1
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Li S, Wu B, Luo YL, Han W. Simulations of Functional Motions of Super Large Biomolecules with a Mixed-Resolution Model. J Chem Theory Comput 2024; 20:2228-2245. [PMID: 38374639 PMCID: PMC10938502 DOI: 10.1021/acs.jctc.3c01046] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2023] [Revised: 01/18/2024] [Accepted: 01/29/2024] [Indexed: 02/21/2024]
Abstract
Many large protein machines function through an interplay between large-scale movements and intricate conformational changes. Understanding functional motions of these proteins through simulations becomes challenging for both all-atom and coarse-grained (CG) modeling techniques because neither approach alone can readily capture the full details of these motions. In this study, we develop a multiscale model by employing the popular MARTINI CG model to represent a heterogeneous environment and structurally stable proteins and using the united-atom (UA) model PACE to describe proteins undergoing subtle conformational changes. PACE was previously developed to be compatible with the MARTINI solvent and membrane. Here, we couple the protein descriptions of the two models by directly mixing UA and CG interaction parameters to greatly simplify parameter determination. Through extensive validations with diverse protein systems in solution or membrane, we demonstrate that only additional parameter rescaling is needed to enable the resulting model to recover the stability of native structures of proteins under mixed representation. Moreover, we identify the optimal scaling factors that can be applied to various protein systems, rendering the model potentially transferable. To further demonstrate its applicability for realistic systems, we apply the model to a mechanosensitive ion channel Piezo1 that has peripheral arms for sensing membrane tension and a central pore for ion conductance. The model can reproduce the coupling between Piezo1's large-scale arm movement and subtle pore opening in response to membrane stress while consuming much less computational costs than all-atom models. Therefore, our model shows promise for studying functional motions of large protein machines.
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Affiliation(s)
- Shu Li
- Centre
for Artificial Intelligence Driven Drug Discovery, Faculty of Applied
Sciences, Macao Polytechnic University, Macao 999078, China
- State
Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key
Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Bohua Wu
- State
Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key
Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
| | - Yun Lyna Luo
- Department
of Biotechnology and Pharmaceutical Sciences, Western University of Health Sciences, Pomona, California 91766, United States
| | - Wei Han
- State
Key Laboratory of Chemical Oncogenomics, Guangdong Provincial Key
Laboratory of Chemical Genomics, School of Chemical Biology and Biotechnology, Peking University Shenzhen Graduate School, Shenzhen 518055, China
- Department
of Chemistry, Faculty of Science, Hong Kong
Baptist University, Hong Kong SAR 999077, China
- Shenzhen
Bay Laboratory, Institute of Chemical Biology, Shenzhen 518132, China
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2
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Majumder A, Straub JE. The role of structural heterogeneity in the homodimerization of transmembrane proteins. J Chem Phys 2023; 159:134101. [PMID: 37782254 PMCID: PMC10547497 DOI: 10.1063/5.0159801] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2023] [Accepted: 07/27/2023] [Indexed: 10/03/2023] Open
Abstract
The equilibrium association of transmembrane proteins plays a fundamental role in membrane protein function and cellular signaling. While the study of the equilibrium binding of single pass transmembrane proteins has received significant attention in experiment and simulation, the accurate assessment of equilibrium association constants remains a challenge to experiment and simulation. In experiment, there remain wide variations in association constants derived from experimental studies of the most widely studied transmembrane proteins. In simulation, state-of-the art methods have failed to adequately sample the thermodynamically relevant structures of the dimer state ensembles using coarse-grained models. In addition, all-atom force fields often fail to accurately assess the relative free energies of the dimer and monomer states. Given the importance of this fundamental biophysical process, it is essential to address these shortcomings. In this work, we establish an effective computational protocol for the calculation of equilibrium association constants for transmembrane homodimer formation. A set of transmembrane protein homodimers, used in the parameterization of the MARTINI v3 force field, are simulated using metadynamics, based on three collective variables. The method is found to be accurate and computationally efficient, providing a standard to be used in the future simulation studies using coarse-grained or all-atom models.
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Affiliation(s)
- Ayan Majumder
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
| | - John E. Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston, Massachusetts 02215, USA
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3
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Medvedev KE, Schaeffer RD, Chen KS, Grishin NV. Pan-cancer structurome reveals overrepresentation of beta sandwiches and underrepresentation of alpha helical domains. Sci Rep 2023; 13:11988. [PMID: 37491511 PMCID: PMC10368619 DOI: 10.1038/s41598-023-39273-5] [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: 04/25/2023] [Accepted: 07/22/2023] [Indexed: 07/27/2023] Open
Abstract
The recent progress in the prediction of protein structures marked a historical milestone. AlphaFold predicted 200 million protein models with an accuracy comparable to experimental methods. Protein structures are widely used to understand evolution and to identify potential drug targets for the treatment of various diseases, including cancer. Thus, these recently predicted structures might convey previously unavailable information about cancer biology. Evolutionary classification of protein domains is challenging and different approaches exist. Recently our team presented a classification of domains from human protein models released by AlphaFold. Here we evaluated the pan-cancer structurome, domains from over and under expressed proteins in 21 cancer types, using the broadest levels of the ECOD classification: the architecture (A-groups) and possible homology (X-groups) levels. Our analysis reveals that AlphaFold has greatly increased the three-dimensional structural landscape for proteins that are differentially expressed in these 21 cancer types. We show that beta sandwich domains are significantly overrepresented and alpha helical domains are significantly underrepresented in the majority of cancer types. Our data suggest that the prevalence of the beta sandwiches is due to the high levels of immunoglobulins and immunoglobulin-like domains that arise during tumor development-related inflammation. On the other hand, proteins with exclusively alpha domains are important elements of homeostasis, apoptosis and transmembrane transport. Therefore cancer cells tend to reduce representation of these proteins to promote successful oncogeneses.
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Affiliation(s)
- Kirill E Medvedev
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - R Dustin Schaeffer
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Kenneth S Chen
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Children's Medical Center Research Institute, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
| | - Nick V Grishin
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, TX, 75390, USA
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4
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Kim M, Bezprozvanny I. Potential direct role of synuclein in dopamine transport and its implications for Parkinson's disease pathogenesis. Biochem Biophys Res Commun 2023; 671:18-25. [PMID: 37290280 DOI: 10.1016/j.bbrc.2023.05.110] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2023] [Accepted: 05/25/2023] [Indexed: 06/10/2023]
Abstract
Parkinson Disease (PD) is a progressive neurodegenerative disorder that is caused by dysfunction and death of dopaminergic neurons. Mutations in the gene encoding α-synuclein (ASYN) have been linked with familial PD (FPD). Despite important role of ASYN in PD pathology, its normal biological function has not been clarified, although direct action of ASYN in synaptic transmission and dopamine (DA+) release have been proposed. In the present report we propose a novel hypothesis that ASYN functions as DA+/H+ exchanger that can facilitate transport of dopamine across synaptic vesicle (SV) membrane by taking advantage of proton gradient between SV lumen and cytoplasm. According to this hypothesis, normal physiological role of ASYN consists of fine-tuning levels of dopamine in the SVs based on cytosolic concentration of dopamine and intraluminal pH. This hypothesis is based on similarity in domain structure of ASYN and pHILP, a designed peptide developed to mediate loading of lipid nanoparticles with the cargo molecules. We reason that carboxy-terminal acidic loop D2b domain in both ASYN and pHILP binds cargo molecules. By mimicking DA+ association with E/D residues in D2b domain of ASYN using Tyrosine replacement approach (TR) we have been able to estimate that ASYN is able to transfer 8-12 molecules of dopamine across SV membrane on each DA+/H+ exchange cycle. Our results suggest that familial PD mutations (A30P, E46K, H50Q, G51D, A53T and A53E) will interfere with different steps of the exchange cycle, resulting in partial loss of dopamine transport function phenotype. We also predict that similar impairment in ASYN DA+/H+ exchange function also occurs as a result on neuronal aging due to changes in SV lipid composition and size and also dissipation of pH gradient across SV membrane. Proposed novel functional role of ASYN provides novel insights into its biological role and its role in PD pathogenesis.
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Affiliation(s)
- Meewhi Kim
- Dept of Physiology, UT Southwestern Medical Center, Dallas, TX, 75390, USA.
| | - Ilya Bezprozvanny
- Dept of Physiology, UT Southwestern Medical Center, Dallas, TX, 75390, USA; Laboratory of Molecular Neurodegeneration, St Petersburg State Polytechnical Universty, St Petersburg, 195251, Russian Federation.
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5
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Sahoo AR, Souza PCT, Meng Z, Buck M. Transmembrane dimers of type 1 receptors sample alternate configurations: MD simulations using coarse grain Martini 3 versus AlphaFold2 Multimer. Structure 2023; 31:735-745.e2. [PMID: 37075749 PMCID: PMC10833135 DOI: 10.1016/j.str.2023.03.014] [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: 10/06/2022] [Revised: 02/07/2023] [Accepted: 03/23/2023] [Indexed: 04/21/2023]
Abstract
Structures and dynamics of transmembrane (TM) receptor regions are key to understanding their signaling mechanism across membranes. Here we examine configurations of TM region dimers, assembled using the recent Martini 3 force field for coarse-grain (CG) molecular dynamics simulations. At first glance, our results show only a reasonable agreement with ab initio predictions using PREDDIMER and AlphaFold2 Multimer and with nuclear magnetic resonance (NMR)-derived structures. 5 of 11 CG TM structures are similar to the NMR structures (within <3.5 Å root-mean-square deviation [RMSD]) compared with 10 and 9 using PREDDIMER and AlphaFold2, respectively (with 8 structures of the later within 1.5 Å). Surprisingly, AlphaFold2 predictions are closer to NMR structures when the 2001 instead of 2020 database is used for training. The CG simulations reveal that alternative configurations of TM dimers readily interconvert with a predominant population. The implications for transmembrane signaling are discussed, including for the development of peptide-based pharmaceuticals.
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Affiliation(s)
- Amita R Sahoo
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Paulo C T Souza
- Molecular Microbiology and Structural Biochemistry (MMSB, UMR 5086), CNRS & University of Lyon, 7 Passage du Vercors, 69007 Lyon, France
| | - Zhiyuan Meng
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA
| | - Matthias Buck
- Department of Physiology and Biophysics, Case Western Reserve University, School of Medicine, 10900 Euclid Avenue, Cleveland, OH 44106, USA.
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6
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Jackson V, Hermann J, Tynan CJ, Rolfe DJ, Corey RA, Duncan AL, Noriega M, Chu A, Kalli AC, Jones EY, Sansom MSP, Martin-Fernandez ML, Seiradake E, Chavent M. The guidance and adhesion protein FLRT2 dimerizes in cis via dual small-X 3-small transmembrane motifs. Structure 2022; 30:1354-1365.e5. [PMID: 35700726 DOI: 10.1016/j.str.2022.05.014] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 03/03/2022] [Accepted: 05/18/2022] [Indexed: 10/18/2022]
Abstract
Fibronectin Leucine-rich Repeat Transmembrane (FLRT 1-3) proteins are a family of broadly expressed single-spanning transmembrane receptors that play key roles in development. Their extracellular domains mediate homotypic cell-cell adhesion and heterotypic protein interactions with other receptors to regulate cell adhesion and guidance. These in trans FLRT interactions determine the formation of signaling complexes of varying complexity and function. Whether FLRTs also interact at the surface of the same cell, in cis, remains unknown. Here, molecular dynamics simulations reveal two dimerization motifs in the FLRT2 transmembrane helix. Single particle tracking experiments show that these Small-X3-Small motifs synergize with a third dimerization motif encoded in the extracellular domain to permit the cis association and co-diffusion patterns of FLRT2 receptors on cells. These results may point to a competitive switching mechanism between in cis and in trans interactions, which suggests that homotypic FLRT interaction mirrors the functionalities of classic adhesion molecules.
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Affiliation(s)
- Verity Jackson
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Julia Hermann
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Christopher J Tynan
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Harwell Campus, Didcot, OX11 0FA, UK
| | - Daniel J Rolfe
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Harwell Campus, Didcot, OX11 0FA, UK
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Maxime Noriega
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France
| | - Amy Chu
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Antreas C Kalli
- Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine and Astbury Center for Structural Molecular Biology, University of Leeds, Leeds, LS2 9NL, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK
| | - Marisa L Martin-Fernandez
- Central Laser Facility, Research Complex at Harwell, Science and Technology Facilities Council, Harwell Campus, Didcot, OX11 0FA, UK.
| | - Elena Seiradake
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 5RJ, UK.
| | - Matthieu Chavent
- Institut de Pharmacologie et Biologie Structurale, IPBS, Université de Toulouse, CNRS, UPS, 205 route de Narbonne, 31400 Toulouse, France.
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7
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Chu LY, Huang BL, Huang XC, Peng YH, Xie JJ, Xu YW. EFNA1 in gastrointestinal cancer: Expression, regulation and clinical significance. World J Gastrointest Oncol 2022; 14:973-988. [PMID: 35646281 PMCID: PMC9124989 DOI: 10.4251/wjgo.v14.i5.973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 09/17/2021] [Accepted: 04/04/2022] [Indexed: 02/06/2023] Open
Abstract
Ephrin-A1 is a protein that in humans is encoded by the EFNA1 gene. The ephrins and EPH-related receptors comprise the largest subfamily of receptor protein-tyrosine kinases which play an indispensable role in normal growth and development or in the pathophysiology of various tumors. The role of EFNA1 in tumorigenesis and development is complex and depends on the cell type and microenvironment which in turn affect the expression of EFNA1. This article reviews the expression, prognostic value, regulation and clinical significance of EFNA1 in gastrointestinal tumors.
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Affiliation(s)
- Ling-Yu Chu
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, Guangdong Province, China
| | - Bin-Liang Huang
- Department of Clinical Laboratory Medicine, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
| | - Xu-Chun Huang
- Department of Clinical Laboratory Medicine, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
| | - Yu-Hui Peng
- Department of Clinical Laboratory Medicine, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
- Guangdong Esophageal Cancer Research Institute, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
| | - Jian-Jun Xie
- Department of Biochemistry and Molecular Biology, Shantou University Medical College, Shantou 515041, Guangdong Province, China
| | - Yi-Wei Xu
- Department of Clinical Laboratory Medicine, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
- Guangdong Esophageal Cancer Research Institute, The Cancer Hospital of Shantou University Medical College, Shantou 515041, Guangdong Province, China
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8
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Majeed S, Ahmad AB, Sehar U, Georgieva ER. Lipid Membrane Mimetics in Functional and Structural Studies of Integral Membrane Proteins. MEMBRANES 2021; 11:685. [PMID: 34564502 PMCID: PMC8470526 DOI: 10.3390/membranes11090685] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 07/27/2021] [Revised: 08/18/2021] [Accepted: 08/30/2021] [Indexed: 12/12/2022]
Abstract
Integral membrane proteins (IMPs) fulfill important physiological functions by providing cell-environment, cell-cell and virus-host communication; nutrients intake; export of toxic compounds out of cells; and more. However, some IMPs have obliterated functions due to polypeptide mutations, modifications in membrane properties and/or other environmental factors-resulting in damaged binding to ligands and the adoption of non-physiological conformations that prevent the protein from returning to its physiological state. Thus, elucidating IMPs' mechanisms of function and malfunction at the molecular level is important for enhancing our understanding of cell and organism physiology. This understanding also helps pharmaceutical developments for restoring or inhibiting protein activity. To this end, in vitro studies provide invaluable information about IMPs' structure and the relation between structural dynamics and function. Typically, these studies are conducted on transferred from native membranes to membrane-mimicking nano-platforms (membrane mimetics) purified IMPs. Here, we review the most widely used membrane mimetics in structural and functional studies of IMPs. These membrane mimetics are detergents, liposomes, bicelles, nanodiscs/Lipodisqs, amphipols, and lipidic cubic phases. We also discuss the protocols for IMPs reconstitution in membrane mimetics as well as the applicability of these membrane mimetic-IMP complexes in studies via a variety of biochemical, biophysical, and structural biology techniques.
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Affiliation(s)
- Saman Majeed
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Akram Bani Ahmad
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Ujala Sehar
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
| | - Elka R Georgieva
- Department of Chemistry and Biochemistry, Texas Tech University, Lubbock, TX 79409, USA
- Department of Cell Physiology and Molecular Biophysics, Texas Tech University Health Science Center, Lubbock, TX 79409, USA
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9
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Sahoo AR, Buck M. Structural and Functional Insights into the Transmembrane Domain Association of Eph Receptors. Int J Mol Sci 2021; 22:ijms22168593. [PMID: 34445298 PMCID: PMC8395321 DOI: 10.3390/ijms22168593] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/06/2021] [Revised: 08/02/2021] [Accepted: 08/06/2021] [Indexed: 12/04/2022] Open
Abstract
Eph receptors are the largest family of receptor tyrosine kinases and by interactions with ephrin ligands mediate a myriad of processes from embryonic development to adult tissue homeostasis. The interaction of Eph receptors, especially at their transmembrane (TM) domains is key to understanding their mechanism of signal transduction across cellular membranes. We review the structural and functional aspects of EphA1/A2 association and the techniques used to investigate their TM domains: NMR, molecular modelling/dynamics simulations and fluorescence. We also introduce transmembrane peptides, which can be used to alter Eph receptor signaling and we provide a perspective for future studies.
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Affiliation(s)
- Amita R. Sahoo
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA;
| | - Matthias Buck
- Department of Physiology and Biophysics, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA;
- Department of Neurosciences, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Department of Pharmacology, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Case Comprehensive Cancer Center, School of Medicine, Case Western Reserve University, 10900 Euclid Avenue, Cleveland, OH 44106, USA
- Correspondence:
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10
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Lamprakis C, Andreadelis I, Manchester J, Velez-Vega C, Duca JS, Cournia Z. Evaluating the Efficiency of the Martini Force Field to Study Protein Dimerization in Aqueous and Membrane Environments. J Chem Theory Comput 2021; 17:3088-3102. [PMID: 33913726 DOI: 10.1021/acs.jctc.0c00507] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Protein-protein complex assembly is one of the major drivers of biological response. Understanding the mechanisms of protein oligomerization/dimerization would allow one to elucidate how these complexes participate in biological activities and could ultimately lead to new approaches in designing novel therapeutic agents. However, determining the exact association pathways and structures of such complexes remains a challenge. Here, we use parallel tempering metadynamics simulations in the well-tempered ensemble to evaluate the performance of Martini 2.2P and Martini open-beta 3 (Martini 3) force fields in reproducing the structure and energetics of the dimerization process of membrane proteins and proteins in an aqueous solution in reasonable accuracy and throughput. We find that Martini 2.2P systematically overestimates the free energy of association by estimating large barriers in distinct areas, which likely leads to overaggregation when multiple monomers are present. In comparison, the less viscous Martini 3 results in a systematic underestimation of the free energy of association for proteins in solution, while it performs well in describing the association of membrane proteins. In all cases, the near-native dimer complexes are identified as minima in the free energy surface albeit not always as the lowest minima. In the case of Martini 3, we find that the spurious supramolecular protein aggregation present in Martini 2.2P multimer simulations is alleviated and thus this force field may be more suitable for the study of protein oligomerization. We propose that the use of enhanced sampling simulations with a refined coarse-grained force field and appropriately defined collective variables is a robust approach for studying the protein dimerization process, although one should be cautious of the ranking of energy minima.
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Affiliation(s)
- Christos Lamprakis
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - Ioannis Andreadelis
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
| | - John Manchester
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Camilo Velez-Vega
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - José S Duca
- Computer-Aided Drug Discovery, Global Discovery Chemistry, Novartis Institutes for BioMedical Research, 181 Massachusetts Avenue, Cambridge, Massachusetts 02139, United States
| | - Zoe Cournia
- Biomedical Research Foundation, Academy of Athens, 4 Soranou Ephessiou, 11527 Athens, Greece
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11
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Majumder A, Straub JE. Addressing the Excessive Aggregation of Membrane Proteins in the MARTINI Model. J Chem Theory Comput 2021; 17:2513-2521. [PMID: 33720709 DOI: 10.1021/acs.jctc.0c01253] [Citation(s) in RCA: 18] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The MARTINI model is a widely used coarse-grained force field popular for its capacity to represent a diverse array of complex biomolecules. However, efforts to simulate increasingly realistic models of membranes, involving complex lipid mixtures and multiple proteins, suggest that membrane protein aggregates are overstabilized by the MARTINI v2.2 force field. In this study, we address this shortcoming of the MARTINI model. We determined the free energy of dimerization of four transmembrane protein systems using the nonpolarizable MARTINI model. Comparison with experimental FRET-based estimates of the dimerization free energy was used to quantify the significant overstabilization of each protein homodimer studied. To improve the agreement between simulation and experiment, a single uniform scaling factor, α, was used to enhance the protein-lipid Lennard-Jones interaction. A value of α = 1.04-1.045 was found to provide the best fit to the dimerization free energies for the proteins studied while maintaining the specificity of contacts at the dimer interface. To further validate the modified force field, we performed a multiprotein simulation using both MARTINI v2.2 and the reparameterized MARTINI model. While the original MARTINI model predicts oligomerization of protein into a single aggregate, the reparameterized MARTINI model maintains a dynamic equilibrium between monomers and dimers as predicted by experimental studies. The proposed reparameterization is an alternative to the standard MARTINI model for use in simulations of realistic models of a biological membrane containing diverse lipids and proteins.
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Affiliation(s)
- Ayan Majumder
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston 02215, Massachusetts, United States
| | - John E Straub
- Department of Chemistry, Boston University, 590 Commonwealth Avenue, Boston 02215, Massachusetts, United States
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12
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Danmaliki GI, Hwang PM. Solution NMR spectroscopy of membrane proteins. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183356. [PMID: 32416193 DOI: 10.1016/j.bbamem.2020.183356] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 05/08/2020] [Accepted: 05/10/2020] [Indexed: 02/06/2023]
Abstract
Integral membrane proteins (IMPs) perform unique and indispensable functions in the cell, making them attractive targets for fundamental research and drug discovery. Developments in protein production, isotope labeling, sample preparation, and pulse sequences have extended the utility of solution NMR spectroscopy for studying IMPs with multiple transmembrane segments. Here we review some recent applications of solution NMR for studying structure, dynamics, and interactions of polytopic IMPs, emphasizing strategies used to overcome common technical challenges.
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Affiliation(s)
- Gaddafi I Danmaliki
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada
| | - Peter M Hwang
- Department of Biochemistry, University of Alberta, Edmonton, Alberta T6G 2H7, Canada; Department of Medicine, University of Alberta, Edmonton, Alberta T6G 2H7, Canada.
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13
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Resolving the conformational dynamics of ErbB growth factor receptor dimers. J Struct Biol 2019; 207:225-233. [PMID: 31163211 DOI: 10.1016/j.jsb.2019.05.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 05/20/2019] [Accepted: 05/31/2019] [Indexed: 12/30/2022]
Abstract
The combinatorial dimerization of the ErbB growth factor receptors (ErbB1- ErbB4) are critical for their function. Here, we have characterized the conformational dynamics of ErbB transmembrane homo-dimers and hetero-dimers by using a coarse-grain simulation framework. All dimers, except ErbB4-4 and ErbB1-4, exhibit at least two conformations. The reported NMR structures correspond to one of these conformations, representing the N-terminal active state in ErbB1-1 (RH2), ErbB2-2 (RH1) and ErbB4-4 (RH) homo-dimers and the LH dimer in ErbB3-3 homo-dimer, validating the computational approach. Further, we predict a right-handed ErbB3-3 dimer conformer that warrants experimental testing. The five hetero-dimers that have not yet been experimentally resolved display prominent right-handed dimers associating by the SmXXXSm motif. Our results provide insights into the constitutive signaling of ErbB4 after cleavage of the extracellular region. The presence of the inactive-like dimer conformers leading to symmetric kinase domains gives clues on the autoinhibition of the receptor dimers. The dimer states characterized here represent an important step towards understanding the combinatorial cross associations in the ErbB family.
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14
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TerBush AA, Hafkamp F, Lee HJ, Coscoy L. A Kaposi's Sarcoma-Associated Herpesvirus Infection Mechanism Is Independent of Integrins α3β1, αVβ3, and αVβ5. J Virol 2018; 92:e00803-18. [PMID: 29899108 PMCID: PMC6096800 DOI: 10.1128/jvi.00803-18] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2018] [Accepted: 06/08/2018] [Indexed: 12/24/2022] Open
Abstract
Host receptor usage by Kaposi's sarcoma-associated herpesvirus (KSHV) has been best studied using primary microvascular endothelial and fibroblast cells, although the virus infects a wide variety of cell types in culture and in natural infections. In these two infection models, KSHV adheres to the cell though heparan sulfate (HS) binding and then interacts with a complex of EphA2, xCT, and integrins α3β1, αVβ3, and αVβ5 to catalyze viral entry. We dissected this receptor complex at the genetic level with CRISPR-Cas9 to precisely determine receptor usage in two epithelial cell lines. Surprisingly, we discovered an infection mechanism that requires HS and EphA2 but is independent of αV- and β1-family integrin expression. Furthermore, infection appears to be independent of the EphA2 intracellular domain. We also demonstrated that while two other endogenous Eph receptors were dispensable for KSHV infection, transduced EphA4 and EphA5 significantly enhanced infection of cells lacking EphA2.IMPORTANCE Our data reveal an integrin-independent route of KSHV infection and suggest that multiple Eph receptors besides EphA2 can promote and regulate infection. Since integrins and Eph receptors are large protein families with diverse expression patterns across cells and tissues, we propose that KSHV may engage with several proteins from both families in different combinations to negotiate successful entry into diverse cell types.
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Affiliation(s)
- Allison Alwan TerBush
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Florianne Hafkamp
- Graduate School of Life Sciences, Utrecht University, Utrecht, Netherlands
| | - Hee Jun Lee
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
| | - Laurent Coscoy
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, California, USA
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15
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Sinclair JKL, Walker AS, Doerner AE, Schepartz A. Mechanism of Allosteric Coupling into and through the Plasma Membrane by EGFR. Cell Chem Biol 2018; 25:857-870.e7. [PMID: 29731426 DOI: 10.1016/j.chembiol.2018.04.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2017] [Revised: 03/05/2018] [Accepted: 04/04/2018] [Indexed: 12/12/2022]
Abstract
Epidermal growth factor receptor (EGFR) interacts through its extracellular domain with seven different growth factors. These factors induce different structures within the cytoplasmic juxtamembrane (JM) segment of the dimeric receptor and propagate different growth factor-dependent signals to the cell interior. How this process occurs is unknown. Here we apply diverse experimental and computational tools to show that growth factor identity is encoded by the EGFR transmembrane (TM) helix into discrete helix dimer populations that differ in both cross-location and cross-angle. Helix dimers with smaller cross-angles at multiple cross locations are decoded to induce an EGF-type coiled coil in the adjacent JM, whereas helix dimers with larger cross-angles at fewer cross locations induce the TGF-α-type coiled coil. We propose an updated model for how conformational coupling across multiple EGFR domains results in growth factor-specific information transfer, and demonstrate that this model applies to both EGFR and the related receptor ErbB2.
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Affiliation(s)
| | - Allison S Walker
- Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
| | - Amy E Doerner
- Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA
| | - Alanna Schepartz
- Department of Chemistry, Yale University, New Haven, CT 06520-8107, USA; Department of Molecular, Cellular, and Developmental Biology, Yale University, New Haven, CT 06520-8103, USA.
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16
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Joh NH, Grigoryan G, Wu Y, DeGrado WF. Design of self-assembling transmembrane helical bundles to elucidate principles required for membrane protein folding and ion transport. Philos Trans R Soc Lond B Biol Sci 2018. [PMID: 28630154 DOI: 10.1098/rstb.2016.0214] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Ion transporters and channels are able to identify and act on specific substrates among myriads of ions and molecules critical to cellular processes, such as homeostasis, cell signalling, nutrient influx and drug efflux. Recently, we designed Rocker, a minimalist model for Zn2+/H+ co-transport. The success of this effort suggests that de novo membrane protein design has now come of age so as to serve a key approach towards probing the determinants of membrane protein folding, assembly and function. Here, we review general principles that can be used to design membrane proteins, with particular reference to helical assemblies with transport function. We also provide new functional and NMR data that probe the dynamic mechanism of conduction through Rocker.This article is part of the themed issue 'Membrane pores: from structure and assembly, to medicine and technology'.
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Affiliation(s)
- Nathan H Joh
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - Gevorg Grigoryan
- Department of Computer Science, Dartmouth College, Hanover, NH 03755, USA.,Department of Biological Sciences, Dartmouth College, Hanover, NH 03755, USA
| | - Yibing Wu
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
| | - William F DeGrado
- Department of Pharmaceutical Chemistry, Cardiovascular Research Institute, University of California, San Francisco, San Francisco, CA 94158, USA
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17
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Excessive aggregation of membrane proteins in the Martini model. PLoS One 2017; 12:e0187936. [PMID: 29131844 PMCID: PMC5683612 DOI: 10.1371/journal.pone.0187936] [Citation(s) in RCA: 119] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2017] [Accepted: 10/27/2017] [Indexed: 11/19/2022] Open
Abstract
The coarse-grained Martini model is employed extensively to study membrane protein oligomerization. While this approach is exceptionally promising given its computational efficiency, it is alarming that a significant fraction of these studies demonstrate unrealistic protein clusters, whose formation is essentially an irreversible process. This suggests that the protein-protein interactions are exaggerated in the Martini model. If this held true, then it would limit the applicability of Martini to study multi-protein complexes, as the rapidly clustering proteins would not be able to properly sample the correct dimerization conformations. In this work we first demonstrate the excessive protein aggregation by comparing the dimerization free energies of helical transmembrane peptides obtained with the Martini model to those determined from FRET experiments. Second, we show that the predictions provided by the Martini model for the structures of transmembrane domain dimers are in poor agreement with the corresponding structures resolved using NMR. Next, we demonstrate that the first issue can be overcome by slightly scaling down the Martini protein-protein interactions in a manner, which does not interfere with the other Martini interaction parameters. By preventing excessive, irreversible, and non-selective aggregation of membrane proteins, this approach renders the consideration of lateral dynamics and protein-lipid interactions in crowded membranes by the Martini model more realistic. However, this adjusted model does not lead to an improvement in the predicted dimer structures. This implicates that the poor agreement between the Martini model and NMR structures cannot be cured by simply uniformly reducing the interactions between all protein beads. Instead, a careful amino-acid specific adjustment of the protein-protein interactions is likely required.
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18
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Anderson SM, Mueller BK, Lange EJ, Senes A. Combination of Cα-H Hydrogen Bonds and van der Waals Packing Modulates the Stability of GxxxG-Mediated Dimers in Membranes. J Am Chem Soc 2017; 139:15774-15783. [PMID: 29028318 PMCID: PMC5927632 DOI: 10.1021/jacs.7b07505] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The GxxxG motif is frequently found at the dimerization interface of a transmembrane structural motif called GASright, which is characterized by a short interhelical distance and a right-handed crossing angle between the helices. In GASright dimers, such as glycophorin A (GpA), BNIP3, and members of the ErbB family, the backbones of the helices are in contact, and they invariably display networks of 4 to 8 weak hydrogen bonds between Cα-H carbon donors and carbonyl acceptors on opposing helices (Cα-H···O═C hydrogen bonds). These networks of weak hydrogen bonds at the helix-helix interface are presumably stabilizing, but their energetic contribution to dimerization has yet to be determined experimentally. Here, we present a computational and experimental structure-based analysis of GASright dimers of different predicted stabilities, which show that a combination of van der Waals packing and Cα-H hydrogen bonding predicts the experimental trend of dimerization propensities. This finding provides experimental support for the hypothesis that the networks of Cα-H hydrogen bonds are major contributors to the free energy of association of GxxxG-mediated dimers. The structural comparison between groups of GASright dimers of different stabilities reveals distinct sequence as well as conformational preferences. Stability correlates with shorter interhelical distances, narrower crossing angles, better packing, and the formation of larger networks of Cα-H hydrogen bonds. The identification of these structural rules provides insight on how nature could modulate stability in GASright and finely tune dimerization to support biological function.
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Affiliation(s)
- Samantha M Anderson
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Benjamin K Mueller
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Evan J Lange
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
| | - Alessandro Senes
- Department of Biochemistry, University of Wisconsin-Madison , 433 Babcock Drive, Madison, Wisconsin 53706, United States
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19
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Cao H, Ng MCK, Jusoh SA, Tai HK, Siu SWI. TMDIM: an improved algorithm for the structure prediction of transmembrane domains of bitopic dimers. J Comput Aided Mol Des 2017; 31:855-865. [DOI: 10.1007/s10822-017-0047-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Accepted: 08/17/2017] [Indexed: 12/01/2022]
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20
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Dutagaci B, Sayadi M, Feig M. Heterogeneous dielectric generalized Born model with a van der Waals term provides improved association energetics of membrane-embedded transmembrane helices. J Comput Chem 2017; 38:1308-1320. [PMID: 28160300 DOI: 10.1002/jcc.24691] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Revised: 10/18/2016] [Accepted: 11/17/2016] [Indexed: 11/07/2022]
Abstract
The heterogeneous dielectric generalized Born (HDGB) implicit membrane formalism is extended by the addition of a van der Waals dispersion term to better describe the nonpolar components of the free energy of solvation. The new model, termed HDGBvdW, improves the energy estimates in the hydrophobic interior of the membrane, where polar and charged species are rarely found and nonpolar interactions become significant. The implicit van der Waals term for the membrane environment extends the model from Gallicchio et al. (J. Comput. Chem. 2004, 25, 479) by combining separate contributions from each of the membrane components. The HDGBvdW model is validated with a series of test cases ranging from membrane insertion and pair association profiles of amino acid side chain analogs and transmembrane helices. Overall, the HDGBvdW model leads to increased agreement with explicit membrane simulation results and experimental data. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Bercem Dutagaci
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824
| | - Maryam Sayadi
- Department of Chemistry, Michigan State University, East Lansing, Michigan, 48824
| | - Michael Feig
- Department of Biochemistry and Molecular Biology, Michigan State University, East Lansing, Michigan, 48824
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21
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Bocharov EV, Mineev KS, Pavlov KV, Akimov SA, Kuznetsov AS, Efremov RG, Arseniev AS. Helix-helix interactions in membrane domains of bitopic proteins: Specificity and role of lipid environment. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1859:561-576. [PMID: 27884807 DOI: 10.1016/j.bbamem.2016.10.024] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/18/2016] [Accepted: 10/20/2016] [Indexed: 12/23/2022]
Abstract
Interaction between transmembrane helices often determines biological activity of membrane proteins. Bitopic proteins, a broad subclass of membrane proteins, form dimers containing two membrane-spanning helices. Some aspects of their structure-function relationship cannot be fully understood without considering the protein-lipid interaction, which can determine the protein conformational ensemble. Experimental and computer modeling data concerning transmembrane parts of bitopic proteins are reviewed in the present paper. They highlight the importance of lipid-protein interactions and resolve certain paradoxes in the behavior of such proteins. Besides, some properties of membrane organization provided a clue to understanding of allosteric interactions between distant parts of proteins. Interactions of these kinds appear to underlie a signaling mechanism, which could be widely employed in the functioning of many membrane proteins. Treatment of membrane proteins as parts of integrated fine-tuned proteolipid system promises new insights into biological function mechanisms and approaches to drug design. This article is part of a Special Issue entitled: Lipid order/lipid defects and lipid-control of protein activity edited by Dirk Schneider.
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Affiliation(s)
- Eduard V Bocharov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation; National Research Centre "Kurchatov Institute", Akad. Kurchatova pl. 1, Moscow, 123182, Russian Federation.
| | - Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation
| | - Konstantin V Pavlov
- Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Leninskiy prospect 31/5, Moscow, 119071, Russian Federation
| | - Sergey A Akimov
- Frumkin Institute of Physical Chemistry and Electrochemistry RAS, Leninskiy prospect 31/5, Moscow, 119071, Russian Federation; National University of Science and Technology "MISiS", Leninskiy prospect 4, Moscow, 119049, Russian Federation
| | - Andrey S Kuznetsov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation
| | - Roman G Efremov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation; Higher School of Economics, Myasnitskaya ul. 20, Moscow, 101000, Russian Federation
| | - Alexander S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry RAS, Miklukho-Maklaya ul. 16/10, Moscow, 117997, Russian Federation.
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22
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Abstract
Axon guidance relies on a combinatorial code of receptor and ligand interactions that direct adhesive/attractive and repulsive cellular responses. Recent structural data have revealed many of the molecular mechanisms that govern these interactions and enabled the design of sophisticated mutant tools to dissect their biological functions. Here, we discuss the structure/function relationships of four major classes of guidance cues (ephrins, semaphorins, slits, netrins) and examples of morphogens (Wnt, Shh) and of cell adhesion molecules (FLRT). These cell signaling systems rely on specific modes of receptor-ligand binding that are determined by selective binding sites; however, defined structure-encoded receptor promiscuity also enables cross talk between different receptor/ligand families and can also involve extracellular matrix components. A picture emerges in which a multitude of highly context-dependent structural assemblies determines the finely tuned cellular behavior required for nervous system development.
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Affiliation(s)
- Elena Seiradake
- Department of Biochemistry, Oxford University, Oxford OX1 3QU, United Kingdom;
| | - E Yvonne Jones
- Wellcome Trust Centre for Human Genetics, Oxford University, Oxford OX3 7BN, United Kingdom;
| | - Rüdiger Klein
- Max Planck Institute of Neurobiology, 82152 Munich-Martinsried, Germany;
- Munich Cluster for Systems Neurology (SyNergy), 81377 Munich, Germany
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23
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Averaimo S, Assali A, Ros O, Couvet S, Zagar Y, Genescu I, Rebsam A, Nicol X. A plasma membrane microdomain compartmentalizes ephrin-generated cAMP signals to prune developing retinal axon arbors. Nat Commun 2016; 7:12896. [PMID: 27694812 PMCID: PMC5059439 DOI: 10.1038/ncomms12896] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 08/11/2016] [Indexed: 01/11/2023] Open
Abstract
The development of neuronal circuits is controlled by guidance molecules that are hypothesized to interact with the cholesterol-enriched domains of the plasma membrane termed lipid rafts. Whether such domains enable local intracellular signalling at the submicrometre scale in developing neurons and are required for shaping the nervous system connectivity in vivo remains controversial. Here, we report a role for lipid rafts in generating domains of local cAMP signalling in axonal growth cones downstream of ephrin-A repulsive guidance cues. Ephrin-A-dependent retraction of retinal ganglion cell axons involves cAMP signalling restricted to the vicinity of lipid rafts and is independent of cAMP modulation outside of this microdomain. cAMP modulation near lipid rafts controls the pruning of ectopic axonal branches of retinal ganglion cells in vivo, a process requiring intact ephrin-A signalling. Together, our findings indicate that lipid rafts structure the subcellular organization of intracellular cAMP signalling shaping axonal arbors during the nervous system development.
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Affiliation(s)
- Stefania Averaimo
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
| | - Ahlem Assali
- Sorbonne Universités, UPMC University Paris 06, UMR_S 839, Paris F-75005, France.,INSERM UMR_S 839, Paris F-75005, France.,Institut du Fer à Moulin, Paris F-75005, France
| | - Oriol Ros
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
| | - Sandrine Couvet
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
| | - Yvrick Zagar
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
| | - Ioana Genescu
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
| | - Alexandra Rebsam
- Sorbonne Universités, UPMC University Paris 06, UMR_S 839, Paris F-75005, France.,INSERM UMR_S 839, Paris F-75005, France.,Institut du Fer à Moulin, Paris F-75005, France
| | - Xavier Nicol
- Sorbonne Universités, UPMC University Paris 06, UMR_S 968, Institut de la Vision, Paris F-75012, France.,CNRS, UMR_7210, Paris F-75012, France.,INSERM, UMR_S 968, Paris F-75012, France
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24
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Ng DP, Deber CM. Modulating Transmembrane α-Helix Interactions through pH-Sensitive Boundary Residues. Biochemistry 2016; 55:4306-15. [DOI: 10.1021/acs.biochem.6b00380] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Derek P. Ng
- Department
of Biology, University of Toronto Mississauga, Mississauga, Ontario, Canada L5L 1C6
- Institute
of Medical Science, University of Toronto, Toronto, Ontario, Canada M5S 1A8
| | - Charles M. Deber
- Division of Molecular Structure & Function, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada M5G 1X8
- Department
of Biochemistry, University of Toronto, Toronto, Ontario, Canada M5S 1A8
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25
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Trenker R, Call MJ, Call ME. Progress and prospects for structural studies of transmembrane interactions in single-spanning receptors. Curr Opin Struct Biol 2016; 39:115-123. [DOI: 10.1016/j.sbi.2016.07.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 06/20/2016] [Accepted: 07/01/2016] [Indexed: 11/28/2022]
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26
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Bugge K, Lindorff-Larsen K, Kragelund BB. Understanding single-pass transmembrane receptor signaling from a structural viewpoint-what are we missing? FEBS J 2016; 283:4424-4451. [PMID: 27350538 DOI: 10.1111/febs.13793] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Revised: 06/10/2016] [Accepted: 06/27/2016] [Indexed: 11/30/2022]
Abstract
Single-pass transmembrane receptors are involved in essential processes of both physiological and pathological nature and represent more than 1300 proteins in the human genome. Despite the high biological relevance of these receptors, the mechanisms of the signal transductions they facilitate are incompletely understood. One major obstacle is the lack of structures of the transmembrane domains that connect the extracellular ligand-binding domains to the intracellular signaling platforms. Over a period of almost 20 years since the first structure was reported, only 21 of these receptors have become represented by a transmembrane domain structure. This scarceness stands in strong contrast to the significance of these transmembrane α-helices for receptor functionality. In this review, we explore the properties and qualities of the current set of structures, as well as the methodological difficulties associated with their characterization and the challenges left to be overcome. Without an increased and focused effort to bring this class of proteins on par with the remaining membrane protein field, a serious lag in their biological understanding looms. Design of pharmaceutical agents, prediction of mutational affects in relation to disease, and deciphering of functional mechanisms require high-resolution structural information, especially when dealing with a domain carrying so much functionality in so few residues.
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Affiliation(s)
- Katrine Bugge
- Department of Biology, Structural Biology and NMR Laboratory, University of Copenhagen, Denmark
| | - Kresten Lindorff-Larsen
- Department of Biology, Structural Biology and NMR Laboratory, University of Copenhagen, Denmark
| | - Birthe B Kragelund
- Department of Biology, Structural Biology and NMR Laboratory, University of Copenhagen, Denmark
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27
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Ried CL, Scharnagl C, Langosch D. Entrapment of Water at the Transmembrane Helix–Helix Interface of Quiescin Sulfhydryl Oxidase 2. Biochemistry 2016; 55:1287-90. [DOI: 10.1021/acs.biochem.5b01239] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Christian L. Ried
- Lehrstuhl
Chemie der Biopolymere, Technische Universität München, Weihenstephaner
Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPSM), Germany
| | - Christina Scharnagl
- Fakultät
für Physik E14, Technische Universität München, Maximus-von-Imhof-Forum
4, 85354 Freising, Germany
| | - Dieter Langosch
- Lehrstuhl
Chemie der Biopolymere, Technische Universität München, Weihenstephaner
Berg 3, 85354 Freising, and Munich Center For Integrated Protein Science (CIPSM), Germany
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28
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Chavent M, Seiradake E, Jones EY, Sansom MSP. Structures of the EphA2 Receptor at the Membrane: Role of Lipid Interactions. Structure 2016; 24:337-47. [PMID: 26724997 PMCID: PMC4744086 DOI: 10.1016/j.str.2015.11.008] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2015] [Revised: 10/19/2015] [Accepted: 11/13/2015] [Indexed: 11/29/2022]
Abstract
Ephs are transmembrane receptors that mediate cell-cell signaling. The N-terminal ectodomain binds ligands and enables receptor clustering, which activates the intracellular kinase. Relatively little is known about the function of the membrane-proximal fibronectin domain 2 (FN2) of the ectodomain. Multiscale molecular dynamics simulations reveal that FN2 interacts with lipid bilayers via a site comprising K441, R443, R465, Q462, S464, S491, W467, F490, and P459-461. FN2 preferentially binds anionic lipids, a preference that is reduced in the mutant K441E + R443E. We confirm these results by measuring the binding of wild-type and mutant FN2 domains to lipid vesicles. In simulations of the complete EphA2 ectodomain plus the transmembrane region, we show that FN2 anchors the otherwise flexible ectodomain at the surface of the bilayer. Altogether, our data suggest that FN2 serves a dual function of interacting with anionic lipids and constraining the structure of the EphA2 ectodomain to adopt membrane-proximal configurations.
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Affiliation(s)
- Matthieu Chavent
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK
| | - Elena Seiradake
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK; Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - E Yvonne Jones
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK.
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29
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Bragin PE, Mineev KS, Bocharova OV, Volynsky PE, Bocharov EV, Arseniev AS. HER2 Transmembrane Domain Dimerization Coupled with Self-Association of Membrane-Embedded Cytoplasmic Juxtamembrane Regions. J Mol Biol 2015; 428:52-61. [PMID: 26585403 DOI: 10.1016/j.jmb.2015.11.007] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2015] [Revised: 10/23/2015] [Accepted: 11/10/2015] [Indexed: 01/05/2023]
Abstract
Receptor tyrosine kinases of the human epidermal growth factor receptor (HER or ErbB) family transduce biochemical signals across plasma membrane, playing a significant role in vital cellular processes and in various cancers. Inactive HER/ErbB receptors exist in equilibrium between the monomeric and unspecified pre-dimerized states. After ligand binding, the receptors are involved in strong lateral dimerization with proper assembly of their extracellular ligand-binding, single-span transmembrane, and cytoplasmic kinase domains. The dimeric conformation of the HER2 transmembrane domain that is believed to support the cytoplasmic kinase domain configuration corresponding to the receptor active state was previously described in lipid bicelles. Here we used high-resolution NMR spectroscopy in another membrane-mimicking micellar environment and identified an alternative HER2 transmembrane domain dimerization coupled with self-association of membrane-embedded cytoplasmic juxtamembrane region. Such a dimerization mode appears to be capable of effectively inhibiting the receptor kinase activity. This finding refines the molecular mechanism regarding the signal propagation steps from the extracellular to cytoplasmic domains of HER/ErbB receptors.
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Affiliation(s)
- Pavel E Bragin
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation; Lomonosov Moscow State University, Leninskie Gory, 1, Moscow 119991, Russian Federation
| | - Konstantin S Mineev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation
| | - Olga V Bocharova
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation
| | - Pavel E Volynsky
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation
| | - Eduard V Bocharov
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation.
| | - Alexander S Arseniev
- Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 16/10 Miklukho-Maklaya Street, Moscow 117997, Russian Federation; Moscow Institute of Physics and Technology, Institutsky Per., 9, Dolgoprudnyi 141700, Russian Federation
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30
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Abstract
Transmembrane (TM) helices of integral membrane proteins can facilitate strong and specific noncovalent protein-protein interactions. Mutagenesis and structural analyses have revealed numerous examples in which the interaction between TM helices of single-pass membrane proteins is dependent on a GxxxG or (small)xxx(small) motif. It is therefore tempting to use the presence of these simple motifs as an indicator of TM helix interactions. In this Current Topic review, we point out that these motifs are quite common, with more than 50% of single-pass TM domains containing a (small)xxx(small) motif. However, the actual interaction strength of motif-containing helices depends strongly on sequence context and membrane properties. In addition, recent studies have revealed several GxxxG-containing TM domains that interact via alternative interfaces involving hydrophobic, polar, aromatic, or even ionizable residues that do not form recognizable motifs. In multipass membrane proteins, GxxxG motifs can be important for protein folding, and not just oligomerization. Our current knowledge thus suggests that the presence of a GxxxG motif alone is a weak predictor of protein dimerization in the membrane.
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Affiliation(s)
- Mark G Teese
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München , 85354 Freising, Germany.,Center for Integrated Protein Science Munich (CIPSM) , 81377 Munich, Germany
| | - Dieter Langosch
- Lehrstuhl für Chemie der Biopolymere, Technische Universität München , 85354 Freising, Germany.,Center for Integrated Protein Science Munich (CIPSM) , 81377 Munich, Germany
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31
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Maruyama IN. Activation of transmembrane cell-surface receptors via a common mechanism? The "rotation model". Bioessays 2015; 37:959-67. [PMID: 26241732 PMCID: PMC5054922 DOI: 10.1002/bies.201500041] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
It has long been thought that transmembrane cell-surface receptors, such as receptor tyrosine kinases and cytokine receptors, among others, are activated by ligand binding through ligand-induced dimerization of the receptors. However, there is growing evidence that prior to ligand binding, various transmembrane receptors have a preformed, yet inactive, dimeric structure on the cell surface. Various studies also demonstrate that during transmembrane signaling, ligand binding to the extracellular domain of receptor dimers induces a rotation of transmembrane domains, followed by rearrangement and/or activation of intracellular domains. The paper here describes transmembrane cell-surface receptors that are known or proposed to exist in dimeric form prior to ligand binding, and discusses how these preformed dimers are activated by ligand binding.
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Affiliation(s)
- Ichiro N Maruyama
- Okinawa Institute of Science and Technology Graduate University, Onna, Okinawa, Japan
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32
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Sun F, Xu L, Chen P, Wei P, Qu J, Chen J, Luo SZ. Insights into the Packing Switching of the EphA2 Transmembrane Domain by Molecular Dynamic Simulations. J Phys Chem B 2015; 119:7816-24. [PMID: 26022644 DOI: 10.1021/acs.jpcb.5b01116] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Receptor tyrosine kinases play an important role in mediating cell migration and adhesion associated with various biology processes. With a single-span transmembrane domain (TMD), the activities of the receptors are regulated by the definite packing configurations of the TMDs. For the EphA2 receptor, increasing studies have been conducted to investigate the packing domains that induce its switching TMD dimerization. However, the inherent transformation mechanisms including the interrelations among the involved packing domains remain unclear. Herein, we applied multiple simulation methods to explore the underlying packing mechanisms within the EphA2 TMD dimer. Our results demonstrated that the G(540)xxxG(544) contributed to the formation of the right-handed configuration while the heptad repeat L(535)xxxG(539)xxA(542)xxxV(546)xxL(549)xxxG(553) motif together with the FFxH(559) region mediated the parallel mode. Furthermore, the FF(557) residues packing mutually as rigid riveting structures were found comparable to the heptad repeat motif in maintaining the parallel configuration. In addition, the H(559) residue associated definitely with the lower bilayer leaflet, which was proved to stabilize the parallel mode significantly. The simulations provide a full range of insights into the essential packing motifs or residues involved in the switching TMD dimer configurations, which can enrich our comprehension toward the EphA2 receptor.
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Affiliation(s)
- Fude Sun
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Lida Xu
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Peng Chen
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Peng Wei
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jing Qu
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Jialin Chen
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
| | - Shi-Zhong Luo
- Beijing Key Laboratory of Bioprocess, College of Life Science and Technology, Beijing University of Chemical Technology, Beijing 100029, China
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33
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Wang Y, Barth P. Evolutionary-guided de novo structure prediction of self-associated transmembrane helical proteins with near-atomic accuracy. Nat Commun 2015; 6:7196. [PMID: 25995083 DOI: 10.1038/ncomms8196] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2014] [Accepted: 04/15/2015] [Indexed: 11/09/2022] Open
Abstract
How specific protein associations regulate the function of membrane receptors remains poorly understood. Conformational flexibility currently hinders the structure determination of several classes of membrane receptors and associated oligomers. Here we develop EFDOCK-TM, a general method to predict self-associated transmembrane protein helical (TMH) structures from sequence guided by co-evolutionary information. We show that accurate intermolecular contacts can be identified using a combination of protein sequence covariation and TMH binding surfaces predicted from sequence. When applied to diverse TMH oligomers, including receptors characterized in multiple conformational and functional states, the method reaches unprecedented near-atomic accuracy for most targets. Blind predictions of structurally uncharacterized receptor tyrosine kinase TMH oligomers provide a plausible hypothesis on the molecular mechanisms of disease-associated point mutations and binding surfaces for the rational design of selective inhibitors. The method sets the stage for uncovering novel determinants of molecular recognition and signalling in single-spanning eukaryotic membrane receptors.
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Affiliation(s)
- Y Wang
- Structural and Computational Biology and Molecular Biophysics Graduate Program, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
| | - P Barth
- 1] Structural and Computational Biology and Molecular Biophysics Graduate Program, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA [2] Verna and Marrs McLean Department of Biochemistry and Molecular Biology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA [3] Department of Pharmacology, Baylor College of Medicine, One Baylor Plaza, Houston, Texas 77030, USA
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34
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Kucharska I, Edrington TC, Liang B, Tamm LK. Optimizing nanodiscs and bicelles for solution NMR studies of two β-barrel membrane proteins. JOURNAL OF BIOMOLECULAR NMR 2015; 61:261-74. [PMID: 25869397 PMCID: PMC4397663 DOI: 10.1007/s10858-015-9905-z] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Accepted: 01/21/2015] [Indexed: 05/22/2023]
Abstract
Solution NMR spectroscopy has become a robust method to determine structures and explore the dynamics of integral membrane proteins. The vast majority of previous studies on membrane proteins by solution NMR have been conducted in lipid micelles. Contrary to the lipids that form a lipid bilayer in biological membranes, micellar lipids typically contain only a single hydrocarbon chain or two chains that are too short to form a bilayer. Therefore, there is a need to explore alternative more bilayer-like media to mimic the natural environment of membrane proteins. Lipid bicelles and lipid nanodiscs have emerged as two alternative membrane mimetics that are compatible with solution NMR spectroscopy. Here, we have conducted a comprehensive comparison of the physical and spectroscopic behavior of two outer membrane proteins from Pseudomonas aeruginosa, OprG and OprH, in lipid micelles, bicelles, and nanodiscs of five different sizes. Bicelles stabilized with a fraction of negatively charged lipids yielded spectra of almost comparable quality as in the best micellar solutions and the secondary structures were found to be almost indistinguishable in the two environments. Of the five nanodiscs tested, nanodiscs assembled from MSP1D1ΔH5 performed the best with both proteins in terms of sample stability and spectral resolution. Even in these optimal nanodiscs some broad signals from the membrane embedded barrel were severely overlapped with sharp signals from the flexible loops making their assignments difficult. A mutant OprH that had two of the flexible loops truncated yielded very promising spectra for further structural and dynamical analysis in MSP1D1ΔH5 nanodiscs.
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35
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Chavent M, Chetwynd AP, Stansfeld PJ, Sansom MSP. Dimerization of the EphA1 receptor tyrosine kinase transmembrane domain: Insights into the mechanism of receptor activation. Biochemistry 2014; 53:6641-52. [PMID: 25286141 PMCID: PMC4298228 DOI: 10.1021/bi500800x] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
![]()
EphA1
is a receptor tyrosine kinase (RTK) that plays a key role
in developmental processes, including guidance of the migration of
axons and cells in the nervous system. EphA1, in common with other
RTKs, contains an N-terminal extracellular domain, a single transmembrane
(TM) α-helix, and a C-terminal intracellular kinase domain.
The TM helix forms a dimer, as seen in recent NMR studies. We have
modeled the EphA1 TM dimer using a multiscale approach combining coarse-grain
(CG) and atomistic molecular dynamics (MD) simulations. The one-dimensional
potential of mean force (PMF) for this system, based on interhelix
separation, has been calculated using CG MD simulations. This provides
a view of the free energy landscape for helix–helix interactions
of the TM dimer in a lipid bilayer. The resulting PMF profiles suggest
two states, consistent with a rotation-coupled activation mechanism.
The more stable state corresponds to a right-handed helix dimer interacting
via an N-terminal glycine zipper motif, consistent with a recent NMR
structure (2K1K). A second metastable state corresponds to a structure in which
the glycine zipper motif is not involved. Analysis of unrestrained
CG MD simulations based on representative models from the PMF calculations
or on the NMR structure reveals possible pathways of interconversion
between these two states, involving helix rotations about their long
axes. This suggests that the interaction of TM helices in EphA1 dimers
may be intrinsically dynamic. This provides a potential mechanism
for signaling whereby extracellular events drive a shift in the repopulation
of the underlying TM helix dimer energy landscape.
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Affiliation(s)
- Matthieu Chavent
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, United Kingdom
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36
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Flinner N, Mirus O, Schleiff E. The influence of fatty acids on the GpA dimer interface by coarse-grained molecular dynamics simulation. Int J Mol Sci 2014; 15:14247-68. [PMID: 25196522 PMCID: PMC4159849 DOI: 10.3390/ijms150814247] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2014] [Revised: 07/14/2014] [Accepted: 08/06/2014] [Indexed: 11/17/2022] Open
Abstract
The hydrophobic thickness of membranes, which is manly defined by fatty acids, influences the packing of transmembrane domains of proteins and thus can modulate the activity of these proteins. We analyzed the dynamics of the dimerization of Glycophorin A (GpA) by molecular dynamics simulations to describe the fatty acid dependence of the transmembrane region assembly. GpA represents a well-established model for dimerization of single transmembrane helices containing a GxxxG motif in vitro and in silico. We performed simulations of the dynamics of the NMR-derived dimer as well as self-assembly simulations of monomers in membranes composed of different fatty acid chains and monitored the formed interfaces and their transitions. The observed dimeric interfaces, which also include the one known from NMR, are highly dynamic and converted into each other. The frequency of interface formation and the preferred transitions between interfaces similar to the interface observed by NMR analysis strongly depend on the fatty acid used to build the membrane. Molecular dynamic simulations after adaptation of the helix topology parameters to better represent NMR derived structures of single transmembrane helices yielded an enhanced occurrence of the interface determined by NMR in molecular dynamics simulations. Taken together we give insights into the influence of fatty acids and helix conformation on the dynamics of the transmembrane domain of GpA.
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Affiliation(s)
- Nadine Flinner
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
| | - Oliver Mirus
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
| | - Enrico Schleiff
- Cluster of Excellence Macromolecular Complexes, Center of Membrane Proteomics, Department of Biosciences, Molecular Cell Biology of Plants, GU Frankfurt am Main, 60439 Frankfurt, Germany.
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37
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Beaugrand M, Arnold A, Hénin J, Warschawski DE, Williamson PTF, Marcotte I. Lipid concentration and molar ratio boundaries for the use of isotropic bicelles. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:6162-70. [PMID: 24797658 PMCID: PMC4072726 DOI: 10.1021/la5004353] [Citation(s) in RCA: 47] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/03/2014] [Revised: 05/02/2014] [Indexed: 05/27/2023]
Abstract
Bicelles are model membranes generally made of long-chain dimyristoylphosphatidylcholine (DMPC) and short-chain dihexanoyl-PC (DHPC). They are extensively used in the study of membrane interactions and structure determination of membrane-associated peptides, since their composition and morphology mimic the widespread PC-rich natural eukaryotic membranes. At low DMPC/DHPC (q) molar ratios, fast-tumbling bicelles are formed in which the DMPC bilayer is stabilized by DHPC molecules in the high-curvature rim region. Experimental constraints imposed by techniques such as circular dichroism, dynamic light scattering, or microscopy may require the use of bicelles at high dilutions. Studies have shown that such conditions induce the formation of small aggregates and alter the lipid-to-detergent ratio of the bicelle assemblies. The objectives of this work were to determine the exact composition of those DMPC/DHPC isotropic bicelles and study the lipid miscibility. This was done using (31)P nuclear magnetic resonance (NMR) and exploring a wide range of lipid concentrations (2-400 mM) and q ratios (0.15-2). Our data demonstrate how dilution modifies the actual DMPC/DHPC molar ratio in the bicelles. Care must be taken for samples with a total lipid concentration ≤250 mM and especially at q ∼ 1.5-2, since moderate dilutions could lead to the formation of large and slow-tumbling lipid structures that could hinder the use of solution NMR methods, circular dichroism or dynamic light scattering studies. Our results, supported by infrared spectroscopy and molecular dynamics simulations, also show that phospholipids in bicelles are largely segregated only when q > 1. Boundaries are presented within which control of the bicelles' q ratio is possible. This work, thus, intends to guide the choice of q ratio and total phospholipid concentration when using isotropic bicelles.
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Affiliation(s)
- Maïwenn Beaugrand
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
| | - Alexandre
A. Arnold
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
| | - Jérôme Hénin
- Laboratoire
de Biochimie Théorique, CNRS, Université
Paris Diderot and Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie-Curie, 75005 Paris, France
| | - Dror E. Warschawski
- Laboratoire
de Biologie Physico-Chimique des Protéines Membranaires, CNRS, Université Paris Diderot and Institut de Biologie Physico-Chimique, 13 rue Pierre et Marie-Curie, 75005 Paris, France
| | - Philip T. F. Williamson
- School
of Biological Sciences, Highfield Campus,
University of Southampton, Southampton, SO17 1BJ, United Kingdom
| | - Isabelle Marcotte
- Department
of Chemistry, Université du Québec
à Montréal and Centre Québécois sur les
Matériaux Fonctionnels, P.O. Box 8888, Downtown Station, Montreal, Canada H3C 3P8
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38
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Sharonov GV, Bocharov EV, Kolosov PM, Astapova MV, Arseniev AS, Feofanov AV. Point mutations in dimerization motifs of the transmembrane domain stabilize active or inactive state of the EphA2 receptor tyrosine kinase. J Biol Chem 2014; 289:14955-64. [PMID: 24733396 DOI: 10.1074/jbc.m114.558783] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023] Open
Abstract
The EphA2 receptor tyrosine kinase plays a central role in the regulation of cell adhesion and guidance in many human tissues. The activation of EphA2 occurs after proper dimerization/oligomerization in the plasma membrane, which occurs with the participation of extracellular and cytoplasmic domains. Our study revealed that the isolated transmembrane domain (TMD) of EphA2 embedded into the lipid bicelle dimerized via the heptad repeat motif L(535)X3G(539)X2A(542)X3V(546)X2L(549) rather than through the alternative glycine zipper motif A(536)X3G(540)X3G(544) (typical for TMD dimerization in many proteins). To evaluate the significance of TMD interactions for full-length EphA2, we substituted key residues in the heptad repeat motif (HR variant: G539I, A542I, G553I) or in the glycine zipper motif (GZ variant: G540I, G544I) and expressed YFP-tagged EphA2 (WT, HR, and GZ variants) in HEK293T cells. Confocal microscopy revealed a similar distribution of all EphA2-YFP variants in cells. The expression of EphA2-YFP variants and their kinase activity (phosphorylation of Tyr(588) and/or Tyr(594)) and ephrin-A3 binding were analyzed with flow cytometry on a single cell basis. Activation of any EphA2 variant is found to occur even without ephrin stimulation when the EphA2 content in cells is sufficiently high. Ephrin-A3 binding is not affected in mutant variants. Mutations in the TMD have a significant effect on EphA2 activity. Both ligand-dependent and ligand-independent activities are enhanced for the HR variant and reduced for the GZ variant compared with the WT. These findings allow us to suggest TMD dimerization switching between the heptad repeat and glycine zipper motifs, corresponding to inactive and active receptor states, respectively, as a mechanism underlying EphA2 signal transduction.
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Affiliation(s)
- George V Sharonov
- From the Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of RAS, 117997 Moscow, Russia, the Faculty of Medicine, Moscow State University, 119992 Moscow, Russia
| | - Eduard V Bocharov
- From the Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of RAS, 117997 Moscow, Russia
| | - Peter M Kolosov
- the Department of Molecular Neurobiology, Institute of Higher Nervous Activity and Neurophysiology of RAS, 117485 Moscow, Russia, and
| | - Maria V Astapova
- From the Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of RAS, 117997 Moscow, Russia
| | - Alexander S Arseniev
- From the Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of RAS, 117997 Moscow, Russia
| | - Alexey V Feofanov
- From the Department of Structural Biology, Shemyakin-Ovchinnikov Institute of Bioorganic Chemistry of RAS, 117997 Moscow, Russia, the Biological Faculty, Moscow State University, 119992 Moscow, Russia
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39
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Overman RC, Debreczeni JE, Truman CM, McAlister MS, Attwood TK. Completing the structural family portrait of the human EphB tyrosine kinase domains. Protein Sci 2014; 23:627-38. [PMID: 24677421 DOI: 10.1002/pro.2445] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2013] [Revised: 02/12/2014] [Accepted: 02/12/2014] [Indexed: 11/09/2022]
Abstract
The EphB receptors have key roles in cell morphology, adhesion, migration and invasion, and their aberrant action has been linked with the development and progression of many different tumor types. Their conflicting expression patterns in cancer tissues, combined with their high sequence and structural identity, present interesting challenges to those seeking to develop selective therapeutic molecules targeting this large receptor family. Here, we present the first structure of the EphB1 tyrosine kinase domain determined by X-ray crystallography to 2.5Å. Our comparative crystalisation analysis of the human EphB family kinases has also yielded new crystal forms of the human EphB2 and EphB4 catalytic domains. Unable to crystallize the wild-type EphB3 kinase domain, we used rational engineering (based on our new structures of EphB1, EphB2, and EphB4) to identify a single point mutation which facilitated its crystallization and structure determination to 2.2 Å. This mutation also improved the soluble recombinant yield of this kinase within Escherichia coli, and increased both its intrinsic stability and catalytic turnover, without affecting its ligand-binding profile. The partial ordering of the activation loop in the EphB3 structure alludes to a potential cis-phosphorylation mechanism for the EphB kinases. With the kinase domain structures of all four catalytically competent human EphB receptors now determined, a picture begins to emerge of possible opportunities to produce EphB isozyme-selective kinase inhibitors for mechanistic studies and therapeutic applications.
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Affiliation(s)
- Ross C Overman
- AstraZeneca PLC, Alderley Park, Cheshire, SK10 4TG, United Kingdom
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40
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Barton WA, Dalton AC, Seegar TCM, Himanen JP, Nikolov DB. Tie2 and Eph receptor tyrosine kinase activation and signaling. Cold Spring Harb Perspect Biol 2014; 6:cshperspect.a009142. [PMID: 24478383 DOI: 10.1101/cshperspect.a009142] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
The Eph and Tie cell surface receptors mediate a variety of signaling events during development and in the adult organism. As other receptor tyrosine kinases, they are activated on binding of extracellular ligands and their catalytic activity is tightly regulated on multiple levels. The Eph and Tie receptors display some unique characteristics, including the requirement of ligand-induced receptor clustering for efficient signaling. Interestingly, both Ephs and Ties can mediate different, even opposite, biological effects depending on the specific ligand eliciting the response and on the cellular context. Here we discuss the structural features of these receptors, their interactions with various ligands, as well as functional implications for downstream signaling initiation. The Eph/ephrin structures are already well reviewed and we only provide a brief overview on the initial binding events. We go into more detail discussing the Tie-angiopoietin structures and recognition.
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Affiliation(s)
- William A Barton
- Department of Biochemistry and Molecular Biology, School of Medicine, Virginia Commonwealth University, Richmond, Virginia 23298
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41
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A frequent, GxxxG-mediated, transmembrane association motif is optimized for the formation of interhelical Cα-H hydrogen bonds. Proc Natl Acad Sci U S A 2014; 111:E888-95. [PMID: 24569864 DOI: 10.1073/pnas.1319944111] [Citation(s) in RCA: 80] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Carbon hydrogen bonds between Cα-H donors and carbonyl acceptors are frequently observed between transmembrane helices (Cα-H···O=C). Networks of these interactions occur often at helix-helix interfaces mediated by GxxxG and similar patterns. Cα-H hydrogen bonds have been hypothesized to be important in membrane protein folding and association, but evidence that they are major determinants of helix association is still lacking. Here we present a comprehensive geometric analysis of homodimeric helices that demonstrates the existence of a single region in conformational space with high propensity for Cα-H···O=C hydrogen bond formation. This region corresponds to the most frequent motif for parallel dimers, GASright, whose best-known example is glycophorin A. The finding suggests a causal link between the high frequency of occurrence of GASright and its propensity for carbon hydrogen bond formation. Investigation of the sequence dependency of the motif determined that Gly residues are required at specific positions where only Gly can act as a donor with its "side chain" Hα. Gly also reduces the steric barrier for non-Gly amino acids at other positions to act as Cα donors, promoting the formation of cooperative hydrogen bonding networks. These findings offer a structural rationale for the occurrence of GxxxG patterns at the GASright interface. The analysis identified the conformational space and the sequence requirement of Cα-H···O=C mediated motifs; we took advantage of these results to develop a structural prediction method. The resulting program, CATM, predicts ab initio the known high-resolution structures of homodimeric GASright motifs at near-atomic level.
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42
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Sarabipour S, Hristova K. FGFR3 transmembrane domain interactions persist in the presence of its extracellular domain. Biophys J 2014; 105:165-71. [PMID: 23823235 DOI: 10.1016/j.bpj.2013.05.053] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2013] [Revised: 05/17/2013] [Accepted: 05/31/2013] [Indexed: 01/30/2023] Open
Abstract
Isolated receptor tyrosine kinase transmembrane (TM) domains have been shown to form sequence-specific dimers in membranes. Yet, it is not clear whether studies of isolated TM domains yield knowledge that is relevant to full-length receptors or whether the large glycosylated extracellular domains alter the interactions between the TM helices. Here, we address this question by quantifying the effect of the pathogenic A391E TM domain mutation on the stability of the fibroblast growth factor receptor 3 dimer in the presence of the extracellular domain and comparing these results to the case of the isolated TM fibroblast growth factor receptor 3 domains. We perform the measurements in plasma membrane-derived vesicles using a Förster-resonance-energy-transfer-based method. The effect of the mutation on dimer stability in both cases is the same (∼-1.5 kcal/mol), suggesting that the interactions observed in simple TM-peptide model systems are relevant in a biological context.
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Affiliation(s)
- Sarvenaz Sarabipour
- Department of Materials Sciences and Engineering, Johns Hopkins University, Baltimore, Maryland, USA
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Reddy T, Manrique S, Buyan A, Hall BA, Chetwynd A, Sansom MSP. Primary and secondary dimer interfaces of the fibroblast growth factor receptor 3 transmembrane domain: characterization via multiscale molecular dynamics simulations. Biochemistry 2014; 53:323-32. [PMID: 24397339 PMCID: PMC4871223 DOI: 10.1021/bi401576k] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
Receptor tyrosine kinases are single-pass membrane proteins that form dimers within the membrane. The interactions of their transmembrane domains (TMDs) play a key role in dimerization and signaling. Fibroblast growth factor receptor 3 (FGFR3) is of interest as a G380R mutation in its TMD is the underlying cause of ~99% of the cases of achondroplasia, the most common form of human dwarfism. The structural consequences of this mutation remain uncertain: the mutation shifts the position of the TMD relative to the lipid bilayer but does not alter the association free energy. We have combined coarse-grained and all-atom molecular dynamics simulations to study the dimerization of wild-type, heterodimer, and mutant FGFR3 TMDs. The simulations reveal that the helices pack together in the dimer to form a flexible interface. The primary packing mode is mediated by a Gx3G motif. There is also a secondary dimer interface that is more highly populated in heterodimer and mutant configurations that may feature in the molecular mechanism of pathology. Both coarse-grained and atomistic simulations reveal a significant shift of the G380R mutant dimer TMD relative to the bilayer to allow interactions of the arginine side chain with lipid headgroup phosphates.
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Affiliation(s)
- Tyler Reddy
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, U.K
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Mineev KS, Lesovoy DM, Usmanova DR, Goncharuk SA, Shulepko MA, Lyukmanova EN, Kirpichnikov MP, Bocharov EV, Arseniev AS. NMR-based approach to measure the free energy of transmembrane helix–helix interactions. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2014; 1838:164-72. [DOI: 10.1016/j.bbamem.2013.08.021] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2013] [Revised: 08/27/2013] [Accepted: 08/30/2013] [Indexed: 11/30/2022]
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Maltsev S, Lorigan GA. Membrane proteins structure and dynamics by nuclear magnetic resonance. Compr Physiol 2013; 1:2175-87. [PMID: 23733702 DOI: 10.1002/cphy.c110022] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Abstract
Membrane proteins represent a challenging class of biological systems to study. They are extremely difficult to crystallize and in most cases they retain their structure and functions only in membrane environments. Therefore, commonly used diffraction methods fail to give detailed molecular structure and other approaches have to be utilized to obtain biologically relevant information. Nuclear magnetic resonance (NMR) spectroscopy, however, can provide powerful structural and dynamical constraints on these complicated systems. Solution- and solid-state NMR are powerful methods for investigating membrane proteins studies. In this work, we briefly review both solution and solid-state NMR techniques for membrane protein studies and illustrate the applications of these methods to elucidate proteins structure, conformation, topology, dynamics, and function. Recent advances in electronics, biological sample preparation, and spectral processing provided opportunities for complex biological systems, such as membrane proteins inside lipid vesicles, to be studied faster and with outstanding quality. New analysis methods therefore have emerged, that benefit from the combination of sample preparation and corresponding specific high-end NMR techniques, which give access to more structural and dynamic information.
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Affiliation(s)
- Sergey Maltsev
- Department of Chemistry and Biochemistry, Miami University, Oxford, Ohio, USA
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Li PC, Miyashita N, Im W, Ishido S, Sugita Y. Multidimensional umbrella sampling and replica-exchange molecular dynamics simulations for structure prediction of transmembrane helix dimers. J Comput Chem 2013; 35:300-8. [PMID: 24258786 DOI: 10.1002/jcc.23494] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2013] [Revised: 10/02/2013] [Accepted: 11/02/2013] [Indexed: 01/01/2023]
Abstract
Structural information of a transmembrane (TM) helix dimer is useful in understanding molecular mechanisms of important biological phenomena such as signal transduction across the cell membrane. Here, we describe an umbrella sampling (US) scheme for predicting the structure of a TM helix dimer in implicit membrane using the interhelical crossing angle and the TM-TM relative rotation angles as the reaction coordinates. This scheme conducts an efficient conformational search on TM-TM contact interfaces, and its robustness is tested by predicting the structures of glycophorin A (GpA) and receptor tyrosine kinase EphA1 (EphA1) TM dimers. The nuclear magnetic resonance (NMR) structures of both proteins correspond to the global free-energy minimum states in their free-energy landscapes. In addition, using the landscape of GpA as a reference, we also examine the protocols of temperature replica-exchange molecular dynamics (REMD) simulations for structure prediction of TM helix dimers in implicit membrane. A wide temperature range in REMD simulations, for example, 250-1000 K, is required to efficiently obtain a free-energy landscape consistent with the US simulations. The interhelical crossing angle and the TM-TM relative rotation angles can be used as reaction coordinates in multidimensional US and be good measures for conformational sampling of REMD simulations.
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Affiliation(s)
- Pai-Chi Li
- RIKEN Research Center for Allergy and Immunology (RCAI), 1-7-22 Suehiro-cho, Tsurumi-ku,Yokohama, Kanagawa, 230-0045, Japan; RIKEN Theoretical Molecular Science Laboratory, 2-1 Hirosawa, Wako, Saitama, 351-0198, Japan
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Claridge JK, Aittoniemi J, Cooper DM, Schnell JR. Isotropic bicelles stabilize the juxtamembrane region of the influenza M2 protein for solution NMR studies. Biochemistry 2013; 52:8420-9. [PMID: 24168642 DOI: 10.1021/bi401035m] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
The protein M2 from influenza is a tetrameric membrane protein with several roles in the viral life cycle. The transmembrane helix (TMH) of M2 has proton channel activity that is required for unpackaging the viral genome. Additionally a C-terminal juxtamembrane region includes an amphipathic helix (APH) important for virus budding and scission. The APH interacts with membranes and is required for M2 localization to the site of viral budding. As a step toward obtaining high resolution information on the structure and lipid interactions of the M2 APH, we sought to develop a fast tumbling bicelle system, which would make studies of M2 in a membrane-like environment by solution NMR possible. Since M2 is highly sensitive to the solubilizing environment, an M2 construct containing the APH was studied under micelle and bicelle conditions while maintaining the same detergent and lipid headgroup chemistry to facilitate interpretation of the spectroscopic results. The sequence from a human H1N1 "swine flu" isolate was used to design an M2 construct (swM2) similar in amino acid sequence to currently circulating viruses. Comparison of swM2 solubilized in either the diacyl detergent 1,2-dihexanoyl-sn-glycero-3-phosphocholine (DHPC) or a mixture of DHPC and the lipid 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) (q = 0.4) indicated that the largest changes were a decrease in helicity at the N-terminus of the TMH and a decrease in dynamics for the juxtamembrane linker residues connecting the TMH and the APH. Whereas the linker region is very dynamic and the amide protons are rapidly exchanged with water protons in micelles, the dynamics and water exchange are largely suppressed in the presence of lipid. Chemical shift changes and relaxation measurements were consistent with an overall stabilization of the linker region, with only modest changes in conformation or environment of the APH itself. Such changes are consistent with differences observed in structures of M2 in lipid bilayers and detergent micelles, indicating that the bicelle system provides a more membrane-like environment.
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Affiliation(s)
- Jolyon K Claridge
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford, OX1 3QU, United Kingdom
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Bocharova OV, Urban AS, Nadezhdin KD, Bocharov EV, Arseniev AS. Bacterial and cell-free production of APP671-726 containing amyloid precursor protein transmembrane and metal-binding domains. BIOCHEMISTRY (MOSCOW) 2013; 78:1263-71. [DOI: 10.1134/s0006297913110060] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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Rösner HI, Kragelund BB. Structure and dynamic properties of membrane proteins using NMR. Compr Physiol 2013; 2:1491-539. [PMID: 23798308 DOI: 10.1002/cphy.c110036] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
Integral membrane proteins are one of the most challenging groups of macromolecules despite their apparent conformational simplicity. They manage and drive transport, circulate information, and participate in cellular movements via interactions with other proteins and through intricate conformational changes. Their structural and functional decoding is challenging and has imposed demanding experimental development. Solution nuclear magnetic resonance (NMR) spectroscopy is one of the techniques providing the capacity to make a significant difference in the deciphering of the membrane protein structure-function paradigm. The method has evolved dramatically during the last decade resulting in a plethora of new experiments leading to a significant increase in the scientific repertoire for studying membrane proteins. Besides solving the three-dimensional structures using state-of-the-art approaches, a large variety of developments of well-established techniques are available providing insight into membrane protein flexibility, dynamics, and interactions. Inspired by the speed of development in the application of new strategies, by invention of methods to measure solvent accessibility and describe low-populated states, this review seeks to introduce the vast possibilities solution NMR can offer to the study of membrane protein structure-function analyses with special focus on applicability.
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Affiliation(s)
- Heike I Rösner
- Structural Biology and NMR Laboratory, Department of Biology, University of Copenhagen, Copenhagen, Denmark
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Jost C, Schilling J, Tamaskovic R, Schwill M, Honegger A, Plückthun A. Structural basis for eliciting a cytotoxic effect in HER2-overexpressing cancer cells via binding to the extracellular domain of HER2. Structure 2013; 21:1979-91. [PMID: 24095059 DOI: 10.1016/j.str.2013.08.020] [Citation(s) in RCA: 95] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2013] [Revised: 08/25/2013] [Accepted: 08/26/2013] [Indexed: 12/31/2022]
Abstract
Human epidermal growth factor receptor-2 (HER2) is a receptor tyrosine kinase directly linked to the growth of malignancies from various origins and a validated target for monoclonal antibodies and kinase inhibitors. Utilizing a new approach with designed ankyrin repeat proteins (DARPins) as alternative binders, we show that binding of two DARPins connected by a short linker, one targeting extracellular subdomain I and the other subdomain IV, causes much stronger cytotoxic effects on the HER2-addicted breast cancer cell line BT474, surpassing the therapeutic antibody trastuzumab. We determined crystal structures of these DARPins in complex with the respective subdomains. Detailed models of the full-length receptor, constrained by its rigid domain structures and its membrane anchoring, explain how the bispecific DARPins connect two membrane-bound HER2 molecules, distorting them such that they cannot form signaling-competent dimers with any EGFR family member, preventing any kinase dimerization, and thus leading to a complete loss of signaling.
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Affiliation(s)
- Christian Jost
- Department of Biochemistry, University of Zürich, 8057 Zürich, Switzerland
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