I receptor (AT1R) and uncover the unusual molecular basis of their receptor antagonism. We further show that our nanobodies can simultaneously bind to AT1R with specific small-molecule antagonists and demonstrate that ligand selectivity can be readily tuned. Our work illustrates that antibody fragments can exhibit rich and evolvable pharmacology, attesting to their potential as next-generation GPCR modulators.
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Affiliation(s)
- Meredith A. Skiba
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Sarah M. Sterling
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Shaun Rawson
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Morgan S.A. Gilman
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Huixin Xu
- Department of Pathology, Boston Children’s Hospital, Boston, MA, 02115, USA
| | - Genevieve R. Nemeth
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Joseph D. Hurley
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Pengxiang Shen
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, 02138, USA
| | - Dean P. Staus
- Department of Medicine and Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Jihee Kim
- Department of Medicine and Howard Hughes Medical Institute, Duke University Medical Center, Durham, NC 27710, USA
| | - Conor McMahon
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Maria K. Lehtinen
- Department of Pathology, Boston Children’s Hospital, Boston, MA, 02115, USA
| | - Laura M. Wingler
- Department of Pharmacology and Cancer Biology, Duke University School of Medicine, Durham, NC 27710, USA
| | - Andrew C. Kruse
- Department of Biological Chemistry and Molecular Pharmacology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
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13
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Erramilli SK, Dominik PK, Deneka D, Tokarz P, Kim SS, Reddy BG, Skrobek BM, Dalmas O, Perozo E, Kossiakoff AA. Conformation-specific synthetic antibodies discriminate multiple functional states of the ion channel CorA. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.07.539746. [PMID: 37205530 PMCID: PMC10187328 DOI: 10.1101/2023.05.07.539746] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
CorA, the primary magnesium ion channel in prokaryotes and archaea, is a prototypical homopentameric ion channel that undergoes ion-dependent conformational transitions. CorA adopts five-fold symmetric non-conductive states in the presence of high concentrations of Mg 2+ , and highly asymmetric flexible states in its complete absence. However, the latter were of insufficient resolution to be thoroughly characterized. In order to gain additional insights into the relationship between asymmetry and channel activation, we exploited phage display selection strategies to generate conformation-specific synthetic antibodies (sABs) against CorA in the absence of Mg 2+ . Two sABs from these selections, C12 and C18, showed different degrees of Mg 2+ -sensitivity. Through structural, biochemical, and biophysical characterization, we found the sABs are both conformation-specific but probe different features of the channel under open-like conditions. C18 is highly specific to the Mg 2+ -depleted state of CorA and through negative-stain electron microscopy (ns-EM), we show sAB binding reflects the asymmetric arrangement of CorA protomers in Mg 2+ -depleted conditions. We used X-ray crystallography to determine a structure at 2.0 Å resolution of sAB C12 bound to the soluble N-terminal regulatory domain of CorA. The structure shows C12 is a competitive inhibitor of regulatory magnesium binding through its interaction with the divalent cation sensing site. We subsequently exploited this relationship to capture and visualize asymmetric CorA states in different [Mg 2+ ] using ns-EM. We additionally utilized these sABs to provide insights into the energy landscape that governs the ion-dependent conformational transitions of CorA.
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14
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Cao C, Roth BL. The structure, function, and pharmacology of MRGPRs. Trends Pharmacol Sci 2023; 44:237-251. [PMID: 36870785 PMCID: PMC10066734 DOI: 10.1016/j.tips.2023.02.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2022] [Revised: 02/01/2023] [Accepted: 02/09/2023] [Indexed: 03/06/2023]
Abstract
Mas-related G protein-coupled receptor (MRGPR) family members play important roles in the sensation of noxious stimuli and represent novel targets for the treatment of itch and pain. MRGPRs recognize a diversity of agonists and display complicated downstream signaling profiles, high sequence diversity across species, and many polymorphisms in humans. The recent structural advances on MRGPRs reveal unique structural features and diverse agonist recognition modes of this receptor family, which should facilitate the structure-based drug discovery at MRGPRs. In addition, the newly discovered ligands also provide valuable tools to explore the function and the therapeutic potential of MRGPRs. In this review, we discuss these progresses in our understanding of MRGPRs and highlight the challenges and potential opportunities for the future drug discovery at these receptors.
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Affiliation(s)
- Can Cao
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA
| | - Bryan L Roth
- Department of Pharmacology, University of North Carolina School of Medicine, Chapel Hill, NC 27599, USA; Division of Chemical Biology and Medicinal Chemistry, Eschelman School of Pharmacy and NIMH Psychoactive Drug Screening Program, University of North Carolina, Chapel Hill, NC 27599, USA.
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15
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He Z, Zhao Y, Rau MJ, Fitzpatrick JAJ, Sah R, Hu H, Yuan P. Structural and functional analysis of human pannexin 2 channel. Nat Commun 2023; 14:1712. [PMID: 36973289 PMCID: PMC10043284 DOI: 10.1038/s41467-023-37413-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2023] [Accepted: 03/16/2023] [Indexed: 03/29/2023] Open
Abstract
The pannexin 2 channel (PANX2) participates in multiple physiological processes including skin homeostasis, neuronal development, and ischemia-induced brain injury. However, the molecular basis of PANX2 channel function remains largely unknown. Here, we present a cryo-electron microscopy structure of human PANX2, which reveals pore properties contrasting with those of the intensely studied paralog PANX1. The extracellular selectivity filter, defined by a ring of basic residues, more closely resembles that of the distantly related volume-regulated anion channel (VRAC) LRRC8A, rather than PANX1. Furthermore, we show that PANX2 displays a similar anion permeability sequence as VRAC, and that PANX2 channel activity is inhibited by a commonly used VRAC inhibitor, DCPIB. Thus, the shared channel properties between PANX2 and VRAC may complicate dissection of their cellular functions through pharmacological manipulation. Collectively, our structural and functional analysis provides a framework for development of PANX2-specific reagents that are needed for better understanding of channel physiology and pathophysiology.
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Affiliation(s)
- Zhihui He
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
| | - Yonghui Zhao
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, Saint Louis, MO, USA
| | - Michael J Rau
- Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
| | - James A J Fitzpatrick
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA
- Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO, USA
| | - Rajan Sah
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, Saint Louis, MO, USA
| | - Hongzhen Hu
- Department of Anesthesiology, Washington University School of Medicine, Saint Louis, MO, USA.
- Center for the Study of Itch and Sensory Disorders, Washington University School of Medicine, Saint Louis, MO, USA.
| | - Peng Yuan
- Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO, USA.
- Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, USA.
- Department of Pharmacological Sciences, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, NY, USA.
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16
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Kern DM, Bleier J, Mukherjee S, Hill JM, Kossiakoff AA, Isacoff EY, Brohawn SG. Structural basis for assembly and lipid-mediated gating of LRRC8A:C volume-regulated anion channels. Nat Struct Mol Biol 2023:10.1038/s41594-023-00944-6. [PMID: 36928458 DOI: 10.1038/s41594-023-00944-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 02/22/2023] [Indexed: 03/18/2023]
Abstract
Leucine-rich repeat-containing protein 8 (LRRC8) family members form volume-regulated anion channels activated by hypoosmotic cell swelling. LRRC8 channels are ubiquitously expressed in vertebrate cells as heteromeric assemblies of LRRC8A (SWELL1) and LRRC8B-E subunits. Channels of different subunit composition have distinct properties that explain the functional diversity of LRRC8 currents across cell types. However, the basis for heteromeric LRRC8 channel assembly and function is unknown. Here we leverage a fiducial-tagging strategy to determine single-particle cryo-EM structures of heterohexameric LRRC8A:C channels in multiple conformations. Compared to homomers, LRRC8A:C channels show pronounced differences in architecture due to heterotypic LRR interactions that displace subunits away from the conduction axis and poise the channel for activation. Structures and functional studies further reveal that lipids embedded in the channel pore block ion conduction in the closed state. These results provide insight into determinants for heteromeric LRRC8 channel assembly, activity and gating by lipids.
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Affiliation(s)
- David M Kern
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,California Institute for Quantitative Biology (QB3), University of California, Berkeley, CA, USA
| | - Julia Bleier
- Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.,Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
| | - Jennifer M Hill
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, University of Chicago, Chicago, IL, USA.,Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA
| | - Ehud Y Isacoff
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA.,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA.,California Institute for Quantitative Biology (QB3), University of California, Berkeley, CA, USA
| | - Stephen G Brohawn
- Department of Molecular & Cell Biology, University of California, Berkeley, CA, USA. .,Helen Wills Neuroscience Institute, University of California, Berkeley, CA, USA. .,California Institute for Quantitative Biology (QB3), University of California, Berkeley, CA, USA.
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17
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Sriramulu DK, Lee SG. Analysis of protein-protein interface with incorporating low-frequency molecular interactions in molecular dynamics simulation. J Mol Graph Model 2023; 122:108461. [PMID: 37012187 DOI: 10.1016/j.jmgm.2023.108461] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/16/2023] [Accepted: 03/20/2023] [Indexed: 03/30/2023]
Abstract
Protein-protein interactions are vital for various biological processes such as immune reaction, signal transduction, and viral infection. Molecular Dynamics (MD) simulation is a powerful tool for analyzing non-covalent interactions between two protein molecules. In general, MD simulation studies on the protein-protein interface have focused on the analysis of major and frequent molecular interactions. In this study, we demonstrate that minor interactions with low-frequency need to be incorporated to analyze the molecular interactions in the protein-protein interface more efficiently using the complex of SARS-CoV2-RBD and ACE2 receptor as a model system. It was observed that the dominance of interactions in the MD-simulated structures didn't directly correlate with the interactions in the experimentally determined structure. The interactions from the experimentally determined structure could be reproduced better in the ensemble of MD simulated structures by including the less frequent interactions compared to the norm of choosing only highly frequent interactions. Residue Interaction Networks (RINs) analysis also showed that the critical residues in the protein-protein interface could be more efficiently identified by incorporating low-frequency interactions in MD simulation. It is expected that the approach proposed in this study can be a new way of studying protein-protein interaction through MD simulation.
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18
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Cui W, Niu Y, Chen L. The Protein Fusion Strategy Facilitates the Structure Determination of Small Membrane Proteins by Cryo-EM. Biochemistry 2023; 62:196-200. [PMID: 35909370 DOI: 10.1021/acs.biochem.2c00319] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Despite the resolution revolution of cryo-EM, structures of small membrane proteins (<80 kDa) are still understudied. These proteins are notoriously reluctant to structure determination by single-particle cryo-EM. Protein fusion might represent a plausible strategy to overcome such difficulties. This Perspective enumerates recent exemplary progress and discusses the future potential of the protein fusion strategy.
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Affiliation(s)
- Wenhao Cui
- State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Beijing 100871, China
| | - Yange Niu
- State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Beijing 100871, China
| | - Lei Chen
- State Key Laboratory of Membrane Biology, College of Future Technology, Institute of Molecular Medicine, Peking University, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Beijing 100871, China.,Peking-Tsinghua Center for Life Sciences, Peking University, Beijing 100871, China
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19
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Dang Y, Zhou D, Du X, Zhao H, Lee CH, Yang J, Wang Y, Qin C, Guo Z, Zhang Z. Molecular mechanism of substrate recognition by folate transporter SLC19A1. Cell Discov 2022; 8:141. [PMID: 36575193 PMCID: PMC9794768 DOI: 10.1038/s41421-022-00508-w] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2022] [Accepted: 12/09/2022] [Indexed: 12/29/2022] Open
Abstract
Folate (vitamin B9) is the coenzyme involved in one-carbon transfer biochemical reactions essential for cell survival and proliferation, with its inadequacy causing developmental defects or severe diseases. Notably, mammalian cells lack the ability to de novo synthesize folate but instead rely on its intake from extracellular sources via specific transporters or receptors, among which SLC19A1 is the ubiquitously expressed one in tissues. However, the mechanism of substrate recognition by SLC19A1 remains unclear. Here we report the cryo-EM structures of human SLC19A1 and its complex with 5-methyltetrahydrofolate at 3.5-3.6 Å resolution and elucidate the critical residues for substrate recognition. In particular, we reveal that two variant residues among SLC19 subfamily members designate the specificity for folate. Moreover, we identify intracellular thiamine pyrophosphate as the favorite coupled substrate for folate transport by SLC19A1. Together, this work establishes the molecular basis of substrate recognition by this central folate transporter.
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Affiliation(s)
- Yu Dang
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Dong Zhou
- grid.11135.370000 0001 2256 9319Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China
| | - Xiaojuan Du
- grid.11135.370000 0001 2256 9319School of Life Sciences, Peking University, Beijing, China ,grid.411472.50000 0004 1764 1621Present Address: Peking University First Hospital, Peking University Health Science Center, Beijing, China
| | - Hongtu Zhao
- grid.240871.80000 0001 0224 711XDepartment of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN USA
| | - Chia-Hsueh Lee
- grid.240871.80000 0001 0224 711XDepartment of Structural Biology, St. Jude Children’s Research Hospital, Memphis, TN USA
| | - Jing Yang
- grid.11135.370000 0001 2256 9319School of Life Sciences, Peking University, Beijing, China
| | - Yijie Wang
- grid.11135.370000 0001 2256 9319School of Life Sciences, Peking University, Beijing, China
| | - Changdong Qin
- grid.11135.370000 0001 2256 9319Cryo-EM Platform, School of Life Sciences, Peking University, Beijing, China
| | - Zhenxi Guo
- grid.11135.370000 0001 2256 9319Cryo-EM Platform, School of Life Sciences, Peking University, Beijing, China
| | - Zhe Zhang
- grid.11135.370000 0001 2256 9319State Key Laboratory of Membrane Biology, Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China ,grid.11135.370000 0001 2256 9319Center for Life Sciences, Academy for Advanced Interdisciplinary Studies, Peking University, Beijing, China ,grid.11135.370000 0001 2256 9319School of Life Sciences, Peking University, Beijing, China
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20
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Kaiser J, Gertzen CG, Bernauer T, Höfner G, Niessen KV, Seeger T, Paintner FF, Wanner KT, Worek F, Thiermann H, Gohlke H. A novel binding site in the nicotinic acetylcholine receptor for MB327 can explain its allosteric modulation relevant for organophosphorus-poisoning treatment. Toxicol Lett 2022; 373:160-171. [DOI: 10.1016/j.toxlet.2022.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2022] [Accepted: 11/25/2022] [Indexed: 11/27/2022]
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21
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Wentinck K, Gogou C, Meijer DH. Putting on molecular weight: Enabling cryo-EM structure determination of sub-100-kDa proteins. Curr Res Struct Biol 2022; 4:332-337. [PMID: 36248264 PMCID: PMC9562432 DOI: 10.1016/j.crstbi.2022.09.005] [Citation(s) in RCA: 15] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2022] [Revised: 09/22/2022] [Accepted: 09/25/2022] [Indexed: 11/17/2022] Open
Abstract
Significant advances in the past decade have enabled high-resolution structure determination of a vast variety of proteins by cryogenic electron microscopy single particle analysis. Despite improved sample preparation, next-generation imaging hardware, and advanced single particle analysis algorithms, small proteins remain elusive for reconstruction due to low signal-to-noise and lack of distinctive structural features. Multiple efforts have therefore been directed at the development of size-increase techniques for small proteins. Here we review the latest methods for increasing effective molecular weight of proteins <100 kDa through target protein binding or target protein fusion - specifically by using nanobody-based assemblies, fusion tags, and symmetric scaffolds. Finally, we summarize these state-of-the-art techniques into a decision-tree to facilitate the design of tailored future approaches, and thus for further exploration of ever-smaller proteins that make up the largest part of the human genome.
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Key Words
- BRIL, cytochromeb562 RIL
- DARPin, Design Ankyrin Repeat Protein
- Fab, antigen binding fragment
- GFP, Green Fluorecent Protein
- GPCR, G protein-coupled receptor
- MW, molecular weight
- Mb, megabody
- Nb, nanobody
- SNR, signal-to-noise ratio
- SPA, single particle analysis
- TM, transmembrane
- cryo-EM, cryogenic electron microscopy
- kDa, kiloDalton
- κOR ICL3, κ-opiod receptor intracellular loop 3
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22
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Parker HP, Dawson A, Jones MJ, Yan R, Ouyang J, Hong R, Hunter WN. Delineating the activity of the potent nicotinic acetylcholine receptor agonists (+)-anatoxin-a and (−)-hosieine-A. Acta Crystallogr F Struct Biol Commun 2022; 78:313-323. [PMID: 36048081 PMCID: PMC9435674 DOI: 10.1107/s2053230x22007762] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Accepted: 08/01/2022] [Indexed: 11/10/2022] Open
Abstract
The affinity and thermodynamic parameters for the interactions of two naturally occurring neurotoxins, (+)-anatoxin-a and (−)-hosieine-A, with acetylcholine-binding protein were investigated using a fluorescence-quenching assay and isothermal titration calorimetry. The crystal structures of their complexes with acetylcholine-binding protein from Aplysia californica (AcAChBP) were determined and reveal details of molecular recognition in the orthosteric binding site. Comparisons treating AcAChBP as a surrogate for human α4β2 and α7 nicotinic acetylcholine receptors (nAChRs) suggest that the molecular features involved in ligand recognition and affinity for the protein targets are conserved. The ligands exploit interactions with similar residues as the archetypal nAChR agonist nicotine, but with greater affinity. (−)-Hosieine-A in particular has a high affinity for AcAChBP driven by a favorable entropic contribution to binding. The ligand affinities help to rationalize the potent biological activity of these alkaloids. The structural data, together with comparisons with related molecules, suggest that there may be opportunities to extend the hosieine-A scaffold to incorporate new interactions with the complementary side of the orthosteric binding site. Such a strategy may guide the design of new entities to target human α4β2 nAChR that may have therapeutic benefit.
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23
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Thangaratnarajah C, Rheinberger J, Paulino C. Cryo-EM studies of membrane proteins at 200 keV. Curr Opin Struct Biol 2022; 76:102440. [PMID: 36029606 DOI: 10.1016/j.sbi.2022.102440] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Revised: 07/01/2022] [Accepted: 07/06/2022] [Indexed: 11/03/2022]
Abstract
Single-particle cryogenic electron-microscopy (cryo-EM) has emerged as a powerful technique for the structural characterisation of membrane proteins, especially for targets previously thought to be intractable. Taking advantage of the latest hard- and software developments, high-resolution three-dimensional (3D) reconstructions of membrane proteins by cryo-EM has become routine, with 300-kV transmission electron microscopes (TEMs) being the current standard. The use of 200-kV cryo-TEMs is gaining increasingly prominence, showing the capabilities of reaching better than 2 Å resolution for soluble proteins and better than 3 Å resolution for membrane proteins. Here, we highlight the challenges working with membrane proteins and the impact of cryo-EM, and review the technical and practical benefits, achievements and limitations of imaging at lower electron acceleration voltages.
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Affiliation(s)
- Chancievan Thangaratnarajah
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy and Membrane Enzymology Group, Nijenborgh 4, 9747 AG, Groningen, Netherlands.
| | - Jan Rheinberger
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy and Membrane Enzymology Group, Nijenborgh 4, 9747 AG, Groningen, Netherlands. https://twitter.com/rheinbergerj
| | - Cristina Paulino
- University of Groningen, Faculty of Science and Engineering, Groningen Biomolecular Sciences and Biotechnology, Electron Microscopy and Membrane Enzymology Group, Nijenborgh 4, 9747 AG, Groningen, Netherlands.
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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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25
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Zhang K, Wu H, Hoppe N, Manglik A, Cheng Y. Fusion protein strategies for cryo-EM study of G protein-coupled receptors. Nat Commun 2022; 13:4366. [PMID: 35902590 PMCID: PMC9334595 DOI: 10.1038/s41467-022-32125-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2021] [Accepted: 07/19/2022] [Indexed: 11/15/2022] Open
Abstract
Single particle cryogenic-electron microscopy (cryo-EM) is used extensively to determine structures of activated G protein-coupled receptors (GPCRs) in complex with G proteins or arrestins. However, applying it to GPCRs without signaling proteins remains challenging because most receptors lack structural features in their soluble domains to facilitate image alignment. In GPCR crystallography, inserting a fusion protein between transmembrane helices 5 and 6 is a highly successful strategy for crystallization. Although a similar strategy has the potential to broadly facilitate cryo-EM structure determination of GPCRs alone without signaling protein, the critical determinants that make this approach successful are not yet clear. Here, we address this shortcoming by exploring different fusion protein designs, which lead to structures of antagonist bound A2A adenosine receptor at 3.4 Å resolution and unliganded Smoothened at 3.7 Å resolution. The fusion strategies explored here are likely applicable to cryo-EM interrogation of other GPCRs and small integral membrane proteins.
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Affiliation(s)
- Kaihua Zhang
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Hao Wu
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Nicholas Hoppe
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA
| | - Aashish Manglik
- Department of Pharmaceutical Chemistry, University of California San Francisco, San Francisco, CA, 94158, USA.
- Department of Anesthesia and Perioperative Care, University of California San Francisco, San Francisco, CA, 94158, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, 94158, USA.
| | - Yifan Cheng
- Department of Biochemistry and Biophysics, University of California San Francisco, San Francisco, CA, 94158, USA.
- Howard Hughes Medical Institute, University of California San Francisco, San Francisco, CA, 94158, USA.
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26
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Chen H, Qi X, Faulkner RA, Schumacher MM, Donnelly LM, DeBose-Boyd RA, Li X. Regulated degradation of HMG CoA reductase requires conformational changes in sterol-sensing domain. Nat Commun 2022; 13:4273. [PMID: 35879350 PMCID: PMC9314443 DOI: 10.1038/s41467-022-32025-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2022] [Accepted: 07/12/2022] [Indexed: 01/20/2023] Open
Abstract
3-Hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) is the rate-limiting enzyme in cholesterol synthesis and target of cholesterol-lowering statin drugs. Accumulation of sterols in endoplasmic reticulum (ER) membranes accelerates degradation of HMGCR, slowing the synthesis of cholesterol. Degradation of HMGCR is inhibited by its binding to UBIAD1 (UbiA prenyltransferase domain-containing protein-1). This inhibition contributes to statin-induced accumulation of HMGCR, which limits their cholesterol-lowering effects. Here, we report cryo-electron microscopy structures of the HMGCR-UBIAD1 complex, which is maintained by interactions between transmembrane helix (TM) 7 of HMGCR and TMs 2-4 of UBIAD1. Disrupting this interface by mutagenesis prevents complex formation, enhancing HMGCR degradation. TMs 2-6 of HMGCR contain a 170-amino acid sterol sensing domain (SSD), which exists in two conformations-one of which is essential for degradation. Thus, our data supports a model that rearrangement of the TMs in the SSD permits recruitment of proteins that initate HMGCR degradation, a key reaction in the regulatory system that governs cholesterol synthesis.
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Affiliation(s)
- Hongwen Chen
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Xiaofeng Qi
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Rebecca A Faulkner
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Marc M Schumacher
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Linda M Donnelly
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Russell A DeBose-Boyd
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Xiaochun Li
- Department of Molecular Genetics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, USA.
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27
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Bley CJ, Nie S, Mobbs GW, Petrovic S, Gres AT, Liu X, Mukherjee S, Harvey S, Huber FM, Lin DH, Brown B, Tang AW, Rundlet EJ, Correia AR, Chen S, Regmi SG, Stevens TA, Jette CA, Dasso M, Patke A, Palazzo AF, Kossiakoff AA, Hoelz A. Architecture of the cytoplasmic face of the nuclear pore. Science 2022; 376:eabm9129. [PMID: 35679405 DOI: 10.1126/science.abm9129] [Citation(s) in RCA: 58] [Impact Index Per Article: 29.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
INTRODUCTION The subcellular compartmentalization of eukaryotic cells requires selective transport of folded proteins and protein-nucleic acid complexes. Embedded in nuclear envelope pores, which are generated by the circumscribed fusion of the inner and outer nuclear membranes, nuclear pore complexes (NPCs) are the sole bidirectional gateways for nucleocytoplasmic transport. The ~110-MDa human NPC is an ~1000-protein assembly that comprises multiple copies of ~34 different proteins, collectively termed nucleoporins. The symmetric core of the NPC is composed of an inner ring encircling the central transport channel and outer rings formed by Y‑shaped coat nucleoporin complexes (CNCs) anchored atop both sides of the nuclear envelope. The outer rings are decorated with compartment‑specific asymmetric nuclear basket and cytoplasmic filament nucleoporins, which establish transport directionality and provide docking sites for transport factors and the small guanosine triphosphatase Ran. The cytoplasmic filament nucleoporins also play an essential role in the irreversible remodeling of messenger ribonucleoprotein particles (mRNPs) as they exit the central transport channel. Unsurprisingly, the NPC's cytoplasmic face represents a hotspot for disease‑associated mutations and is commonly targeted by viral virulence factors. RATIONALE Previous studies established a near-atomic composite structure of the human NPC's symmetric core by combining (i) biochemical reconstitution to elucidate the interaction network between symmetric nucleoporins, (ii) crystal and single-particle cryo-electron microscopy structure determination of nucleoporins and nucleoporin complexes to reveal their three-dimensional shape and the molecular details of their interactions, (iii) quantitative docking in cryo-electron tomography (cryo-ET) maps of the intact human NPC to uncover nucleoporin stoichiometry and positioning, and (iv) cell‑based assays to validate the physiological relevance of the biochemical and structural findings. In this work, we extended our approach to the cytoplasmic filament nucleoporins to reveal the near-atomic architecture of the cytoplasmic face of the human NPC. RESULTS Using biochemical reconstitution, we elucidated the protein-protein and protein-RNA interaction networks of the human and Chaetomium thermophilum cytoplasmic filament nucleoporins, establishing an evolutionarily conserved heterohexameric cytoplasmic filament nucleoporin complex (CFNC) held together by a central heterotrimeric coiled‑coil hub that tethers two separate mRNP‑remodeling complexes. Further biochemical analysis and determination of a series of crystal structures revealed that the metazoan‑specific cytoplasmic filament nucleoporin NUP358 is composed of 16 distinct domains, including an N‑terminal S‑shaped α‑helical solenoid followed by a coiled‑coil oligomerization element, numerous Ran‑interacting domains, an E3 ligase domain, and a C‑terminal prolyl‑isomerase domain. Physiologically validated quantitative docking into cryo-ET maps of the intact human NPC revealed that pentameric NUP358 bundles, conjoined by the oligomerization element, are anchored through their N‑terminal domains to the central stalk regions of the CNC, projecting flexibly attached domains as far as ~600 Å into the cytoplasm. Using cell‑based assays, we demonstrated that NUP358 is dispensable for the architectural integrity of the assembled interphase NPC and RNA export but is required for efficient translation. After NUP358 assignment, the remaining 4-shaped cryo‑ET density matched the dimensions of the CFNC coiled‑coil hub, in close proximity to an outer-ring NUP93. Whereas the N-terminal NUP93 assembly sensor motif anchors the properly assembled related coiled‑coil channel nucleoporin heterotrimer to the inner ring, biochemical reconstitution confirmed that the NUP93 assembly sensor is reused in anchoring the CFNC to the cytoplasmic face of the human NPC. By contrast, two C. thermophilum CFNCs are anchored by a divergent mechanism that involves assembly sensors located in unstructured portions of two CNC nucleoporins. Whereas unassigned cryo‑ET density occupies the NUP358 and CFNC binding sites on the nuclear face, docking of the nuclear basket component ELYS established that the equivalent position on the cytoplasmic face is unoccupied, suggesting that mechanisms other than steric competition promote asymmetric distribution of nucleoporins. CONCLUSION We have substantially advanced the biochemical and structural characterization of the asymmetric nucleoporins' architecture and attachment at the cytoplasmic and nuclear faces of the NPC. Our near‑atomic composite structure of the human NPC's cytoplasmic face provides a biochemical and structural framework for elucidating the molecular basis of mRNP remodeling, viral virulence factor interference with NPC function, and the underlying mechanisms of nucleoporin diseases at the cytoplasmic face of the NPC. [Figure: see text].
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Affiliation(s)
- Christopher J Bley
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Si Nie
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - George W Mobbs
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Stefan Petrovic
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Anna T Gres
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Xiaoyu Liu
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - Sho Harvey
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ferdinand M Huber
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Daniel H Lin
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Bonnie Brown
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Aaron W Tang
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Emily J Rundlet
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Ana R Correia
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Shane Chen
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Saroj G Regmi
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Taylor A Stevens
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Claudia A Jette
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Mary Dasso
- Division of Molecular and Cellular Biology, National Institute of Child Health and Human Development, National Institutes of Health, Bethesda, MD 20892, USA
| | - Alina Patke
- Division of Biology and Biological Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
| | - Alexander F Palazzo
- Department of Biochemistry, University of Toronto, Toronto, ON M5G 1M1, Canada
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of Chicago, Chicago, IL 60637, USA
| | - André Hoelz
- Division of Chemistry and Chemical Engineering, California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125, USA
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28
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Clementel D, Del Conte A, Monzon AM, Camagni GF, Minervini G, Piovesan D, Tosatto SCE. RING 3.0: fast generation of probabilistic residue interaction networks from structural ensembles. Nucleic Acids Res 2022; 50:W651-W656. [PMID: 35554554 PMCID: PMC9252747 DOI: 10.1093/nar/gkac365] [Citation(s) in RCA: 61] [Impact Index Per Article: 30.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2022] [Revised: 04/15/2022] [Accepted: 04/30/2022] [Indexed: 12/18/2022] Open
Abstract
Residue interaction networks (RINs) are used to represent residue contacts in protein structures. Thanks to the advances in network theory, RINs have been proved effective as an alternative to coordinate data in the analysis of complex systems. The RING server calculates high quality and reliable non-covalent molecular interactions based on geometrical parameters. Here, we present the new RING 3.0 version extending the previous functionality in several ways. The underlying software library has been re-engineered to improve speed by an order of magnitude. RING now also supports the mmCIF format and provides typed interactions for the entire PDB chemical component dictionary, including nucleic acids. Moreover, RING now employs probabilistic graphs, where multiple conformations (e.g. NMR or molecular dynamics ensembles) are mapped as weighted edges, opening up new ways to analyze structural data. The web interface has been expanded to include a simultaneous view of the RIN alongside a structure viewer, with both synchronized and clickable. Contact evolution across models (or time) is displayed as a heatmap and can help in the discovery of correlating interaction patterns. The web server, together with an extensive help and tutorial, is available from URL: https://ring.biocomputingup.it/.
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Affiliation(s)
- Damiano Clementel
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | - Alessio Del Conte
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | | | - Giorgia F Camagni
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | - Giovanni Minervini
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | - Damiano Piovesan
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
| | - Silvio C E Tosatto
- Department of Biomedical Sciences, University of Padova, Padova 35131, Italy
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29
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Chen H, Huang W, Li X. Structures of oxysterol sensor EBI2/GPR183, a key regulator of the immune response. Structure 2022; 30:1016-1024.e5. [DOI: 10.1016/j.str.2022.04.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2022] [Revised: 03/23/2022] [Accepted: 04/13/2022] [Indexed: 12/11/2022]
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30
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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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31
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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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32
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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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33
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Lees JA, Dias JM, Han S. Applications of Cryo-EM in small molecule and biologics drug design. Biochem Soc Trans 2021; 49:2627-2638. [PMID: 34812853 PMCID: PMC8786282 DOI: 10.1042/bst20210444] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 10/22/2021] [Accepted: 10/27/2021] [Indexed: 02/03/2023]
Abstract
Electron cryo-microscopy (cryo-EM) is a powerful technique for the structural characterization of biological macromolecules, enabling high-resolution analysis of targets once inaccessible to structural interrogation. In recent years, pharmaceutical companies have begun to utilize cryo-EM for structure-based drug design. Structural analysis of integral membrane proteins, which comprise a large proportion of druggable targets and pose particular challenges for X-ray crystallography, by cryo-EM has enabled insights into important drug target families such as G protein-coupled receptors (GPCRs), ion channels, and solute carrier (SLCs) proteins. Structural characterization of biologics, such as vaccines, viral vectors, and gene therapy agents, has also become significantly more tractable. As a result, cryo-EM has begun to make major impacts in bringing critical therapeutics to market. In this review, we discuss recent instructive examples of impacts from cryo-EM in therapeutics design, focusing largely on its implementation at Pfizer. We also discuss the opportunities afforded by emerging technological advances in cryo-EM, and the prospects for future development of the technique.
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Affiliation(s)
- Joshua A. Lees
- Discovery Sciences, Medicine Design, Pfizer Worldwide Research and Development, Groton, CT 06340, U.S.A
| | - Joao M. Dias
- Discovery Sciences, Medicine Design, Pfizer Worldwide Research and Development, Groton, CT 06340, U.S.A
| | - Seungil Han
- Discovery Sciences, Medicine Design, Pfizer Worldwide Research and Development, Groton, CT 06340, U.S.A
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34
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Wigge C, Stefanovic A, Radjainia M. The rapidly evolving role of cryo-EM in drug design. DRUG DISCOVERY TODAY. TECHNOLOGIES 2021; 38:91-102. [PMID: 34895645 DOI: 10.1016/j.ddtec.2020.12.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2020] [Revised: 12/09/2020] [Accepted: 12/22/2020] [Indexed: 01/18/2023]
Abstract
Since the early 2010s, cryo-electron microscopy (cryo-EM) has evolved to a mainstream structural biology method in what has been dubbed the "resolution revolution". Pharma companies also began to use cryo-EM in drug discovery, evidenced by a growing number of industry publications. Hitherto limited in resolution, throughput and attainable molecular weight, cryo-EM is rapidly overcoming its main limitations for more widespread use through a new wave of technological advances. This review discusses how cryo-EM has already impacted drug discovery, and how the state-of-the-art is poised to further revolutionize its application to previously intractable proteins as well as new use cases.
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Affiliation(s)
- Christoph Wigge
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands
| | | | - Mazdak Radjainia
- Thermo Fisher Scientific, Achtseweg Noord 5, 5651 GG Eindhoven, The Netherlands.
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35
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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: 35] [Impact Index Per Article: 11.7] [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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36
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Conquer by cryo-EM without physically dividing. Biochem Soc Trans 2021; 49:2287-2298. [PMID: 34709401 DOI: 10.1042/bst20210360] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2021] [Revised: 09/29/2021] [Accepted: 10/05/2021] [Indexed: 12/15/2022]
Abstract
This mini-review provides an update regarding the substantial progress that has been made in using single-particle cryo-EM to obtain high-resolution structures for proteins and other macromolecules whose particle sizes are smaller than 100 kDa. We point out that establishing the limits of what can be accomplished, both in terms of particle size and attainable resolution, serves as a guide for what might be expected when attempting to improve the resolution of small flexible portions of a larger structure using focused refinement approaches. These approaches, which involve computationally ignoring all but a specific, targeted region of interest on the macromolecules, is known as 'masking and refining,' and it thus is the computational equivalent of the 'divide and conquer' approach that has been used so successfully in X-ray crystallography. The benefit of masked refinement, however, is that one is able to determine structures in their native architectural context, without physically separating them from the biological connections that they require for their function. This mini-review also compares where experimental achievements currently stand relative to various theoretical estimates for the smallest particle size that can be successfully reconstructed to high resolution. Since it is clear that a substantial gap still remains between the two, we briefly recap the areas in which further improvement seems possible, both in equipment and in methods.
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37
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Pursuing High-Resolution Structures of Nicotinic Acetylcholine Receptors: Lessons Learned from Five Decades. Molecules 2021; 26:molecules26195753. [PMID: 34641297 PMCID: PMC8510392 DOI: 10.3390/molecules26195753] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2021] [Revised: 09/19/2021] [Accepted: 09/20/2021] [Indexed: 01/04/2023] Open
Abstract
Since their discovery, nicotinic acetylcholine receptors (nAChRs) have been extensively studied to understand their function, as well as the consequence of alterations leading to disease states. Importantly, these receptors represent pharmacological targets to treat a number of neurological and neurodegenerative disorders. Nevertheless, their therapeutic value has been limited by the absence of high-resolution structures that allow for the design of more specific and effective drugs. This article offers a comprehensive review of five decades of research pursuing high-resolution structures of nAChRs. We provide a historical perspective, from initial structural studies to the most recent X-ray and cryogenic electron microscopy (Cryo-EM) nAChR structures. We also discuss the most relevant structural features that emerged from these studies, as well as perspectives in the field.
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38
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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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39
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Elephants in the Dark: Insights and Incongruities in Pentameric Ligand-gated Ion Channel Models. J Mol Biol 2021; 433:167128. [PMID: 34224751 DOI: 10.1016/j.jmb.2021.167128] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2021] [Revised: 06/25/2021] [Accepted: 06/25/2021] [Indexed: 02/06/2023]
Abstract
The superfamily of pentameric ligand-gated ion channels (pLGICs) comprises key players in electrochemical signal transduction across evolution, including historic model systems for receptor allostery and targets for drug development. Accordingly, structural studies of these channels have steadily increased, and now approach 250 depositions in the protein data bank. This review contextualizes currently available structures in the pLGIC family, focusing on morphology, ligand binding, and gating in three model subfamilies: the prokaryotic channel GLIC, the cation-selective nicotinic acetylcholine receptor, and the anion-selective glycine receptor. Common themes include the challenging process of capturing and annotating channels in distinct functional states; partially conserved gating mechanisms, including remodeling at the extracellular/transmembrane-domain interface; and diversity beyond the protein level, arising from posttranslational modifications, ligands, lipids, and signaling partners. Interpreting pLGIC structures can be compared to describing an elephant in the dark, relying on touch alone to comprehend the many parts of a monumental beast: each structure represents a snapshot in time under specific experimental conditions, which must be integrated with further structure, function, and simulations data to build a comprehensive model, and understand how one channel may fundamentally differ from another.
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40
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Drew D, North RA, Nagarathinam K, Tanabe M. Structures and General Transport Mechanisms by the Major Facilitator Superfamily (MFS). Chem Rev 2021; 121:5289-5335. [PMID: 33886296 PMCID: PMC8154325 DOI: 10.1021/acs.chemrev.0c00983] [Citation(s) in RCA: 157] [Impact Index Per Article: 52.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Indexed: 12/12/2022]
Abstract
The major facilitator superfamily (MFS) is the largest known superfamily of secondary active transporters. MFS transporters are responsible for transporting a broad spectrum of substrates, either down their concentration gradient or uphill using the energy stored in the electrochemical gradients. Over the last 10 years, more than a hundred different MFS transporter structures covering close to 40 members have provided an atomic framework for piecing together the molecular basis of their transport cycles. Here, we summarize the remarkable promiscuity of MFS members in terms of substrate recognition and proton coupling as well as the intricate gating mechanisms undergone in achieving substrate translocation. We outline studies that show how residues far from the substrate binding site can be just as important for fine-tuning substrate recognition and specificity as those residues directly coordinating the substrate, and how a number of MFS transporters have evolved to form unique complexes with chaperone and signaling functions. Through a deeper mechanistic description of glucose (GLUT) transporters and multidrug resistance (MDR) antiporters, we outline novel refinements to the rocker-switch alternating-access model, such as a latch mechanism for proton-coupled monosaccharide transport. We emphasize that a full understanding of transport requires an elucidation of MFS transporter dynamics, energy landscapes, and the determination of how rate transitions are modulated by lipids.
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Affiliation(s)
- David Drew
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Rachel A. North
- Department
of Biochemistry and Biophysics, Stockholm
University, SE 106 91 Stockholm, Sweden
| | - Kumar Nagarathinam
- Center
of Structural and Cell Biology in Medicine, Institute of Biochemistry, University of Lübeck, D-23538, Lübeck, Germany
| | - Mikio Tanabe
- Structural
Biology Research Center, Institute of Materials Structure Science, High Energy Accelerator Research Organization (KEK), Oho 1-1, Tsukuba, Ibaraki 305-0801, Japan
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41
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Tamura-Sakaguchi R, Aruga R, Hirose M, Ekimoto T, Miyake T, Hizukuri Y, Oi R, Kaneko MK, Kato Y, Akiyama Y, Ikeguchi M, Iwasaki K, Nogi T. Moving toward generalizable NZ-1 labeling for 3D structure determination with optimized epitope-tag insertion. Acta Crystallogr D Struct Biol 2021; 77:645-662. [PMID: 33950020 PMCID: PMC8098476 DOI: 10.1107/s2059798321002527] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2020] [Accepted: 03/08/2021] [Indexed: 11/10/2022] Open
Abstract
Antibody labeling has been conducted extensively for structure determination using both X-ray crystallography and electron microscopy (EM). However, establishing target-specific antibodies is a prerequisite for applying antibody-assisted structural analysis. To expand the applicability of this strategy, an alternative method has been developed to prepare an antibody complex by inserting an exogenous epitope into the target. It has already been demonstrated that the Fab of the NZ-1 monoclonal antibody can form a stable complex with a target containing a PA12 tag as an inserted epitope. Nevertheless, it was also found that complex formation through the inserted PA12 tag inevitably caused structural changes around the insertion site on the target. Here, an attempt was made to improve the tag-insertion method, and it was consequently discovered that an alternate tag (PA14) could replace various loops on the target without inducing large structural changes. Crystallographic analysis demonstrated that the inserted PA14 tag adopts a loop-like conformation with closed ends in the antigen-binding pocket of the NZ-1 Fab. Due to proximity of the termini in the bound conformation, the more optimal PA14 tag had only a minor impact on the target structure. In fact, the PA14 tag could also be inserted into a sterically hindered loop for labeling. Molecular-dynamics simulations also showed a rigid structure for the target regardless of PA14 insertion and complex formation with the NZ-1 Fab. Using this improved labeling technique, negative-stain EM was performed on a bacterial site-2 protease, which enabled an approximation of the domain arrangement based on the docking mode of the NZ-1 Fab.
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Affiliation(s)
| | - Rie Aruga
- Graduate School of Medical Life Science, Yokohama City University, Japan
| | - Mika Hirose
- Institute for Protein Research, Osaka University, Japan
| | - Toru Ekimoto
- Graduate School of Medical Life Science, Yokohama City University, Japan
| | - Takuya Miyake
- Institute for Frontier Life and Medical Sciences, Kyoto University, Japan
| | - Yohei Hizukuri
- Institute for Frontier Life and Medical Sciences, Kyoto University, Japan
| | - Rika Oi
- Graduate School of Medical Life Science, Yokohama City University, Japan
| | - Mika K. Kaneko
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Japan
| | - Yukinari Kato
- Department of Antibody Drug Development, Tohoku University Graduate School of Medicine, Japan
- New Industry Creation Hatchery Center, Tohoku University, Japan
| | - Yoshinori Akiyama
- Institute for Frontier Life and Medical Sciences, Kyoto University, Japan
| | - Mitsunori Ikeguchi
- Graduate School of Medical Life Science, Yokohama City University, Japan
- RIKEN, Medical Life Sciences Innovation Hub Program, Japan
| | - Kenji Iwasaki
- Life Science Center for Survival Dynamics, Tsukuba Advanced Research Alliance (TARA), University of Tsukuba, Japan
| | - Terukazu Nogi
- Graduate School of Medical Life Science, Yokohama City University, Japan
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42
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Henderson PJF, Maher C, Elbourne LDH, Eijkelkamp BA, Paulsen IT, Hassan KA. Physiological Functions of Bacterial "Multidrug" Efflux Pumps. Chem Rev 2021; 121:5417-5478. [PMID: 33761243 DOI: 10.1021/acs.chemrev.0c01226] [Citation(s) in RCA: 63] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Bacterial multidrug efflux pumps have come to prominence in human and veterinary pathogenesis because they help bacteria protect themselves against the antimicrobials used to overcome their infections. However, it is increasingly realized that many, probably most, such pumps have physiological roles that are distinct from protection of bacteria against antimicrobials administered by humans. Here we undertake a broad survey of the proteins involved, allied to detailed examples of their evolution, energetics, structures, chemical recognition, and molecular mechanisms, together with the experimental strategies that enable rapid and economical progress in understanding their true physiological roles. Once these roles are established, the knowledge can be harnessed to design more effective drugs, improve existing microbial production of drugs for clinical practice and of feedstocks for commercial exploitation, and even develop more sustainable biological processes that avoid, for example, utilization of petroleum.
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Affiliation(s)
- Peter J F Henderson
- School of Biomedical Sciences and Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, United Kingdom
| | - Claire Maher
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia
| | - Liam D H Elbourne
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Bart A Eijkelkamp
- College of Science and Engineering, Flinders University, Bedford Park 5042, South Australia, Australia
| | - Ian T Paulsen
- Department of Biomolecular Sciences, Macquarie University, Sydney 2109, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
| | - Karl A Hassan
- School of Environmental and Life Sciences, University of Newcastle, Callaghan 2308, New South Wales, Australia.,ARC Centre of Excellence in Synthetic Biology, Macquarie University, Sydney 2019, New South Wales, Australia
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43
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Wang N, Clark LD, Gao Y, Kozlov MM, Shemesh T, Rapoport TA. Mechanism of membrane-curvature generation by ER-tubule shaping proteins. Nat Commun 2021; 12:568. [PMID: 33495454 PMCID: PMC7835363 DOI: 10.1038/s41467-020-20625-y] [Citation(s) in RCA: 34] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 12/07/2020] [Indexed: 12/15/2022] Open
Abstract
The endoplasmic reticulum (ER) network consists of tubules with high membrane curvature in cross-section, generated by the reticulons and REEPs. These proteins have two pairs of trans-membrane (TM) segments, followed by an amphipathic helix (APH), but how they induce curvature is poorly understood. Here, we show that REEPs form homodimers by interaction within the membrane. When overexpressed or reconstituted at high concentrations with phospholipids, REEPs cause extreme curvature through their TMs, generating lipoprotein particles instead of vesicles. The APH facilitates curvature generation, as its mutation prevents ER network formation of reconstituted proteoliposomes, and synthetic L- or D-amino acid peptides abolish ER network formation in Xenopus egg extracts. In Schizosaccharomyces japonicus, the APH is required for reticulon’s exclusive ER-tubule localization and restricted mobility. Thus, the TMs and APH cooperate to generate high membrane curvature. We propose that the formation of splayed REEP/reticulon dimers is responsible for ER tubule formation. The endoplasmic reticulum network consists of tubules with high membrane curvature in cross-section, generated by the reticulons and REEPs, but how they introduce curvature is poorly understood. Here authors show that REEPs form homodimers and use their amphipathic helix and trans-membrane segments to introduce high membrane curvature that can even lead to the formation of lipoprotein particles.
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Affiliation(s)
- Ning Wang
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Lindsay D Clark
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Yuan Gao
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA
| | - Michael M Kozlov
- Department of Physiology and Pharmacology, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, 69978, Israel
| | - Tom Shemesh
- Faculty of Biology, Technion-Israel Institute of Technology, Haifa, 32000, Israel
| | - Tom A Rapoport
- Howard Hughes Medical Institute and Department of Cell Biology, Harvard Medical School, Boston, MA, 02115, USA.
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44
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Cheloha RW, Harmand TJ, Wijne C, Schwartz TU, Ploegh HL. Exploring cellular biochemistry with nanobodies. J Biol Chem 2020; 295:15307-15327. [PMID: 32868455 PMCID: PMC7650250 DOI: 10.1074/jbc.rev120.012960] [Citation(s) in RCA: 56] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2020] [Revised: 08/27/2020] [Indexed: 12/21/2022] Open
Abstract
Reagents that bind tightly and specifically to biomolecules of interest remain essential in the exploration of biology and in their ultimate application to medicine. Besides ligands for receptors of known specificity, agents commonly used for this purpose are monoclonal antibodies derived from mice, rabbits, and other animals. However, such antibodies can be expensive to produce, challenging to engineer, and are not necessarily stable in the context of the cellular cytoplasm, a reducing environment. Heavy chain-only antibodies, discovered in camelids, have been truncated to yield single-domain antibody fragments (VHHs or nanobodies) that overcome many of these shortcomings. Whereas they are known as crystallization chaperones for membrane proteins or as simple alternatives to conventional antibodies, nanobodies have been applied in settings where the use of standard antibodies or their derivatives would be impractical or impossible. We review recent examples in which the unique properties of nanobodies have been combined with complementary methods, such as chemical functionalization, to provide tools with unique and useful properties.
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Affiliation(s)
- Ross W Cheloha
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Thibault J Harmand
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Charlotte Wijne
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA
| | - Thomas U Schwartz
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Hidde L Ploegh
- Program in Cellular and Molecular Medicine, Boston Children's Hospital, Boston, Massachusetts, USA; Harvard Medical School, Boston, Massachusetts, USA.
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45
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Nygaard R, Kim J, Mancia F. Cryo-electron microscopy analysis of small membrane proteins. Curr Opin Struct Biol 2020; 64:26-33. [PMID: 32603877 PMCID: PMC7665978 DOI: 10.1016/j.sbi.2020.05.009] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2020] [Revised: 05/05/2020] [Accepted: 05/19/2020] [Indexed: 12/31/2022]
Abstract
Recent advances in single-particle cryogenic-electron microscopy have facilitated an exponential growth in the number of membrane protein structures determined to close to atomic resolution. Nevertheless, despite improvements in microscope hardware, cryo-EM software and sample preparation techniques, challenges remain for structural analysis of small-sized membrane proteins (i.e.<150 kilodalton). Here we discuss recent examples of structures of macromolecules from this category determined by cryo-EM. We analyze the underlying difficulties, the enabling technologies such as the use of antibody fragments to gain size and provide fiducials for particle alignment, and the unresolved issues like dislocation of complexes at the air-water interface. Finally, we briefly highlight the biological relevance of some of these success stories, and our predictions for the future.
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Affiliation(s)
- Rie Nygaard
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Jonathan Kim
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY 10032, USA
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University Irving Medical Center, New York, NY 10032, USA.
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46
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Tsutsumi N, Mukherjee S, Waghray D, Janda CY, Jude KM, Miao Y, Burg JS, Aduri NG, Kossiakoff AA, Gati C, Garcia KC. Structure of human Frizzled5 by fiducial-assisted cryo-EM supports a heterodimeric mechanism of canonical Wnt signaling. eLife 2020; 9:e58464. [PMID: 32762848 PMCID: PMC7442489 DOI: 10.7554/elife.58464] [Citation(s) in RCA: 63] [Impact Index Per Article: 15.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2020] [Accepted: 08/06/2020] [Indexed: 01/19/2023] Open
Abstract
Frizzleds (Fzd) are the primary receptors for Wnt morphogens, which are essential regulators of stem cell biology, yet the structural basis of Wnt signaling through Fzd remains poorly understood. Here we report the structure of an unliganded human Fzd5 determined by single-particle cryo-EM at 3.7 Å resolution, with the aid of an antibody chaperone acting as a fiducial marker. We also analyzed the topology of low-resolution XWnt8/Fzd5 complex particles, which revealed extreme flexibility between the Wnt/Fzd-CRD and the Fzd-TM regions. Analysis of Wnt/β-catenin signaling in response to Wnt3a versus a 'surrogate agonist' that cross-links Fzd to LRP6, revealed identical structure-activity relationships. Thus, canonical Wnt/β-catenin signaling appears to be principally reliant on ligand-induced Fzd/LRP6 heterodimerization, versus the allosteric mechanisms seen in structurally analogous class A G protein-coupled receptors, and Smoothened. These findings deepen our mechanistic understanding of Wnt signal transduction, and have implications for harnessing Wnt agonism in regenerative medicine.
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Affiliation(s)
- Naotaka Tsutsumi
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- Howard Hughes Medical Institute, Stanford University School of MedicineStanfordUnited States
| | - Somnath Mukherjee
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Deepa Waghray
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
| | - Claudia Y Janda
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- Princess Máxima Center for Pediatric OncologyUtrechtNetherlands
| | - Kevin M Jude
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- Howard Hughes Medical Institute, Stanford University School of MedicineStanfordUnited States
| | - Yi Miao
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
| | - John S Burg
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
| | - Nanda Gowtham Aduri
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- SLAC National Accelerator Laboratory, Bioscience DivisionMenlo ParkUnited States
| | - Anthony A Kossiakoff
- Department of Biochemistry and Molecular Biology, The University of ChicagoChicagoUnited States
| | - Cornelius Gati
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- SLAC National Accelerator Laboratory, Bioscience DivisionMenlo ParkUnited States
| | - K Christopher Garcia
- Department of Molecular and Cellular Physiology, Stanford University School of MedicineStanfordUnited States
- Department of Structural Biology, Stanford University School of MedicineStanfordUnited States
- Howard Hughes Medical Institute, Stanford University School of MedicineStanfordUnited States
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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: 12] [Impact Index Per Article: 3.0] [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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