1
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Ansell TB, Song W, Coupland CE, Carrique L, Corey RA, Duncan AL, Cassidy CK, Geurts MMG, Rasmussen T, Ward AB, Siebold C, Stansfeld PJ, Sansom MSP. LipIDens: simulation assisted interpretation of lipid densities in cryo-EM structures of membrane proteins. Nat Commun 2023; 14:7774. [PMID: 38012131 PMCID: PMC10682427 DOI: 10.1038/s41467-023-43392-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2022] [Accepted: 11/07/2023] [Indexed: 11/29/2023] Open
Abstract
Cryo-electron microscopy (cryo-EM) enables the determination of membrane protein structures in native-like environments. Characterising how membrane proteins interact with the surrounding membrane lipid environment is assisted by resolution of lipid-like densities visible in cryo-EM maps. Nevertheless, establishing the molecular identity of putative lipid and/or detergent densities remains challenging. Here we present LipIDens, a pipeline for molecular dynamics (MD) simulation-assisted interpretation of lipid and lipid-like densities in cryo-EM structures. The pipeline integrates the implementation and analysis of multi-scale MD simulations for identification, ranking and refinement of lipid binding poses which superpose onto cryo-EM map densities. Thus, LipIDens enables direct integration of experimental and computational structural approaches to facilitate the interpretation of lipid-like cryo-EM densities and to reveal the molecular identities of protein-lipid interactions within a bilayer environment. We demonstrate this by application of our open-source LipIDens code to ten diverse membrane protein structures which exhibit lipid-like densities.
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Affiliation(s)
- T Bertie Ansell
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Wanling Song
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- MSD R&D Innovation Centre, 120 Moorgate, London, EC2M 6UR, UK
| | - Claire E Coupland
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
- Molecular Medicine Program, The Hospital for Sick Children, Toronto, ON, M5G 0A4, Canada
| | - Loic Carrique
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Robin A Corey
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- School of Physiology, Pharmacology and Neuroscience, University of Bristol, Bristol, BS8 1TD, UK
| | - Anna L Duncan
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- Department of Chemistry, Aarhus University, Lagelsandsgade 140, 8000, Aarhus C, Denmark
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, MO, 65211, USA
| | - Maxwell M G Geurts
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Tim Rasmussen
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, Haus D15, Josef-Schneider-Str. 2, 97080, Würzburg, Germany
| | - Andrew B Ward
- Department of Integrative Structural and Computational Biology, The Scripps Research Institute, La Jolla, CA, 92037, USA
| | - Christian Siebold
- Division of Structural Biology, Wellcome Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford, OX3 7BN, UK
| | - Phillip J Stansfeld
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK.
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2
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Cassidy CK, Qin Z, Frosio T, Gosink K, Yang Z, Sansom MSP, Stansfeld PJ, Parkinson JS, Zhang P. Structure of the native chemotaxis core signaling unit from phage E-protein lysed E. coli cells. mBio 2023; 14:e0079323. [PMID: 37772839 PMCID: PMC10653900 DOI: 10.1128/mbio.00793-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2023] [Accepted: 08/09/2023] [Indexed: 09/30/2023] Open
Abstract
IMPORTANCE Bacterial chemotaxis is a ubiquitous behavior that enables cell movement toward or away from specific chemicals. It serves as an important model for understanding cell sensory signal transduction and motility. Characterization of the molecular mechanisms underlying chemotaxis is of fundamental interest and requires a high-resolution structural picture of the sensing machinery, the chemosensory array. In this study, we combine cryo-electron tomography and molecular simulation to present the complete structure of the core signaling unit, the basic building block of chemosensory arrays, from Escherichia coli. Our results provide new insight into previously poorly-resolved regions of the complex and offer a structural basis for designing new experiments to test mechanistic hypotheses.
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Affiliation(s)
- C. Keith Cassidy
- Diamond Light Source, Didcot, United Kingdom
- Department of Physics and Astronomy, University of Missouri-Columbia, Columbia, Missouri, USA
| | - Zhuan Qin
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
| | | | - Khoosheh Gosink
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Mark S. P. Sansom
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
| | | | - John S. Parkinson
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Peijun Zhang
- Diamond Light Source, Didcot, United Kingdom
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, United Kingdom
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, United Kingdom
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3
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Dietz L, Ellison CJ, Riechmann C, Cassidy CK, Felfoldi FD, Pinto-Fernández A, Kessler BM, Elliott PR. Structural basis for SMAC-mediated antagonism of caspase inhibition by the giant ubiquitin ligase BIRC6. Science 2023; 379:1112-1117. [PMID: 36758106 DOI: 10.1126/science.ade8840] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Accepted: 01/31/2023] [Indexed: 02/11/2023]
Abstract
Certain inhibitor of apoptosis (IAP) family members are sentinel proteins that prevent untimely cell death by inhibiting caspases. Antagonists, including second mitochondria-derived activator of caspases (SMAC), regulate IAPs and drive cell death. Baculoviral IAP repeat-containing protein 6 (BIRC6), a giant IAP with dual E2 and E3 ubiquitin ligase activity, regulates programmed cell death through unknown mechanisms. We show that BIRC6 directly restricts executioner caspase-3 and -7 and ubiquitinates caspase-3, -7, and -9, working exclusively with noncanonical E1, UBA6. Notably, we show that SMAC suppresses both mechanisms. Cryo-electron microscopy structures of BIRC6 alone and in complex with SMAC reveal that BIRC6 is an antiparallel dimer juxtaposing the substrate-binding module against the catalytic domain. Furthermore, we discover that SMAC multisite binding to BIRC6 results in a subnanomolar affinity interaction, enabling SMAC to competitively displace caspases, thus antagonizing BIRC6 anticaspase function.
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Affiliation(s)
- Larissa Dietz
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Cara J Ellison
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Carlos Riechmann
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - F Daniel Felfoldi
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
| | - Adán Pinto-Fernández
- Target Discovery Institute, Centre for Medicines Discovery, University of Oxford, Oxford, OX3 7FZ, UK
- Chinese Academy for Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Benedikt M Kessler
- Target Discovery Institute, Centre for Medicines Discovery, University of Oxford, Oxford, OX3 7FZ, UK
- Chinese Academy for Medical Sciences Oxford Institute, Nuffield Department of Medicine, University of Oxford, Oxford, OX3 7FZ, UK
| | - Paul R Elliott
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
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4
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Hadjidemetriou K, Kaur S, Cassidy CK, Zhang P. Mechanisms of E. coli chemotaxis signaling pathways visualized using cryoET and computational approaches. Biochem Soc Trans 2022; 50:1595-1605. [PMID: 36421737 PMCID: PMC9788364 DOI: 10.1042/bst20220191] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 11/08/2022] [Accepted: 11/11/2022] [Indexed: 11/25/2022]
Abstract
Chemotaxis signaling pathways enable bacteria to sense and respond to their chemical environment and, in some species, are critical for lifestyle processes such as biofilm formation and pathogenesis. The signal transduction underlying chemotaxis behavior is mediated by large, highly ordered protein complexes known as chemosensory arrays. For nearly two decades, cryo-electron tomography (cryoET) has been used to image chemosensory arrays, providing an increasingly detailed understanding of their structure and function. In this mini-review, we provide an overview of the use of cryoET to study chemosensory arrays, including imaging strategies, key results, and outstanding questions. We further discuss the application of molecular modeling and simulation techniques to complement structure determination efforts and provide insight into signaling mechanisms. We close the review with a brief outlook, highlighting promising future directions for the field.
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Affiliation(s)
| | - Satinder Kaur
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - C. Keith Cassidy
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
| | - Peijun Zhang
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot OX11 0DE, U.K
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford OX3 7BN, U.K
- Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford OX3 7BN, U.K
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5
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Ouyang R, Costa AR, Cassidy CK, Otwinowska A, Williams VCJ, Latka A, Stansfeld PJ, Drulis-Kawa Z, Briers Y, Pelt DM, Brouns SJJ, Briegel A. High-resolution reconstruction of a Jumbo-bacteriophage infecting capsulated bacteria using hyperbranched tail fibers. Nat Commun 2022; 13:7241. [PMID: 36433970 PMCID: PMC9700779 DOI: 10.1038/s41467-022-34972-5] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2022] [Accepted: 11/14/2022] [Indexed: 11/26/2022] Open
Abstract
The Klebsiella jumbo myophage ϕKp24 displays an unusually complex arrangement of tail fibers interacting with a host cell. In this study, we combine cryo-electron microscopy methods, protein structure prediction methods, molecular simulations, microbiological and machine learning approaches to explore the capsid, tail, and tail fibers of ϕKp24. We determine the structure of the capsid and tail at 4.1 Å and 3.0 Å resolution. We observe the tail fibers are branched and rearranged dramatically upon cell surface attachment. This complex configuration involves fourteen putative tail fibers with depolymerase activity that provide ϕKp24 with the ability to infect a broad panel of capsular polysaccharide (CPS) types of Klebsiella pneumoniae. Our study provides structural and functional insight into how ϕKp24 adapts to the variable surfaces of capsulated bacterial pathogens, which is useful for the development of phage therapy approaches against pan-drug resistant K. pneumoniae strains.
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Affiliation(s)
- Ruochen Ouyang
- grid.43169.390000 0001 0599 1243MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter, School of Physics, Xi’an Jiaotong University, Xianning West Road 28, Xi’an, 710049 China ,grid.5132.50000 0001 2312 1970Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Ana Rita Costa
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands ,grid.5292.c0000 0001 2097 4740Kavli Institute of Nanoscience, Delft, The Netherlands
| | - C. Keith Cassidy
- grid.4991.50000 0004 1936 8948Department of Biochemistry, University of Oxford, Oxford, UK
| | - Aleksandra Otwinowska
- grid.8505.80000 0001 1010 5103Department of Pathogen Biology and Immunology, University of Wroclaw, Przybyszewskiego 63-77, 51-148 Wroclaw, Poland
| | - Vera C. J. Williams
- grid.5132.50000 0001 2312 1970Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
| | - Agnieszka Latka
- grid.8505.80000 0001 1010 5103Department of Pathogen Biology and Immunology, University of Wroclaw, Przybyszewskiego 63-77, 51-148 Wroclaw, Poland ,grid.5342.00000 0001 2069 7798Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium
| | - Phill J. Stansfeld
- grid.7372.10000 0000 8809 1613School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, CV4 7AL UK
| | - Zuzanna Drulis-Kawa
- grid.8505.80000 0001 1010 5103Department of Pathogen Biology and Immunology, University of Wroclaw, Przybyszewskiego 63-77, 51-148 Wroclaw, Poland
| | - Yves Briers
- grid.5342.00000 0001 2069 7798Department of Biotechnology, Ghent University, Valentin Vaerwyckweg 1, 9000 Ghent, Belgium
| | - Daniël M. Pelt
- grid.5132.50000 0001 2312 1970Leiden Institute of Advanced Computer Science, Leiden University, Niels Bohrweg 1, 2333CA Leiden, The Netherlands
| | - Stan J. J. Brouns
- grid.5292.c0000 0001 2097 4740Department of Bionanoscience, Delft University of Technology, Van der Maasweg 9, 2629 HZ Delft, The Netherlands ,grid.5292.c0000 0001 2097 4740Kavli Institute of Nanoscience, Delft, The Netherlands
| | - Ariane Briegel
- grid.5132.50000 0001 2312 1970Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333 BE Leiden, The Netherlands
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6
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Zhu Y, Koo CW, Cassidy CK, Spink MC, Ni T, Zanetti-Domingues LC, Bateman B, Martin-Fernandez ML, Shen J, Sheng Y, Song Y, Yang Z, Rosenzweig AC, Zhang P. Structure and activity of particulate methane monooxygenase arrays in methanotrophs. Nat Commun 2022; 13:5221. [PMID: 36064719 PMCID: PMC9445010 DOI: 10.1038/s41467-022-32752-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2022] [Accepted: 08/16/2022] [Indexed: 01/29/2023] Open
Abstract
Methane-oxidizing bacteria play a central role in greenhouse gas mitigation and have potential applications in biomanufacturing. Their primary metabolic enzyme, particulate methane monooxygenase (pMMO), is housed in copper-induced intracytoplasmic membranes (ICMs), of which the function and biogenesis are not known. We show by serial cryo-focused ion beam (cryoFIB) milling/scanning electron microscope (SEM) volume imaging and lamellae-based cellular cryo-electron tomography (cryoET) that these ICMs are derived from the inner cell membrane. The pMMO trimer, resolved by cryoET and subtomogram averaging to 4.8 Å in the ICM, forms higher-order hexagonal arrays in intact cells. Array formation correlates with increased enzymatic activity, highlighting the importance of studying the enzyme in its native environment. These findings also demonstrate the power of cryoET to structurally characterize native membrane enzymes in the cellular context.
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Affiliation(s)
- Yanan Zhu
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Christopher W. Koo
- grid.16753.360000 0001 2299 3507Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL USA
| | - C. Keith Cassidy
- grid.4991.50000 0004 1936 8948Department of Biochemistry, University of Oxford, Oxford, UK
| | - Matthew C. Spink
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Tao Ni
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Laura C. Zanetti-Domingues
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Benji Bateman
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Marisa L. Martin-Fernandez
- grid.76978.370000 0001 2296 6998Central Laser Facility, Science and Technology Facility Council, Rutherford Appleton Laboratory, Didcot, Oxfordshire UK
| | - Juan Shen
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Yuewen Sheng
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Yun Song
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK
| | - Zhengyi Yang
- grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK ,grid.4709.a0000 0004 0495 846XPresent Address: Imaging Centre, European Molecular Biology Laboratory, Heidelberg, Germany
| | - Amy C. Rosenzweig
- grid.16753.360000 0001 2299 3507Departments of Molecular Biosciences and of Chemistry, Northwestern University, Evanston, IL USA
| | - Peijun Zhang
- grid.4991.50000 0004 1936 8948Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK ,grid.18785.330000 0004 1764 0696Diamond Light Source, Harwell Science and Innovation Campus, Didcot, UK ,grid.4991.50000 0004 1936 8948Chinese Academy of Medical Sciences Oxford Institute, University of Oxford, Oxford, UK
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7
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Song W, Corey RA, Ansell TB, Cassidy CK, Horrell MR, Duncan AL, Stansfeld PJ, Sansom MSP. PyLipID: A Python Package for Analysis of Protein-Lipid Interactions from Molecular Dynamics Simulations. J Chem Theory Comput 2022; 18:1188-1201. [PMID: 35020380 PMCID: PMC8830038 DOI: 10.1021/acs.jctc.1c00708] [Citation(s) in RCA: 48] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2021] [Indexed: 12/11/2022]
Abstract
Lipids play important modulatory and structural roles for membrane proteins. Molecular dynamics simulations are frequently used to provide insights into the nature of these protein-lipid interactions. Systematic comparative analysis requires tools that provide algorithms for objective assessment of such interactions. We introduce PyLipID, a Python package for the identification and characterization of specific lipid interactions and binding sites on membrane proteins from molecular dynamics simulations. PyLipID uses a community analysis approach for binding site detection, calculating lipid residence times for both the individual protein residues and the detected binding sites. To assist structural analysis, PyLipID produces representative bound lipid poses from simulation data, using a density-based scoring function. To estimate residue contacts robustly, PyLipID uses a dual-cutoff scheme to differentiate between lipid conformational rearrangements while bound from full dissociation events. In addition to the characterization of protein-lipid interactions, PyLipID is applicable to analysis of the interactions of membrane proteins with other ligands. By combining automated analysis, efficient algorithms, and open-source distribution, PyLipID facilitates the systematic analysis of lipid interactions from large simulation data sets of multiple species of membrane proteins.
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Affiliation(s)
- Wanling Song
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
- Rahko,
Clifton House, 46 Clifton
Terrace, Finsbury Park, London N4 3JP, United Kingdom
| | - Robin A. Corey
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - T. Bertie Ansell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - C. Keith Cassidy
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Michael R. Horrell
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Anna L. Duncan
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
| | - Phillip J. Stansfeld
- School
of Life Sciences & Department of Chemistry, University of Warwick, Coventry CV4 7AL, United Kingdom
| | - Mark S. P. Sansom
- Department
of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, United Kingdom
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8
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Piñas GE, DeSantis MD, Cassidy CK, Parkinson JS. Hexameric rings of the scaffolding protein CheW enhance response sensitivity and cooperativity in Escherichia coli chemoreceptor arrays. Sci Signal 2022; 15:eabj1737. [PMID: 35077199 DOI: 10.1126/scisignal.abj1737] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The Escherichia coli chemoreceptor array is a supramolecular assembly that enables cells to respond to extracellular cues dynamically and with great precision and sensitivity. In the array, transmembrane receptors organized as trimers of dimers are connected at their cytoplasmic tips by hexameric rings of alternating subunits of the kinase CheA and the scaffolding protein CheW (CheA-CheW rings). Interactions of CheW molecules with the members of receptor trimers not directly bound to CheA-CheW rings may lead to the formation of hexameric CheW rings in the chemoreceptor array. Here, we detected such CheW rings with a cellular cysteine-directed cross-linking assay and explored the requirements for their formation and their participation in array assembly. We found that CheW ring formation varied with cellular CheW abundance, depended on the presence of receptors capable of a trimer-of-dimers arrangement, and did not require CheA. Cross-linking studies of a CheA~CheW fusion protein incapable of forming homomeric CheW oligomers demonstrated that CheW rings were not essential for the assembly of CheA-containing arrays. Förster resonance energy transfer (FRET)-based kinase assays of arrays containing variable amounts of CheW rings revealed that CheW rings enhanced the cooperativity and the sensitivity of the responses to attractants. We propose that six-membered CheW rings provide the additional interconnectivity required for optimal signaling and gradient tracking performance by chemosensory arrays.
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Affiliation(s)
- Germán E Piñas
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - Michael D DeSantis
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK
| | - John S Parkinson
- School of Biological Sciences, University of Utah, Salt Lake City, UT 84112, USA
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9
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Depelteau JS, Renault L, Althof N, Cassidy CK, Mendonça LM, Jensen GJ, Resch GP, Briegel A. UVC inactivation of pathogenic samples suitable for cryo-EM analysis. Commun Biol 2022; 5:29. [PMID: 35017666 PMCID: PMC8752862 DOI: 10.1038/s42003-021-02962-w] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2021] [Accepted: 12/07/2021] [Indexed: 12/22/2022] Open
Abstract
Cryo-electron microscopy has become an essential tool to understand structure and function of biological samples. Especially for pathogens, such as disease-causing bacteria and viruses, insights gained by cryo-EM can aid in developing cures. However, due to the biosafety restrictions of pathogens, samples are often treated by chemical fixation to render the pathogen inert, affecting the ultrastructure of the sample. Alternatively, researchers use in vitro or ex vivo models, which are non-pathogenic but lack the complexity of the pathogen of interest. Here we show that ultraviolet-C (UVC) radiation applied at cryogenic temperatures can be used to eliminate or dramatically reduce the infectivity of Vibrio cholerae and the bacterial virus, the ICP1 bacteriophage. We show no discernable structural impact of this treatment of either sample using two cryo-EM methods: cryo-electron tomography followed by sub-tomogram averaging, and single particle analysis (SPA). Additionally, we applied the UVC irradiation to the protein apoferritin (ApoF), which is a widely used test sample for high-resolution SPA studies. The UVC-treated ApoF sample resulted in a 2.1 Å structure indistinguishable from an untreated published map. This research demonstrates that UVC treatment is an effective and inexpensive addition to the cryo-EM sample preparation toolbox. Depelteau et al. present a new method to inactivate cryo-EM samples from pathogenic organisms before imaging using ultraviolet-C radiation in cryogenic conditions. This method allows for the inexpensive preparation of cryo-EM samples with no discernable structural impact of the treatment.
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Affiliation(s)
- Jamie S Depelteau
- Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333, BE, Leiden, The Netherlands
| | - Ludovic Renault
- Netherlands Centre for Electron Nanoscopy (NeCEN), Leiden University, Leiden, The Netherlands
| | - Nynke Althof
- Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333, BE, Leiden, The Netherlands
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford, UK
| | - Luiza M Mendonça
- Biology and Bioengineering Department, California Institute of Technology, Pasadena, CA, USA.,Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, UK
| | - Grant J Jensen
- Biology and Bioengineering Department, California Institute of Technology, Pasadena, CA, USA and Department of Chemistry and Biochemistry, Brigham Young University, Provo, UT, USA
| | - Guenter P Resch
- Nexperion e.U.-Solutions for Electron Microscopy, Vienna, Austria
| | - Ariane Briegel
- Department of Microbial Sciences, Institute of Biology, Leiden University, Sylviusweg 72, 2333, BE, Leiden, The Netherlands. .,Netherlands Centre for Electron Nanoscopy (NeCEN), Leiden University, Leiden, The Netherlands.
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10
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Burt A, Cassidy CK, Stansfeld PJ, Gutsche I. Alternative Architecture of the E. coli Chemosensory Array. Biomolecules 2021; 11:biom11040495. [PMID: 33806045 PMCID: PMC8064477 DOI: 10.3390/biom11040495] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 03/19/2021] [Accepted: 03/23/2021] [Indexed: 11/16/2022] Open
Abstract
Chemotactic responses in motile bacteria are the result of sophisticated signal transduction by large, highly organized arrays of sensory proteins. Despite tremendous progress in the understanding of chemosensory array structure and function, a structural basis for the heightened sensitivity of networked chemoreceptors is not yet complete. Here, we present cryo-electron tomography visualisations of native-state chemosensory arrays in E. coli minicells. Strikingly, these arrays appear to exhibit a p2-symmetric array architecture that differs markedly from the p6-symmetric architecture previously described in E. coli. Based on this data, we propose molecular models of this alternative architecture and the canonical p6-symmetric assembly. We evaluate our observations and each model in the context of previously published data, assessing the functional implications of an alternative architecture and effects for future studies.
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Affiliation(s)
- Alister Burt
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, F-38044 Grenoble, France;
| | - C. Keith Cassidy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford OX1 3QU, UK;
| | - Phillip J. Stansfeld
- Department of Chemistry, School of Life Sciences, University of Warwick, Gibbet Hill Campus, Coventry CV4 7AL, UK;
| | - Irina Gutsche
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des Martyrs, F-38044 Grenoble, France;
- Correspondence:
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Burt A, Cassidy CK, Ames P, Bacia-Verloop M, Baulard M, Huard K, Luthey-Schulten Z, Desfosses A, Stansfeld PJ, Margolin W, Parkinson JS, Gutsche I. Complete structure of the chemosensory array core signalling unit in an E. coli minicell strain. Nat Commun 2020; 11:743. [PMID: 32029744 PMCID: PMC7005262 DOI: 10.1038/s41467-020-14350-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2019] [Accepted: 12/21/2019] [Indexed: 12/01/2022] Open
Abstract
Motile bacteria sense chemical gradients with transmembrane receptors organised in supramolecular signalling arrays. Understanding stimulus detection and transmission at the molecular level requires precise structural characterisation of the array building block known as a core signalling unit. Here we introduce an Escherichia coli strain that forms small minicells possessing extended and highly ordered chemosensory arrays. We use cryo-electron tomography and subtomogram averaging to provide a three-dimensional map of a complete core signalling unit, with visible densities corresponding to the HAMP and periplasmic domains. This map, combined with previously determined high resolution structures and molecular dynamics simulations, yields a molecular model of the transmembrane core signalling unit and enables spatial localisation of its individual domains. Our work thus offers a solid structural basis for the interpretation of a wide range of existing data and the design of further experiments to elucidate signalling mechanisms within the core signalling unit and larger array.
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Affiliation(s)
- Alister Burt
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - Peter Ames
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Maria Bacia-Verloop
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Megghane Baulard
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Karine Huard
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Zaida Luthey-Schulten
- Department of Chemistry, University of Illinois Urbana-Champaign, Urbana, IL, 61801, USA
| | - Ambroise Desfosses
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, South Parks Road, Oxford, OX1 3QU, UK
| | - William Margolin
- Department of Microbiology & Molecular Genetics, The University of Texas Health Science Center at Houston, Houston, TX, 77030, USA
| | - John S Parkinson
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Irina Gutsche
- Institut de Biologie Structurale, Université Grenoble Alpes, CEA, CNRS, IBS, 71 Avenue des martyrs, F-38044, Grenoble, France.
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Cassidy CK, Himes BA, Sun D, Ma J, Zhao G, Parkinson JS, Stansfeld PJ, Luthey-Schulten Z, Zhang P. Structure and dynamics of the E. coli chemotaxis core signaling complex by cryo-electron tomography and molecular simulations. Commun Biol 2020; 3:24. [PMID: 31925330 PMCID: PMC6954272 DOI: 10.1038/s42003-019-0748-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2019] [Accepted: 12/19/2019] [Indexed: 01/08/2023] Open
Abstract
To enable the processing of chemical gradients, chemotactic bacteria possess large arrays of transmembrane chemoreceptors, the histidine kinase CheA, and the adaptor protein CheW, organized as coupled core-signaling units (CSU). Despite decades of study, important questions surrounding the molecular mechanisms of sensory signal transduction remain unresolved, owing especially to the lack of a high-resolution CSU structure. Here, we use cryo-electron tomography and sub-tomogram averaging to determine a structure of the Escherichia coli CSU at sub-nanometer resolution. Based on our experimental data, we use molecular simulations to construct an atomistic model of the CSU, enabling a detailed characterization of CheA conformational dynamics in its native structural context. We identify multiple, distinct conformations of the critical P4 domain as well as asymmetries in the localization of the P3 bundle, offering several novel insights into the CheA signaling mechanism.
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Affiliation(s)
- C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK.
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, USA
| | - Dapeng Sun
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, USA
| | - Jun Ma
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, USA
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, USA
| | - John S Parkinson
- School of Biological Sciences, University of Utah, Salt Lake City, UT, 84112, USA
| | - Phillip J Stansfeld
- Department of Biochemistry, University of Oxford, Oxford, OX1 3QU, UK
- School of Life Sciences & Department of Chemistry, University of Warwick, Coventry, CV4 7AL, UK
| | - Zaida Luthey-Schulten
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
- Department of Chemistry and Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, 15260, USA.
- Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Oxford, OX3 7BN, UK.
- Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot, OX11 0DE, UK.
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Yang W, Cassidy CK, Ames P, Diebolder CA, Schulten K, Luthey-Schulten Z, Parkinson JS, Briegel A. In Situ Conformational Changes of the Escherichia coli Serine Chemoreceptor in Different Signaling States. mBio 2019; 10:e00973-19. [PMID: 31266867 PMCID: PMC6606802 DOI: 10.1128/mbio.00973-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2019] [Accepted: 05/31/2019] [Indexed: 11/20/2022] Open
Abstract
Tsr, the serine chemoreceptor in Escherichia coli, transduces signals from a periplasmic ligand-binding site to its cytoplasmic tip, where it controls the activity of the CheA kinase. To function, Tsr forms trimers of homodimers (TODs), which associate in vivo with the CheA kinase and CheW coupling protein. Together, these proteins assemble into extended hexagonal arrays. Here, we use cryo-electron tomography and molecular dynamics simulation to study Tsr in the context of a near-native array, characterizing its signaling-related conformational changes at both the individual dimer and the trimer level. In particular, we show that individual Tsr dimers within a trimer exhibit asymmetric flexibilities that are a function of the signaling state, highlighting the effect of their different protein interactions at the receptor tips. We further reveal that the dimer compactness of the Tsr trimer changes between signaling states, transitioning at the glycine hinge from a compact conformation in the kinase-OFF state to an expanded conformation in the kinase-ON state. Hence, our results support a crucial role for the glycine hinge: to allow the receptor flexibility necessary to achieve different signaling states while also maintaining structural constraints imposed by the membrane and extended array architecture.IMPORTANCE In Escherichia coli, membrane-bound chemoreceptors, the histidine kinase CheA, and coupling protein CheW form highly ordered chemosensory arrays. In core signaling complexes, chemoreceptor trimers of dimers undergo conformational changes, induced by ligand binding and sensory adaptation, which regulate kinase activation. Here, we characterize by cryo-electron tomography the kinase-ON and kinase-OFF conformations of the E. coli serine receptor in its native array context. We found distinctive structural differences between the members of a receptor trimer, which contact different partners in the signaling unit, and structural differences between the ON and OFF signaling complexes. Our results provide new insights into the signaling mechanism of chemoreceptor arrays and suggest an important functional role for a previously postulated flexible region and glycine hinge in the receptor molecule.
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Affiliation(s)
- Wen Yang
- Institute of Biology, Leiden University, Leiden, The Netherlands
| | - C Keith Cassidy
- Department of Biochemistry, University of Oxford, Oxford, United Kingdom
- Department of Physics and Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Peter Ames
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | | | - Klaus Schulten
- Department of Physics and Beckman Institute, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - Zaida Luthey-Schulten
- Department of Chemistry and Center for the Physics of Living Cells, University of Illinois Urbana-Champaign, Urbana, Illinois, USA
| | - John S Parkinson
- School of Biological Sciences, University of Utah, Salt Lake City, Utah, USA
| | - Ariane Briegel
- Institute of Biology, Leiden University, Leiden, The Netherlands
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Cassidy CK, Himes BA, Luthey-Schulten Z, Zhang P. CryoEM-based hybrid modeling approaches for structure determination. Curr Opin Microbiol 2018; 43:14-23. [PMID: 29107896 PMCID: PMC5934336 DOI: 10.1016/j.mib.2017.10.002] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2017] [Revised: 10/04/2017] [Accepted: 10/09/2017] [Indexed: 12/21/2022]
Abstract
Recent advances in cryo-electron microscopy (cryoEM) have dramatically improved the resolutions at which vitrified biological specimens can be studied, revealing new structural and mechanistic insights over a broad range of spatial scales. Bolstered by these advances, much effort has been directed toward the development of hybrid modeling methodologies for the construction and refinement of high-fidelity atomistic models from cryoEM data. In this brief review, we will survey the key elements of cryoEM-based hybrid modeling, providing an overview of available computational tools and strategies as well as several recent applications.
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Affiliation(s)
- C Keith Cassidy
- Department of Physics, Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - Zaida Luthey-Schulten
- Department of Chemistry, Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, IL, USA
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Division of Structural Biology, Wellcome Trust Centre for Human Genetics, University of Oxford, Roosevelt Drive, Oxford OX3 7BN, UK; Electron Bio-Imaging Centre, Diamond Light Sources, Harwell Science and Innovation Campus, Didcot OX11 0DE, UK.
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Goh BC, Hadden JA, Bernardi RC, Singharoy A, McGreevy R, Rudack T, Cassidy CK, Schulten K. Computational Methodologies for Real-Space Structural Refinement of Large Macromolecular Complexes. Annu Rev Biophys 2016; 45:253-78. [PMID: 27145875 DOI: 10.1146/annurev-biophys-062215-011113] [Citation(s) in RCA: 53] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The rise of the computer as a powerful tool for model building and refinement has revolutionized the field of structure determination for large biomolecular systems. Despite the wide availability of robust experimental methods capable of resolving structural details across a range of spatiotemporal resolutions, computational hybrid methods have the unique ability to integrate the diverse data from multimodal techniques such as X-ray crystallography and electron microscopy into consistent, fully atomistic structures. Here, commonly employed strategies for computational real-space structural refinement are reviewed, and their specific applications are illustrated for several large macromolecular complexes: ribosome, virus capsids, chemosensory array, and photosynthetic chromatophore. The increasingly important role of computational methods in large-scale structural refinement, along with current and future challenges, is discussed.
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Affiliation(s)
- Boon Chong Goh
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Jodi A Hadden
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Rafael C Bernardi
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Abhishek Singharoy
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Ryan McGreevy
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Till Rudack
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - C Keith Cassidy
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Klaus Schulten
- Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Energy Biosciences Institute, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Center for the Physics of Living Cells, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Center for Biophysics and Computational Biology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801;
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16
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Cassidy CK, Himes BA, Alvarez FJ, Ma J, Zhao G, Perilla JR, Schulten K, Zhang P. CryoEM and computer simulations reveal a novel kinase conformational switch in bacterial chemotaxis signaling. eLife 2015; 4. [PMID: 26583751 PMCID: PMC6746300 DOI: 10.7554/elife.08419] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2015] [Accepted: 11/18/2015] [Indexed: 11/13/2022] Open
Abstract
Chemotactic responses in bacteria require large, highly ordered arrays of sensory proteins to mediate the signal transduction that ultimately controls cell motility. A mechanistic understanding of the molecular events underlying signaling, however, has been hampered by the lack of a high-resolution structural description of the extended array. Here, we report a novel reconstitution of the array, involving the receptor signaling domain, histidine kinase CheA, and adaptor protein CheW, as well as a density map of the core-signaling unit at 11.3 Å resolution, obtained by cryo-electron tomography and sub-tomogram averaging. Extracting key structural constraints from our density map, we computationally construct and refine an atomic model of the core array structure, exposing novel interfaces between the component proteins. Using all-atom molecular dynamics simulations, we further reveal a distinctive conformational change in CheA. Mutagenesis and chemical cross-linking experiments confirm the importance of the conformational dynamics of CheA for chemotactic function.
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Affiliation(s)
- C Keith Cassidy
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Benjamin A Himes
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Frances J Alvarez
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Jun Ma
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Gongpu Zhao
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
| | - Juan R Perilla
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Klaus Schulten
- Department of Physics and Beckman Institute, University of Illinois at Urbana-Champaign, Urbana, United States
| | - Peijun Zhang
- Department of Structural Biology, University of Pittsburgh School of Medicine, Pittsburgh, United States
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Cassidy CK, Himes B, Alvarez FJD, Perilla JR, Ma J, Zhao G, Zhang P, Schulten K. Molecular Insights into the Signaling Mechanism of the Histidine Kinase CheA within an Intact Bacterial Chemosensory Array. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.1724] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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18
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Himes BA, Cassidy CK, Ma J, Alvarez FJD, Perilla JR, Zhao G, Schulten K, Zhang P. Cryo-Electron Tomography and Computer Simulations Reveal Distinct CheA Kinase Conformation in Bacterial Chemotaxis Signaling Receptor Complex. Biophys J 2015. [DOI: 10.1016/j.bpj.2014.11.2290] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
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Fraiberg M, Afanzar O, Cassidy CK, Gabashvili A, Schulten K, Levin Y, Eisenbach M. CheY's acetylation sites responsible for generating clockwise flagellar rotation in Escherichia coli. Mol Microbiol 2014; 95:231-44. [PMID: 25388160 DOI: 10.1111/mmi.12858] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/06/2014] [Indexed: 11/30/2022]
Abstract
Stimulation of Escherichia coli with acetate elevates the acetylation level of the chemotaxis response regulator CheY. This elevation, in an unknown mechanism, activates CheY to generate clockwise rotation. Here, using quantitative selective reaction monitoring mass spectrometry and high-resolution targeted mass spectrometry, we identified K91 and K109 as the major sites whose acetylation level in vivo increases in response to acetate. Employing single and multiple lysine replacements in CheY, we found that K91 and K109 are also the sites mainly responsible for acetate-dependent clockwise generation. Furthermore, we showed that clockwise rotation is repressed when residue K91 is nonmodified, as evidenced by an increased ability of CheY to generate clockwise rotation when K91 was acetylated or replaced by specific amino acids. Using molecular dynamics simulations, we show that K91 repression is manifested in the conformational dynamics of the β4α4 loop, shifted toward an active state upon mutation. Removal of β4α4 loop repression may represent a general activation mechanism in CheY, pertaining also to the canonical phosphorylation activation pathway as suggested by crystal structures of active and inactive CheY from Thermotoga maritima. By way of elimination, we further suggest that K109 acetylation is actively involved in generating clockwise rotation.
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Affiliation(s)
- Milana Fraiberg
- Department of Biological Chemistry, The Weizmann Institute of Science, 7610001, Rehovot, Israel
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