1
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Mordukhova EA, Kim J, Jin H, No KT, Pan JG. The efficacy of the food-grade antimicrobial xanthorrhizol against Staphylococcus aureus is associated with McsL channel expression. Front Microbiol 2024; 15:1439009. [PMID: 39021623 PMCID: PMC11251944 DOI: 10.3389/fmicb.2024.1439009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2024] [Accepted: 06/18/2024] [Indexed: 07/20/2024] Open
Abstract
Background The emergence and spread of multidrug-resistant Staphylococcus aureus strains demonstrates the urgent need for new antimicrobials. Xanthorrhizol, a plant-derived sesquiterpenoid compound, has a rapid killing effect on methicillin-susceptible strains and methicillin-resistant strains of S. aureus achieving the complete killing of staphylococcal cells within 2 min using 64 μg/mL xanthorrhizol. However, the mechanism of its action is not yet fully understood. Methods The S. aureus cells treated with xanthorrhizol were studied using optical diffraction tomography. Activity of xanthorrhizol against the wild-type and mscL null mutant of S. aureus ATCC 29213 strain was evaluated in the time-kill assay. Molecular docking was conducted to predict the binding of xanthorrhizol to the SaMscL protein. Results Xanthorrhizol treatment of S. aureus cells revealed a decrease in cell volume, dry weight, and refractive index (RI), indicating efflux of the cell cytoplasm, which is consistent with the spontaneous activation of the mechanosensitive MscL channel. S. aureus ATCC 29213ΔmscL was significantly more resistant to xanthorrhizol than was the wild-type strain. Xanthorrhizol had an enhanced inhibitory effect on the growth and viability of exponentially growing S. aureus ATCC 29213ΔmscL cells overexpressing the SaMscL protein and led to a noticeable decrease in their viability in the stationary growth phase. The amino acid residues F5, V14, M23, A79, and V84 were predicted to be the residues of the binding pocket for xanthorrhizol. We also showed that xanthorrhizol increased the efflux of solutes such as K+ and glutamate from S. aureus ATCC 29213ΔmscL cells overexpressing SaMscL. Xanthorrhizol enhanced the antibacterial activity of the antibiotic dihydrostreptomycin, which targets the MscL protein. Conclusion Our findings indicate that xanthorrhizol targets the SaMscL protein in S. aureus cells and may have important implications for the development of a safe antimicrobial agent.
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Affiliation(s)
| | - Jongwan Kim
- Bioinformatics and Molecular Design Research Center (BMDRC), Incheon, Republic of Korea
| | - Haiyan Jin
- The Interdisciplinary Graduate Program in Integrative Biotechnology and Translational Medicine, Yonsei University, Incheon, Republic of Korea
| | - Kyoung Tai No
- Department of Biotechnology, Yonsei University, Seoul, Republic of Korea
| | - Jae-Gu Pan
- GenoFocus Ltd., Daejeon, Republic of Korea
- Infectious Disease Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), Daejeon, Republic of Korea
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2
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Singh G, George G, Raja SO, Kandaswamy P, Kumar M, Thutupalli S, Laxman S, Gulyani A. A molecular rotor FLIM probe reveals dynamic coupling between mitochondrial inner membrane fluidity and cellular respiration. Proc Natl Acad Sci U S A 2023; 120:e2213241120. [PMID: 37276406 PMCID: PMC10268597 DOI: 10.1073/pnas.2213241120] [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: 08/31/2022] [Accepted: 04/13/2023] [Indexed: 06/07/2023] Open
Abstract
The inner mitochondrial membrane (IMM), housing components of the electron transport chain (ETC), is the site for respiration. The ETC relies on mobile carriers; therefore, it has long been argued that the fluidity of the densely packed IMM can potentially influence ETC flux and cell physiology. However, it is unclear if cells temporally modulate IMM fluidity upon metabolic or other stimulation. Using a photostable, red-shifted, cell-permeable molecular-rotor, Mitorotor-1, we present a multiplexed approach for quantitatively mapping IMM fluidity in living cells. This reveals IMM fluidity to be linked to cellular-respiration and responsive to stimuli. Multiple approaches combining in vitro experiments and live-cell fluorescence (FLIM) lifetime imaging microscopy (FLIM) show Mitorotor-1 to robustly report IMM 'microviscosity'/fluidity through changes in molecular free volume. Interestingly, external osmotic stimuli cause controlled swelling/compaction of mitochondria, thereby revealing a graded Mitorotor-1 response to IMM microviscosity. Lateral diffusion measurements of IMM correlate with microviscosity reported via Mitorotor-1 FLIM-lifetime, showing convergence of independent approaches for measuring IMM local-order. Mitorotor-1 FLIM reveals mitochondrial heterogeneity in IMM fluidity; between-and-within cells and across single mitochondrion. Multiplexed FLIM lifetime imaging of Mitorotor-1 and NADH autofluorescence reveals that IMM fluidity positively correlates with respiration, across individual cells. Remarkably, we find that stimulating respiration, through nutrient deprivation or chemically, also leads to increase in IMM fluidity. These data suggest that modulating IMM fluidity supports enhanced respiratory flux. Our study presents a robust method for measuring IMM fluidity and suggests a dynamic regulatory paradigm of modulating IMM local order on changing metabolic demand.
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Affiliation(s)
- Gaurav Singh
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Geen George
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Sufi O. Raja
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, 500046Hyderabad, India
| | - Ponnuvel Kandaswamy
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Manoj Kumar
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, 560065Bangalore, India
| | - Shashi Thutupalli
- Simons Centre for the Study of Living Machines, National Centre for Biological Sciences, Tata Institute of Fundamental Research, 560065Bangalore, India
- International Centre for Theoretical Sciences, Tata Institute for Fundamental Research, 560089 Bangalore, India
| | - Sunil Laxman
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
| | - Akash Gulyani
- Institute for Stem Cell Science and Regenerative Medicine, 560065Bangalore, India
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, 500046Hyderabad, India
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3
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Morra R, Pratama F, Butterfield T, Tomazetto G, Young K, Lopez R, Dixon N. arfA antisense RNA regulates MscL excretory activity. Life Sci Alliance 2023; 6:e202301954. [PMID: 37012050 PMCID: PMC10070815 DOI: 10.26508/lsa.202301954] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2023] [Revised: 03/20/2023] [Accepted: 03/20/2023] [Indexed: 04/05/2023] Open
Abstract
Excretion of cytoplasmic protein (ECP) is a commonly observed phenomenon in bacteria, and this partial extracellular localisation of the intracellular proteome has been implicated in a variety of stress response mechanisms. In response to hypoosmotic shock and ribosome stalling in Escherichia coli, ECP is dependent upon the presence of the large-conductance mechanosensitive channel and the alternative ribosome-rescue factor A gene products. However, it is not known if a mechanistic link exists between the corresponding genes and the respective stress response pathways. Here, we report that the corresponding mscL and arfA genes are commonly co-located on the genomes of Gammaproteobacteria and display overlap in their respective 3' UTR and 3' CDS. We show this unusual genomic arrangement permits an antisense RNA-mediated regulatory control between mscL and arfA, and this modulates MscL excretory activity in E. coli These findings highlight a mechanistic link between osmotic, translational stress responses and ECP in E. coli, further elucidating the previously unknown regulatory function of arfA sRNA.
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Affiliation(s)
- Rosa Morra
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Fenryco Pratama
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
- Institut Teknologi Bandung, Bandung, Indonesia
| | - Thomas Butterfield
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Geizecler Tomazetto
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Kate Young
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Ruth Lopez
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
| | - Neil Dixon
- Department of Chemistry, Manchester Institute of Biotechnology, The University of Manchester, Manchester, UK
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4
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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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5
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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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6
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Gibbons E, Tamanna M, Cherayil BJ. The rpoS gene confers resistance to low osmolarity conditions in Salmonella enterica serovar Typhi. PLoS One 2022; 17:e0279372. [PMID: 36525423 PMCID: PMC9757558 DOI: 10.1371/journal.pone.0279372] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Accepted: 12/06/2022] [Indexed: 12/23/2022] Open
Abstract
Salmonella enterica serovars Typhimurium and Typhi are enteropathogens that differ in host range and the diseases that they cause. We found that exposure to a combination of hypotonicity and the detergent Triton X-100 significantly reduced the viability of the S. Typhi strain Ty2 but had no effect on the S. Typhimurium strain SL1344. Further analysis revealed that hypotonicity was the critical factor: incubation in distilled water alone was sufficient to kill Ty2, while the addition of sodium chloride inhibited killing in a dose-dependent manner. Ty2's loss of viability in water was modified by culture conditions: bacteria grown in well-aerated shaking cultures were more susceptible than bacteria grown under less aerated static conditions. Ty2, like many S. Typhi clinical isolates, has an inactivating mutation in the rpoS gene, a transcriptional regulator of stress responses, whereas most S. Typhimurium strains, including SL1344, have the wild-type gene. Transformation of Ty2 with a plasmid expressing wild-type rpoS, but not the empty vector, significantly increased survival in distilled water. Moreover, an S. Typhi strain with wild-type rpoS had unimpaired survival in water. Inactivation of the wild-type gene in this strain significantly reduced survival, while replacement with an arabinose-inducible allele of rpoS restored viability in water under inducing conditions. Our observations on rpoS-dependent differences in susceptibility to hypotonic conditions may be relevant to the ability of S. Typhi and S. Typhimurium to tolerate the various environments they encounter during the infectious cycle. They also have implications for the handling of these organisms during experimental manipulations.
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Affiliation(s)
- Eamon Gibbons
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
| | - Mehbooba Tamanna
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Medical Sciences Program, Boston University School of Medicine, Boston, Massachusetts, United States of America
| | - Bobby J. Cherayil
- Mucosal Immunology and Biology Research Center, Massachusetts General Hospital, Charlestown, Massachusetts, United States of America
- Department of Pediatrics, Harvard Medical School, Boston, Massachusetts, United States of America
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7
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Miller K, Strychalski W, Nickaeen M, Carlsson A, Haswell ES. In vitro experiments and kinetic models of Arabidopsis pollen hydration mechanics show that MSL8 is not a simple tension-gated osmoregulator. Curr Biol 2022; 32:2921-2934.e3. [PMID: 35660140 DOI: 10.1016/j.cub.2022.05.033] [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] [Received: 10/18/2021] [Revised: 04/12/2022] [Accepted: 05/12/2022] [Indexed: 10/18/2022]
Abstract
Pollen, a neighbor-less cell containing the male gametes, undergoes mechanical challenges during plant sexual reproduction, including desiccation and rehydration. It was previously shown that the pollen-specific mechanosensitive ion channel MscS-like (MSL)8 is essential for pollen survival during hydration and proposed that it functions as a tension-gated osmoregulator. Here, we test this hypothesis with a combination of mathematical modeling and laboratory experiments. Time-lapse imaging revealed that wild-type pollen grains swell, and then they stabilize in volume rapidly during hydration. msl8 mutant pollen grains, however, continue to expand and eventually burst. We found that a mathematical model, wherein MSL8 acts as a simple-tension-gated osmoregulator, does not replicate this behavior. A better fit was obtained from variations of the model, wherein MSL8 inactivates independent of its membrane tension gating threshold or MSL8 strengthens the cell wall without osmotic regulation. Experimental and computational testing of several perturbations, including hydration in an osmolyte-rich solution, hyper-desiccation of the grains, and MSL8-YFP overexpression, indicated that the cell wall strengthening model best simulated experimental responses. Finally, the expression of a nonconducting MSL8 variant did not complement the msl8 overexpansion phenotype. These data indicate that contrary to our hypothesis and to the current understanding of MS ion channel function in bacteria, MSL8 does not act as a simple membrane tension-gated osmoregulator. Instead, they support a model wherein ion flux through MSL8 is required to alter pollen cell wall properties. These results demonstrate the utility of pollen as a cellular scale model system and illustrate how mathematical models can correct intuitive hypotheses.
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Affiliation(s)
- Kari Miller
- Department of Biology, Washington University, St. Louis, MO 63130, USA; NSF Center for Engineering Mechanobiology, Cleveland, OH, USA
| | - Wanda Strychalski
- Department of Mathematics, Applied Mathematics, and Statistics, Case Western Reserve University, Cleveland, OH 44106, USA
| | - Masoud Nickaeen
- University of Connecticut School of Medicine, Farmington, CT 06030, USA
| | - Anders Carlsson
- NSF Center for Engineering Mechanobiology, Cleveland, OH, USA; Department of Physics, Washington University, St. Louis, MO 63130, USA
| | - Elizabeth S Haswell
- Department of Biology, Washington University, St. Louis, MO 63130, USA; NSF Center for Engineering Mechanobiology, Cleveland, OH, USA.
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8
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Marmion M, Macori G, Ferone M, Whyte P, Scannell A. Survive and thrive: Control mechanisms that facilitate bacterial adaptation to survive manufacturing-related stress. Int J Food Microbiol 2022; 368:109612. [DOI: 10.1016/j.ijfoodmicro.2022.109612] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/02/2021] [Revised: 02/21/2022] [Accepted: 03/02/2022] [Indexed: 10/18/2022]
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9
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Gomez D, Peña Ccoa WJ, Singh Y, Rojas E, Hocky GM. Molecular Paradigms for Biological Mechanosensing. J Phys Chem B 2021; 125:12115-12124. [PMID: 34709040 DOI: 10.1021/acs.jpcb.1c06330] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Many proteins in living cells are subject to mechanical forces, which can be generated internally by molecular machines, or externally, e.g., by pressure gradients. In general, these forces fall in the piconewton range, which is similar in magnitude to forces experienced by a molecule due to thermal fluctuations. While we would naively expect such moderate forces to produce only minimal changes, a wide variety of "mechanosensing" proteins have evolved with functions that are responsive to forces in this regime. The goal of this article is to provide a physical chemistry perspective on protein-based molecular mechanosensing paradigms used in living systems, and how these paradigms can be explored using novel computational methods.
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Affiliation(s)
- David Gomez
- Department of Biology, New York University, New York, New York 10003, United States.,Department of Chemistry, New York University, New York, New York 10003, United States
| | - Willmor J Peña Ccoa
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Yuvraj Singh
- Department of Chemistry, New York University, New York, New York 10003, United States
| | - Enrique Rojas
- Department of Biology, New York University, New York, New York 10003, United States
| | - Glen M Hocky
- Department of Chemistry, New York University, New York, New York 10003, United States
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10
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Wong F, Wilson S, Helbig R, Hegde S, Aftenieva O, Zheng H, Liu C, Pilizota T, Garner EC, Amir A, Renner LD. Understanding Beta-Lactam-Induced Lysis at the Single-Cell Level. Front Microbiol 2021; 12:712007. [PMID: 34421870 PMCID: PMC8372035 DOI: 10.3389/fmicb.2021.712007] [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: 05/19/2021] [Accepted: 06/30/2021] [Indexed: 12/04/2022] Open
Abstract
Mechanical rupture, or lysis, of the cytoplasmic membrane is a common cell death pathway in bacteria occurring in response to β-lactam antibiotics. A better understanding of the cellular design principles governing the susceptibility and response of individual cells to lysis could indicate methods of potentiating β-lactam antibiotics and clarify relevant aspects of cellular physiology. Here, we take a single-cell approach to bacterial cell lysis to examine three cellular features—turgor pressure, mechanosensitive channels, and cell shape changes—that are expected to modulate lysis. We develop a mechanical model of bacterial cell lysis and experimentally analyze the dynamics of lysis in hundreds of single Escherichia coli cells. We find that turgor pressure is the only factor, of these three cellular features, which robustly modulates lysis. We show that mechanosensitive channels do not modulate lysis due to insufficiently fast solute outflow, and that cell shape changes result in more severe cellular lesions but do not influence the dynamics of lysis. These results inform a single-cell view of bacterial cell lysis and underscore approaches of combatting antibiotic tolerance to β-lactams aimed at targeting cellular turgor.
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Affiliation(s)
- Felix Wong
- Department of Biological Engineering, Institute for Medical Engineering & Science, Massachusetts Institute of Technology, Cambridge, MA, United States.,Infectious Disease and Microbiome Program, Broad Institute of MIT and Harvard, Cambridge, MA, United States.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States
| | - Sean Wilson
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, United States.,Center for Systems Biology, Harvard University, Cambridge, MA, United States
| | - Ralf Helbig
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, Dresden, Germany
| | - Smitha Hegde
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Olha Aftenieva
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, Dresden, Germany
| | - Hai Zheng
- CAS Key Laboratory for Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Chenli Liu
- CAS Key Laboratory for Quantitative Engineering Biology, Shenzhen Institute of Synthetic Biology, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen, China
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, MA, United States.,Center for Systems Biology, Harvard University, Cambridge, MA, United States
| | - Ariel Amir
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, United States
| | - Lars D Renner
- Leibniz Institute of Polymer Research and the Max Bergmann Center of Biomaterials, Dresden, Germany
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11
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Abstract
Bacteria thrive both in liquids and attached to surfaces. The concentration of bacteria on surfaces is generally much higher than in the surrounding environment, offering bacteria ample opportunity for mutualistic, symbiotic, and pathogenic interactions. To efficiently populate surfaces, they have evolved mechanisms to sense mechanical or chemical cues upon contact with solid substrata. This is of particular importance for pathogens that interact with host tissue surfaces. In this review we discuss how bacteria are able to sense surfaces and how they use this information to adapt their physiology and behavior to this new environment. We first survey mechanosensing and chemosensing mechanisms and outline how specific macromolecular structures can inform bacteria about surfaces. We then discuss how mechanical cues are converted to biochemical signals to activate specific cellular processes in a defined chronological order and describe the role of two key second messengers, c-di-GMP and cAMP, in this process.
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Affiliation(s)
| | - Urs Jenal
- Biozentrum, University of Basel, CH-4056 Basel, Switzerland; ,
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12
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Chure G, Lee HJ, Rasmussen A, Phillips R. Connecting the Dots between Mechanosensitive Channel Abundance, Osmotic Shock, and Survival at Single-Cell Resolution. J Bacteriol 2018; 200:e00460-18. [PMID: 30201782 PMCID: PMC6222198 DOI: 10.1128/jb.00460-18] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 08/05/2018] [Indexed: 12/17/2022] Open
Abstract
Rapid changes in extracellular osmolarity are one of many insults microbial cells face on a daily basis. To protect against such shocks, Escherichia coli and other microbes express several types of transmembrane channels that open and close in response to changes in membrane tension. In E. coli, one of the most abundant channels is the mechanosensitive channel of large conductance (MscL). While this channel has been heavily characterized through structural methods, electrophysiology, and theoretical modeling, our understanding of its physiological role in preventing cell death by alleviating high membrane tension remains tenuous. In this work, we examine the contribution of MscL alone to cell survival after osmotic shock at single-cell resolution using quantitative fluorescence microscopy. We conducted these experiments in an E. coli strain which is lacking all mechanosensitive channel genes save for MscL, whose expression was tuned across 3 orders of magnitude through modifications of the Shine-Dalgarno sequence. While theoretical models suggest that only a few MscL channels would be needed to alleviate even large changes in osmotic pressure, we find that between 500 and 700 channels per cell are needed to convey upwards of 80% survival. This number agrees with the average MscL copy number measured in wild-type E. coli cells through proteomic studies and quantitative Western blotting. Furthermore, we observed zero survival events in cells with fewer than ∼100 channels per cell. This work opens new questions concerning the contribution of other mechanosensitive channels to survival, as well as regulation of their activity.IMPORTANCE Mechanosensitive (MS) channels are transmembrane protein complexes which open and close in response to changes in membrane tension as a result of osmotic shock. Despite extensive biophysical characterization, the contribution of these channels to cell survival remains largely unknown. In this work, we used quantitative video microscopy to measure the abundance of a single species of MS channel in single cells, followed by their survival after a large osmotic shock. We observed total death of the population with fewer than ∼100 channels per cell and determined that approximately 500 to 700 channels were needed for 80% survival. The number of channels we found to confer nearly full survival is consistent with the counts of the numbers of channels in wild-type cells in several earlier studies. These results prompt further studies to dissect the contribution of other channel species to survival.
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Affiliation(s)
- Griffin Chure
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
| | - Heun Jin Lee
- Department of Applied Physics, California Institute of Technology, Pasadena, California, USA
| | - Akiko Rasmussen
- Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen, United Kingdom
| | - Rob Phillips
- Department of Biology and Biological Engineering, California Institute of Technology, Pasadena, California, USA
- Department of Physics, California Institute of Technology, Pasadena, California, USA
- Department of Applied Physics, California Institute of Technology, Pasadena, California, USA
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