1
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Caprini D, Battista F, Zajdel P, Di Muccio G, Guardiani C, Trump B, Carter M, Yakovenko AA, Amayuelas E, Bartolomé L, Meloni S, Grosu Y, Casciola CM, Giacomello A. Bubbles enable volumetric negative compressibility in metastable elastocapillary systems. Nat Commun 2024; 15:5076. [PMID: 38871721 DOI: 10.1038/s41467-024-49136-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2023] [Accepted: 05/21/2024] [Indexed: 06/15/2024] Open
Abstract
Although coveted in applications, few materials expand when subject to compression or contract under decompression, i.e., exhibit negative compressibility. A key step to achieve such counterintuitive behaviour is the destabilisations of (meta)stable equilibria of the constituents. Here, we propose a simple strategy to obtain negative compressibility exploiting capillary forces both to precompress the elastic material and to release such precompression by a threshold phenomenon - the reversible formation of a bubble in a hydrophobic flexible cavity. We demonstrate that the solid part of such metastable elastocapillary systems displays negative compressibility across different scales: hydrophobic microporous materials, proteins, and millimetre-sized laminae. This concept is applicable to fields such as porous materials, biomolecules, sensors and may be easily extended to create unexpected material susceptibilities.
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Affiliation(s)
- Davide Caprini
- Center for Life Nano- & Neuro-Science, Istituto Italiano di Tecnologia, Viale Regina Elena 291, Rome, Italy
| | - Francesco Battista
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Via Eudossiana 18, Rome, Italy
| | - Paweł Zajdel
- A. Chełkowski Institute of Physics, University of Silesia, ul 75 Pułku Piechoty 1, Chorzów, Poland
| | - Giovanni Di Muccio
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Via Eudossiana 18, Rome, Italy
| | - Carlo Guardiani
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Via Eudossiana 18, Rome, Italy
| | - Benjamin Trump
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Marcus Carter
- Center for Neutron Research, National Institute of Standards and Technology, Gaithersburg, Maryland, USA
| | - Andrey A Yakovenko
- X-Ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois, USA
| | - Eder Amayuelas
- Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, Vitoria-Gasteiz, Spain
| | - Luis Bartolomé
- Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, Vitoria-Gasteiz, Spain
| | - Simone Meloni
- Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Ferrara, Via Luigi Borsari 46, Ferrara, Italy.
| | - Yaroslav Grosu
- Centre for Cooperative Research on Alternative Energies (CIC energiGUNE), Basque Research and Technology Alliance (BRTA), Alava Technology Park, Albert Einstein 48, Vitoria-Gasteiz, Spain.
- Institute of Chemistry, University of Silesia, Katowice, Poland.
| | - Carlo Massimo Casciola
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Via Eudossiana 18, Rome, Italy.
| | - Alberto Giacomello
- Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, Via Eudossiana 18, Rome, Italy.
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2
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Zhang M, Tang S, Wang X, Fang S, Li Y. Mechanosensitive channel MscL gating transitions coupling with constriction point shift. Protein Sci 2024; 33:e4965. [PMID: 38501596 PMCID: PMC10949393 DOI: 10.1002/pro.4965] [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: 10/25/2023] [Revised: 02/23/2024] [Accepted: 03/04/2024] [Indexed: 03/20/2024]
Abstract
The mechanosensitive channel of large conductance (MscL) acts as an "emergency release valve" that protects bacterial cells from acute hypoosmotic stress, and it serves as a paradigm for studying the mechanism underlying the transduction of mechanical forces. MscL gating is proposed to initiate with an expansion without opening, followed by subsequent pore opening via a number of intermediate substates, and ends in a full opening. However, the details of gating process are still largely unknown. Using in vivo viability assay, single channel patch clamp recording, cysteine cross-linking, and tryptophan fluorescence quenching approach, we identified and characterized MscL mutants with different occupancies of constriction region in the pore domain. The results demonstrated the shifts of constriction point along the gating pathway towards cytoplasic side from residue G26, though G22, to L19 upon gating, indicating the closed-expanded transitions coupling of the expansion of tightly packed hydrophobic constriction region to conduct the initial ion permeation in response to the membrane tension. Furthermore, these transitions were regulated by the hydrophobic and lipidic interaction with the constricting "hot spots". Our data reveal a new resolution of the transitions from the closed to the opening substate of MscL, providing insights into the gating mechanisms of MscL.
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Affiliation(s)
- Mingfeng Zhang
- Department of Cell Biology, College of MedicineJiaxing UniversityJiaxingChina
- School of Life ScienceWestlake UniversityHangzhouChina
- School of Brain Science and Brain MedicineZhejiang University School of MedicineHangzhouChina
| | - Siyang Tang
- School of Brain Science and Brain MedicineZhejiang University School of MedicineHangzhouChina
| | - Xiaomin Wang
- Department of Cell Biology, College of MedicineJiaxing UniversityJiaxingChina
| | - Sanhua Fang
- Core FacilitiesZhejiang University School of MedicineHangzhouChina
| | - Yuezhou Li
- Department of Cell Biology, College of MedicineJiaxing UniversityJiaxingChina
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3
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Ozu M, Galizia L, Alvear-Arias JJ, Fernández M, Caviglia A, Zimmermann R, Guastaferri F, Espinoza-Muñoz N, Sutka M, Sigaut L, Pietrasanta LI, González C, Amodeo G, Garate JA. Mechanosensitive aquaporins. Biophys Rev 2023; 15:497-513. [PMID: 37681084 PMCID: PMC10480384 DOI: 10.1007/s12551-023-01098-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Accepted: 07/04/2023] [Indexed: 09/09/2023] Open
Abstract
Cellular systems must deal with mechanical forces to satisfy their physiological functions. In this context, proteins with mechanosensitive properties play a crucial role in sensing and responding to environmental changes. The discovery of aquaporins (AQPs) marked a significant breakthrough in the study of water transport. Their transport capacity and regulation features make them key players in cellular processes. To date, few AQPs have been reported to be mechanosensitive. Like mechanosensitive ion channels, AQPs respond to tension changes in the same range. However, unlike ion channels, the aquaporin's transport rate decreases as tension increases, and the molecular features of the mechanism are unknown. Nevertheless, some clues from mechanosensitive ion channels shed light on the AQP-membrane interaction. The GxxxG motif may play a critical role in the water permeation process associated with structural features in AQPs. Consequently, a possible gating mechanism triggered by membrane tension changes would involve a conformational change in the cytoplasmic extreme of the single file region of the water pathway, where glycine and histidine residues from loop B play a key role. In view of their transport capacity and their involvement in relevant processes related to mechanical forces, mechanosensitive AQPs are a fundamental piece of the puzzle for understanding cellular responses.
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Affiliation(s)
- Marcelo Ozu
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Luciano Galizia
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Juan José Alvear-Arias
- Interdisciplinary Center of Neurosciences of Valparaiso, University of Valparaiso, CINV, 2360102 Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Santiago, Chile
| | - Miguel Fernández
- Interdisciplinary Center of Neurosciences of Valparaiso, University of Valparaiso, CINV, 2360102 Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Santiago, Chile
| | - Agustín Caviglia
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Rosario Zimmermann
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Florencia Guastaferri
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
- Present Address: Instituto de Biología Molecular y Celular de Rosario (IBR-CONICET-UNR), Rosario, Argentina
| | - Nicolás Espinoza-Muñoz
- Interdisciplinary Center of Neurosciences of Valparaiso, University of Valparaiso, CINV, 2360102 Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Santiago, Chile
| | - Moira Sutka
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lorena Sigaut
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Buenos Aires, Argentina
- Instituto de Física de Buenos Aires (IFIBA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Lía Isabel Pietrasanta
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Física, Buenos Aires, Argentina
- Instituto de Física de Buenos Aires (IFIBA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - Carlos González
- Millennium Nucleus in NanoBioPhysics, Santiago, Chile
- Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, FL 33136 USA
- Present Address: Molecular Bioscience Department, University of Texas, Austin, TX 78712 USA
| | - Gabriela Amodeo
- Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Biodiversidad y Biología Experimental, Buenos Aires, Argentina
- Instituto de Biodiversidad y Biología Experimental y Aplicada (IBBEA), Universidad de Buenos Aires y Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET), Buenos Aires, Argentina
| | - José Antonio Garate
- Interdisciplinary Center of Neurosciences of Valparaiso, University of Valparaiso, CINV, 2360102 Valparaíso, Chile
- Millennium Nucleus in NanoBioPhysics, Santiago, Chile
- Facultad de Ingeniería, Arquitectura y Diseño, Universidad San Sebastián, Bellavista, Santiago, Chile
- Centro Científico y Tecnológico de Excelencia Ciencia y Vida, Universidad San Sebastián, 7750000 Santiago, Chile
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4
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Raffo A, Gagliardi L, Fugacci U, Sagresti L, Grandinetti S, Brancato G, Biasotti S, Rocchia W. Chanalyzer: A Computational Geometry Approach for the Analysis of Protein Channel Shape and Dynamics. Front Mol Biosci 2022; 9:933924. [PMID: 35959458 PMCID: PMC9358003 DOI: 10.3389/fmolb.2022.933924] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2022] [Accepted: 06/13/2022] [Indexed: 11/18/2022] Open
Abstract
Morphological analysis of protein channels is a key step for a thorough understanding of their biological function and mechanism. In this respect, molecular dynamics (MD) is a very powerful tool, enabling the description of relevant biological events at the atomic level, which might elude experimental observations, and pointing to the molecular determinants thereof. In this work, we present a computational geometry-based approach for the characterization of the shape and dynamics of biological ion channels or pores to be used in combination with MD trajectories. This technique relies on the earliest works of Edelsbrunner and on the NanoShaper software, which makes use of the alpha shape theory to build the solvent-excluded surface of a molecular system in an aqueous solution. In this framework, a channel can be simply defined as a cavity with two entrances on the opposite sides of a molecule. Morphological characterization, which includes identification of the main axis, the corresponding local radius, and the detailed description of the global shape of the cavity, is integrated with a physico-chemical description of the surface facing the pore lumen. Remarkably, the possible existence or temporary appearance of fenestrations from the channel interior towards the outer lipid matrix is also accounted for. As a test case, we applied the present approach to the analysis of an engineered protein channel, the mechanosensitive channel of large conductance.
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Affiliation(s)
- Andrea Raffo
- Istituto di Matematica Applicata e Tecnologie Informatiche “E. Magenes”, Consiglio Nazionale delle Ricerche, Genova, Italy
| | - Luca Gagliardi
- CONCEPT Lab, Istituto Italiano di Tecnologia, Genova, Italy
| | - Ulderico Fugacci
- Istituto di Matematica Applicata e Tecnologie Informatiche “E. Magenes”, Consiglio Nazionale delle Ricerche, Genova, Italy
- *Correspondence: Ulderico Fugacci, ; Silvia Biasotti, ; Walter Rocchia,
| | - Luca Sagresti
- Scuola Normale Superiore, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Pisa, Italy
- Consorzio Interuniversitario per lo sviluppo dei Sistemi a Grande Interfase (CSGI), Sesto Fiorentino, Italy
| | - Simone Grandinetti
- Scuola Normale Superiore, Pisa, Italy
- Dipartimento di Ingegneria Civile ed Industriale, Università di Pisa, Pisa, Italy
| | - Giuseppe Brancato
- Scuola Normale Superiore, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), Pisa, Italy
- Consorzio Interuniversitario per lo sviluppo dei Sistemi a Grande Interfase (CSGI), Sesto Fiorentino, Italy
| | - Silvia Biasotti
- Istituto di Matematica Applicata e Tecnologie Informatiche “E. Magenes”, Consiglio Nazionale delle Ricerche, Genova, Italy
- *Correspondence: Ulderico Fugacci, ; Silvia Biasotti, ; Walter Rocchia,
| | - Walter Rocchia
- Istituto di Matematica Applicata e Tecnologie Informatiche “E. Magenes”, Consiglio Nazionale delle Ricerche, Genova, Italy
- CONCEPT Lab, Istituto Italiano di Tecnologia, Genova, Italy
- *Correspondence: Ulderico Fugacci, ; Silvia Biasotti, ; Walter Rocchia,
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5
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Wang B, Lane BJ, Kapsalis C, Ault JR, Sobott F, El Mkami H, Calabrese AN, Kalli AC, Pliotas C. Pocket delipidation induced by membrane tension or modification leads to a structurally analogous mechanosensitive channel state. Structure 2022; 30:608-622.e5. [PMID: 34986323 PMCID: PMC9033278 DOI: 10.1016/j.str.2021.12.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2021] [Revised: 10/13/2021] [Accepted: 12/07/2021] [Indexed: 01/06/2023]
Abstract
The mechanosensitive ion channel of large conductance MscL gates in response to membrane tension changes. Lipid removal from transmembrane pockets leads to a concerted structural and functional MscL response, but it remains unknown whether there is a correlation between the tension-mediated state and the state derived by pocket delipidation in the absence of tension. Here, we combined pulsed electron paramagnetic resonance spectroscopy and hydrogen-deuterium exchange mass spectrometry, coupled with molecular dynamics simulations under membrane tension, to investigate the structural changes associated with the distinctively derived states. Whether it is tension- or modification-mediated pocket delipidation, we find that MscL samples a similar expanded subconducting state. This is the final step of the delipidation pathway, but only an intermediate stop on the tension-mediated path, with additional tension triggering further channel opening. Our findings hint at synergistic modes of regulation by lipid molecules in membrane tension-activated mechanosensitive channels.
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Affiliation(s)
- Bolin Wang
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Benjamin J Lane
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Charalampos Kapsalis
- Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews KY16 9ST, UK
| | - James R Ault
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Frank Sobott
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Hassane El Mkami
- School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS, UK
| | - Antonio N Calabrese
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Molecular and Cellular Biology, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK
| | - Antreas C Kalli
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; Leeds Institute of Cardiovascular and Metabolic Medicine, School of Medicine, University of Leeds, Leeds LS2 9NL, UK
| | - Christos Pliotas
- Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds LS2 9JT, UK; School of Biomedical Sciences, Faculty of Biological Sciences, University of Leeds, Leeds LS2 9JT, UK; Biomedical Sciences Research Complex, School of Biology, University of St Andrews, St Andrews KY16 9ST, UK.
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6
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Immadisetty K, Polasa A, Shelton R, Moradi M. Elucidating the molecular basis of spontaneous activation in an engineered mechanosensitive channel. Comput Struct Biotechnol J 2022; 20:2539-2550. [PMID: 35685356 PMCID: PMC9156883 DOI: 10.1016/j.csbj.2022.05.022] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/11/2022] [Accepted: 05/12/2022] [Indexed: 12/11/2022] Open
Abstract
Mechanosensitive channel of large conductance (MscL) detects and responds to changes in the pressure profile of cellular membranes and transduces the mechanical energy into electrical and/or chemical signals. MscL can be activated using ultrasonic or chemical activation methods to improve the absorption of medicines and bioactive compounds into cells. However, re-engineering chemical signals such as pH change can trigger channel activation in MscL. This study elucidates the activation mechanism of an engineered MscL at an atomic level through a combination of equilibrium and non-equilibrium (NE) molecular dynamics (MD) simulations. Comparing the wild-type (WT) and engineered MscL activation processes suggests that the two systems are likely associated with different active states and different transition pathways. These findings indicate that (1) periplasmic loops play a key role in the activation process of MscL, (2) the loss of various backbone-backbone hydrogen bonds and salt bridge interactions in the engineered MscL channel causes the spontaneous opening of the channel, and (3) the most significant interactions lost during the activation process are between the transmembrane helices 1 and 2 in engineered MscL channel. The orientation-based biasing approach for producing and optimizing an open MscL model used in this work is a promising way to characterize unknown protein functional states and investigate the activation processes in ion channels and transmembrane proteins in general. This work paves the way for a computational framework for engineering more efficient pH-sensing mechanosensitive channels.
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Affiliation(s)
- Kalyan Immadisetty
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, United States
| | - Adithya Polasa
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, United States
| | - Reid Shelton
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, United States
| | - Mahmoud Moradi
- Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, AR 72701, United States
- Corresponding author.
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7
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Yazdani M, Jia Z, Chen J. Hydrophobic dewetting in gating and regulation of transmembrane protein ion channels. J Chem Phys 2021; 153:110901. [PMID: 32962356 DOI: 10.1063/5.0017537] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Water is at the heart of almost all biological phenomena, without which no life that we know of would have been possible. It is a misleadingly complex liquid that exists in near coexistence with the vapor phase under ambient conditions. Confinement within a hydrophobic cavity can tip this balance enough to drive a cooperative dewetting transition. For a nanometer-scale pore, the dewetting transition leads to a stable dry state that is physically open but impermeable to ions. This phenomenon is often referred to as hydrophobic gating. Numerous transmembrane protein ion channels have now been observed to utilize hydrophobic gating in their activation and regulation. Here, we review recent theoretical, simulation, and experimental studies that together have started to establish the principles of hydrophobic gating and discuss how channels of various sizes, topologies, and biological functions can utilize these principles to control the thermodynamic properties of water within their interior pores for gating and regulation. Exciting opportunities remain in multiple areas, particularly on direct experimental detection of hydrophobic dewetting in biological channels and on understanding how the cell may control the hydrophobic gating in regulation of ion channels.
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Affiliation(s)
- Mahdieh Yazdani
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Zhiguang Jia
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
| | - Jianhan Chen
- Department of Chemistry, University of Massachusetts, Amherst, Massachusetts 01003, USA
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8
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Zhang X, Zhang Y, Tang S, Ma S, Shen Y, Chen Y, Tong Q, Li Y, Yang J. Hydrophobic Gate of Mechanosensitive Channel of Large Conductance in Lipid Bilayers Revealed by Solid-State NMR Spectroscopy. J Phys Chem B 2021; 125:2477-2490. [DOI: 10.1021/acs.jpcb.0c07487] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Affiliation(s)
- Xuning Zhang
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology and the Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430074, China
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Yan Zhang
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
- University of Chinese Academy of Sciences, Beijing 100049, P. R. China
| | - Siyang Tang
- Children’s Hospital and Department of Biophysics, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Shaojie Ma
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology and the Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430074, China
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
| | - Yang Shen
- Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States
| | - Yanke Chen
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology and the Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Qiong Tong
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology and the Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Yuezhou Li
- Children’s Hospital and Department of Biophysics, NHC and CAMS Key Laboratory of Medical Neurobiology, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310058, China
| | - Jun Yang
- Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology and the Collaborative Innovation Center for Brain Science, Huazhong University of Science and Technology, Wuhan 430074, China
- National Center for Magnetic Resonance in Wuhan, Key Laboratory of Magnetic Resonance in Biological Systems, State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Innovation Academy for Precision Measurement Science and Technology, Chinese Academy of Sciences, Wuhan 430071, P. R. China
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9
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Hammerschmid D, van Dyck JF, Sobott F, Calabrese AN. Interrogating Membrane Protein Structure and Lipid Interactions by Native Mass Spectrometry. Methods Mol Biol 2021; 2168:233-261. [PMID: 33582995 DOI: 10.1007/978-1-0716-0724-4_11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/23/2023]
Abstract
Native mass spectrometry and native ion mobility mass spectrometry are now established techniques in structural biology, with recent work developing these methods for the study of integral membrane proteins reconstituted in both lipid bilayer and detergent environments. Here we show how native mass spectrometry can be used to interrogate integral membrane proteins, providing insights into conformation, oligomerization, subunit composition/stoichiometry, and interactions with detergents/lipids/drugs. Furthermore, we discuss the sample requirements and experimental considerations unique to integral membrane protein native mass spectrometry research.
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Affiliation(s)
- Dietmar Hammerschmid
- Protein Chemistry, Proteomics and Epigenetic Signalling (PPES), Department of Biomedical Sciences, University of Antwerp, Wilrijk, Belgium.,Biomolecular & Analytical Mass Spectrometry Group, Chemistry Department, University of Antwerp, Antwerp, Belgium
| | - Jeroen F van Dyck
- Biomolecular & Analytical Mass Spectrometry Group, Chemistry Department, University of Antwerp, Antwerp, Belgium
| | - Frank Sobott
- Biomolecular & Analytical Mass Spectrometry Group, Chemistry Department, University of Antwerp, Antwerp, Belgium.,Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds, UK.,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK
| | - Antonio N Calabrese
- Faculty of Biological Sciences, School of Molecular and Cellular Biology, University of Leeds, Leeds, UK. .,Astbury Centre for Structural Molecular Biology, University of Leeds, Leeds, UK.
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10
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Setyawati I, Stanek WK, Majsnerowska M, Swier LJYM, Pardon E, Steyaert J, Guskov A, Slotboom DJ. In vitro reconstitution of dynamically interacting integral membrane subunits of energy-coupling factor transporters. eLife 2020; 9:64389. [PMID: 33350937 PMCID: PMC7755397 DOI: 10.7554/elife.64389] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2020] [Accepted: 12/02/2020] [Indexed: 01/03/2023] Open
Abstract
Energy-coupling factor (ECF) transporters mediate import of micronutrients in prokaryotes. They consist of an integral membrane S-component (that binds substrate) and ECF module (that powers transport by ATP hydrolysis). It has been proposed that different S-components compete for docking onto the same ECF module, but a minimal liposome-reconstituted system, required to substantiate this idea, is lacking. Here, we co-reconstituted ECF transporters for folate (ECF-FolT2) and pantothenate (ECF-PanT) into proteoliposomes, and assayed for crosstalk during active transport. The kinetics of transport showed that exchange of S-components is part of the transport mechanism. Competition experiments suggest much slower substrate association with FolT2 than with PanT. Comparison of a crystal structure of ECF-PanT with previously determined structures of ECF-FolT2 revealed larger conformational changes upon binding of folate than pantothenate, which could explain the kinetic differences. Our work shows that a minimal in vitro system with two reconstituted transporters recapitulates intricate kinetics behaviour observed in vivo.
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Affiliation(s)
- Inda Setyawati
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands.,Biochemistry Department, Bogor Agricultural University, Bogor, Indonesia
| | - Weronika K Stanek
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Maria Majsnerowska
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Lotteke J Y M Swier
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Els Pardon
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium.,VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Jan Steyaert
- Structural Biology Brussels, Vrije Universiteit Brussel, VUB, Brussels, Belgium.,VIB-VUB Center for Structural Biology, VIB, Brussels, Belgium
| | - Albert Guskov
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands.,Moscow Institute of Physics and Technology, Dolgoprudny, Russian Federation
| | - Dirk J Slotboom
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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11
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Li C, Yue Z, Espinoza-Fonseca LM, Voth GA. Multiscale Simulation Reveals Passive Proton Transport Through SERCA on the Microsecond Timescale. Biophys J 2020; 119:1033-1040. [PMID: 32814059 DOI: 10.1016/j.bpj.2020.07.027] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2020] [Revised: 07/20/2020] [Accepted: 07/24/2020] [Indexed: 12/11/2022] Open
Abstract
The sarcoplasmic reticulum Ca2+-ATPase (SERCA) transports two Ca2+ ions from the cytoplasm to the reticulum lumen at the expense of ATP hydrolysis. In addition to transporting Ca2+, SERCA facilitates bidirectional proton transport across the sarcoplasmic reticulum to maintain the charge balance of the transport sites and to balance the charge deficit generated by the exchange of Ca2+. Previous studies have shown the existence of a transient water-filled pore in SERCA that connects the Ca2+ binding sites with the lumen, but the capacity of this pathway to sustain passive proton transport has remained unknown. In this study, we used the multiscale reactive molecular dynamics method and free energy sampling to quantify the free energy profile and timescale of the proton transport across this pathway while also explicitly accounting for the dynamically coupled hydration changes of the pore. We find that proton transport from the central binding site to the lumen has a microsecond timescale, revealing a novel passive cytoplasm-to-lumen proton flow beside the well-known inverse proton countertransport occurring in active Ca2+ transport. We propose that this proton transport mechanism is operational and serves as a functional conduit for passive proton transport across the sarcoplasmic reticulum.
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Affiliation(s)
- Chenghan Li
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois
| | - Zhi Yue
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois
| | - L Michel Espinoza-Fonseca
- Center for Arrhythmia Research, Department of Internal Medicine, Division of Cardiovascular Medicine, University of Michigan, Ann Arbor, Michigan
| | - Gregory A Voth
- Department of Chemistry, Chicago Center for Theoretical Chemistry, James Franck Institute, and Institute for Biophysical Dynamics, The University of Chicago, Chicago, Illinois.
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12
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Structural and Functional Characterization of NadR from Lactococcus lactis. Molecules 2020; 25:molecules25081940. [PMID: 32331317 PMCID: PMC7221760 DOI: 10.3390/molecules25081940] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2020] [Revised: 04/19/2020] [Accepted: 04/21/2020] [Indexed: 12/02/2022] Open
Abstract
NadR is a bifunctional enzyme that converts nicotinamide riboside (NR) into nicotinamide mononucleotide (NMN), which is then converted into nicotinamide adenine dinucleotide (NAD). Although a crystal structure of the enzyme from the Gram-negative bacterium Haemophilus influenzae is known, structural understanding of its catalytic mechanism remains unclear. Here, we purified the NadR enzyme from Lactococcus lactis and established an assay to determine the combined activity of this bifunctional enzyme. The conversion of NR into NAD showed hyperbolic dependence on the NR concentration, but sigmoidal dependence on the ATP concentration. The apparent cooperativity for ATP may be explained because both reactions catalyzed by the bifunctional enzyme (phosphorylation of NR and adenylation of NMN) require ATP. The conversion of NMN into NAD followed simple Michaelis-Menten kinetics for NMN, but again with the sigmoidal dependence on the ATP concentration. In this case, the apparent cooperativity is unexpected since only a single ATP is used in the NMN adenylyltransferase catalyzed reaction. To determine the possible structural determinants of such cooperativity, we solved the crystal structure of NadR from L. lactis (NadRLl). Co-crystallization with NAD, NR, NMN, ATP, and AMP-PNP revealed a ‘sink’ for adenine nucleotides in a location between two domains. This sink could be a regulatory site, or it may facilitate the channeling of substrates between the two domains.
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13
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Life with Bacterial Mechanosensitive Channels, from Discovery to Physiology to Pharmacological Target. Microbiol Mol Biol Rev 2020; 84:84/1/e00055-19. [PMID: 31941768 DOI: 10.1128/mmbr.00055-19] [Citation(s) in RCA: 40] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
General principles in biology have often been elucidated from the study of bacteria. This is true for the bacterial mechanosensitive channel of large conductance, MscL, the channel highlighted in this review. This channel functions as a last-ditch emergency release valve discharging cytoplasmic solutes upon decreases in osmotic environment. Opening the largest gated pore, MscL passes molecules up to 30 Å in diameter; exaggerated conformational changes yield advantages for study, including in vivo assays. MscL contains structural/functional themes that recur in higher organisms and help elucidate how other, structurally more complex, channels function. These features of MscL include (i) the ability to directly sense, and respond to, biophysical changes in the membrane, (ii) an α helix ("slide helix") or series of charges ("knot in a rope") at the cytoplasmic membrane boundary to guide transmembrane movements, and (iii) important subunit interfaces that, when disrupted, appear to cause the channel to gate inappropriately. MscL may also have medical applications: the modality of the MscL channel can be changed, suggesting its use as a triggered nanovalve in nanodevices, including those for drug targeting. In addition, recent studies have shown that the antibiotic streptomycin opens MscL and uses it as one of the primary paths to the cytoplasm. Moreover, the recent identification and study of novel specific agonist compounds demonstrate that the channel is a valid drug target. Such compounds may serve as novel-acting antibiotics and adjuvants, a way of permeabilizing the bacterial cell membrane and, thus, increasing the potency of commonly used antibiotics.
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14
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Characterizing the mechanosensitive response of Paraburkholderia graminis membranes. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2020; 1862:183176. [PMID: 31923411 DOI: 10.1016/j.bbamem.2020.183176] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 12/10/2019] [Accepted: 01/02/2020] [Indexed: 11/23/2022]
Abstract
Bacterial mechanosensitive channels gate in response to membrane tension, driven by shifts in environmental osmolarity. The mechanosensitive channels of small conductance (MscS) and large conductance (MscL) from Escherichia coli (Ec) gate in response to mechanical force applied to the membrane. Ec-MscS is the foundational member of the MscS superfamily of ion channels, a diverse family with at least fifteen subfamilies identified by homology to the pore lining helix of Ec-MscS, as well as significant diversity on the N- and C-termini. The MscL family of channels are homologous to Ec-MscL. In a rhizosphere associated bacterium, Paraburkholderia graminis C4D1M, mechanosensitive channels are essential for cell survival during changing osmotic environments such as a rainstorm. Utilizing bioinformatics, we predicted six MscS superfamily members and a single MscL homologue. The MscS superfamily members fall into at least three subfamilies: bacterial cyclic nucleotide gated, multi-TM, and extended N-terminus. Osmotic downshock experiments show that wildtype P. graminis cells contain a survival mechanism that prevents cell lysis in response to hypoosmotic shock. To determine if this rescue is due to mechanosensitive channels, we developed a method to create giant spheroplasts of P. graminis to explore the single channel response to applied mechanical tension. Patch clamp electrophysiology on these spheroplasts shows two unique conductances: MscL-like and MscS-like. These conductances are due to likely three unique proteins. This indicates that channels that gate in response to mechanical tension are present in the membrane. Here, we report the first single channel evidence of mechanosensitive ion channels from P. graminis membranes.
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15
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Yang SK, Yusoff K, Ajat M, Thomas W, Abushelaibi A, Akseer R, Lim SHE, Lai KS. Disruption of KPC-producing Klebsiella pneumoniae membrane via induction of oxidative stress by cinnamon bark (Cinnamomum verum J. Presl) essential oil. PLoS One 2019; 14:e0214326. [PMID: 30939149 PMCID: PMC6445408 DOI: 10.1371/journal.pone.0214326] [Citation(s) in RCA: 35] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 03/10/2019] [Indexed: 01/09/2023] Open
Abstract
Klebsiella pneumoniae (KP) remains the most prevalent nosocomial pathogen and carries the carbapenemase (KPC) gene which confers resistance towards carbapenem. Thus, it is necessary to discover novel antimicrobials to address the issue of antimicrobial resistance in such pathogens. Natural products such as essential oils are a promising source due to their complex composition. Essential oils have been shown to be effective against pathogens, but the overall mechanisms have yet to be fully explained. Understanding the molecular mechanisms of essential oil towards KPC-KP cells would provide a deeper understanding of their potential use in clinical settings. Therefore, we aimed to investigate the mode of action of essential oil against KPC-KP cells from a proteomic perspective by comparing the overall proteome profile of KPC-KP cells treated with cinnamon bark (Cinnamomum verum J. Presl) essential oil (CBO) at their sub-inhibitory concentration of 0.08% (v/v). A total of 384 proteins were successfully identified from the non-treated cells, whereas only 242 proteins were identified from the CBO-treated cells. Proteins were then categorized based on their biological processes, cellular components and molecular function prior to pathway analysis. Pathway analysis showed that CBO induced oxidative stress in the KPC-KP cells as indicated by the abundance of oxidative stress regulator proteins such as glycyl radical cofactor, catalase peroxidase and DNA mismatch repair protein. Oxidative stress is likely to oxidize and disrupt the bacterial membrane as shown by the loss of major membrane proteins. Several genes selected for qRT-PCR analysis validated the proteomic profile and were congruent with the proteomic abundance profiles. In conclusion, KPC-KP cells exposed to CBO undergo oxidative stress that eventually disrupts the bacterial membrane possibly via interaction with the phospholipid bilayer. Interestingly, several pathways involved in the bacterial membrane repair system were also affected by oxidative stress, contributing to the loss of cells viability.
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Affiliation(s)
- Shun-Kai Yang
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Khatijah Yusoff
- Department of Microbiology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Mokrish Ajat
- Department of Veterinary Preclinical Sciences, Faculty of Veterinary Medicine, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
| | - Warren Thomas
- Perdana University-Royal College of Surgeons in Ireland, School of Medicine, Perdana University, Serdang, Selangor, Malaysia
| | - Aisha Abushelaibi
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi, United Arab Emirates
| | - Riaz Akseer
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi, United Arab Emirates
| | - Swee-Hua Erin Lim
- Perdana University-Royal College of Surgeons in Ireland, School of Medicine, Perdana University, Serdang, Selangor, Malaysia
- Health Sciences Division, Abu Dhabi Women’s College, Higher Colleges of Technology, Abu Dhabi, United Arab Emirates
| | - Kok-Song Lai
- Department of Cell and Molecular Biology, Faculty of Biotechnology and Biomolecular Sciences, Universiti Putra Malaysia, Serdang, Selangor, Malaysia
- * E-mail:
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16
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Ke S, Ulmschneider MB, Wallace BA, Ulmschneider JP. Role of the Interaction Motif in Maintaining the Open Gate of an Open Sodium Channel. Biophys J 2018; 115:1920-1930. [PMID: 30366630 DOI: 10.1016/j.bpj.2018.10.001] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2018] [Revised: 09/27/2018] [Accepted: 10/01/2018] [Indexed: 01/09/2023] Open
Abstract
Voltage-gated sodium channels undergo transitions between open, closed, and inactivated states, enabling regulation of the translocation of sodium ions across membranes. A recently published crystal structure of the full-length prokaryotic NavMs crystal structure in the activated open conformation has revealed the presence of a novel motif consisting of an extensive network of salt bridges involving residues in the voltage sensor, S4-S5 linker, pore, and C-terminal domains. This motif has been proposed to be responsible for maintaining an open conformation that enables ion translocation through the channel. In this study, we have used long-time molecular dynamics calculations without artificial restraints to demonstrate that the interaction network of full-length NavMs indeed prevents a rapid collapse and closure of the gate, in marked difference to earlier studies of the pore-only construct in which the gate had to be restrained to remain open. Interestingly, a frequently discussed "hydrophobic gating" mechanism at nanoscopic level is also observed in our simulations, in which the discontinuous water wire close to the gate region leads to an energetic barrier for ion conduction. In addition, we demonstrate the effects of in silico mutations of several of the key residues in the motif on the open channel's stability and functioning, correlating them with existing functional studies on this channel and homologous disease-associated mutations in human sodium channels; we also examine the effects of truncating/removing the voltage sensor and C-terminal domains in maintaining an open gate.
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Affiliation(s)
- Song Ke
- Institute of Natural Sciences and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China
| | | | - B A Wallace
- Institute of Structural and Molecular Biology, Birkbeck College, University of London, London, United Kingdom.
| | - Jakob P Ulmschneider
- Institute of Natural Sciences and School of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai, China.
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17
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Hollingsworth SA, Dror RO. Molecular Dynamics Simulation for All. Neuron 2018; 99:1129-1143. [PMID: 30236283 PMCID: PMC6209097 DOI: 10.1016/j.neuron.2018.08.011] [Citation(s) in RCA: 932] [Impact Index Per Article: 155.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2018] [Revised: 07/17/2018] [Accepted: 08/07/2018] [Indexed: 12/12/2022]
Abstract
The impact of molecular dynamics (MD) simulations in molecular biology and drug discovery has expanded dramatically in recent years. These simulations capture the behavior of proteins and other biomolecules in full atomic detail and at very fine temporal resolution. Major improvements in simulation speed, accuracy, and accessibility, together with the proliferation of experimental structural data, have increased the appeal of biomolecular simulation to experimentalists-a trend particularly noticeable in, although certainly not limited to, neuroscience. Simulations have proven valuable in deciphering functional mechanisms of proteins and other biomolecules, in uncovering the structural basis for disease, and in the design and optimization of small molecules, peptides, and proteins. Here we describe, in practical terms, the types of information MD simulations can provide and the ways in which they typically motivate further experimental work.
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Affiliation(s)
- Scott A Hollingsworth
- Department of Computer Science, Stanford University, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University, Stanford, CA 94305, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA
| | - Ron O Dror
- Department of Computer Science, Stanford University, Stanford, CA 94305, USA; Department of Molecular and Cellular Physiology, Stanford University, Stanford, CA 94305, USA; Department of Structural Biology, Stanford University, Stanford, CA 94305, USA; Institute for Computational and Mathematical Engineering, Stanford University, Stanford, CA 94305, USA.
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18
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Calabrese AN, Radford SE. Mass spectrometry-enabled structural biology of membrane proteins. Methods 2018; 147:187-205. [DOI: 10.1016/j.ymeth.2018.02.020] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2017] [Revised: 01/30/2018] [Accepted: 02/21/2018] [Indexed: 01/01/2023] Open
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19
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Assur Sanghai Z, Liu Q, Clarke OB, Belcher-Dufrisne M, Wiriyasermkul P, Giese MH, Leal-Pinto E, Kloss B, Tabuso S, Love J, Punta M, Banerjee S, Rajashankar KR, Rost B, Logothetis D, Quick M, Hendrickson WA, Mancia F. Structure-based analysis of CysZ-mediated cellular uptake of sulfate. eLife 2018; 7:27829. [PMID: 29792261 PMCID: PMC5967866 DOI: 10.7554/elife.27829] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2017] [Accepted: 04/11/2018] [Indexed: 01/25/2023] Open
Abstract
Sulfur, most abundantly found in the environment as sulfate (SO42-), is an essential element in metabolites required by all living cells, including amino acids, co-factors and vitamins. However, current understanding of the cellular delivery of SO42- at the molecular level is limited. CysZ has been described as a SO42- permease, but its sequence family is without known structural precedent. Based on crystallographic structure information, SO42- binding and flux experiments, we provide insight into the molecular mechanism of CysZ-mediated translocation of SO42- across membranes. CysZ structures from three different bacterial species display a hitherto unknown fold and have subunits organized with inverted transmembrane topology. CysZ from Pseudomonas denitrificans assembles as a trimer of antiparallel dimers and the CysZ structures from two other species recapitulate dimers from this assembly. Mutational studies highlight the functional relevance of conserved CysZ residues.
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Affiliation(s)
- Zahra Assur Sanghai
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Qun Liu
- Biology Department, Brookhaven National Laboratory, Upton, United States
| | - Oliver B Clarke
- Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Meagan Belcher-Dufrisne
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
| | - Pattama Wiriyasermkul
- Center for Molecular Recognition, Department of Psychiatry, Columbia University, New York, United States
| | - M Hunter Giese
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States
| | - Edgar Leal-Pinto
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, United States.,Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, United States
| | - Brian Kloss
- New York Structural Biology Center, New York, United States
| | | | - James Love
- New York Structural Biology Center, New York, United States
| | - Marco Punta
- Centre for Evolution and Cancer, The Institute of Cancer Research, London, United Kingdom
| | - Surajit Banerjee
- Department of Chemistry and Chemical Biology, Cornell University, NE-CAT, Argonne, United States
| | | | - Burkhard Rost
- Department of Informatics, Technical University of Munich, Munich, Germany
| | - Diomedes Logothetis
- Department of Physiology and Biophysics, Virginia Commonwealth University School of Medicine, Richmond, United States.,Department of Pharmaceutical Sciences, School of Pharmacy, Bouvé College of Health Sciences, Northeastern University, Boston, United States
| | - Matthias Quick
- Center for Molecular Recognition, Department of Psychiatry, Columbia University, New York, United States.,Division of Molecular Therapeutics, New York State Psychiatric Institute, New York, United States
| | - Wayne A Hendrickson
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States.,Department of Biochemistry and Molecular Biophysics, Columbia University, New York, United States.,New York Structural Biology Center, New York, United States
| | - Filippo Mancia
- Department of Physiology and Cellular Biophysics, Columbia University, New York, United States
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20
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Kasimova MA, Yazici A, Yudin Y, Granata D, Klein ML, Rohacs T, Carnevale V. Ion Channel Sensing: Are Fluctuations the Crux of the Matter? J Phys Chem Lett 2018; 9:1260-1264. [PMID: 29439562 PMCID: PMC6310152 DOI: 10.1021/acs.jpclett.7b03396] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2023]
Abstract
The nonselective cation channel TRPV1 is responsible for transducing noxious stimuli into action potentials propagating through peripheral nerves. It is activated by temperatures greater than 43 °C, while remaining completely nonconductive at temperatures lower than this threshold. The origin of this sharp response, which makes TRPV1 a biological temperature sensor, is not understood. Here we used molecular dynamics simulations and free energy calculations to characterize the molecular determinants of the transition between nonconductive and conductive states. We found that hydration of the pore and thus ion permeation depends critically on the polar character of its molecular surface: in this narrow hydrophobic enclosure, the motion of a polar side-chain is sufficient to stabilize either the dry or wet state. The conformation of this side-chain is in turn coupled to the hydration state of four peripheral cavities, which undergo a dewetting transition at the activation temperature.
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Affiliation(s)
- Marina A. Kasimova
- Institute for Computational Molecular Science, Temple University, Philadelphia, PA 19122
| | - Aysenur Yazici
- Department of Pharmacology, Physiology and Neuroscience, Rutgers–New Jersey, Medical School, Newark, NJ 07103
| | - Yevgen Yudin
- Department of Pharmacology, Physiology and Neuroscience, Rutgers–New Jersey, Medical School, Newark, NJ 07103
| | - Daniele Granata
- Institute for Computational Molecular Science, Temple University, Philadelphia, PA 19122
| | - Michael L. Klein
- Institute for Computational Molecular Science, Temple University, Philadelphia, PA 19122
| | - Tibor Rohacs
- Department of Pharmacology, Physiology and Neuroscience, Rutgers–New Jersey, Medical School, Newark, NJ 07103
| | - Vincenzo Carnevale
- Institute for Computational Molecular Science, Temple University, Philadelphia, PA 19122
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21
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Abstract
Mechanosensitive (MS) channels protect bacteria against hypo-osmotic shock and fulfil additional functions. Hypo-osmotic shock leads to high turgor pressure that can cause cell rupture and death. MS channels open under these conditions and release unspecifically solutes and consequently the turgor pressure. They can recognise the raised pressure via the increased tension in the cell membrane. Currently, a better understanding how MS channels can sense tension on molecular level is developing because the interaction of the lipid bilayer with the channel is being investigated in detail. The MS channel of large conductance (MscL) and of small conductance (MscS) have been distinguished and studied in molecular detail. In addition, larger channels were found that contain a homologous region corresponding to MscS so that MscS represents a family of channels. Often several members of this family are present in a species. The importance of this family is underlined by the fact that members can be found not only in bacteria but also in higher organisms. While MscL and MscS have been studied for years in particular by electrophysiology, mutagenesis, molecular dynamics, X-ray crystallography and other biophysical techniques, only recently more details are emerging about other members of the MscS-family.
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22
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Jaehme M, Singh R, Garaeva AA, Duurkens RH, Slotboom DJ. PnuT uses a facilitated diffusion mechanism for thiamine uptake. J Gen Physiol 2017; 150:41-50. [PMID: 29203477 PMCID: PMC5749112 DOI: 10.1085/jgp.201711850] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/26/2017] [Indexed: 12/17/2022] Open
Abstract
Membrane transporters of the bacterial pyridine nucleotide uptake (Pnu) family mediate the uptake of various B-type vitamins. For example, the PnuT transporters have specificity for vitamin B1 (thiamine). It has been hypothesized that Pnu transporters are facilitators that allow passive transport of the vitamin substrate across the membrane. Metabolic trapping by phosphorylation would then lead to accumulation of the transported substrates in the cytoplasm. However, experimental evidence for such a transport mechanism is lacking. Here, to determine the mechanism of thiamine transport, we purify PnuTSw from Shewanella woodyi and reconstitute it in liposomes to determine substrate binding and transport properties. We show that the electrochemical gradient of thiamine solely determines the direction of transport, consistent with a facilitated diffusion mechanism. Further, PnuTSw can bind and transport thiamine as well as the thiamine analogues pyrithiamine and oxythiamine, but does not recognize the phosphorylated derivatives thiamine monophosphate and thiamine pyrophosphate as substrates, consistent with a metabolic trapping mechanism. Guided by the crystal structure of the homologous nicotinamide riboside transporter PnuC, we perform mutagenesis experiments, which reveal residues involved in substrate binding and gating. The facilitated diffusion mechanism of transport used by PnuTSw contrasts sharply with the active transport mechanisms used by other bacterial thiamine transporters.
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Affiliation(s)
- Michael Jaehme
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Rajkumar Singh
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Alisa A Garaeva
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Ria H Duurkens
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, Netherlands
| | - Dirk-Jan Slotboom
- Groningen Biomolecular Science and Biotechnology Institute, University of Groningen, Groningen, Netherlands
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23
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Single-molecule visualization of conformational changes and substrate transport in the vitamin B 12 ABC importer BtuCD-F. Nat Commun 2017; 8:1652. [PMID: 29162829 PMCID: PMC5698293 DOI: 10.1038/s41467-017-01815-7] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/25/2016] [Accepted: 10/18/2017] [Indexed: 11/15/2022] Open
Abstract
ATP-binding cassette (ABC) transporters form the largest class of active membrane transport proteins. Binding and hydrolysis of ATP by their highly conserved nucleotide-binding domains drive conformational changes of the complex that mediate transport of substrate across the membrane. The vitamin B12 importer BtuCD-F in Escherichia coli is an extensively studied model system. The periplasmic soluble binding protein BtuF binds the ligand; the transmembrane and ATPase domains BtuCD mediate translocation. Here we report the direct observation at the single-molecule level of ATP, vitamin B12 and BtuF-induced events in the transporter complex embedded in liposomes. Single-molecule fluorescence imaging techniques reveal that membrane-embedded BtuCD forms a stable complex with BtuF, regardless of the presence of ATP and vitamin B12. We observe that a vitamin B12 molecule remains bound to the complex for tens of seconds, during which several ATP hydrolysis cycles can take place, before it is being transported across the membrane. The vitamin B12 importer BtuCD-F is a type II ATP-binding cassette transporter. Here the authors use single-molecule fluorescence techniques to analyse ATP hydrolysis and substrate transport in individual BtuCD-F complexes embedded in liposomes, and propose a transport model.
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Meng Z, Yang J, Liu Q, de Vries JW, Gruszka A, Rodríguez-Pulido A, Crielaard BJ, Kros A, Herrmann A. Efficient Fusion of Liposomes by Nucleobase Quadruple-Anchored DNA. Chemistry 2017; 23:9391-9396. [DOI: 10.1002/chem.201701379] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Indexed: 12/29/2022]
Affiliation(s)
- Zhuojun Meng
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Jian Yang
- Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry; Leiden University, P.O. Box 9502; 2300 RA Leiden The Netherlands
| | - Qing Liu
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Jan Willem de Vries
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Agnieszka Gruszka
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Alberto Rodríguez-Pulido
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
| | - Bart J. Crielaard
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
- Institute for Biomedical Engineering and Materials Science; University Medical Center Groningen; Antonius Deusinglaan 1 9713AV Groningen The Netherlands
| | - Alexander Kros
- Supramolecular & Biomaterials Chemistry, Leiden Institute of Chemistry; Leiden University, P.O. Box 9502; 2300 RA Leiden The Netherlands
| | - Andreas Herrmann
- Zernike Institute for Advanced Materials; University of Groningen; Nijenborgh 4 9747 AG Groningen The Netherlands
- Institute for Biomedical Engineering and Materials Science; University Medical Center Groningen; Antonius Deusinglaan 1 9713AV Groningen The Netherlands
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25
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Native Mass Spectrometry for the Characterization of Structure and Interactions of Membrane Proteins. Methods Mol Biol 2017; 1635:205-232. [PMID: 28755371 DOI: 10.1007/978-1-4939-7151-0_11] [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] [Indexed: 12/12/2022]
Abstract
Over the past years, native mass spectrometry and ion mobility have grown into techniques that are widely applicable to the study of aspects of protein structure. More recently, it has become apparent that this approach provides a very promising avenue for the investigation of integral membrane proteins in lipid or detergent environments.In this chapter, we discuss applications of native mass spectrometry and ion mobility in membrane protein research-what is important to take into consideration when working with membrane proteins, and what the requirements are for sample preparation for native mass spectrometry. Furthermore, we will discuss the types of information provided by the measurements, including the oligomeric state, subunit composition and stoichiometry, interactions with detergents or lipids, conformational transitions, and the binding and structural effect of ligands and drugs.
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26
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Xiao K, Zhou Y, Kong XY, Xie G, Li P, Zhang Z, Wen L, Jiang L. Electrostatic-Charge- and Electric-Field-Induced Smart Gating for Water Transportation. ACS NANO 2016; 10:9703-9709. [PMID: 27648730 DOI: 10.1021/acsnano.6b05682] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
Regulating and controlling the transport of water across nanochannels is of great importance in both fundamental research and practical applications because it is difficult to externally control water flow through nanochannels as in biological channels. To date, only a few hydrophobic nanochannels controlling the transport of water have been reported, all of which use exotic hydrophobic molecules. However, the effect of electrostatic charges, which plays an indispensable role in membrane proteins and dominates the energetics of water permeation across aquaporins, has not gained enough attention to control water transport through a solid-state nanochannel/nanopore. Here, we report electrostatic-charge-induced water gating of a single ion track-etched sub-10 nm channel. This system can directly realize the gating transition between an open, conductive state and a closed, nonconductive state by regulating the surface charge density through a process that involves alternating capillary evaporation and capillary condensation. Compared to the introduction of exotic hydrophobic molecules, water gating controlled by electrostatic charges is simple, convenient, and effective. Such a system anticipates potential applications including desalination, controllable valves, and drug delivery systems.
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Affiliation(s)
- Kai Xiao
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Yahong Zhou
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Xiang-Yu Kong
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Ganhua Xie
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Pei Li
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Zhen Zhang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Liping Wen
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
| | - Lei Jiang
- Beijing National Laboratory for Molecular Sciences (BNLMS), Key Laboratory of Green Printing, Institute of Chemistry, and ‡Key Laboratory of Bioinspired Smart Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences , Beijing, 100190, People's Republic of China
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27
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Dimitrova A, Walko M, Hashemi Shabestari M, Kumar P, Huber M, Kocer A. In situ, Reversible Gating of a Mechanosensitive Ion Channel through Protein-Lipid Interactions. Front Physiol 2016; 7:409. [PMID: 27708587 PMCID: PMC5030285 DOI: 10.3389/fphys.2016.00409] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2016] [Accepted: 08/30/2016] [Indexed: 12/14/2022] Open
Abstract
Understanding the functioning of ion channels, as well as utilizing their properties for biochemical applications requires control over channel activity. Herein we report a reversible control over the functioning of a mechanosensitive ion channel by interfering with its interaction with the lipid bilayer. The mechanosensitive channel of large conductance from Escherichia coli is reconstituted into liposomes and activated to its different sub-open states by titrating lysophosphatidylcholine (LPC) into the lipid bilayer. Activated channels are closed back by the removal of LPC out of the membrane by bovine serum albumin (BSA). Electron paramagnetic resonance spectra showed the LPC-dose-dependent gradual opening of the channel pore in the form of incrementally increasing spin label mobility and decreasing spin-spin interaction. A method to reversibly open and close mechanosensitive channels to distinct sub-open conformations during their journey from the closed to the fully open state enables detailed structural studies to follow the conformational changes during channel functioning. The ability of BSA to revert the action of LPC opens new perspectives for the functional studies of other membrane proteins that are known to be activated by LPC.
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Affiliation(s)
- Anna Dimitrova
- Department of Biochemistry, University of GroningenGroningen, Netherlands
| | - Martin Walko
- Department of Biochemistry, University of GroningenGroningen, Netherlands
| | | | - Pravin Kumar
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden UniversityLeiden, Netherlands
| | - Martina Huber
- Huygens-Kamerlingh Onnes Laboratory, Department of Physics, Leiden UniversityLeiden, Netherlands
| | - Armagan Kocer
- Neuroscience Department, University of Groningen, University Medical Center GroningenGroningen, Netherlands
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28
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Wray R, Iscla I, Gao Y, Li H, Wang J, Blount P. Dihydrostreptomycin Directly Binds to, Modulates, and Passes through the MscL Channel Pore. PLoS Biol 2016; 14:e1002473. [PMID: 27280286 PMCID: PMC4900634 DOI: 10.1371/journal.pbio.1002473] [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: 11/20/2015] [Accepted: 05/04/2016] [Indexed: 12/23/2022] Open
Abstract
The primary mechanism of action of the antibiotic dihydrostreptomycin is binding to and modifying the function of the bacterial ribosome, thus leading to decreased and aberrant translation of proteins; however, the routes by which it enters the bacterial cell are largely unknown. The mechanosensitive channel of large conductance, MscL, is found in the vast majority of bacterial species, where it serves as an emergency release valve rescuing the cell from sudden decreases in external osmolarity. While it is known that MscL expression increases the potency of dihydrostreptomycin, it has remained unclear if this effect is due to a direct interaction. Here, we use a combination of genetic screening, MD simulations, and biochemical and mutational approaches to determine if dihydrostreptomycin directly interacts with MscL. Our data strongly suggest that dihydrostreptomycin binds to a specific site on MscL and modifies its conformation, thus allowing the passage of K+ and glutamate out of, and dihydrostreptomycin into, the cell.
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Affiliation(s)
- Robin Wray
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Irene Iscla
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Ya Gao
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Hua Li
- School of Pharmacy, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- School of Traditional Chinese Materia Medica, Shenyang Pharmaceutical University, Shenyang, China
| | - Junmei Wang
- Green Center for Systems Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
| | - Paul Blount
- Department of Physiology, University of Texas Southwestern Medical Center, Dallas, Texas, United States of America
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29
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Jones PD, Stelzle M. Can Nanofluidic Chemical Release Enable Fast, High Resolution Neurotransmitter-Based Neurostimulation? Front Neurosci 2016; 10:138. [PMID: 27065794 PMCID: PMC4815362 DOI: 10.3389/fnins.2016.00138] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/02/2016] [Accepted: 03/18/2016] [Indexed: 11/13/2022] Open
Abstract
Artificial chemical stimulation could provide improvements over electrical neurostimulation. Physiological neurotransmission between neurons relies on the nanoscale release and propagation of specific chemical signals to spatially-localized receptors. Current knowledge of nanoscale fluid dynamics and nanofluidic technology allows us to envision artificial mechanisms to achieve fast, high resolution neurotransmitter release. Substantial technological development is required to reach this goal. Nanofluidic technology—rather than microfluidic—will be necessary; this should come as no surprise given the nanofluidic nature of neurotransmission. This perspective reviews the state of the art of high resolution electrical neuroprostheses and their anticipated limitations. Chemical release rates from nanopores are compared to rates achieved at synapses and with iontophoresis. A review of microfluidic technology justifies the analysis that microfluidic control of chemical release would be insufficient. Novel nanofluidic mechanisms are discussed, and we propose that hydrophobic gating may allow control of chemical release suitable for mimicking neurotransmission. The limited understanding of hydrophobic gating in artificial nanopores and the challenges of fabrication and large-scale integration of nanofluidic components are emphasized. Development of suitable nanofluidic technology will require dedicated, long-term efforts over many years.
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30
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Structural insight in the toppling mechanism of an energy-coupling factor transporter. Nat Commun 2016; 7:11072. [PMID: 27026363 PMCID: PMC4820897 DOI: 10.1038/ncomms11072] [Citation(s) in RCA: 44] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/17/2016] [Indexed: 11/08/2022] Open
Abstract
Energy-coupling factor (ECF) transporters mediate uptake of micronutrients in prokaryotes. The transporters consist of an S-component that binds the transported substrate and an ECF module (EcfAA′T) that binds and hydrolyses ATP. The mechanism of transport is poorly understood but presumably involves an unusual step in which the membrane-embedded S-component topples over to carry the substrate across the membrane. In many ECF transporters, the S-component dissociates from the ECF module after transport. Subsequently, substrate-bound S-components out-compete the empty proteins for re-binding to the ECF module in a new round of transport. Here we present crystal structures of the folate-specific transporter ECF–FolT from Lactobacillus delbrueckii. Interaction of the ECF module with FolT stabilizes the toppled state, and simultaneously destroys the high-affinity folate-binding site, allowing substrate release into the cytosol. We hypothesize that differences in the kinetics of toppling can explain how substrate-loaded FolT out-competes apo-FolT for association with the ECF module. Prokaryotes use energy-coupling factor transporters to uptake required micronutrients and an unusual toppling mechanism has been proposed for their function. Here, the authors provide structural support for this mechanism, allowing direct visualization of the toppled state.
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31
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Bavi O, Vossoughi M, Naghdabadi R, Jamali Y. The Combined Effect of Hydrophobic Mismatch and Bilayer Local Bending on the Regulation of Mechanosensitive Ion Channels. PLoS One 2016; 11:e0150578. [PMID: 26958847 PMCID: PMC4784931 DOI: 10.1371/journal.pone.0150578] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2015] [Accepted: 02/17/2016] [Indexed: 12/03/2022] Open
Abstract
The hydrophobic mismatch between the lipid bilayer and integral membrane proteins has well-defined effect on mechanosensitive (MS) ion channels. Also, membrane local bending is suggested to modulate MS channel activity. Although a number of studies have already shown the significance of each individual factor, the combined effect of these physical factors on MS channel activity have not been investigated. Here using finite element simulation, we study the combined effect of hydrophobic mismatch and local bending on the archetypal mechanosensitive channel MscL. First we show how the local curvature direction impacts on MS channel modulation. In the case of MscL, we show inward (cytoplasmic) bending can more effectively gate the channel compared to outward bending. Then we indicate that in response to a specific local curvature, MscL inserted in a bilayer with the same hydrophobic length is more expanded in the constriction pore region compared to when there is a protein-lipid hydrophobic mismatch. Interestingly in the presence of a negative mismatch (thicker lipids), MscL constriction pore is more expanded than in the presence of positive mismatch (thinner lipids) in response to an identical membrane curvature. These results were confirmed by a parametric energetic calculation provided for MscL gating. These findings have several biophysical consequences for understanding the function of MS channels in response to two major physical stimuli in mechanobiology, namely hydrophobic mismatch and local membrane curvature.
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Affiliation(s)
- Omid Bavi
- Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
| | - Manouchehr Vossoughi
- Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
- Biochemical & Bioenvironmental Research Center (BBRC), Tehran, Iran
| | - Reza Naghdabadi
- Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran, Iran
- Department of Mechanical Engineering, Sharif University of Technology, Tehran, Iran
| | - Yousef Jamali
- Department of Mathematics, Tarbiat Modares University, Tehran, Iran
- Computational physical Sciences Research Laboratory, School of Nano-Science, Institute for Research in Fundamental Sciences (IPM), Tehran, Iran
- * E-mail:
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32
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Kocer A. Mechanisms of mechanosensing - mechanosensitive channels, function and re-engineering. Curr Opin Chem Biol 2015; 29:120-7. [PMID: 26610201 DOI: 10.1016/j.cbpa.2015.10.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2015] [Revised: 09/30/2015] [Accepted: 10/06/2015] [Indexed: 10/22/2022]
Abstract
Sensing and responding to mechanical stimuli is an ancient behavior and ubiquitous to all forms of life. One of its players 'mechanosensitive ion channels' are involved in processes from osmosensing in bacteria to pain in humans. However, the mechanism of mechanosensing is yet to be elucidated. This review describes recent developments in the understanding of a bacterial mechanosensitive channel. Force from the lipid principle of mechanosensation, new methods to understand protein-lipid interactions, the role of water in the gating, the use of engineered mechanosensitive channels in the understanding of the gating mechanism and application of the accumulated knowledge in the field of drug delivery, drug design and sensor technologies are discussed.
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Affiliation(s)
- Armagan Kocer
- University of Groningen, University Medical Center Groningen, Ant. Deusinglaan 1, 9713 AV Groningen, The Netherlands.
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33
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Characterization of a novel water pocket inside the human Cx26 hemichannel structure. Biophys J 2015; 107:599-612. [PMID: 25099799 DOI: 10.1016/j.bpj.2014.05.037] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Revised: 05/12/2014] [Accepted: 05/14/2014] [Indexed: 01/09/2023] Open
Abstract
Connexins (Cxs) are a family of vertebrate proteins constituents of gap junction channels (GJCs) that connect the cytoplasm of adjacent cells by the end-to-end docking of two Cx hemichannels. The intercellular transfer through GJCs occurs by passive diffusion allowing the exchange of water, ions, and small molecules. Despite the broad interest to understand, at the molecular level, the functional state of Cx-based channels, there are still many unanswered questions regarding structure-function relationships, perm-selectivity, and gating mechanisms. In particular, the ordering, structure, and dynamics of water inside Cx GJCs and hemichannels remains largely unexplored. In this work, we describe the identification and characterization of a believed novel water pocket-termed the IC pocket-located in-between the four transmembrane helices of each human Cx26 (hCx26) monomer at the intracellular (IC) side. Using molecular dynamics (MD) simulations to characterize hCx26 internal water structure and dynamics, six IC pockets were identified per hemichannel. A detailed characterization of the dynamics and ordering of water including conformational variability of residues forming the IC pockets, together with multiple sequence alignments, allowed us to propose a functional role for this cavity. An in vitro assessment of tracer uptake suggests that the IC pocket residue Arg-143 plays an essential role on the modulation of the hCx26 hemichannel permeability.
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Yilmaz D, Dimitrova AI, Walko M, Kocer A. Study of light-induced MscL gating by EPR spectroscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:557-65. [PMID: 26286445 PMCID: PMC4562997 DOI: 10.1007/s00249-015-1063-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/08/2015] [Revised: 07/14/2015] [Accepted: 07/14/2015] [Indexed: 11/30/2022]
Abstract
A number of techniques developed to investigate protein structure and function depend on chemically modifying and/or labeling of proteins. However, in the case of homooligomeric proteins, the presence of multiple identical subunits obstructs the introduction of residue-specific labels to only one or several subunits, selectively. Here, in order to study the initial conformational changes of a homopentameric mechanosensitive ion channel during its gating, we developed a method for labeling a defined number of subunits of the channel with two different cysteine-specific compounds simultaneously. The first one is a light-sensitive channel activator that determines the degree of openness of the ion channel upon irradiation. The second one is a spin label, containing an unpaired electron, which allows following the resulting structural changes upon channel gating by electron paramagnetic resonance spectroscopy. With this method, we could open MscL into different sub-open states. As the number of light switches per channel increased, the intersubunit spin–spin interactions became less, indicating changes in intersubunit proximities and opening of the channel. The ability of controlled activation of MscL into different open states with a noninvasive trigger and following the resulting conformational changes by spectroscopy will pave the way for detailed spectroscopic studies in the area of mechanosensation.
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Affiliation(s)
- Duygu Yilmaz
- Department of Biochemistry, University of Groningen, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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35
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Pacheco-Torres J, Mukherjee N, Walko M, López-Larrubia P, Ballesteros P, Cerdan S, Kocer A. Image guided drug release from pH-sensitive Ion channel-functionalized stealth liposomes into an in vivo glioblastoma model. NANOMEDICINE-NANOTECHNOLOGY BIOLOGY AND MEDICINE 2015; 11:1345-54. [DOI: 10.1016/j.nano.2015.03.014] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/09/2014] [Revised: 03/03/2015] [Accepted: 03/29/2015] [Indexed: 01/11/2023]
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36
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Majsnerowska M, Ter Beek J, Stanek WK, Duurkens RH, Slotboom DJ. Competition between Different S-Components for the Shared Energy Coupling Factor Module in Energy Coupling Factor Transporters. Biochemistry 2015. [PMID: 26217920 DOI: 10.1021/acs.biochem.5b00609] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Energy coupling factor (ECF) transporters take up micronutrients in Bacteria and Archaea. They consist of a membrane-embedded S-component that provides substrate specificity and a three-subunit ECF module that couples ATP hydrolysis to transport. The S-components ThiT (for thiamin) and NiaX (for niacin) from Lactococcus lactis form complexes with the same ECF module. Here, we assayed the uptake of thiamin and niacin in Escherichia coli cells expressing the transporter genes. We demonstrate that the two different S-components compete for the ECF module, and that competition is more efficient in the presence of the transported substrate. The data suggest that binding and release of the S-components is a step in the transport cycle.
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Affiliation(s)
- Maria Majsnerowska
- †Department of Biochemistry, University of Groningen, Groningen Biomolecular Science and Biotechnology Institute, Nijenborg 4, 9747 AG Groningen, The Netherlands.,‡University of Groningen, Zernike Institute for Advanced Materials, Nijenborg 4, 9747 AG Groningen, The Netherlands
| | - Josy Ter Beek
- †Department of Biochemistry, University of Groningen, Groningen Biomolecular Science and Biotechnology Institute, Nijenborg 4, 9747 AG Groningen, The Netherlands.,‡University of Groningen, Zernike Institute for Advanced Materials, Nijenborg 4, 9747 AG Groningen, The Netherlands
| | - Weronika K Stanek
- †Department of Biochemistry, University of Groningen, Groningen Biomolecular Science and Biotechnology Institute, Nijenborg 4, 9747 AG Groningen, The Netherlands
| | - Ria H Duurkens
- †Department of Biochemistry, University of Groningen, Groningen Biomolecular Science and Biotechnology Institute, Nijenborg 4, 9747 AG Groningen, The Netherlands
| | - Dirk J Slotboom
- †Department of Biochemistry, University of Groningen, Groningen Biomolecular Science and Biotechnology Institute, Nijenborg 4, 9747 AG Groningen, The Netherlands.,‡University of Groningen, Zernike Institute for Advanced Materials, Nijenborg 4, 9747 AG Groningen, The Netherlands
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Inducible release of particulates from liposomes using the mechanosensitive channel of large conductance and L-α-lysophosphatidylcholine. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2015; 44:521-30. [PMID: 26143502 DOI: 10.1007/s00249-015-1055-4] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2014] [Revised: 06/07/2015] [Accepted: 06/17/2015] [Indexed: 01/05/2023]
Abstract
The mechanosensitive channel of large conductance (MscL) from Escherichia coli is a prototype for the mechanosensitive class of ion channels and opens one of the largest known gated transmembrane pores. As such, MscL offers the structural framework for the development of liposomal nanovalves for biotechnological applications. Here we incorporated MscL into liposomes and investigated the effects of L-α-lysophosphatidylcholine (LPC) with varying acyl chain lengths or saturation on its pore gating. This was measured by the efflux of encapsulated 5,6-carboxyfluorescein (CF) from the MscL proteoliposomes. Efflux improved in the presence of shorter and double-bonded LPC acyl chains. It was also dependent on the detergent concentration employed during MscL purification. MscL purified in 2 mM dodecyl β-D-maltopyranoside (DDM) had a marked increase in CF efflux compared to MscL purified in 1 mM DDM when treated with LPC. The purification conditions also resulted in increased efflux from proteoliposomes containing the G22C-MscL pore mutant channel, which requires higher membrane tension for its activation compared to WT-MscL.
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38
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Soo RM, Woodcroft BJ, Parks DH, Tyson GW, Hugenholtz P. Back from the dead; the curious tale of the predatory cyanobacterium Vampirovibrio chlorellavorus. PeerJ 2015; 3:e968. [PMID: 26038723 PMCID: PMC4451040 DOI: 10.7717/peerj.968] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/26/2015] [Accepted: 04/30/2015] [Indexed: 01/03/2023] Open
Abstract
An uncultured non-photosynthetic basal lineage of the Cyanobacteria, the Melainabacteria, was recently characterised by metagenomic analyses of aphotic environmental samples. However, a predatory bacterium, Vampirovibrio chlorellavorus, originally described in 1972 appears to be the first cultured representative of the Melainabacteria based on a 16S rRNA sequence recovered from a lyophilised co-culture of the organism. Here, we sequenced the genome of V. chlorellavorus directly from 36 year-old lyophilised material that could not be resuscitated confirming its identity as a member of the Melainabacteria. We identified attributes in the genome that likely allow V. chlorellavorus to function as an obligate predator of the microalga Chlorella vulgaris, and predict that it is the first described predator to use an Agrobacterium tumefaciens-like conjugative type IV secretion system to invade its host. V. chlorellavorus is the first cyanobacterium recognised to have a predatory lifestyle and further supports the assertion that Melainabacteria are non-photosynthetic.
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Affiliation(s)
- Rochelle M Soo
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia
| | - Ben J Woodcroft
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia
| | - Donovan H Parks
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia
| | - Gene W Tyson
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia ; Advanced Water Management Centre, The University of Queensland , St Lucia, QLD , Australia
| | - Philip Hugenholtz
- Australian Centre for Ecogenomics, School of Chemistry and Molecular Biosciences, The University of Queensland , St Lucia, QLD , Australia ; Institute for Molecular Bioscience, The University of Queensland , St Lucia, QLD , Australia
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39
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Chandramouli B, Di Maio D, Mancini G, Barone V, Brancato G. Breaking the hydrophobicity of the MscL pore: insights into a charge-induced gating mechanism. PLoS One 2015; 10:e0120196. [PMID: 25825909 PMCID: PMC4380313 DOI: 10.1371/journal.pone.0120196] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2014] [Accepted: 02/06/2015] [Indexed: 01/17/2023] Open
Abstract
The mechanosensitive channel of large conductance (MscL) is a protein that responds to membrane tension by opening a transient pore during osmotic downshock. Due to its large pore size and functional reconstitution into lipid membranes, MscL has been proposed as a promising artificial nanovalve suitable for biotechnological applications. For example, site-specific mutations and tailored chemical modifications have shown how MscL channel gating can be triggered in the absence of tension by introducing charged residues at the hydrophobic pore level. Recently, engineered MscL proteins responsive to stimuli like pH or light have been reported. Inspired by experiments, we present a thorough computational study aiming at describing, with atomistic detail, the artificial gating mechanism and the molecular transport properties of a light-actuated bacterial MscL channel, in which a charge-induced gating mechanism has been enabled through the selective cleavage of photo-sensitive alkylating agents. Properties such as structural transitions, pore dimension, ion flux and selectivity have been carefully analyzed. Besides, the effects of charge on alternative sites of the channel with respect to those already reported have been addressed. Overall, our results provide useful molecular insights into the structural events accompanying the engineered MscL channel gating and the interplay of electrostatic effects, channel opening and permeation properties. In addition, we describe how the experimentally observed ionic current in a single-subunit charged MscL mutant is obtained through a hydrophobicity breaking mechanism involving an asymmetric inter-subunit motion.
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Affiliation(s)
| | - Danilo Di Maio
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), sezione di Pisa, Largo Bruno Pontecorvo 3, 56127, Pisa, Italy
| | - Giordano Mancini
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), sezione di Pisa, Largo Bruno Pontecorvo 3, 56127, Pisa, Italy
| | - Vincenzo Barone
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), sezione di Pisa, Largo Bruno Pontecorvo 3, 56127, Pisa, Italy
| | - Giuseppe Brancato
- Scuola Normale Superiore, Piazza dei Cavalieri 7, I-56126, Pisa, Italy
- Istituto Nazionale di Fisica Nucleare (INFN), sezione di Pisa, Largo Bruno Pontecorvo 3, 56127, Pisa, Italy
- * E-mail:
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40
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Aryal P, Sansom MSP, Tucker SJ. Hydrophobic gating in ion channels. J Mol Biol 2015; 427:121-30. [PMID: 25106689 PMCID: PMC4817205 DOI: 10.1016/j.jmb.2014.07.030] [Citation(s) in RCA: 191] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2014] [Revised: 07/24/2014] [Accepted: 07/28/2014] [Indexed: 02/01/2023]
Abstract
Biological ion channels are nanoscale transmembrane pores. When water and ions are enclosed within the narrow confines of a sub-nanometer hydrophobic pore, they exhibit behavior not evident from macroscopic descriptions. At this nanoscopic level, the unfavorable interaction between the lining of a hydrophobic pore and water may lead to stochastic liquid-vapor transitions. These transient vapor states are "dewetted", i.e. effectively devoid of water molecules within all or part of the pore, thus leading to an energetic barrier to ion conduction. This process, termed "hydrophobic gating", was first observed in molecular dynamics simulations of model nanopores, where the principles underlying hydrophobic gating (i.e., changes in diameter, polarity, or transmembrane voltage) have now been extensively validated. Computational, structural, and functional studies now indicate that biological ion channels may also exploit hydrophobic gating to regulate ion flow within their pores. Here we review the evidence for this process and propose that this unusual behavior of water represents an increasingly important element in understanding the relationship between ion channel structure and function.
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Affiliation(s)
- Prafulla Aryal
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK; Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK
| | - Mark S P Sansom
- Department of Biochemistry, University of Oxford, Oxford OX1 3QU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK.
| | - Stephen J Tucker
- Clarendon Laboratory, Department of Physics, University of Oxford, Oxford OX1 3PU, UK; OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford OX1 2JD, UK.
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41
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Trick JL, Wallace EJ, Bayley H, Sansom MSP. Designing a hydrophobic barrier within biomimetic nanopores. ACS NANO 2014; 8:11268-11279. [PMID: 25317664 DOI: 10.1021/nn503930p] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Nanopores in membranes have a range of potential applications. Biomimetic design of nanopores aims to mimic key functions of biological pores within a stable template structure. Molecular dynamics simulations have been used to test whether a simple β-barrel protein nanopore can be modified to incorporate a hydrophobic barrier to permeation. Simulations have been used to evaluate functional properties of such nanopores, using water flux as a proxy for ionic conductance. The behavior of these model pores has been characterized as a function of pore size and of the hydrophobicity of the amino acid side chains lining the narrow central constriction of the pore. Potential of mean force calculations have been used to calculate free energy landscapes for water and for ion permeation in selected models. These studies demonstrate that a hydrophobic barrier can indeed be designed into a β-barrel protein nanopore, and that the height of the barrier can be adjusted by modifying the number of consecutive rings of hydrophobic side chains. A hydrophobic barrier prevents both water and ion permeation even though the pore is sterically unoccluded. These results both provide insights into the nature of hydrophobic gating in biological pores and channels, and furthermore demonstrate that simple design features may be computationally transplanted into β-barrel membrane proteins to generate functionally complex nanopores.
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Affiliation(s)
- Jemma L Trick
- Department of Biochemistry, University of Oxford , South Parks Road, Oxford OX1 3QU, Oxford, United Kingdom
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42
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Global structural changes of an ion channel during its gating are followed by ion mobility mass spectrometry. Proc Natl Acad Sci U S A 2014; 111:17170-5. [PMID: 25404294 DOI: 10.1073/pnas.1413118111] [Citation(s) in RCA: 56] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Mechanosensitive ion channels are sensors probing membrane tension in all species; despite their importance and vital role in many cell functions, their gating mechanism remains to be elucidated. Here, we determined the conditions for releasing intact mechanosensitive channel of large conductance (MscL) proteins from their detergents in the gas phase using native ion mobility-mass spectrometry (IM-MS). By using IM-MS, we could detect the native mass of MscL from Escherichia coli, determine various global structural changes during its gating by measuring the rotationally averaged collision cross-sections, and show that it can function in the absence of a lipid bilayer. We could detect global conformational changes during MscL gating as small as 3%. Our findings will allow studying native structure of many other membrane proteins.
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43
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Jaehme M, Guskov A, Slotboom DJ. Crystal structure of the vitamin B3 transporter PnuC, a full-length SWEET homolog. Nat Struct Mol Biol 2014; 21:1013-5. [PMID: 25291599 DOI: 10.1038/nsmb.2909] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/27/2014] [Accepted: 09/30/2014] [Indexed: 12/31/2022]
Abstract
PnuC transporters catalyze cellular uptake of the NAD+ precursor nicotinamide riboside (NR) and belong to a large superfamily that includes the SWEET sugar transporters. We present a crystal structure of Neisseria mucosa PnuC, which adopts a highly symmetrical fold with 3+1+3 membrane topology not previously observed in any protein. The high symmetry of PnuC with a single NR bound in the center suggests a simple alternating-access translocation mechanism.
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Affiliation(s)
- Michael Jaehme
- University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, the Netherlands
| | - Albert Guskov
- University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, the Netherlands
| | - Dirk Jan Slotboom
- University of Groningen, Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, the Netherlands
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44
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Mukherjee N, Jose MD, Birkner JP, Walko M, Ingólfsson HI, Dimitrova A, Arnarez C, Marrink SJ, Koçer A. The activation mode of the mechanosensitive ion channel, MscL, by lysophosphatidylcholine differs from tension-induced gating. FASEB J 2014; 28:4292-302. [PMID: 24958207 DOI: 10.1096/fj.14-251579] [Citation(s) in RCA: 37] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
One of the best-studied mechanosensitive channels is the mechanosensitive channel of large conductance (MscL). MscL senses tension in the membrane evoked by an osmotic down shock and directly couples it to large conformational changes leading to the opening of the channel. Spectroscopic techniques offer unique possibilities to monitor these conformational changes if it were possible to generate tension in the lipid bilayer, the native environment of MscL, during the measurements. To this end, asymmetric insertion of l-α-lysophosphatidylcholine (LPC) into the lipid bilayer has been effective; however, how LPC activates MscL is not fully understood. Here, the effects of LPC on tension-sensitive mutants of a bacterial MscL and on MscL homologs with different tension sensitivities are reported, leading to the conclusion that the mode of action of LPC is different from that of applied tension. Our results imply that LPC shifts the free energy of gating by interfering with MscL-membrane coupling. Furthermore, we demonstrate that the fine-tuned addition of LPC can be used for controlled activation of MscL in spectroscopic studies.
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Affiliation(s)
- Nobina Mukherjee
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Mac Donald Jose
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Jan Peter Birkner
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands; Zernike Institute for Advanced Materials, University of Groningen, Groningen, The Netherlands; and
| | - Martin Walko
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Helgi I Ingólfsson
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Anna Dimitrova
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Clément Arnarez
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Siewert J Marrink
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands
| | - Armağan Koçer
- Groningen Biomolecular Sciences and Biotechnology Institute, Groningen, The Netherlands; Neuroscience Department, University Medical Centre Groningen, Groningen, The Netherlands
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45
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He Z, Corry B, Lu X, Zhou J. A mechanical nanogate based on a carbon nanotube for reversible control of ion conduction. NANOSCALE 2014; 6:3686-3694. [PMID: 24566473 DOI: 10.1039/c3nr06238d] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Control of mass transport through nanochannels is of critical importance in many nanoscale devices and nanofiltration membranes. The gates in biological channels, which control the transport of substances across cell membranes, can provide inspiration for this purpose. Gates in many biological channels are formed by a constriction ringed with hydrophobic residues which can prevent ion conduction even when they are not completely physically occluded. In this work, we use molecular dynamics simulations to design a nanogate inspired by this hydrophobic gating mechanism. Deforming a carbon nanotube (12,12) with an external force can form a hydrophobic constriction in the centre of the tube that controls ion conduction. The simulation results show that increasing the magnitude of the applied force narrows the constriction and lowers the fluxes of K(+) and Cl(-) found under an electric field. With the exerted force larger than 5 nN, the constriction blocks the conduction of K(+) and Cl(-) due to partial dehydration while allowing for a noticeable water flux. Ion conduction can revert back to the unperturbed level upon force retraction, suggesting the reversibility of the nanogate. The force can be exerted by available experimental facilities, such as atomic force microscope (AFM) tips. It is found that partial dehydration in a continuous water-filled hydrophobic constriction is enough to close the channel, while full dewetting is not necessarily required. This mechanically deformed nanogate has many potential applications, such as a valve in nanofluidic systems to reversibly control ion conduction and a high-performance nanomachine for desalination and water treatment.
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Affiliation(s)
- Zhongjin He
- School of Chemistry and Chemical Engineering, South China University of Technology, Guangzhou, Guangdong 510640, China.
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46
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Asymmetric perturbations of signalling oligomers. PROGRESS IN BIOPHYSICS AND MOLECULAR BIOLOGY 2014; 114:153-69. [PMID: 24650570 DOI: 10.1016/j.pbiomolbio.2014.03.001] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2013] [Revised: 02/26/2014] [Accepted: 03/04/2014] [Indexed: 01/06/2023]
Abstract
This review focuses on rapid and reversible noncovalent interactions for symmetric oligomers of signalling proteins. Symmetry mismatch, transient symmetry breaking and asymmetric perturbations via chemical (ligand binding) and physical (electric or mechanic) effects can initiate the signalling events. Advanced biophysical methods can reveal not only structural symmetries of stable membrane-bound signalling proteins but also asymmetric functional transition states. Relevant techniques amenable to distinguish between symmetric and asymmetric architectures are discussed including those with the capability of capturing low-populated transient conformational states. Typical examples of signalling proteins are overviewed for symmetry breaking in dimers (GPCRs, growth factor receptors, transcription factors); trimers (acid-sensing ion channels); tetramers (voltage-gated cation channels, ionotropic glutamate receptor, CNG and CHN channels); pentameric ligand-gated and mechanosensitive channels; higher order oligomers (gap junction channel, chaperonins, proteasome, virus capsid); as well as primary and secondary transporters. In conclusion, asymmetric perturbations seem to play important functional roles in a broad range of communicating networks.
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47
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Barthmes M, Jose MDF, Birkner JP, Brüggemann A, Wahl-Schott C, Koçer A. Studying mechanosensitive ion channels with an automated patch clamp. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2014; 43:97-104. [DOI: 10.1007/s00249-014-0944-2] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/04/2013] [Accepted: 02/01/2014] [Indexed: 10/25/2022]
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48
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Nicotinic acetylcholine receptor and the structural basis of neuromuscular transmission: insights from Torpedo postsynaptic membranes. Q Rev Biophys 2013; 46:283-322. [PMID: 24050525 PMCID: PMC3820380 DOI: 10.1017/s0033583513000061] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
The nicotinic acetylcholine (ACh) receptor, at the neuromuscular junction, is a neurotransmitter-gated ion channel that has been fine-tuned through evolution to transduce a chemical signal into an electrical signal with maximum efficiency and speed. It is composed from three similar and two identical polypeptide chains, arranged in a ring around a narrow membrane pore. Central to the design of this assembly is a hydrophobic gate in the pore, more than 50 Å away from sites in the extracellular domain where ACh binds. Although the molecular properties of the receptor have been explored intensively over the last few decades, only recently have structures emerged revealing its complex architecture and illuminating how ACh entering the binding sites opens the distant gate. Postsynaptic membranes isolated from the (muscle-derived) electric organ of the Torpedo ray have underpinned most of the structural studies: the membranes form tubular vesicles having receptors arranged on a regular surface lattice, which can be imaged directly in frozen physiological solutions. Advances in electron crystallographic techniques have also been important, enabling analysis of the closed- and open-channel forms of the receptor in unreacted tubes or tubes reacted briefly with ACh. The structural differences between these two forms show that all five subunits participate in a concerted conformational change communicating the effect of ACh binding to the gate, but that three of them (αγ, β and δ) play a dominant role. Flexing of oppositely facing pore-lining α-helices is the principal motion determining the closed/open state of the gate. These results together with the findings of biochemical, biophysical and other structural studies allow an integrated description of the receptor and of its mode of action at the synapse.
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49
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Liang C, Louhivuori M, Marrink SJ, Jansen TLC, Knoester J. Vibrational Spectra of a Mechanosensitive Channel. J Phys Chem Lett 2013; 4:448-452. [PMID: 26281739 DOI: 10.1021/jz3019258] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
We report the simulated vibrational spectra of a mechanosensitive membrane channel in different gating states. Our results show that while linear absorption is insensitive to structural differences, linear dichroism and sum-frequency generation spectroscopies are sensitive to the orientation of the transmembrane helices, which is changing during the opening process. Linear dichroism cannot distinguish an intermediate structure from the closed structure, but sum-frequency generation can. In addition, we find that two-dimensional infrared spectroscopy can be used to distinguish all three investigated gating states of the mechanosensitive membrane channel.
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Affiliation(s)
- Chungwen Liang
- †Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Martti Louhivuori
- ‡Groningen Biomolecular Sciences and Biotechnology Institute, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Siewert J Marrink
- ‡Groningen Biomolecular Sciences and Biotechnology Institute, Nijenborgh 7, 9747 AG Groningen, The Netherlands
| | - Thomas L C Jansen
- †Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
| | - Jasper Knoester
- †Center for Theoretical Physics and Zernike Institute for Advanced Materials, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands
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50
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Halža E, Bro TH, Bilenberg B, Koçer A. Well-Defined Microapertures for Ion Channel Biosensors. Anal Chem 2012; 85:811-5. [DOI: 10.1021/ac303005g] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Erik Halža
- Groningen Biomolecular Sciences and Biotechnology Institute & BioMaDe Technology Foundation, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
| | | | - Brian Bilenberg
- NIL Technology ApS, Diplomvej 381, DK-2800, Kongens Lyngby, Denmark
| | - Armağan Koçer
- Groningen Biomolecular Sciences and Biotechnology Institute & BioMaDe Technology Foundation, Nijenborgh 4, 9747 AG, Groningen, The Netherlands
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