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Ramsey K, Britt M, Maramba J, Ushijima B, Moller E, Anishkin A, Häse C, Sukharev S. The dynamic hypoosmotic response of Vibrio cholerae relies on the mechanosensitive channel MscS. iScience 2024; 27:110001. [PMID: 38868203 PMCID: PMC11167432 DOI: 10.1016/j.isci.2024.110001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2023] [Revised: 03/04/2024] [Accepted: 05/14/2024] [Indexed: 06/14/2024] Open
Abstract
Vibrio cholerae adapts to osmotic down-shifts by releasing metabolites through two mechanosensitive (MS) channels, low-threshold MscS and high-threshold MscL. To investigate each channel's contribution to the osmotic response, we generated ΔmscS, ΔmscL, and double ΔmscL ΔmscS mutants in V. cholerae O395. We characterized their tension-dependent activation in patch-clamp, and the millisecond-scale osmolyte release kinetics using a stopped-flow light scattering technique. We additionally generated numerical models describing osmolyte and water fluxes. We illustrate the sequence of events and define the parameters that characterize discrete phases of the osmotic response. Survival is correlated to the extent of cell swelling, the rate of osmolyte release, and the completeness of post-shock membrane resealing. Not only do the two channels interact functionally, but there is also an up-regulation of MscS in the ΔmscL strain, suggesting transcriptional crosstalk. The data reveal the role of MscS in the termination of the osmotic permeability response in V. cholerae.
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Affiliation(s)
- Kristen Ramsey
- Department of Biology, University of Maryland, College Park, MD, USA
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, CT, USA
| | - Madolyn Britt
- Department of Biology, University of Maryland, College Park, MD, USA
- Biophysics Graduate Program, University of Maryland, College Park, MD, USA
| | - Joseph Maramba
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Blake Ushijima
- Biology and Marine Biology, University of North Carolina Wilmington, Wilmington, NC, USA
| | - Elissa Moller
- Department of Biology, University of Maryland, College Park, MD, USA
- Biophysics Graduate Program, University of Maryland, College Park, MD, USA
| | - Andriy Anishkin
- Department of Biology, University of Maryland, College Park, MD, USA
| | - Claudia Häse
- Carlson College of Veterinary Medicine, Oregon State University, Corvallis, OR, USA
| | - Sergei Sukharev
- Department of Biology, University of Maryland, College Park, MD, USA
- Biophysics Graduate Program, University of Maryland, College Park, MD, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, MD, USA
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Moller E, Britt M, Zhou F, Yang H, Anshkin A, Ernst R, Sukharev S, Matthies D. Polymer-extracted structure of the mechanosensitive channel MscS reveals the role of protein-lipid interactions in the gating cycle. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.22.576751. [PMID: 38328078 PMCID: PMC10849555 DOI: 10.1101/2024.01.22.576751] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
Membrane protein structure determination is not only technically challenging but is further complicated by the removal or displacement of lipids, which can result in non-native conformations or a strong preference for certain states at the exclusion of others. This is especially applicable to mechanosensitive channels (MSC's) that evolved to gate in response to subtle changes in membrane tension transmitted through the lipid bilayer. E. coli MscS, a model bacterial system, is an ancestral member of the large family of MSCs found across all phyla of walled organisms. As a tension sensor, MscS is very sensitive and highly adaptive; it readily opens under super-threshold tension and closes under no tension, but under lower tensions, it slowly inactivates and can only recover when tension is released. However, existing cryo-EM structures do not explain the entire functional gating cycle of open, closed, and inactivated states. A central question in the field has been the assignment of the frequently observed non-conductive conformation to either a closed or inactivated state. Here, we present a 3 Å MscS structure in native nanodiscs obtained with Glyco-DIBMA polymer extraction, eliminating the lipid removal step that is common to all previous structures. Besides the protein in the non-conductive conformation, we observe well-resolved densities of four endogenous phospholipid molecules intercalating between the lipid-facing and pore-lining helices in preferred orientations. Mutations of positively charged residues coordinating these lipids inhibit MscS inactivation, whereas removal of a negative charge near the lipid-filled crevice increases inactivation. The functional data allows us to assign this class of structures to the inactivated state. This structure reveals preserved lipids in their native locations, and the functional effects of their destabilization illustrate a novel inactivation mechanism based on an uncoupling of the peripheral tension-sensing helices from the gate.
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Britt M, Sawasato K, Moller E, Kidd G, Bogdanov M, Sukharev S. On the lipid dependence of bacterial mechanosensitive channel gating in situ. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.01.22.576706. [PMID: 38328048 PMCID: PMC10849563 DOI: 10.1101/2024.01.22.576706] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/09/2024]
Abstract
For bacterial mechanosensitive channels acting as turgor-adjusting osmolyte release valves, membrane tension is the primary stimulus driving opening transitions. Because tension is transmitted through the surrounding lipid bilayer, it is possible that the presence or absence of different lipid species may influence the function of these channels. In this work, we characterize the lipid dependence of chromosome-encoded MscS and MscL in E. coli strains with genetically altered lipid composition. We use two previously generated strains that lack one or two major lipid species (PE, PG, or CL) and engineer a third strain that is highly enriched in CL due to the presence of hyperactive cardiolipin synthase ClsA. We characterize the functional behavior of these channels using patch-clamp and quantify the relative tension midpoints, closing rates, inactivation depth, and the rate of recovery back to the closed state. We also measure the osmotic survival of lipid-deficient strains, which characterizes the functional consequences of lipid-mediated channel function at the cell level. We find that the opening and closing behavior of MscS and MscL tolerate the absence of specific lipid species remarkably well. The lack of cardiolipin (CL), however, reduces the active MscS population relative to MscL and decreases the closing rate, slightly increasing the propensity of MscS toward inactivation and slowing the recovery process. The data points to the robustness of the osmolyte release system and the importance of cardiolipin for the adaptive behavior of MscS.
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Britt M, Moller E, Maramba J, Anishkin A, Sukharev S. MscS inactivation and recovery are slow voltage-dependent processes sensitive to interactions with lipids. Biophys J 2024; 123:195-209. [PMID: 38098232 PMCID: PMC10808034 DOI: 10.1016/j.bpj.2023.12.007] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Revised: 10/28/2023] [Accepted: 12/07/2023] [Indexed: 12/26/2023] Open
Abstract
Mechanosensitive channel MscS, the major bacterial osmolyte release valve, shows a characteristic adaptive behavior. With a sharp onset of activating tension the channel population readily opens, but under prolonged action of moderate tension it inactivates. The inactivated state is non-conductive and tension insensitive, which suggests that the gate becomes uncoupled from the lipid-facing domains. Because the distinct opening and inactivation transitions are both driven from the closed state by tension transmitted through the lipid bilayer, here we explore how mutations of two conserved positively charged lipid anchors, R46 and R74, affect 1) the rates of opening and inactivation and 2) the voltage dependences of these transitions. Previously estimated kinetic rates for opening-closing transitions in wild-type MscS at low voltages were 3-6 orders of magnitude higher than the rates for inactivation and recovery. Here we show that MscS activation exhibits a shallow nearly symmetric dependence on voltage, whereas inactivation is substantially augmented and recovery is slowed down by depolarization. Conversely, hyperpolarization impedes inactivation and speeds up recovery. Mutations of R46 and R74 anchoring the lipid-facing helices to the inner interface to an aromatic residue (W) do not substantially change the activation energy and closing rates, but instead change the kinetics of both inactivation and recovery and essentially eliminate their voltage dependence. Uncharged polar substitutions (S or Q) for these anchors produce functional channels but increase the inactivation and reduce the recovery rates. The data clearly delineate the activation-closing and the inactivation-recovery pathways and strongly suggest that only the latter involves extensive rearrangements of the protein-lipid boundary associated with the uncoupling of the lipid-facing helices from the gate. The discovery that hyperpolarization robustly assists MscS recovery suggests that membrane potential is one of the factors that regulates osmolyte release valves by putting them either on "ready" or "standby" based on the cell's metabolic state.
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Affiliation(s)
- Madolyn Britt
- Department of Biology, University of Maryland, College Park, Maryland; Maryland Biophysics Program, University of Maryland, College Park, Maryland
| | - Elissa Moller
- Department of Biology, University of Maryland, College Park, Maryland; Maryland Biophysics Program, University of Maryland, College Park, Maryland
| | - Joseph Maramba
- Department of Biology, University of Maryland, College Park, Maryland
| | - Andriy Anishkin
- Department of Biology, University of Maryland, College Park, Maryland
| | - Sergei Sukharev
- Department of Biology, University of Maryland, College Park, Maryland; Instiute for Physical Science and Technology, University of Maryland, College Park, Maryland; Maryland Biophysics Program, University of Maryland, College Park, Maryland.
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Qin Y, Yu D, Wu D, Dong J, Li WT, Ye C, Cheung KC, Zhang Y, Xu Y, Wang Y, Shi YS, Dang S. Cryo-EM structure of TMEM63C suggests it functions as a monomer. Nat Commun 2023; 14:7265. [PMID: 37945568 PMCID: PMC10636204 DOI: 10.1038/s41467-023-42956-2] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2023] [Accepted: 10/26/2023] [Indexed: 11/12/2023] Open
Abstract
The TMEM63 family proteins (A, B, and C), calcium-permeable channels in animals that are preferentially activated by hypo-osmolality, have been implicated in various physiological functions. Deficiency of these channels would cause many diseases including hearing loss. However, their structures and physiological roles are not yet well understood. In this study, we determine the cryo-electron microscopy (cryo-EM) structure of the mouse TMEM63C at 3.56 Å, and revealed structural differences compared to TMEM63A, TMEM63B, and the plant orthologues OSCAs. Further structural guided mutagenesis and calcium imaging demonstrated the important roles of the coupling of TM0 and TM6 in channel activity. Additionally, we confirm that TMEM63C exists primarily as a monomer under physiological conditions, in contrast, TMEM63B is a mix of monomer and dimer in cells, suggesting that oligomerization is a regulatory mechanism for TMEM63 proteins.
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Affiliation(s)
- Yuqi Qin
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Daqi Yu
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Dan Wu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Nanjing Drum Tower Hospital Affiliated to Medical School, Nanjing University, Nanjing, 210032, China
| | - Jiangqing Dong
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - William Thomas Li
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Chang Ye
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Nanjing Drum Tower Hospital Affiliated to Medical School, Nanjing University, Nanjing, 210032, China
| | - Kai Chit Cheung
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Yingyi Zhang
- Biological Cryo-EM Center, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, China
| | - Yun Xu
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Nanjing Drum Tower Hospital Affiliated to Medical School, Nanjing University, Nanjing, 210032, China
| | - YongQiang Wang
- Howard Hughes Medical Institute, University of California, San Francisco, CA, 94158, USA.
| | - Yun Stone Shi
- State Key Laboratory of Pharmaceutical Biotechnology, Department of Neurology, Nanjing Drum Tower Hospital Affiliated to Medical School, Nanjing University, Nanjing, 210032, China.
- Guangdong Institute of Intelligence Science and Technology, Hengqin, Zhuhai, 519031, China.
| | - Shangyu Dang
- Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.
- Southern Marine Science and Engineering Guangdong Laboratory (Guangzhou), Guangzhou, China.
- HKUST-Shenzhen Research Institute, Nanshan, Shenzhen, 518057, China.
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Ramsey K, Britt M, Maramba J, Ushijima B, Moller E, Anishkin A, Hase C, Sukharev S. The dynamic hypoosmotic response of Vibrio cholerae relies on the mechanosensitive channel MscS. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539864. [PMID: 37214804 PMCID: PMC10197554 DOI: 10.1101/2023.05.08.539864] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Like other intestinal bacteria, the facultative pathogen Vibrio cholerae adapts to a wide range of osmotic environments. Under drastic osmotic down-shifts, Vibrio avoids mechanical rupture by rapidly releasing excessive metabolites through mechanosensitive (MS) channels that belong to two major types, low-threshold MscS and high-threshold MscL. To investigate each channel individual contribution to V. cholerae osmotic permeability response, we generated individual ΔmscS, ∆mscL, and double ΔmscL ΔmscS mutants in V. cholerae O395 and characterized their tension-dependent activation in patch-clamp experiments, as well as their millisecond-scale osmolyte release kinetics using a stopped-flow light scattering technique. We additionally generated numerical models reflecting the kinetic competition of osmolyte release with water influx. Both mutants lacking MscS exhibited delayed osmolyte release kinetics and decreased osmotic survival rates compared to WT. The ΔmscL mutant showed comparable release kinetics to WT, but a higher osmotic survival, while ΔmscS had low survival, comparable to the double ΔmscL ΔmscS mutant. By analyzing release kinetics following rapid medium dilution, we illustrate the sequence of events and define the set of parameters that characterize discrete phases of the osmotic response. Osmotic survival rates are directly correlated to the extent and duration of cell swelling, the rate of osmolyte release and the onset time, and the completeness of the post-shock membrane resealing. Not only do the two channels interact functionally during the resealing phase, but there is also a compensatory up-regulation of MscS in the ΔmscL strain suggesting some transcriptional crosstalk. The data reveal the advantage of the low-threshold MscS channel in curbing tension surges, without which MscL becomes toxic, and the role of MscS in the proper termination of the osmotic permeability response in Vibrio.
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Fumadó Navarro J, Lomora M. Mechanoresponsive Drug Delivery Systems for Vascular Diseases. Macromol Biosci 2023; 23:e2200466. [PMID: 36670512 DOI: 10.1002/mabi.202200466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 01/16/2023] [Indexed: 01/22/2023]
Abstract
Mechanoresponsive drug delivery systems (DDS) have emerged as promising candidates to improve the current effectiveness and lower the side effects typically associated with direct drug administration in the context of vascular diseases. Despite tremendous research efforts to date, designing drug delivery systems able to respond to mechanical stimuli to potentially treat these diseases is still in its infancy. By understanding relevant biological forces emerging in healthy and pathological vascular endothelium, it is believed that better-informed design strategies can be deduced for the fabrication of simple-to-complex macromolecular assemblies capable of sensing mechanical forces. These responsive systems are discussed through insights into essential parameter design (composition, size, shape, and aggregation state) , as well as their functionalization with (macro)molecules that are intrinsically mechanoresponsive (e.g., mechanosensitive ion channels and mechanophores). Mechanical forces, including the pathological shear stress and exogenous stimuli (e.g., ultrasound, magnetic fields), used for the activation of mechanoresponsive DDS are also introduced, followed by in vitro and in vivo experimental models used to investigate and validate such novel therapies. Overall, this review aims to propose a fresh perspective through identified challenges and proposed solutions that could be of benefit for the further development of this exciting field.
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Affiliation(s)
- Josep Fumadó Navarro
- School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland
- CÚRAM, SFI Research Centre for Medical Devices, University of Galway, Upper Newcastle, Galway, H91 W2TY, Ireland
| | - Mihai Lomora
- School of Biological and Chemical Sciences, University of Galway, University Road, Galway, H91 TK33, Ireland
- CÚRAM, SFI Research Centre for Medical Devices, University of Galway, Upper Newcastle, Galway, H91 W2TY, Ireland
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Song M, Zhang M, He S, Li L, Hu H. Ultrasonic neuromodulation mediated by mechanosensitive ion channels: current and future. Front Neurosci 2023; 17:1232308. [PMID: 37583416 PMCID: PMC10423872 DOI: 10.3389/fnins.2023.1232308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2023] [Accepted: 07/12/2023] [Indexed: 08/17/2023] Open
Abstract
Ultrasound neuromodulation technology is a promising neuromodulation approach, with the advantages of noninvasiveness, high-resolution, deep penetration and good targeting, which aid in circumventing the side effects of drugs and invasive therapeutic interventions. Ultrasound can cause mechanical effects, activate mechanosensitive ion channels and alter neuronal excitability, producing biological effects. The structural determination of mechanosensitive ion channels will greatly contribute to our understanding of the molecular mechanisms underlying mechanosensory transduction. However, the underlying biological mechanism of ultrasonic neuromodulation remains poorly understood. Hence, this review aims to provide an outline of the properties of ultrasound, the structures of specific mechanosensitive ion channels, and their role in ultrasound neuromodulation.
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Affiliation(s)
- Mengyao Song
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- Research and Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
| | - Mingxia Zhang
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- Research and Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
| | - Sixuan He
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- Research and Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
| | - Le Li
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- Research and Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
| | - Huijing Hu
- Institute of Medical Research, Northwestern Polytechnical University, Xi’an, China
- Research and Development Institute of Northwestern Polytechnical University in Shenzhen, Shenzhen, China
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Sawada Y, Nomura T, Martinac B, Sokabe M. A novel force transduction pathway from a tension sensor to the gate in the mechano-gating of MscL channel. Front Chem 2023; 11:1175443. [PMID: 37347044 PMCID: PMC10279863 DOI: 10.3389/fchem.2023.1175443] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2023] [Accepted: 05/22/2023] [Indexed: 06/23/2023] Open
Abstract
The bacterial mechanosensitive channel of large conductance MscL is activated exclusively by increased tension in the membrane bilayer. Despite many proposed models for MscL opening, its precise mechano-gating mechanism, particularly how the received force at the tension sensor transmits to the gate remains incomplete. Previous studies have shown that along with amphipathic N-terminus located near the cytoplasmic surface of the membrane, Phe78 residue near the outer surface also acts as a "tension sensor," while Gly22 is a central constituent of the "hydrophobic gate." Present study focused on elucidating the force transmission mechanism from the sensor Phe78 in the outer transmembrane helix (TM2) to the gate in the inner transmembrane helix (TM1) of MscL by applying the patch clamp and molecular dynamics (MD) simulations to the wild type MscL channel and its single mutants at the sensor (F78N), the gate (G22N) and their combination (G22N/F78N) double mutant. F78N MscL resulted in a severe loss-of-function, while G22N MscL caused a gain-of-function channel exhibiting spontaneous openings at the resting membrane tension. We initially speculated that the spontaneous opening in G22N mutant might occur without tension acting on Phe78 residue. To test this hypothesis, we examined the (G22N/F78N) double mutant, which unexpectedly exhibited neither spontaneous activity nor activity by a relatively high membrane tension. To understand the underlying mechanism, we conducted MD simulations and analyzed the force transduction pathway. Results showed that the mutation at the tension sensor (F78N) in TM2 caused decreased interaction of this residue not only with lipids, but also with a group of amino acids (Ile32-Leu36-Ile40) in the neighboring TM1 helix, which resulted in an inefficient force transmission to the gate-constituting amino acids on TM1. This change also induced a slight tilting of TM1 towards the membrane plane and decreased the size of the channel pore at the gate, which seems to be the major mechanism for the inhibition of spontaneous opening of the double mutant channel. More importantly, the newly identified interaction between the TM2 (Phe78) and adjacent TM1 (Ile32-Leu36-Ile40) helices seems to be an essential force transmitting mechanism for the stretch-dependent activation of MscL given that substitution of any one of these four amino acids with Asn resulted in severe loss-of-function MscL as reported in our previous work.
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Affiliation(s)
- Yasuyuki Sawada
- Department of Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- Institute of Materials Innovation, Institutes of Innovation for Future Society, Nagoya University, Nagoya, Japan
| | - Takeshi Nomura
- International Cooperative Research Project, Solution Oriented Research for Science and Technology (ICORP/SORST), Cell Mechanosensing, Japan Science and Technology Agency (JST), Nagoya, Japan
- Molecular Cardiology and Biophysics Division, Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
- School of Human Science and Environment, University of Hyogo, Himeji, Japan
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Mechanosensory Biophysics Laboratory, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, Australia
| | - Masahiro Sokabe
- Department of Physiology, Nagoya University Graduate School of Medicine, Nagoya, Japan
- International Cooperative Research Project, Solution Oriented Research for Science and Technology (ICORP/SORST), Cell Mechanosensing, Japan Science and Technology Agency (JST), Nagoya, Japan
- Human Information Systems Laboratories, Kanazawa Institute of Technology, Hakusan, Ishikawa, Japan
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Çetiner U, Raz O, Britt M, Sukharev S. Dissipation during the Gating Cycle of the Bacterial Mechanosensitive Ion Channel Approaches the Landauer Limit. ENTROPY (BASEL, SWITZERLAND) 2023; 25:e25050779. [PMID: 37238534 DOI: 10.3390/e25050779] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 05/03/2023] [Accepted: 05/03/2023] [Indexed: 05/28/2023]
Abstract
The Landauer principle sets a thermodynamic bound of kBT ln 2 on the energetic cost of erasing each bit of information. It holds for any memory device, regardless of its physical implementation. It was recently shown that carefully built artificial devices can attain this bound. In contrast, biological computation-like processes, e.g., DNA replication, transcription and translation use an order of magnitude more than their Landauer minimum. Here, we show that reaching the Landauer bound is nevertheless possible with biological devices. This is achieved using a mechanosensitive channel of small conductance (MscS) from E. coli as a memory bit. MscS is a fast-acting osmolyte release valve adjusting turgor pressure inside the cell. Our patch-clamp experiments and data analysis demonstrate that under a slow switching regime, the heat dissipation in the course of tension-driven gating transitions in MscS closely approaches its Landauer limit. We discuss the biological implications of this physical trait.
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Affiliation(s)
- Uğur Çetiner
- Maryland Biophysics Program, Institute for Physical Science and Technology, Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Oren Raz
- Department of Physics of Complex Systems, Faculty of Physics, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Madolyn Britt
- Maryland Biophysics Program, Institute for Physical Science and Technology, Department of Biology, University of Maryland, College Park, MD 20742, USA
| | - Sergei Sukharev
- Maryland Biophysics Program, Institute for Physical Science and Technology, Department of Biology, University of Maryland, College Park, MD 20742, USA
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11
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Britt M, Moller E, Maramba J, Anishkin A, Sukharev S. MscS inactivation and recovery are slow voltage-dependent processes sensitive to interactions with lipids. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.05.08.539870. [PMID: 37215046 PMCID: PMC10197514 DOI: 10.1101/2023.05.08.539870] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
Mechanosensitive channel MscS, the major bacterial osmolyte release valve, shows a characteristic adaptive behavior. With a sharp onset of activating tension, the channel population readily opens, but under prolonged action of moderate near-threshold tension, it inactivates. The inactivated state is non-conductive and tension-insensitive, which suggests that the gate gets uncoupled from the lipid-facing domains. The kinetic rates for tension-driven opening-closing transitions are 4-6 orders of magnitude higher than the rates for inactivation and recovery. Here we show that inactivation is augmented and recovery is slowed down by depolarization. Hyperpolarization, conversely, impedes inactivation and speeds up recovery. We then address the question of whether protein-lipid interactions may set the rates and influence voltage dependence of inactivation and recovery. Mutations of conserved arginines 46 and 74 anchoring the lipid-facing helices to the inner membrane leaflet to tryptophans do not change the closing transitions, but instead change the kinetics of both inactivation and recovery and essentially eliminate their voltage-dependence. Uncharged polar substitutions (S or Q) for these anchors produce functional channels but increase the inactivation and reduce the recovery rates. The data suggest that it is not the activation and closing transitions, but rather the inactivation and recovery pathways that involve substantial rearrangements of the protein-lipid boundary associated with the separation of the lipid-facing helices from the gate. The discovery that hyperpolarization robustly assists MscS recovery indicates that membrane potential can regulate osmolyte release valves by putting them either on the 'ready' or 'standby' mode depending on the cell's metabolic state.
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Moller E, Britt M, Schams A, Cetuk H, Anishkin A, Sukharev S. Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response. J Gen Physiol 2023; 155:e202213168. [PMID: 37022337 PMCID: PMC10082366 DOI: 10.1085/jgp.202213168] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 02/06/2023] [Accepted: 03/20/2023] [Indexed: 04/07/2023] Open
Abstract
Free-living microorganisms are subjected to drastic changes in osmolarity. To avoid lysis under sudden osmotic down-shock, bacteria quickly expel small metabolites through the tension-activated channels MscL, MscS, and MscK. We examined five chromosomal knockout strains, ∆mscL, ∆mscS, a double knockout ∆mscS ∆mscK, and a triple knockout ∆mscL ∆mscS ∆mscK, in comparison to the wild-type parental strain. Stopped-flow experiments confirmed that both MscS and MscL mediate fast osmolyte release and curb cell swelling, but osmotic viability assays indicated that they are not equivalent. MscS alone was capable of rescuing the cell population, but in some strains, MscL did not rescue and additionally became toxic in the absence of both MscS and MscK. Furthermore, MscS was upregulated in the ∆mscL strain, suggesting either a crosstalk between the two genes/proteins or the influence of cell mechanics on mscS expression. The data shows that for the proper termination of the permeability response, the high-threshold (MscL) and the low-threshold (MscS/MscK) channels must act sequentially. In the absence of low-threshold channels, at the end of the release phase, MscL should stabilize membrane tension at around 10 mN/m. Patch-clamp protocols emulating the tension changes during the release phase indicated that the non-inactivating MscL, residing at its own tension threshold, flickers and produces a protracted leakage. The MscS/MscK population, when present, stays open at this stage to reduce tension below the MscL threshold and silence the large channel. When MscS reaches its own threshold, it inactivates and thus ensures proper termination of the hypoosmotic permeability response. This functional interplay between the high- and low-threshold channels is further supported by the compromised osmotic survival of bacteria expressing non-inactivating MscS mutants.
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Affiliation(s)
- Elissa Moller
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
- Biophysics Graduate Program, University of Maryland, College Park, College Park, MD, USA
| | - Madolyn Britt
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
- Biophysics Graduate Program, University of Maryland, College Park, College Park, MD, USA
| | - Anthony Schams
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
| | - Hannah Cetuk
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
| | - Andriy Anishkin
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
| | - Sergei Sukharev
- Department of Biology, University of Maryland, College Park, College Park, MD, USA
- Institute for Physical Science and Technology, University of Maryland, College Park, College Park, MD, USA
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13
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Dienes B, Bazsó T, Szabó L, Csernoch L. The Role of the Piezo1 Mechanosensitive Channel in the Musculoskeletal System. Int J Mol Sci 2023; 24:ijms24076513. [PMID: 37047487 PMCID: PMC10095409 DOI: 10.3390/ijms24076513] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2023] [Revised: 03/23/2023] [Accepted: 03/27/2023] [Indexed: 04/03/2023] Open
Abstract
Since the recent discovery of the mechanosensitive Piezo1 channels, many studies have addressed the role of the channel in various physiological or even pathological processes of different organs. Although the number of studies on their effects on the musculoskeletal system is constantly increasing, we are still far from a precise understanding. In this review, the knowledge available so far regarding the musculoskeletal system is summarized, reviewing the results achieved in the field of skeletal muscles, bones, joints and cartilage, tendons and ligaments, as well as intervertebral discs.
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14
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Moller E, Britt M, Schams A, Cetuk H, Anishkin A, Sukharev S. Mechanosensitive channel MscS is critical for termination of the bacterial hypoosmotic permeability response. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.02.27.530336. [PMID: 36909569 PMCID: PMC10002685 DOI: 10.1101/2023.02.27.530336] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/06/2023]
Abstract
Free-living microorganisms are subjected to drastic changes in osmolarity. To avoid lysis under sudden osmotic down-shock, bacteria quickly expel small metabolites through the tension-activated channels MscL, MscS, and MscK. We examined five chromosomal knockout strains, Δ mscL , Δ mscS , a double knockout Δ mscS Δ mscK , and a triple knockout Δ mscL Δ mscS Δ mscK in comparison to the wild-type parental strain. Stopped-flow experiments confirmed that both MscS and MscL mediate fast osmolyte release and curb cell swelling, but osmotic viability assays indicated that they are not equivalent. MscS alone was capable of rescuing the cell population, but in some strains MscL did not rescue and additionally became toxic in the absence of both MscS and MscK. Furthermore, MscS was upregulated in the Δ mscL strain, suggesting either a cross-talk between the two genes/proteins or the influence of cell mechanics on mscS expression. The data shows that for the proper termination of the permeability response, the high-threshold (MscL) and the low-threshold (MscS/MscK) channels must act sequentially. In the absence of low-threshold channels, at the end of the release phase, MscL should stabilize membrane tension at around 10 mN/m. Patch-clamp protocols emulating the tension changes during the release phase indicated that the non-inactivating MscL, residing at its own tension threshold, flickers and produces a protracted leakage. The MscS/MscK population, when present, stays open at this stage to reduce tension below the MscL threshold and silence the large channel. When MscS reaches its own threshold, it inactivates and thus ensures proper termination of the hypoosmotic permeability response. This functional interplay between the high- and low-threshold channels is further supported by the compromised osmotic survival of bacteria expressing non-inactivating MscS mutants. Summary for the table of contents The kinetics of hypotonic osmolyte release from E. coli is analyzed in conjunction with bacterial survival. It is shown that MscL, the high-threshold 'emergency release valve', rescues bacteria from down-shocks only in the presence of MscS, MscK or other low-threshold channels that are necessary to pacify MscL at the end of the release phase.
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15
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Sukharev S, Anishkin A. Mechanosensitive Channels: History, Diversity, and Mechanisms. BIOCHEMISTRY (MOSCOW), SUPPLEMENT SERIES A: MEMBRANE AND CELL BIOLOGY 2022. [DOI: 10.1134/s1990747822090021] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
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16
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Flegler VJ, Rasmussen T, Böttcher B. How Functional Lipids Affect the Structure and Gating of Mechanosensitive MscS-like Channels. Int J Mol Sci 2022; 23:ijms232315071. [PMID: 36499396 PMCID: PMC9739000 DOI: 10.3390/ijms232315071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Revised: 11/21/2022] [Accepted: 11/23/2022] [Indexed: 12/04/2022] Open
Abstract
The ability to cope with and adapt to changes in the environment is essential for all organisms. Osmotic pressure is a universal threat when environmental changes result in an imbalance of osmolytes inside and outside the cell which causes a deviation from the normal turgor. Cells have developed a potent system to deal with this stress in the form of mechanosensitive ion channels. Channel opening releases solutes from the cell and relieves the stress immediately. In bacteria, these channels directly sense the increased membrane tension caused by the enhanced turgor levels upon hypoosmotic shock. The mechanosensitive channel of small conductance, MscS, from Escherichia coli is one of the most extensively studied examples of mechanically stimulated channels. Different conformational states of this channel were obtained in various detergents and membrane mimetics, highlighting an intimate connection between the channel and its lipidic environment. Associated lipids occupy distinct locations and determine the conformational states of MscS. Not all these features are preserved in the larger MscS-like homologues. Recent structures of homologues from bacteria and plants identify common features and differences. This review discusses the current structural and functional models for MscS opening, as well as the influence of certain membrane characteristics on gating.
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17
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Mount J, Maksaev G, Summers BT, Fitzpatrick JAJ, Yuan P. Structural basis for mechanotransduction in a potassium-dependent mechanosensitive ion channel. Nat Commun 2022; 13:6904. [PMID: 36371466 PMCID: PMC9653487 DOI: 10.1038/s41467-022-34737-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Accepted: 11/04/2022] [Indexed: 11/13/2022] Open
Abstract
Mechanosensitive channels of small conductance, found in many living organisms, open under elevated membrane tension and thus play crucial roles in biological response to mechanical stress. Amongst these channels, MscK is unique in that its activation also requires external potassium ions. To better understand this dual gating mechanism by force and ligand, we elucidate distinct structures of MscK along the gating cycle using cryo-electron microscopy. The heptameric channel comprises three layers: a cytoplasmic domain, a periplasmic gating ring, and a markedly curved transmembrane domain that flattens and expands upon channel opening, which is accompanied by dilation of the periplasmic ring. Furthermore, our results support a potentially unifying mechanotransduction mechanism in ion channels depicted as flattening and expansion of the transmembrane domain.
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Affiliation(s)
- Jonathan Mount
- grid.4367.60000 0001 2355 7002Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO USA
| | - Grigory Maksaev
- grid.4367.60000 0001 2355 7002Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO USA
| | - Brock T. Summers
- grid.4367.60000 0001 2355 7002Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO USA
| | - James A. J. Fitzpatrick
- grid.4367.60000 0001 2355 7002Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Washington University Center for Cellular Imaging, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Department of Neuroscience, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Department of Biomedical Engineering, Washington University in Saint Louis, Saint Louis, MO USA
| | - Peng Yuan
- grid.4367.60000 0001 2355 7002Department of Cell Biology and Physiology, Washington University School of Medicine, Saint Louis, MO USA ,grid.4367.60000 0001 2355 7002Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO USA
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18
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Lecoutre S, Lambert M, Drygalski K, Dugail I, Maqdasy S, Hautefeuille M, Clément K. Importance of the Microenvironment and Mechanosensing in Adipose Tissue Biology. Cells 2022; 11:cells11152310. [PMID: 35954152 PMCID: PMC9367348 DOI: 10.3390/cells11152310] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2022] [Revised: 07/19/2022] [Accepted: 07/23/2022] [Indexed: 11/16/2022] Open
Abstract
The expansion of adipose tissue is an adaptive mechanism that increases nutrient buffering capacity in response to an overall positive energy balance. Over the course of expansion, the adipose microenvironment undergoes continual remodeling to maintain its structural and functional integrity. However, in the long run, adipose tissue remodeling, typically characterized by adipocyte hypertrophy, immune cells infiltration, fibrosis and changes in vascular architecture, generates mechanical stress on adipose cells. This mechanical stimulus is then transduced into a biochemical signal that alters adipose function through mechanotransduction. In this review, we describe the physical changes occurring during adipose tissue remodeling, and how they regulate adipose cell physiology and promote obesity-associated dysfunction in adipose tissue.
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Affiliation(s)
- Simon Lecoutre
- Nutrition and Obesities: Systemic Approaches Research Group (Nutri-Omics), Sorbonne Université, INSERM, F-75013 Paris, France; (S.L.); (K.D.); (I.D.)
| | - Mélanie Lambert
- Labex Inflamex, Université Sorbonne Paris Nord, INSERM, F-93000 Bobigny, France;
| | - Krzysztof Drygalski
- Nutrition and Obesities: Systemic Approaches Research Group (Nutri-Omics), Sorbonne Université, INSERM, F-75013 Paris, France; (S.L.); (K.D.); (I.D.)
| | - Isabelle Dugail
- Nutrition and Obesities: Systemic Approaches Research Group (Nutri-Omics), Sorbonne Université, INSERM, F-75013 Paris, France; (S.L.); (K.D.); (I.D.)
| | - Salwan Maqdasy
- Department of Medicine (H7), Karolinska Institutet Hospital, C2-94, 14186 Stockholm, Sweden;
| | - Mathieu Hautefeuille
- Laboratoire de Biologie du Développement (UMR 7622), IBPS, Sorbonne Université, F-75005 Paris, France;
| | - Karine Clément
- Nutrition and Obesities: Systemic Approaches Research Group (Nutri-Omics), Sorbonne Université, INSERM, F-75013 Paris, France; (S.L.); (K.D.); (I.D.)
- Assistance Publique Hôpitaux de Paris, Nutrition Department, CRNH Ile-de-France, Pitié-Salpêtrière Hospital, F-75013 Paris, France
- Correspondence: or
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19
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Martinac B, Kung C. The force-from-lipid principle and its origin, a ‘ what is true for E. coli is true for the elephant’ refrain. J Neurogenet 2022; 36:44-54. [DOI: 10.1080/01677063.2022.2097674] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022]
Affiliation(s)
- Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, Australia
- School of Clinical Medicine, UNSW Medicine & Health, St Vincent's Healthcare Clinical Campus, Faculty of Medicine and Health, University of New South Wales, Sydney, Australia
| | - Ching Kung
- Laboratory of Molecular Biology and the Department of Genetics, University of Wisconsin–Madison, Madison, WI, USA
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20
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Wray R, Wang J, Blount P, Iscla I. Activation of a Bacterial Mechanosensitive Channel, MscL, Underlies the Membrane Permeabilization of Dual-Targeting Antibacterial Compounds. Antibiotics (Basel) 2022; 11:970. [PMID: 35884223 PMCID: PMC9312261 DOI: 10.3390/antibiotics11070970] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2022] [Revised: 07/13/2022] [Accepted: 07/15/2022] [Indexed: 01/27/2023] Open
Abstract
Resistance to antibiotics is a serious and worsening threat to human health worldwide, and there is an urgent need to develop new antibiotics that can avert it. One possible solution is the development of compounds that possess multiple modes of action, requiring at least two mutations to acquire resistance. Compound SCH-79797 both avoids resistance and has two mechanisms of action: one inhibiting the folate pathway, and a second described as "membrane permeabilization"; however, the mechanism by which membranes from bacterial cells, but not the host, are disrupted has remained mysterious. The opening of the bacterial mechanosensitive channel of large conductance, MscL, which ordinarily serves the physiological role of osmotic emergency release valves gated by hypoosmotic shock, has been previously demonstrated to affect bacterial membrane permeabilization. MscL allows the rapid permeabilization of both ions and solutes through the opening of the largest known gated pore, which has a diameter of 30 Å. We found that SCH-79797 and IRS-16, a more potent derivative, directly bind to the MscL channel and produce membrane permeabilization as a result of its activation. These findings suggest that possessing or adding an MscL-activating component to an antibiotic compound could help to lower toxicity and evade antibiotic resistance.
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Affiliation(s)
- Robin Wray
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA;
| | - Junmei Wang
- Computational Chemical Genomics Screening Center, Department of Pharmaceutical Sciences, School of Pharmacy, University of Pittsburgh, Pittsburg, PA 15261, USA
| | - Paul Blount
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA;
| | - Irene Iscla
- Department of Physiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, USA;
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21
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Notti RQ, Walz T. Native-like environments afford novel mechanistic insights into membrane proteins. Trends Biochem Sci 2022; 47:561-569. [PMID: 35331611 PMCID: PMC9847468 DOI: 10.1016/j.tibs.2022.02.008] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2021] [Revised: 02/14/2022] [Accepted: 02/21/2022] [Indexed: 01/21/2023]
Abstract
Advances in cryogenic electron microscopy (cryo-EM) enabled routine near-atomic structure determination of membrane proteins, while nanodisc technology has provided a way to provide membrane proteins with a native or native-like lipid environment. After giving a brief history of membrane mimetics, we present example structures of membrane proteins in nanodiscs that revealed information not provided by structures obtained in detergent. We describe how the lipid environment surrounding the membrane protein can be custom designed during nanodisc assembly and how it can be modified after assembly to test functional hypotheses. Because nanodiscs most closely replicate the physiologic environment of membrane proteins and often afford novel mechanistic insights, we propose that nanodiscs ought to become the standard for structural studies on membrane proteins.
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Affiliation(s)
- Ryan Q. Notti
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, 1230 York Avenue, New York, NY 10065,Department of Medicine, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, NY 10065
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, 1230 York Avenue, New York, NY 10065,Correspondence: (Walz, T.)
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22
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Miles L, Powell J, Kozak C, Song Y. Mechanosensitive Ion Channels, Axonal Growth, and Regeneration. Neuroscientist 2022:10738584221088575. [PMID: 35414308 PMCID: PMC9556659 DOI: 10.1177/10738584221088575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cells sense and respond to mechanical stimuli by converting those stimuli into biological signals, a process known as mechanotransduction. Mechanotransduction is essential in diverse cellular functions, including tissue development, touch sensitivity, pain, and neuronal pathfinding. In the search for key players of mechanotransduction, several families of ion channels were identified as being mechanosensitive and were demonstrated to be activated directly by mechanical forces in both the membrane bilayer and the cytoskeleton. More recently, Piezo ion channels were discovered as a bona fide mechanosensitive ion channel, and its characterization led to a cascade of research that revealed the diverse functions of Piezo proteins and, in particular, their involvement in neuronal repair.
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Affiliation(s)
- Leann Miles
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Jackson Powell
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Casey Kozak
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Yuanquan Song
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA.,Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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23
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Lv B, Zeng Y, Zhang H, Li Z, Xu Z, Wang Y, Gao Y, Chen Y, Fu X. Mechanosensitive Channels Mediate Hypoionic Shock-Induced Aminoglycoside Potentiation against Bacterial Persisters by Enhancing Antibiotic Uptake. Antimicrob Agents Chemother 2022; 66:e0112521. [PMID: 34902270 PMCID: PMC8846477 DOI: 10.1128/aac.01125-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2021] [Accepted: 12/03/2021] [Indexed: 12/31/2022] Open
Abstract
Improving the efficacy of existing antibiotics is a promising strategy for combating antibiotic-resistant/tolerant bacterial pathogens that have become a severe threat to human health. We previously reported that aminoglycoside antibiotics could be dramatically potentiated against stationary-phase Escherichia coli cells under hypoionic shock conditions (i.e., treatment with ion-free solutions), but the underlying molecular mechanism remains unknown. Here, we show that mechanosensitive (MS) channels, a ubiquitous protein family sensing mechanical forces of cell membrane, mediate such hypoionic shock-induced aminoglycoside potentiation. Two-minute treatment under conditions of hypoionic shock (e.g., in pure water) greatly enhances the bactericidal effects of aminoglycosides against both spontaneous and triggered E. coli persisters, numerous strains of Gram-negative pathogens in vitro, and Pseudomonas aeruginosa in mice. Such potentiation is achieved by hypoionic shock-enhanced bacterial uptake of aminoglycosides and is linked to hypoionic shock-induced destabilization of the cytoplasmic membrane in E. coli. Genetic and biochemical analyses reveal that MscS-family channels directly and redundantly mediate aminoglycoside uptake upon hypoionic shock and thus potentiation, with MscL channel showing reduced effect. Molecular docking and site-directed mutagenesis analyses reveal a putative streptomycin-binding pocket in MscS, critical for streptomycin uptake and potentiation. These results suggest that hypoionic shock treatment destabilizes the cytoplasmic membrane and thus changes the membrane tension, which immediately activates MS channels that are able to effectively transport aminoglycosides into the cytoplasm for downstream killing. Our findings reveal the biological effects of hypoionic shock on bacteria and can help to develop novel adjuvants for aminoglycoside potentiation to combat bacterial pathogens via activating MS channels.
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Affiliation(s)
- Boyan Lv
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Youhui Zeng
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Huaidong Zhang
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Zhongyan Li
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Zhaorong Xu
- Fujian Burn Institute, Fujian Medical University Union Hospital, Fuzhou, Fujian Province, China
| | - Yan Wang
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Yuanyuan Gao
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Yajuan Chen
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Xinmiao Fu
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
- Engineering Research Center of Industrial Microbiology of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
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24
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Zhang Y, Angiulli G, Martinac B, Cox CD, Walz T. Cyclodextrins for structural and functional studies of mechanosensitive channels. J Struct Biol X 2021; 5:100053. [PMID: 34816118 PMCID: PMC8593449 DOI: 10.1016/j.yjsbx.2021.100053] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/12/2021] [Accepted: 10/19/2021] [Indexed: 11/22/2022] Open
Abstract
Mechanosensitive (MS) channels that are activated by the 'force-from-lipids' (FFL) principle rest in the membrane in a closed state but open a transmembrane pore in response to changes in the transmembrane pressure profile. The molecular implementations of the FFL principle vary widely between different MS channel families. The function of MS channels is often studied by patch-clamp electrophysiology, in which mechanical force or amphipathic molecules are used to activate the channels. Structural studies of MS channels in states other than the closed resting state typically relied on the use of mutant channels. Cyclodextrins (CDs) were recently introduced as a relatively easy and convenient approach to generate membrane tension. The principle is that CDs chelate hydrophobic molecules and can remove lipids from membranes, thus forcing the remaining lipids to cover more surface area and creating tension for membrane proteins residing in the membranes. CDs can be used to study the structure of MS channels in a membrane under tension by using single-particle cryo-electron microscopy to image the channels in nanodiscs after incubation with CDs as well as to characterize the function of MS channels by using patch-clamp electrophysiology to record the effect of CDs on channels inserted into membrane patches excised from proteoliposomes. Importantly, because incubation of membrane patches with CDs results in the activation of MscL, an MS channel that opens only shortly before membrane rupture, CD-mediated lipid removal appears to generate sufficient force to open most if not all types of MS channels that follow the FFL principle.
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Affiliation(s)
- Yixiao Zhang
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - Gabriella Angiulli
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
| | - Boris Martinac
- St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia
| | - Charles D. Cox
- St Vincent's Clinical School, University of New South Wales, Sydney, New South Wales, Australia
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, New South Wales, Australia
| | - Thomas Walz
- Laboratory of Molecular Electron Microscopy, The Rockefeller University, New York, NY, USA
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25
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Flegler VJ, Rasmussen A, Borbil K, Boten L, Chen HA, Deinlein H, Halang J, Hellmanzik K, Löffler J, Schmidt V, Makbul C, Kraft C, Hedrich R, Rasmussen T, Böttcher B. Mechanosensitive channel gating by delipidation. Proc Natl Acad Sci U S A 2021; 118:e2107095118. [PMID: 34376558 PMCID: PMC8379960 DOI: 10.1073/pnas.2107095118] [Citation(s) in RCA: 30] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
The mechanosensitive channel of small conductance (MscS) protects bacteria against hypoosmotic shock. It can sense the tension in the surrounding membrane and releases solutes if the pressure in the cell is getting too high. The membrane contacts MscS at sensor paddles, but lipids also leave the membrane and move along grooves between the paddles to reside as far as 15 Å away from the membrane in hydrophobic pockets. One sensing model suggests that a higher tension pulls lipids from the grooves back to the membrane, which triggers gating. However, it is still unclear to what degree this model accounts for sensing and what contribution the direct interaction of the membrane with the channel has. Here, we show that MscS opens when it is sufficiently delipidated by incubation with the detergent dodecyl-β-maltoside or the branched detergent lauryl maltose neopentyl glycol. After addition of detergent-solubilized lipids, it closes again. These results support the model that lipid extrusion causes gating: Lipids are slowly removed from the grooves and pockets by the incubation with detergent, which triggers opening. Addition of lipids in micelles allows lipids to migrate back into the pockets, which closes the channel even in the absence of a membrane. Based on the distribution of the aliphatic chains in the open and closed conformation, we propose that during gating, lipids leave the complex on the cytosolic leaflet at the height of highest lateral tension, while on the periplasmic side, lipids flow into gaps, which open between transmembrane helices.
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Affiliation(s)
| | - Akiko Rasmussen
- Lehrstuhl für Botanik I, Julius-Maximilians-Universität Würzburg, 97082 Würzburg, Germany
| | - Karina Borbil
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Lea Boten
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Hsuan-Ai Chen
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Hanna Deinlein
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Julia Halang
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Kristin Hellmanzik
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Jessica Löffler
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Vanessa Schmidt
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Cihan Makbul
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Christian Kraft
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany
| | - Rainer Hedrich
- Lehrstuhl für Botanik I, Julius-Maximilians-Universität Würzburg, 97082 Würzburg, Germany
| | - Tim Rasmussen
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany;
| | - Bettina Böttcher
- Biocenter and Rudolf-Virchow-Zentrum, Universität Würzburg, 97080 Würzburg, Germany;
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26
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Dave N, Cetiner U, Arroyo D, Fonbuena J, Tiwari M, Barrera P, Lander N, Anishkin A, Sukharev S, Jimenez V. A novel mechanosensitive channel controls osmoregulation, differentiation, and infectivity in Trypanosoma cruzi. eLife 2021; 10:67449. [PMID: 34212856 PMCID: PMC8282336 DOI: 10.7554/elife.67449] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2021] [Accepted: 07/01/2021] [Indexed: 12/19/2022] Open
Abstract
The causative agent of Chagas disease undergoes drastic morphological and biochemical modifications as it passes between hosts and transitions from extracellular to intracellular stages. The osmotic and mechanical aspects of these cellular transformations are not understood. Here we identify and characterize a novel mechanosensitive channel in Trypanosoma cruzi (TcMscS) belonging to the superfamily of small-conductance mechanosensitive channels (MscS). TcMscS is activated by membrane tension and forms a large pore permeable to anions, cations, and small osmolytes. The channel changes its location from the contractile vacuole complex in epimastigotes to the plasma membrane as the parasites develop into intracellular amastigotes. TcMscS knockout parasites show significant fitness defects, including increased cell volume, calcium dysregulation, impaired differentiation, and a dramatic decrease in infectivity. Our work provides mechanistic insights into components supporting pathogen adaptation inside the host, thus opening the exploration of mechanosensation as a prerequisite for protozoan infectivity.
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Affiliation(s)
- Noopur Dave
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, United States
| | - Ugur Cetiner
- Department of Biology, University of Maryland, College Park, United States
| | - Daniel Arroyo
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, United States
| | - Joshua Fonbuena
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, United States
| | - Megna Tiwari
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, United States
| | - Patricia Barrera
- Departmento de Biología, Facultad de Ciencias Exactas y Naturales, Instituto de Histologia y Embriologia IHEM-CONICET, Facultad de Medicina, Universidad Nacional de Cuyo, Mendoza, Argentina
| | - Noelia Lander
- Department of Biological Sciences, University of Cincinnati, Cincinnati, United States
| | - Andriy Anishkin
- Department of Biology, University of Maryland, College Park, United States
| | - Sergei Sukharev
- Department of Biology, University of Maryland, College Park, United States
| | - Veronica Jimenez
- Department of Biological Science, College of Natural Sciences and Mathematics, California State University Fullerton, Fullerton, United States
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27
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Guo J, Gu D, Zhao T, Zhao Z, Xiong Y, Sun M, Xin C, Zhang Y, Pei L, Sun J. Trends in Piezo Channel Research Over the Past Decade: A Bibliometric Analysis. Front Pharmacol 2021; 12:668714. [PMID: 33935792 PMCID: PMC8082452 DOI: 10.3389/fphar.2021.668714] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2021] [Accepted: 03/24/2021] [Indexed: 12/12/2022] Open
Abstract
Purpose: We used bibliometric methods to evaluate the global scientific output of research on Piezo channels and explore the current status and trends in this field over the past decade. Methods: Piezo channel-related studies published in 2010-2020 were retrieved from Web of Science. The R bibliometrix package was used for quantitative and qualitative analyses of publication outputs and author contributions. VOSviewer was used to construct networks based on co-authorship of countries/institutions/authors, co-citation analysis of journals/references, citation analysis of documents, and co-occurrence of keywords. Results: In total, 556 related articles and reviews were included in the final analysis. The number of publications has increased substantially with time. The country and institution contributing the most to this field was the United States and Scripps Research Institute, respectively. Ardem Patapoutian was the most productive author and ranked first among the cited authors, h-index, and m-index. The top cited reference was the article published by Coste B et al. in Science (2010) that identified Piezo1/2 in mammalian cells. The top journals in terms of the number of selected articles and citations were Nature Communications and Nature, respectively. The co-occurrence analysis revealed that Piezo channels are involved a variety of cell types (Merkel cells, neurons, endothelial cells, red blood cells), physiological processes (touch sensation, blood pressure, proprioception, vascular development), related ion channels (transient receptor potential, Gardos), and diseases (pain, distal arthrogryposis, dehydrated hereditary stomatocytosis, cancer), and pharmacology (Yoda1, GsMTx-4). Conclusion: Our bibliometric analysis shows that Piezo channel research continues to be a hotspot. The focus has evolved from Piezo identification to architecture, activation mechanism, roles in diseases, and pharmacology.
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Affiliation(s)
- Jing Guo
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Dongmei Gu
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Tingting Zhao
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Zhanhao Zhao
- Department of Massage, Danyang Hospital of Traditional Chinese Medicine, Danyang, China
| | - Yajun Xiong
- School of Internet of Things Engineering, Jiangnan University, Wuxi, China
| | - Mengzhu Sun
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Chen Xin
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
| | - Yujie Zhang
- Acupuncture and Massage College, Health and Rehabilitation College, Nanjing University of Chinese Medicine, Nanjing, China
| | - Lixia Pei
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- Acupuncture and Moxibustion Disease Project Group of China Evidence-Based Medicine Center of Traditional Chinese Medicine, Nanjing, China
| | - Jianhua Sun
- Department of Acupuncture Rehabilitation, The Affiliated Hospital of Nanjing University of Chinese Medicine, Nanjing, China
- Acupuncture and Moxibustion Disease Project Group of China Evidence-Based Medicine Center of Traditional Chinese Medicine, Nanjing, China
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28
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Lewis AH, Grandl J. Stretch and poke stimulation for characterizing mechanically activated ion channels. Methods Enzymol 2021; 654:225-253. [PMID: 34120715 DOI: 10.1016/bs.mie.2020.12.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Quantitative functional characterization of mechanically activated ion channels is most commonly achieved by a combination of patch-clamp electrophysiology and stimulation by stretch (or pressure-clamp) and poke (or cell-indentation). A variety of stretch and poke protocols can be used to make measurements of many ion channel properties, including channel number, unitary conductance, ion selectivity, stimulus threshold and sensitivity, stimulus adaptation, and gating kinetics (activation, deactivation, inactivation, recovery from inactivation). Here, we review the general methods of stretch and poke stimulation and discuss the advantages and disadvantages of each. We use the vertebrate mechanically activated ion channel Piezo1 to explain equipment components and calibration, demonstrate experimental protocols and data analyses, and discuss underlying concepts and mechanistic interpretations.
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Affiliation(s)
- Amanda H Lewis
- Department of Neurobiology, Duke University Medical Center, Durham, NC, United States
| | - Jörg Grandl
- Department of Neurobiology, Duke University Medical Center, Durham, NC, United States.
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29
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Zhu W, Hou F, Fang J, Bahrani Fard MR, Liu Y, Ren S, Wu S, Qi Y, Sui S, Read AT, Sherwood JM, Zou W, Yu H, Zhang J, Overby DR, Wang N, Ethier CR, Wang K. The role of Piezo1 in conventional aqueous humor outflow dynamics. iScience 2021; 24:102042. [PMID: 33532718 PMCID: PMC7829208 DOI: 10.1016/j.isci.2021.102042] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 12/16/2020] [Accepted: 01/05/2021] [Indexed: 12/16/2022] Open
Abstract
Controlling intraocular pressure (IOP) remains the mainstay of glaucoma therapy. The trabecular meshwork (TM), the key tissue responsible for aqueous humor (AH) outflow and IOP maintenance, is very sensitive to mechanical forces. However, it is not understood whether Piezo channels, very sensitive mechanosensors, functionally influence AH outflow. Here, we characterize the role of Piezo1 in conventional AH outflow. Immunostaining and western blot analysis showed that Piezo1 is widely expressed by TM. Patch-clamp recordings in TM cells confirmed the activation of Piezo1-derived mechanosensitive currents. Importantly, the antagonist GsMTx4 for mechanosensitive channels significantly decreased steady-state facility, yet activation of Piezo1 by the specific agonist Yoda1 did not lead to a facility change. Furthermore, GsMTx4, but not Yoda1, caused a significant increase in ocular compliance, a measure of the eye's transient response to IOP perturbation. Our findings demonstrate a potential role for Piezo1 in conventional outflow, likely under pathological and rapid transient conditions. Piezo1 is functionally expressed in the TM, the most important tissue controlling IOP Suppression of mechanosensitive channel leads to a significant decrease in facility Our data suggest a role for Piezo in pathological situations and rapid IOP transients
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Affiliation(s)
- Wei Zhu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Beijing Advanced Innovation Center for Big Data-Based Precision Medicine, Beihang University & Capital Medical University, Beijing 100730, China
| | - Fei Hou
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Jingwang Fang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Mohammad Reza Bahrani Fard
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | - Yani Liu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shouyan Ren
- Department of Pharmacy, Affiliated Hospital of Qingdao University, Qingdao 266003, China
| | - Shen Wu
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Yunkun Qi
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Shangru Sui
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - A Thomas Read
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA
| | | | - Wei Zou
- School of Mechatronic Engineering, Jiangsu Normal University, Xuzhou 221116, China
| | - Hongxia Yu
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China
| | - Jingxue Zhang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, UK
| | - Ningli Wang
- Beijing Institute of Ophthalmology, Beijing Tongren Hospital Eye Center, Beijing 100730 China
| | - C Ross Ethier
- George W. Woodruff School of Mechanical Engineering, Georgia Institute of Technology, Atlanta 30332, GA, USA.,Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, 30332, GA, United States
| | - KeWei Wang
- Department of Pharmacology, School of Pharmacy, Qingdao University, Qingdao University Medical College, 38 Dengzhou Road, Qingdao 266021, Shandong, China.,Institute of Innovative Drugs, Qingdao University, 38 Dengzhou Road, Qingdao 266021, Shandong, China
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30
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Johnson SC, Veres J, Malcolm HR. Exploring the diversity of mechanosensitive channels in bacterial genomes. EUROPEAN BIOPHYSICS JOURNAL : EBJ 2021; 50:25-36. [PMID: 33244613 DOI: 10.1007/s00249-020-01478-1] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/30/2020] [Revised: 10/08/2020] [Accepted: 11/08/2020] [Indexed: 10/22/2022]
Abstract
Mechanosensitive ion channels are responsible for touch sensation and proprioception in higher level organisms such as humans and recovery after osmotic stress in bacteria. Bacterial mechanosensitive channels are homologous to either the mechanosensitive channel of large conductance (MscL) or the mechanosensitive channel of small conductance (MscS). In the E. coli genome there are seven unique mechanosensitive channels, a single MscL homologue, and six MscS homologues. The six MscS homologues are members of the diverse MscS superfamily of ion channels, and these channels show variation on both the N and C termini when compared to E. coli MscS. In bacterial strains with phenotypic analysis of the endogenous mechanosensors, the quantity of MscS superfamily members in the genome range from 2 to 6 and all of the strains contain a copy of MscL. Here, we show an in-depth analysis of over 150 diverse bacterial genomes, encompassing nine phyla, to determine the number of genomes that contain an MscL homologue and the average number of MscS superfamily members per genome. We determined that the average genome contains 4 ± 3 MscS homologues and 67% of bacterial genomes encode for a MscL homologue.
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Affiliation(s)
- Sarah C Johnson
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA
| | - Jordyn Veres
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA
| | - Hannah R Malcolm
- Department of Chemistry, University of North Florida, Jacksonville, FL, USA.
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31
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Kawasaki H, Martinac B. Mechanosensitive channels of Corynebacterium glutamicum functioning as exporters of l-glutamate and other valuable metabolites. Curr Opin Chem Biol 2020; 59:77-83. [DOI: 10.1016/j.cbpa.2020.05.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/09/2020] [Accepted: 05/17/2020] [Indexed: 01/06/2023]
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32
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Discoveries in structure and physiology of mechanically activated ion channels. Nature 2020; 587:567-576. [PMID: 33239794 DOI: 10.1038/s41586-020-2933-1] [Citation(s) in RCA: 276] [Impact Index Per Article: 69.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2020] [Accepted: 08/19/2020] [Indexed: 01/24/2023]
Abstract
The ability to sense physical forces is conserved across all organisms. Cells convert mechanical stimuli into electrical or chemical signals via mechanically activated ion channels. In recent years, the identification of new families of mechanosensitive ion channels-such as PIEZO and OSCA/TMEM63 channels-along with surprising insights into well-studied mechanosensitive channels have driven further developments in the mechanotransduction field. Several well-characterized mechanosensory roles such as touch, blood-pressure sensing and hearing are now linked with primary mechanotransducers. Unanticipated roles of mechanical force sensing continue to be uncovered. Furthermore, high-resolution structures representative of nearly every family of mechanically activated channel described so far have underscored their diversity while advancing our understanding of the biophysical mechanisms of pressure sensing. Here we summarize recent discoveries in the physiology and structures of known mechanically activated ion channel families and discuss their implications for understanding the mechanisms of mechanical force sensing.
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33
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Kaur A, Taneja M, Tyagi S, Sharma A, Singh K, Upadhyay SK. Genome-wide characterization and expression analysis suggested diverse functions of the mechanosensitive channel of small conductance-like (MSL) genes in cereal crops. Sci Rep 2020; 10:16583. [PMID: 33024170 PMCID: PMC7538590 DOI: 10.1038/s41598-020-73627-7] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 09/21/2020] [Indexed: 11/23/2022] Open
Abstract
Mechanosensitive ion channels are pore-forming transmembrane proteins that allow ions to move down their electrochemical gradient in response to mechanical stimuli. They participate in many plant developmental processes including the maintenance of plastid shape, pollen tube growth, etc. Herein, a total of 11, 10, 6, 30, 9, and 8 MSL genes were identified in Aegilops tauschii, Hordeum vulgare, Sorghum bicolor, Triticum aestivum, Triticum urartu, and Zea mays, respectively. These genes were located on various chromosomes of their respective cereal, while MSLs of T. urartu were found on scaffolds. The phylogenetic analysis, subcellular localization, and sequence homology suggested clustering of MSLs into two classes. These genes consisted of cis-regulatory elements related to growth and development, responsive to light, hormone, and stress. Differential expression of various MSL genes in tissue developmental stages and stress conditions revealed their precise role in development and stress responses. Altered expression during CaCl2 stress suggested their role in Ca2+ homeostasis and signaling. The co-expression analysis suggested their interactions with other genes involved in growth, defense responses etc. A comparative expression profiling of paralogous genes revealed either retention of function or pseudo-functionalization. The present study unfolded various characteristics of MSLs in cereals, which will facilitate their in-depth functional characterization in future studies.
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Affiliation(s)
- Amandeep Kaur
- Department of Botany, Panjab University, Chandigarh, 160014, India
| | - Mehak Taneja
- Department of Botany, Panjab University, Chandigarh, 160014, India
| | - Shivi Tyagi
- Department of Botany, Panjab University, Chandigarh, 160014, India
| | - Alok Sharma
- Department of Botany, Panjab University, Chandigarh, 160014, India
| | - Kashmir Singh
- Department of Biotechnology, Panjab University, Chandigarh, 160014, India
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34
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Cox CD, Bavi N, Martinac B. Biophysical Principles of Ion-Channel-Mediated Mechanosensory Transduction. Cell Rep 2020; 29:1-12. [PMID: 31577940 DOI: 10.1016/j.celrep.2019.08.075] [Citation(s) in RCA: 118] [Impact Index Per Article: 29.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/12/2019] [Revised: 06/09/2019] [Accepted: 08/22/2019] [Indexed: 01/12/2023] Open
Abstract
Recent rapid progress in the field of mechanobiology has been driven by novel emerging tools and methodologies and growing interest from different scientific disciplines. Specific progress has been made toward understanding how cell mechanics is linked to intracellular signaling and the regulation of gene expression in response to a variety of mechanical stimuli. There is a direct link between the mechanoreceptors at the cell surface and intracellular biochemical signaling, which in turn controls downstream effector molecules. Among the mechanoreceptors in the cell membrane, mechanosensitive (MS) ion channels are essential for the ultra-rapid (millisecond) transduction of mechanical stimuli into biologically relevant signals. The three decades of research on mechanosensitive channels resulted in the formulation of two basic principles of mechanosensitive channel gating: force-from-lipids and force-from-filament. In this review, we revisit the biophysical principles that underlie the innate force-sensing ability of mechanosensitive channels as contributors to the force-dependent evolution of life forms.
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Affiliation(s)
- Charles D Cox
- Victor Chang Cardiac Research Institute, Lowy Packer Building, Darlinghurst, NSW 2010, Australia; St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW 2010, Australia
| | - Navid Bavi
- Institute for Biophysical Dynamics, University of Chicago, Chicago, IL 60637, USA
| | - Boris Martinac
- Victor Chang Cardiac Research Institute, Lowy Packer Building, Darlinghurst, NSW 2010, Australia; St. Vincent's Clinical School, University of New South Wales, Darlinghurst, NSW 2010, Australia.
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35
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Zhao Y, Lv B, Sun F, Liu J, Wang Y, Gao Y, Qi F, Chang Z, Fu X. Rapid Freezing Enables Aminoglycosides To Eradicate Bacterial Persisters via Enhancing Mechanosensitive Channel MscL-Mediated Antibiotic Uptake. mBio 2020; 11:e03239-19. [PMID: 32047133 PMCID: PMC7018644 DOI: 10.1128/mbio.03239-19] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Accepted: 01/06/2020] [Indexed: 12/24/2022] Open
Abstract
Bacterial persisters exhibit noninherited antibiotic tolerance and are linked to the recalcitrance of bacterial infections. It is very urgent but also challenging to develop antipersister strategies. Here, we report that 10-s freezing with liquid nitrogen dramatically enhances the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many Gram-negative pathogens, with weaker potentiation effects on Gram-positive bacteria. In particular, antibiotic-tolerant Escherichia coli and Pseudomonas aeruginosa persisters-which were prepared by treating exponential-phase cells with ampicillin, ofloxacin, the protonophore cyanide m-chlorophenyl hydrazone (CCCP), or bacteriostatic antibiotics-can be effectively killed. We demonstrated, as a proof of concept, that freezing potentiated the aminoglycosides' killing of P. aeruginosa persisters in a mouse acute skin wound model. Mechanistically, freezing dramatically increased the bacterial uptake of aminoglycosides regardless of the presence of CCCP, indicating that the effects are independent of the proton motive force (PMF). In line with these results, we found that the effects were linked to freezing-induced cell membrane damage and were attributable, at least partly, to the mechanosensitive ion channel MscL, which was able to directly mediate such freezing-enhanced aminoglycoside uptake. In view of these results, we propose that the freezing-induced aminoglycoside potentiation is achieved by freezing-induced cell membrane destabilization, which, in turn, activates the MscL channel, which is able to effectively take up aminoglycosides in a PMF-independent manner. Our work may pave the way for the development of antipersister strategies that utilize the same mechanism as freezing but do so without causing any injury to animal cells.IMPORTANCE Antibiotics have long been used to successfully kill bacterial pathogens, but antibiotic resistance/tolerance usually has led to the failure of antibiotic therapy, and it has become a severe threat to human health. How to improve the efficacy of existing antibiotics is of importance for combating antibiotic-resistant/tolerant pathogens. Here, we report that 10-s rapid freezing with liquid nitrogen dramatically enhanced the bactericidal action of aminoglycoside antibiotics by 2 to 6 orders of magnitude against many bacterial pathogens in vitro and also in a mouse skin wound model. In particular, such combined treatment was able to effectively kill persister cells of Escherichia coli and Pseudomonas aeruginosa, which are per se tolerant of conventional treatment with bactericidal antibiotics for several hours. We also demonstrated that freezing-induced aminoglycoside potentiation was apparently linked to freezing-induced cell membrane damage that may have activated the mechanosensitive ion channel MscL, which, in turn, was able to effectively uptake aminoglycoside antibiotics in a proton motive force-independent manner. Our report sheds light on the development of a new strategy against bacterial pathogens by combining existing antibiotics with a conventional physical treatment or with MscL agonists.
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Affiliation(s)
- Yanna Zhao
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Boyan Lv
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Fengqi Sun
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Jiafeng Liu
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Yan Wang
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Yuanyuan Gao
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
- Engineering Research Center of Industrial Microbiology of Ministry of Education, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Feng Qi
- Engineering Research Center of Industrial Microbiology of Ministry of Education, Fujian Normal University, Fuzhou City, Fujian Province, China
| | - Zengyi Chang
- State Key Laboratory of Protein and Plant Gene Research, School of Life Sciences, Peking University, Beijing, China
| | - Xinmiao Fu
- Provincial University Key Laboratory of Cellular Stress Response and Metabolic Regulation, Key Laboratory of Optoelectronic Science and Technology for Medicine of Ministry of Education, College of Life Sciences, Fujian Normal University, Fuzhou City, Fujian Province, China
- Engineering Research Center of Industrial Microbiology of Ministry of Education, Fujian Normal University, Fuzhou City, Fujian Province, China
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36
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He Q, Lin Y, Tan H, Zhou Y, Wen Y, Gan J, Li R, Zhang Q. Transcriptomic profiles of Dunaliella salina in response to hypersaline stress. BMC Genomics 2020; 21:115. [PMID: 32013861 PMCID: PMC6998148 DOI: 10.1186/s12864-020-6507-2] [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: 04/25/2019] [Accepted: 01/20/2020] [Indexed: 11/24/2022] Open
Abstract
Background Dunaliella salina is a good model organism for studying salt stress. In order to have a global understanding of the expression profiles of Dunaliella salina in response to hypersaline stress, we performed quantitative transcriptomic analysis of Dunaliella salina under hypersaline stress (2.5 M NaCl) of different time duration by the second and third generation sequencing method. Results Functional enrichment of the up-regulated genes was used to analyze the expression profiles. The enrichment of photosynthesis was observed, accompanied by enrichments of carbon fixation, pigment biosynthetic process and heme biosynthetic process, which also imply the enhancement of photosynthesis. Genes responsible for starch hydrolysis and glycerol synthesis were significantly up-regulated. The enrichment of biosynthesis of unsaturated fatty acids implies the plasma membrane undergoes changes in desaturation pattern. The enrichment of endocytosis implies the degradation of plasma membrane and might help the synthesis of new glycerophospholipid with unsaturated fatty acids. Co-enrichments of protein synthesis and degradation imply a higher protein turnover rate. The enrichments of spliceosome and protein processing in endoplasmic reticulum imply the enhancement of regulations at post-transcriptional and post-translational level. No up-regulation of any Na+ or Cl− channels or transporters was detected, which implies that the extra exclusion of the ions by membrane transporters is possibly not needed. Voltage gated Na+ and Cl− channels, mechanosensitive ion channel are possible signal receptors of salt stress, and Ca2+ and MAP kinase pathways might play a role in signal transduction. Conclusion At global transcriptomic level, the response of Dunaliella salina to hypersaline stress is a systematic work, possibly involving enhancements of photosynthesis, carbon fixation, and heme biosynthetic process, acceleration of protein turnover, spliceosome, protein processing in endoplasmic reticulum, and endocytosis, as well as degradation of starch, synthesis of glycerol, membrane lipid desaturation. Altogether, the changes of these biological processes occurred at trancriptomic level will help understand how a new intracellular balance achieved in Dunaliella salina to adapt to hypersaline environment, which are worth being confirmed at the physiological levels.
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Affiliation(s)
- Qinghua He
- Key Laboratory of Qinghai-Tibetan Plateau Animal genetic Resource Reservation and Utilization, College of Life Science and Technology, Southwest Minzu University, Chengdu, People's Republic of China
| | - Yaqiu Lin
- Key Laboratory of Qinghai-Tibetan Plateau Animal genetic Resource Reservation and Utilization, College of Life Science and Technology, Southwest Minzu University, Chengdu, People's Republic of China
| | - Hong Tan
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, People's Republic of China
| | - Yu Zhou
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, People's Republic of China
| | - Yongli Wen
- Institute of Qinghai-Tibetan Plateau, Southwest Minzu University, Chengdu, People's Republic of China
| | - Jiajia Gan
- Key Laboratory of Qinghai-Tibetan Plateau Animal genetic Resource Reservation and Utilization, College of Life Science and Technology, Southwest Minzu University, Chengdu, People's Republic of China
| | - Ruiwen Li
- Reproductive and endocrine laboratory, Chengdu Woman-Child Central Hospital, Chengdu, 610051, People's Republic of China.
| | - Qinglian Zhang
- School of Laboratory Medicine, Chengdu Medical College, Chengdu, 610500, People's Republic of China.
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Paraschiv A, Hegde S, Ganti R, Pilizota T, Šarić A. Dynamic Clustering Regulates Activity of Mechanosensitive Membrane Channels. PHYSICAL REVIEW LETTERS 2020; 124:048102. [PMID: 32058787 DOI: 10.1103/physrevlett.124.048102] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/20/2019] [Indexed: 06/10/2023]
Abstract
Experiments have suggested that bacterial mechanosensitive channels separate into 2D clusters, the role of which is unclear. By developing a coarse-grained computer model we find that clustering promotes the channel closure, which is highly dependent on the channel concentration and membrane stress. This behaviour yields a tightly regulated gating system, whereby at high tensions channels gate individually, and at lower tensions the channels spontaneously aggregate and inactivate. We implement this positive feedback into the model for cell volume regulation, and find that the channel clustering protects the cell against excessive loss of cytoplasmic content.
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Affiliation(s)
- Alexandru Paraschiv
- Department of Physics and Astronomy, Institute for the Physics of Living Systems University College London, London WC1E 6BT, United Kingdom
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
| | - Smitha Hegde
- Centre for Synthetic and Systems Biology University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Raman Ganti
- Institute for Medical Engineering and Science Massachusetts Institute of Technology, Cambridge, Massachusetts 02142, USA
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology University of Edinburgh, Edinburgh EH9 3FF, United Kingdom
| | - Anđela Šarić
- Department of Physics and Astronomy, Institute for the Physics of Living Systems University College London, London WC1E 6BT, United Kingdom
- MRC Laboratory for Molecular Cell Biology, University College London, London WC1E 6BT, United Kingdom
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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: 43] [Impact Index Per Article: 10.8] [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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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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40
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Amemiya S, Toyoda H, Kimura M, Saito H, Kobayashi H, Ihara K, Kamagata K, Kawabata R, Kato S, Nakashimada Y, Furuta T, Hamamoto S, Uozumi N. The mechanosensitive channel YbdG from Escherichia coli has a role in adaptation to osmotic up-shock. J Biol Chem 2019; 294:12281-12292. [PMID: 31256002 DOI: 10.1074/jbc.ra118.007340] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Revised: 06/20/2019] [Indexed: 01/24/2023] Open
Abstract
Mechanosensitive channels play an important role in the adaptation of cells to hypo-osmotic shock. Among members of this channel family in Escherichia coli, the exact function and physiological role of the mechanosensitive channel homolog YbdG remain unclear. Characterization of YbdG's physiological role has been hampered by its lack of measurable transport activity. Using a nitrosoguanidine mutagenesis-aided screen in combination with next-generation sequencing, here we isolated a mutant with a point mutation in ybdG This mutation (resulting in a I167T change) conferred sensitivity to high osmotic stress, and the mutant cells differed from WT cells in morphology during hyperosmotic stress at alkaline pH. Interestingly, unlike the cells containing the I167T variant, a null-ybdG mutant did not exhibit this sensitivity and phenotype. Although I167T was located near the putative ion-conducting pore in a transmembrane region of YbdG, no change in ion channel activities of YbdG-I167T was detected. Of note, introduction of the WT C-terminal cytosolic region of YbdG into the I167T variant complemented the osmo-sensitive phenotype. Co-precipitation of proteins interacting with the C-terminal YbdG region led to the isolation of HldD and FbaA, whose overexpression in cells containing the YbdG-I167T variant partially rescued the osmo-sensitive phenotype. This study indicates that YbdG functions as a component of a mechanosensing system that transmits signals triggered by external osmotic changes to intracellular factors. The cellular role of YbdG uncovered here goes beyond its predicted function as an ion or solute transport protein.
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Affiliation(s)
- Shun Amemiya
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Hayato Toyoda
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Mami Kimura
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Hiromi Saito
- Department of Biochemistry, Graduate School of Pharmaceutical Science, Chiba University, Chiba 260-8675, Japan
| | - Hiroshi Kobayashi
- Department of Biochemistry, Graduate School of Pharmaceutical Science, Chiba University, Chiba 260-8675, Japan
| | - Kunio Ihara
- Center for Gene Research, Nagoya University, Nagoya 464-8602, Japan
| | - Kiyoto Kamagata
- Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, Katahira 2-1-1, Sendai 980-8577, Japan
| | - Ryuji Kawabata
- School of Engineering, Hiroshima University, Higashi-Hiroshima 739-8527, Japan
| | - Setsu Kato
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Yutaka Nakashimada
- Department of Molecular Biotechnology, Graduate School of Advanced Sciences of Matter, Hiroshima University, Higashi-Hiroshima 739-8530, Japan
| | - Tadaomi Furuta
- School of Life Science and Technology, Tokyo Institute of Technology, B-62 4259 Nagatsuta-cho, Midori-ku, Yokohama 226-8501, Japan
| | - Shin Hamamoto
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan
| | - Nobuyuki Uozumi
- Department of Biomolecular Engineering, Graduate School of Engineering, Tohoku University, Aobayama 6-6-07, Sendai 980-8579, Japan.
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Liu X, Wang J, Sun L. Structure of the hyperosmolality-gated calcium-permeable channel OSCA1.2. Nat Commun 2018; 9:5060. [PMID: 30498218 PMCID: PMC6265326 DOI: 10.1038/s41467-018-07564-5] [Citation(s) in RCA: 99] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 11/09/2018] [Indexed: 01/08/2023] Open
Abstract
In plants, hyperosmolality stimuli triggers opening of the osmosensitive channels, leading to a rapid downstream signaling cascade initiated by cytosolic calcium concentration elevation. Members of the OSCA family in Arabidopsis thaliana, identified as the hyperosmolality-gated calcium-permeable channels, have been suggested to play a key role during the initial phase of hyperosmotic stress response. Here, we report the atomic structure of Arabidopsis OSCA1.2 determined by single-particle cryo-electron microscopy. It contains 11 transmembrane helices and forms a homodimer. It is in an inactivated state, and the pore-lining residues are clearly identified. Its cytosolic domain contains a RNA recognition motif and two unique long helices. The linker between these two helices forms an anchor in the lipid bilayer and may be essential to osmosensing. The structure of AtOSCA1.2 serves as a platform for the study of the mechanism underlying osmotic stress responses and mechanosensing. In plants, hyperosmolality stimuli triggers opening of the osmosensitive channels, leading to a rapid downstream signaling cascade. Here, the authors solve the cryo-EM structure of an osmosensitive channel from Arabidopsis OSCA1.2 in its inactivated state.
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Affiliation(s)
- Xin Liu
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, 230027, Hefei, China
| | - Jiawei Wang
- State Key Laboratory of Membrane Biology, Beijing Advanced Innovation Centre for Structural Biology, School of Life Sciences, Tsinghua University, 100084, Beijing, China.
| | - Linfeng Sun
- Hefei National Laboratory for Physical Sciences at Microscale, School of Life Sciences, University of Science and Technology of China, 230027, Hefei, China. .,CAS Centre for Excellence in Molecular Cell Science, University of Science and Technology of China, Chinese Academy of Sciences, 230027, Hefei, China.
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42
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Gating and inactivation of mechanosensitive channels of small conductance: A continuum mechanics study. J Mech Behav Biomed Mater 2018; 90:502-514. [PMID: 30453114 DOI: 10.1016/j.jmbbm.2018.10.040] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2017] [Revised: 04/27/2018] [Accepted: 10/30/2018] [Indexed: 11/21/2022]
Abstract
Mechanosensitive channels of small conductance (MscS) in Escherichia coli (E. coli) serve as a paradigm for understanding the gating behaviors of the MscS family of ion channels. In this work, we develop a continuum mechanics framework to explore the conformational states of MscS during the gating transition. A complete gating transition trajectory from the closed to the open state along with partially open intermediates is obtained, and the open structure is close to the available structural model from crystallographic studies. The computational efficiency of the modeling framework makes it possible to explore the roles of various structural elements (e.g., loops that connect transmembrane helices) and specific interactions in the gating transition. It is observed that removing either the Asp62-Arg131 salt bridge or the Phe68-Leu111 non-polar interaction leads to essentially non-conducting structures even with a membrane tension close to the lysis limit. The loop connecting TM2 (the second transmembrane helix) and TM3 is found to be essential for force transmission during gating, while the loop connecting TM1 and TM2 does not make any major contribution. Based on the different structural evolutions observed when the TM3 kink is treated as a loop or a helical segment, we propose that the helical propensity of the kink plays a central role in inactivation; i.e., under prolonged sub-threshold membrane tension, transition of the initially flexible loop to a helical segment in TM3 may lead to MscS inactivation. Finally, the gating transition of MscS under different transmembrane voltages is explored and found to be essentially voltage independent. Collectively, results from the current continuum mechanics analysis provide further insights into the gating transition of MscS at structural and physical levels, and specific predictions are proposed for further experimental investigations.
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43
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Nakayama Y, Hashimoto KI, Sawada Y, Sokabe M, Kawasaki H, Martinac B. Corynebacterium glutamicum mechanosensitive channels: towards unpuzzling "glutamate efflux" for amino acid production. Biophys Rev 2018; 10:1359-1369. [PMID: 30209745 PMCID: PMC6233337 DOI: 10.1007/s12551-018-0452-1] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Accepted: 08/27/2018] [Indexed: 12/11/2022] Open
Abstract
Corynebacterium glutamicum has been utilized for industrial amino acid production, especially for monosodium glutamate (MSG), the food-additive for the "UMAMI" category of taste sensation, which is one of the five human basic tastes. Glutamate export from these cells is facilitated by the opening of mechanosensitive channels in the cell membrane within the bacterial cell envelope following specific treatments, such as biotin limitation, addition of Tween 40 or penicillin. A long-unsolved puzzle still remains how and why C. glutamicum mechanosensitive channels are activated by these treatments to export glutamate. Unlike mechanosensitive channels in other bacteria, these channels are not simply osmotic safety valves that prevent these bacteria from bursting upon a hypo-osmotic shock. They also function as metabolic valves to continuously release glutamate as components of a pump-and-leak mechanism regulating the cellular turgor pressure. Recent studies have demonstrated that the opening of the mechanosensitive channel, MscCG, mainly facilitates the efflux of glutamate and not of other amino acids and that the "force-from-lipids" gating mechanism of channels also applies to the MscCG channel. The bacterial types of mechanosensitive channels are found in cell-walled organisms from bacteria to land plants, where their physiological functions have been specialized beyond their basic function in bacterial osmoregulation. In the case of the C. glutamicum MscCG channels, they have evolved to function as specialized glutamate exporters.
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Affiliation(s)
- Yoshitaka Nakayama
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia.
| | - Ken-Ichi Hashimoto
- Department of Green and Sustainable Chemistry, Tokyo Denki University, 5 Asahi-cho, Senju, Adachi-ku, Tokyo, 120-8551, Japan
| | - Yasuyuki Sawada
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Masahiro Sokabe
- Mechanobiology Laboratory, Nagoya University Graduate School of Medicine, 65 Tsurumai-cho, Showa-ku, Nagoya, 466-8550, Japan
| | - Hisashi Kawasaki
- Department of Green and Sustainable Chemistry, Tokyo Denki University, 5 Asahi-cho, Senju, Adachi-ku, Tokyo, 120-8551, Japan
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, 405 Liverpool Street, Darlinghurst, NSW, 2010, Australia
- St Vincent's Clinical School, Faculty of Medicine, University of New South Wales, Darlinghurst, NSW, 2010, Australia
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44
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Herrera N, Maksaev G, Haswell ES, Rees DC. Elucidating a role for the cytoplasmic domain in the Mycobacterium tuberculosis mechanosensitive channel of large conductance. Sci Rep 2018; 8:14566. [PMID: 30275500 PMCID: PMC6167328 DOI: 10.1038/s41598-018-32536-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2018] [Accepted: 08/31/2018] [Indexed: 12/04/2022] Open
Abstract
Microbial survival in dynamic environments requires the ability to successfully respond to abrupt changes in osmolarity. The mechanosensitive channel of large conductance (MscL) is a ubiquitous channel that facilitates the survival of bacteria and archaea under severe osmotic downshock conditions by relieving excess turgor pressure in response to increased membrane tension. A prominent structural feature of MscL, the cytoplasmic C-terminal domain, has been suggested to influence channel assembly and function. In this report, we describe the X-ray crystal structure and electrophysiological properties of a C-terminal domain truncation of the Mycobacterium tuberculosis MscL (MtMscLΔC). A crystal structure of MtMscLΔC solubilized in the detergent n-dodecyl-β-D-maltopyranoside reveals the pentameric, closed state-like architecture for the membrane spanning region observed in the previously solved full-length MtMscL. Electrophysiological characterization demonstrates that MtMscLΔC retains mechanosensitivity, but with conductance and tension sensitivity more closely resembling full length EcMscL than MtMscL. This study establishes that the C-terminal domain of MtMscL is not required for oligomerization of the full-length channel, but rather influences the tension sensitivity and conductance properties of the channel. The collective picture that emerges from these data is that each MscL channel structure has characteristic features, highlighting the importance of studying multiple homologs.
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Affiliation(s)
- Nadia Herrera
- Division of Chemistry and Chemical Engineering 114-96, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, 91125, USA.,Division of Infectious Diseases, Department of Medicine University of California, San Francisco, San Francisco, CA, 94143-0654, USA
| | - Grigory Maksaev
- Department of Biology, NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, 63130, USA.,Department of Cell Biology and Physiology, Center for the Investigation of Membrane Excitability Diseases, Washington University School of Medicine, Saint Louis, MO, 63110, USA
| | - Elizabeth S Haswell
- Department of Biology, NSF Center for Engineering Mechanobiology, Washington University in St. Louis, St. Louis, MO, 63130, USA
| | - Douglas C Rees
- Division of Chemistry and Chemical Engineering 114-96, Howard Hughes Medical Institute, California Institute of Technology, Pasadena, CA, 91125, USA.
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45
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Nakayama Y, Komazawa K, Bavi N, Hashimoto KI, Kawasaki H, Martinac B. Evolutionary specialization of MscCG, an MscS-like mechanosensitive channel, in amino acid transport in Corynebacterium glutamicum. Sci Rep 2018; 8:12893. [PMID: 30150671 PMCID: PMC6110860 DOI: 10.1038/s41598-018-31219-6] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Accepted: 08/14/2018] [Indexed: 11/09/2022] Open
Abstract
MscCG, a mechanosensitive channel of Corynebacterium glutamicum provides a major export mechanism for glutamate in this Gram-positive bacterium, which has for many years been used for industrial production of glutamate and other amino acids. The functional characterization of MscCG is therefore, of great significance to understand its conductive properties for different amino acids. Here we report the first successful giant spheroplast preparation of C. glutamicum amenable to the patch clamp technique, which enabled us to investigate mechanosensitive channel activities of MscCG in the native membrane of this bacterium. Single channel recordings from these spheroplasts revealed the presence of three types of mechanosensitive channels, MscCG, MscCG2, and CgMscL, which differ largely from each other in their conductance and mechanosensitivity. MscCG has a relatively small conductance of ~340 pS followed by an intermediate MscCG2 conductance of ~1.0 nS and comparably very large conductance of 3.7 nS exhibited by CgMscL. By applying Laplace's law, we determined that very moderate membrane tension of ~5.5 mN/m was required for half activation of MscCG compared to ~12 mN/m required for half activation of both MscCG2 and CgMscL. Furthermore, by combining the micropipette aspiration technique with molecular dynamics simulations we measured mechanical properties of the C. glutamicum membrane, whose area elasticity module of KA ≈ 15 mN/m is characteristic of a very soft membrane compared to the three times larger area expansion modulus of KA ≈ 44 mN/m of the more elastic E. coli membrane. Moreover, we demonstrate that the "soft" properties of the C. glutamicum membrane have a significant impact on the MscCG gating characterized by a strong voltage-dependent hysteresis in the membrane of C. glutamicum compared to a complete absence of the hysteresis in the E. coli cell membrane. We thus propose that MscCG has evolved and adapted as an MscS-like channel to the mechanical properties of the C. glutamicum membrane enabling the channel to specialize in transport of amino acids such as glutamate, which are major osmolytes helping the bacterial cells survive extreme osmotic stress.
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Affiliation(s)
- Yoshitaka Nakayama
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia
| | - Kosuke Komazawa
- Department of Green and Sustainable Chemistry, Tokyo Denki University, 5 Asahi-cho, Senju, Adachi-ku, Tokyo, 120-8551, Japan
| | - Navid Bavi
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia.,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Darlinghurst, NSW, 2010, Australia.,Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, 60637, USA
| | - Ken-Ichi Hashimoto
- Department of Green and Sustainable Chemistry, Tokyo Denki University, 5 Asahi-cho, Senju, Adachi-ku, Tokyo, 120-8551, Japan
| | - Hisashi Kawasaki
- Department of Green and Sustainable Chemistry, Tokyo Denki University, 5 Asahi-cho, Senju, Adachi-ku, Tokyo, 120-8551, Japan
| | - Boris Martinac
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Darlinghurst, NSW, 2010, Australia. .,St Vincent's Clinical School, Faculty of Medicine, The University of New South Wales, Darlinghurst, NSW, 2010, Australia.
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46
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Heureaux-Torres J, Luker KE, Haley H, Pirone M, Lee LM, Herrera Y, Luker GD, Liu AP. The effect of mechanosensitive channel MscL expression in cancer cells on 3D confined migration. APL Bioeng 2018; 2:032001. [PMID: 31069318 PMCID: PMC6324216 DOI: 10.1063/1.5019770] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2017] [Accepted: 05/22/2018] [Indexed: 11/15/2022] Open
Abstract
Metastatic cancer cells migrate through constricted spaces and experience significant compressive stress, but mechanisms enabling migration in confined geometries remain unclear. Cancer cell migration within confined 3-dimensional (3D) microfluidic channels has been shown to be distinct from 2D cell migration. However, whether 3D confined migration can be manipulated by mechanosensory components has not been examined in detail. In this work, we exogenously introduced a mechanosensitive channel of large conductance (MscL) into metastatic breast cancer cells MDA-MB-231. We discovered that inducing expression of a gain-of-function G22S mutant of MscL in MDA-MB-231 cells significantly reduced spontaneous lung metastasis without affecting the growth of orthotopic tumor implants. To further investigate the effects of G22S MscL on cell migration, we designed a microfluidic device with channels of various cross-sections ranging from a 2D planar environment to narrow 3D constrictions. Both MscL G22S and control breast cancer cells migrated progressively slower in more constricted environments. Migration of cells expressing MscL G22S did not differ from control cells, even though MscL was activated in cells in constricted channels of 3 μm width. Interestingly, we found MscL expressing cells to be more frequently “stuck” at the entrance of the 3 μm channels and failed to migrate into the microchannel. Our work demonstrates the possibility of engineering mechanotransduction for controlling confined cell migration.
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Affiliation(s)
- Johanna Heureaux-Torres
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Kathryn E Luker
- Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Henry Haley
- Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Matthew Pirone
- Department of Radiology, Center for Molecular Imaging, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Lap Man Lee
- Department of Mechanical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - Yoani Herrera
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, Michigan 48109, USA
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Spatiotemporal relationships defining the adaptive gating of the bacterial mechanosensitive channel MscS. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2018; 47:663-677. [DOI: 10.1007/s00249-018-1303-5] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/30/2017] [Revised: 03/27/2018] [Accepted: 04/13/2018] [Indexed: 12/13/2022]
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Abstract
The growth and development of most fungi take place on a two-dimensional surface or within a three-dimensional matrix. The fungal sense of touch is therefore critical for fungi in the interpretation of their environment and often signals the switch to a new developmental state. Contact sensing, or thigmo-based responses, include thigmo differentiation, such as the induction of invasion structures by plant pathogens in response to topography; thigmonasty, where contact with a motile prey rapidly triggers its capture; and thigmotropism, where the direction of hyphal growth is guided by physical features in the environment. Like plants and some bacteria, fungi grow as walled cells. Despite the well-demonstrated importance of thigmo responses in numerous stages of fungal growth and development, it is not known how fungal cells sense contact through the relatively rigid structure of the cell wall. However, while sensing mechanisms at the molecular level are not entirely understood, the downstream signaling pathways that are activated by contact sensing are being elucidated. In the majority of cases, the response to contact is complemented by chemical cues and both are required, either sequentially or simultaneously, to elicit normal developmental responses. The importance of a sense of touch in the lifestyles and development of diverse fungi is highlighted in this review, and the candidate molecular mechanisms that may be involved in fungal contact sensing are discussed.
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49
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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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Guo YR, MacKinnon R. Structure-based membrane dome mechanism for Piezo mechanosensitivity. eLife 2017; 6:33660. [PMID: 29231809 PMCID: PMC5788504 DOI: 10.7554/elife.33660] [Citation(s) in RCA: 247] [Impact Index Per Article: 35.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2017] [Accepted: 12/11/2017] [Indexed: 12/16/2022] Open
Abstract
Mechanosensitive ion channels convert external mechanical stimuli into electrochemical signals for critical processes including touch sensation, balance, and cardiovascular regulation. The best understood mechanosensitive channel, MscL, opens a wide pore, which accounts for mechanosensitive gating due to in-plane area expansion. Eukaryotic Piezo channels have a narrow pore and therefore must capture mechanical forces to control gating in another way. We present a cryo-EM structure of mouse Piezo1 in a closed conformation at 3.7Å-resolution. The channel is a triskelion with arms consisting of repeated arrays of 4-TM structural units surrounding a pore. Its shape deforms the membrane locally into a dome. We present a hypothesis in which the membrane deformation changes upon channel opening. Quantitatively, membrane tension will alter gating energetics in proportion to the change in projected area under the dome. This mechanism can account for highly sensitive mechanical gating in the setting of a narrow, cation-selective pore.
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Affiliation(s)
- Yusong R Guo
- Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
| | - Roderick MacKinnon
- Laboratory of Molecular Neurobiology and Biophysics, Howard Hughes Medical Institute, The Rockefeller University, New York, United States
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