1
|
Biquet-Bisquert A, Carrio B, Meyer N, Fernandes TFD, Abkarian M, Seduk F, Magalon A, Nord AL, Pedaci F. Spatiotemporal dynamics of the proton motive force on single bacterial cells. SCIENCE ADVANCES 2024; 10:eadl5849. [PMID: 38781330 PMCID: PMC11114223 DOI: 10.1126/sciadv.adl5849] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2023] [Accepted: 04/18/2024] [Indexed: 05/25/2024]
Abstract
Electrochemical gradients across biological membranes are vital for cellular bioenergetics. In bacteria, the proton motive force (PMF) drives essential processes like adenosine triphosphate production and motility. Traditionally viewed as temporally and spatially stable, recent research reveals a dynamic PMF behavior at both single-cell and community levels. Moreover, the observed lateral segregation of respiratory complexes could suggest a spatial heterogeneity of the PMF. Using a light-activated proton pump and detecting the activity of the bacterial flagellar motor, we perturb and probe the PMF of single cells. Spatially homogeneous PMF perturbations reveal millisecond-scale temporal dynamics and an asymmetrical capacitive response. Localized perturbations show a rapid lateral PMF homogenization, faster than proton diffusion, akin to the electrotonic potential spread observed in passive neurons, explained by cable theory. These observations imply a global coupling between PMF sources and consumers along the membrane, precluding sustained PMF spatial heterogeneity but allowing for rapid temporal changes.
Collapse
Affiliation(s)
- Anaïs Biquet-Bisquert
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Baptiste Carrio
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Nathan Meyer
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Thales F. D. Fernandes
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Manouk Abkarian
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Farida Seduk
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402 Marseille, France
| | - Axel Magalon
- Aix Marseille Université, CNRS, Laboratoire de Chimie Bactérienne (UMR7283), IMM, IM2B, 13402 Marseille, France
| | - Ashley L. Nord
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| | - Francesco Pedaci
- Centre de Biologie Structurale, Université de Montpellier, CNRS, INSERM. Montpellier, France
| |
Collapse
|
2
|
Mancini L, Pilizota T. Environmental conditions define the energetics of bacterial dormancy and its antibiotic susceptibility. Biophys J 2023; 122:3207-3218. [PMID: 37403359 PMCID: PMC10465703 DOI: 10.1016/j.bpj.2023.06.023] [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: 02/02/2023] [Revised: 05/17/2023] [Accepted: 06/30/2023] [Indexed: 07/06/2023] Open
Abstract
Bacterial cells that stop growing but maintain viability and the capability to regrow are termed dormant and have been shown to transiently tolerate high concentrations of antimicrobials. Links between tolerance and cellular energetics as a possible explanation for the tolerance, have been investigated and have produced mixed and seemingly contradictory results. Because dormancy merely indicates growth arrest, which can be induced by various stimuli, we hypothesize that dormant cells may exist in a range of energetic states that depend on the environment. To energetically characterize different dormancies, we first induce them in a way that results in dormant populations and subsequently measure both of their main energy sources, the proton motive force magnitude and the concentration of ATP. We find that different types of dormancy exhibit characteristic energetic profiles that vary in level and dynamics. The energetic makeup was associated with survival to some antibiotics but not others. Our findings portray dormancy as a state that is rich in phenotypes with various stress survival capabilities. Because environmental conditions outside of the lab often halt or limit microbial growth, a typologization of dormant states may yield relevant insights on the survival and evolutionary strategies of these organisms.
Collapse
Affiliation(s)
- Leonardo Mancini
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, United Kingdom
| | - Teuta Pilizota
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, United Kingdom.
| |
Collapse
|
3
|
Sensitive bacterial V m sensors revealed the excitability of bacterial V m and its role in antibiotic tolerance. Proc Natl Acad Sci U S A 2023; 120:e2208348120. [PMID: 36623202 PMCID: PMC9934018 DOI: 10.1073/pnas.2208348120] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023] Open
Abstract
As an important free energy source, the membrane voltage (Vm) regulates many essential physiological processes in bacteria. However, in comparison with eukaryotic cells, knowledge of bacterial electrophysiology is very limited. Here, we developed a set of novel genetically encoded bacterial Vm sensors which allow single-cell recording of bacterial Vm dynamics in live cells with high temporal resolution. Using these new sensors, we reveal the electrically "excitable" and "resting" states of bacterial cells dependent on their metabolic status. In the electrically excitable state, frequent hyperpolarization spikes in bacterial Vm are observed, which are regulated by Na+/K+ ratio of the medium and facilitate increased antibiotic tolerance. In the electrically resting state, bacterial Vm displays significant cell-to-cell heterogeneity and is linked to the cell fate after antibiotic treatment. Our findings demonstrate the potential of our newly developed voltage sensors to reveal the underpinning connections between bacterial Vm and antibiotic tolerance.
Collapse
|
4
|
Honda T, Cremer J, Mancini L, Zhang Z, Pilizota T, Hwa T. Coordination of gene expression with cell size enables Escherichia coli to efficiently maintain motility across conditions. Proc Natl Acad Sci U S A 2022; 119:e2110342119. [PMID: 36067284 PMCID: PMC9478672 DOI: 10.1073/pnas.2110342119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2021] [Accepted: 08/04/2022] [Indexed: 11/18/2022] Open
Abstract
To swim and navigate, motile bacteria synthesize a complex motility machinery involving flagella, motors, and a sensory system. A myriad of studies has elucidated the molecular processes involved, but less is known about the coordination of motility expression with cellular physiology: In Escherichia coli, motility genes are strongly up-regulated in nutrient-poor conditions compared to nutrient-replete conditions; yet a quantitative link to cellular motility has not been developed. Here, we systematically investigated gene expression, swimming behavior, cell growth, and available proteomics data across a broad spectrum of exponential growth conditions. Our results suggest that cells up-regulate the expression of motility genes at slow growth to compensate for reduction in cell size, such that the number of flagella per cell is maintained across conditions. The observed four or five flagella per cell is the minimum number needed to keep the majority of cells motile. This simple regulatory objective allows E. coli cells to remain motile across a broad range of growth conditions, while keeping the biosynthetic and energetic demands to establish and drive the motility machinery at the minimum needed. Given the strong reduction in flagella synthesis resulting from cell size increases at fast growth, our findings also provide a different physiological perspective on bacterial cell size control: A larger cell size at fast growth is an efficient strategy to increase the allocation of cellular resources to the synthesis of those proteins required for biomass synthesis and growth, while maintaining processes such as motility that are only needed on a per-cell basis.
Collapse
Affiliation(s)
- Tomoya Honda
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
- US Department of Energy, Joint Genome Institute, Berkeley, CA 94720
| | - Jonas Cremer
- Department of Physics, University of California at San Diego, La Jolla, CA 92093
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Leonardo Mancini
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom
- Department of Physics, Cavendish Laboratory, University of Cambridge, Cambridge, CB3 0HE, United Kingdom
| | - Zhongge Zhang
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
| | - Teuta Pilizota
- School of Biological Sciences, Centre for Synthetic and Systems Biology, University of Edinburgh, Edinburgh, EH9 3FF, United Kingdom
| | - Terence Hwa
- Division of Biological Sciences, University of California at San Diego, La Jolla, CA 92093
- Department of Physics, University of California at San Diego, La Jolla, CA 92093
| |
Collapse
|
5
|
Yeh L, Yen CH, Kao YL, Lien HL, Chang SM. Inactivation of Escherichia coli by dual-functional zerovalent Fe/Al composites in water. CHEMOSPHERE 2022; 299:134371. [PMID: 35351482 DOI: 10.1016/j.chemosphere.2022.134371] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Revised: 03/03/2022] [Accepted: 03/17/2022] [Indexed: 06/14/2023]
Abstract
A bimetallic Fe/Al disinfection system was developed to examine the feasibility of inactivation of water borne microorganisms. In this study, the effectiveness and mechanisms of the bimetallic Fe/Al system on the inactivation of model bacteria, Escherichia coli (E. coli), were investigated. Results revealed that the Fe/Al system effectively inactivated E. coli to reach nearly 2 logs (99%) removal within 20 min and 4 logs (99.99%) at 24 h, indicating that the Fe/Al composite was able to sustain a long-term disinfection capacity. The inactivation ability resulted from hydroxyl radicals produced by a Fenton reaction through in-situ self-generated Fe2+ and H2O2 species in the Fe/Al system. In addition to the attack by the radicals, some of E. coli were adsorbed onto the Fe/Al composite (zeta potential of 30-50 mV) as a result of Coulomb interaction. Scanning electron microscope (SEM) images showed that the adsorbed bacteria had damaged pores at the two ends of their rod-like cells. This phenomenon suggested that a micro-electric field between the Fe/Al galvanic couple induced electroporation of the adsorbed E. coli and thus further advanced additional inactivation ability for the bacteria disinfection.
Collapse
Affiliation(s)
- Lizhi Yeh
- Department of Civil and Environmental Engineering, National University of Kaohsiung, 81148, Kaohsiung, Taiwan
| | - Chia-Hsin Yen
- Institute of Environmental Engineering, National Yang Ming Chiao Tung University, 30010, Hsinchu, Taiwan
| | - Yu-Lin Kao
- Department of Life Science, National University of Kaohsiung, 81148, Kaohsiung, Taiwan
| | - Hsing-Lung Lien
- Department of Civil and Environmental Engineering, National University of Kaohsiung, 81148, Kaohsiung, Taiwan.
| | - Sue-Min Chang
- Institute of Environmental Engineering, National Yang Ming Chiao Tung University, 30010, Hsinchu, Taiwan
| |
Collapse
|
6
|
Gupta R, Rhee KY, Beagle SD, Chawla R, Perdomo N, Lockless SW, Lele PP. Indole modulates cooperative protein-protein interactions in the flagellar motor. PNAS NEXUS 2022; 1. [PMID: 35719892 PMCID: PMC9205328 DOI: 10.1093/pnasnexus/pgac035] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
Indole is a major component of the bacterial exometabolome, and the mechanisms for its wide-ranging effects on bacterial physiology are biomedically significant, although they remain poorly understood. Here, we determined how indole modulates the functions of a widely conserved motility apparatus, the bacterial flagellum. Our experiments in Escherichia coli revealed that indole influences the rotation rates and reversals in the flagellum’s direction of rotation via multiple mechanisms. At concentrations higher than 1 mM, indole decreased the membrane potential to dissipate the power available for the rotation of the motor that operates the flagellum. Below 1 mM, indole did not dissipate the membrane potential. Instead, experiments and modeling indicated that indole weakens cooperative protein interactions within the flagellar complexes to inhibit motility. The metabolite also induced reversals in the rotational direction of the motor to promote a weak chemotactic response, even when the chemotaxis response regulator, CheY, was lacking. Experiments further revealed that indole does not require the transporter Mtr to cross the membrane and influence motor functions. Based on these findings, we propose that indole modulates intra- and inter-protein interactions in the cell to influence several physiological functions.
Collapse
Affiliation(s)
- Rachit Gupta
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA
| | - Kathy Y Rhee
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA
| | - Sarah D Beagle
- Department of Biology, Washington University in St. Louis, St. Louis, Missouri, 63130, USA
| | - Ravi Chawla
- Department of Integrative Structural and Computational Biology, Scripps Research, La Jolla, CA 92037, USA
| | - Nicolas Perdomo
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA
| | - Steve W Lockless
- Department of Biology, Texas A&M University, College Station, TX 77843-3258, USA
| | - Pushkar P Lele
- Artie McFerrin Department of Chemical Engineering, Texas A&M University, College Station, TX 77843-3122, USA
| |
Collapse
|
7
|
Sami Z, Kaouthar M, Nadia C, Hedi BM. Effect of sunlight and salinity on the survival of pathogenic and non-pathogenic strains of Vibrio parahaemolyticus in water microcosms. WATER ENVIRONMENT RESEARCH : A RESEARCH PUBLICATION OF THE WATER ENVIRONMENT FEDERATION 2022; 94:e10689. [PMID: 35112431 DOI: 10.1002/wer.10689] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/07/2021] [Revised: 12/23/2021] [Accepted: 01/07/2022] [Indexed: 06/14/2023]
Abstract
The effect of sunlight and salinities (10, 20, 39, and 60 psu) on the survival of Vibrio parahaemolyticus strains carrying either (thermostable direct hemolysin) tdh, the (thermostable related hemolysin) trh, and both or none of them were studied in water microcosms stabilized at 20°C using plate count agar and acridine orange direct viable count. All V. parahaemolyticus strains exposed to sunlight rapidly lose their culturability and evolve into a viable but non-culturable state (VBNC). However, the tdh positive strains remain more culturable than the non-virulent or trh positive strain but statically insignificant. At tested salinities, the survival time was higher at 10, 20, and 60 psu compared with that observed in seawater (39 psu). In seawater under dark condition, Vibrio strains remain culturable for up to 200 days with a significant difference between strains (p < 0.05). Furthermore, the non-pathogenic strain survives longer than the virulent ones. At different salinities, a better adaptation is observed at 10 and 20 psu compared with 39 and 60 psu. Resuscitations essays performed on VBNC bacteria in a nutrient broth at 20°C and 37°C does not show any revivification. PRACTITIONER POINTS: Effect of sunlight and salinities on the survival of V. parahaemolyticus in the marine environment. Resuscitation essay performed on viable but no cultivable bacteria. Microscope motility examines show that all strains exposed to sunlight remain motile after the loss of cultivability.
Collapse
Affiliation(s)
- Zaafrane Sami
- National Institute of Sciences and Seawater Technologies Salammbô, Salammbo, Tunisia
| | - Maatouk Kaouthar
- National Institute of Sciences and Seawater Technologies Salammbô, Salammbo, Tunisia
| | - Cherif Nadia
- National Institute of Sciences and Seawater Technologies Salammbô, Salammbo, Tunisia
| | - Ben Mansour Hedi
- Unité de Recherche Analyses et Procédés Appliqués à l'Environnement-ISSAT, Mahdia, Tunisia
| |
Collapse
|
8
|
Le D, Krasnopeeva E, Sinjab F, Pilizota T, Kim M. Active Efflux Leads to Heterogeneous Dissipation of Proton Motive Force by Protonophores in Bacteria. mBio 2021; 12:e0067621. [PMID: 34253054 PMCID: PMC8406135 DOI: 10.1128/mbio.00676-21] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2021] [Accepted: 06/04/2021] [Indexed: 11/26/2022] Open
Abstract
Various toxic compounds disrupt bacterial physiology. While bacteria harbor defense mechanisms to mitigate the toxicity, these mechanisms are often coupled to the physiological state of the cells and become ineffective when the physiology is severely disrupted. Here, we characterized such feedback by exposing Escherichia coli to protonophores. Protonophores dissipate the proton motive force (PMF), a fundamental force that drives physiological functions. We found that E. coli cells responded to protonophores heterogeneously, resulting in bimodal distributions of cell growth, substrate transport, and motility. Furthermore, we showed that this heterogeneous response required active efflux systems. The analysis of underlying interactions indicated the heterogeneous response results from efflux-mediated positive feedback between PMF and protonophores' action. Our studies have broad implications for bacterial adaptation to stress, including antibiotics. IMPORTANCE An electrochemical proton gradient across the cytoplasmic membrane, alternatively known as proton motive force, energizes vital cellular processes in bacteria, including ATP synthesis, nutrient uptake, and cell division. Therefore, a wide range of organisms produce the agents that collapse the proton motive force, protonophores, to gain a competitive advantage. Studies have shown that protonophores have significant effects on microbial competition, host-pathogen interaction, and antibiotic action and resistance. Furthermore, protonophores are extensively used in various laboratory studies to perturb bacterial physiology. Here, we have characterized cell growth, substrate transport, and motility of Escherichia coli cells exposed to protonophores. Our findings demonstrate heterogeneous effects of protonophores on cell physiology and the underlying mechanism.
Collapse
Affiliation(s)
- Dai Le
- Department of Physics, Emory University, Atlanta, Georgia, USA
- Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia, USA
| | - Ekaterina Krasnopeeva
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Faris Sinjab
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology, School of Biological Sciences, University of Edinburgh, Edinburgh, United Kingdom
| | - Minsu Kim
- Department of Physics, Emory University, Atlanta, Georgia, USA
- Graduate Division of Biological and Biomedical Sciences, Emory University, Atlanta, Georgia, USA
| |
Collapse
|
9
|
Abstract
Living systems maintain or increase local order by working against the second law of thermodynamics. Thermodynamic consistency is restored as they consume free energy, thereby increasing the net entropy of their environment. Recently introduced estimators for the entropy production rate have provided major insights into the efficiency of important cellular processes. In experiments, however, many degrees of freedom typically remain hidden to the observer, and, in these cases, existing methods are not optimal. Here, by reformulating the problem within an optimization framework, we are able to infer improved bounds on the rate of entropy production from partial measurements of biological systems. Our approach yields provably optimal estimates given certain measurable transition statistics. In contrast to prevailing methods, the improved estimator reveals nonzero entropy production rates even when nonequilibrium processes appear time symmetric and therefore may pretend to obey detailed balance. We demonstrate the broad applicability of this framework by providing improved bounds on the energy consumption rates in a diverse range of biological systems including bacterial flagella motors, growing microtubules, and calcium oscillations within human embryonic kidney cells.
Collapse
Affiliation(s)
- Dominic J Skinner
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139
| | - Jörn Dunkel
- Department of Mathematics, Massachusetts Institute of Technology, Cambridge, MA 02139
| |
Collapse
|
10
|
Biquet-Bisquert A, Labesse G, Pedaci F, Nord AL. The Dynamic Ion Motive Force Powering the Bacterial Flagellar Motor. Front Microbiol 2021; 12:659464. [PMID: 33927708 PMCID: PMC8076557 DOI: 10.3389/fmicb.2021.659464] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2021] [Accepted: 03/02/2021] [Indexed: 11/13/2022] Open
Abstract
The bacterial flagellar motor (BFM) is a rotary molecular motor embedded in the cell membrane of numerous bacteria. It turns a flagellum which acts as a propeller, enabling bacterial motility and chemotaxis. The BFM is rotated by stator units, inner membrane protein complexes that stochastically associate to and dissociate from individual motors at a rate which depends on the mechanical and electrochemical environment. Stator units consume the ion motive force (IMF), the electrochemical gradient across the inner membrane that results from cellular respiration, converting the electrochemical energy of translocated ions into mechanical energy, imparted to the rotor. Here, we review some of the main results that form the base of our current understanding of the relationship between the IMF and the functioning of the flagellar motor. We examine a series of studies that establish a linear proportionality between IMF and motor speed, and we discuss more recent evidence that the stator units sense the IMF, altering their rates of dynamic assembly. This, in turn, raises the question of to what degree the classical dependence of motor speed on IMF is due to stator dynamics vs. the rate of ion flow through the stators. Finally, while long assumed to be static and homogeneous, there is mounting evidence that the IMF is dynamic, and that its fluctuations control important phenomena such as cell-to-cell signaling and mechanotransduction. Within the growing toolbox of single cell bacterial electrophysiology, one of the best tools to probe IMF fluctuations may, ironically, be the motor that consumes it. Perfecting our incomplete understanding of how the BFM employs the energy of ion flow will help decipher the dynamical behavior of the bacterial IMF.
Collapse
Affiliation(s)
- Anaïs Biquet-Bisquert
- Centre de Biologie Structurale (CBS), INSERM, CNRS, Université Montpellier, Montpellier, France
| | - Gilles Labesse
- Centre de Biologie Structurale (CBS), INSERM, CNRS, Université Montpellier, Montpellier, France
| | - Francesco Pedaci
- Centre de Biologie Structurale (CBS), INSERM, CNRS, Université Montpellier, Montpellier, France
| | - Ashley L Nord
- Centre de Biologie Structurale (CBS), INSERM, CNRS, Université Montpellier, Montpellier, France
| |
Collapse
|
11
|
Grobas I, Polin M, Asally M. Swarming bacteria undergo localized dynamic phase transition to form stress-induced biofilms. eLife 2021; 10:62632. [PMID: 33722344 PMCID: PMC7963483 DOI: 10.7554/elife.62632] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2020] [Accepted: 02/26/2021] [Indexed: 12/23/2022] Open
Abstract
Self-organized multicellular behaviors enable cells to adapt and tolerate stressors to a greater degree than isolated cells. However, whether and how cellular communities alter their collective behaviors adaptively upon exposure to stress is largely unclear. Here, we investigate this question using Bacillus subtilis, a model system for bacterial multicellularity. We discover that, upon exposure to a spatial gradient of kanamycin, swarming bacteria activate matrix genes and transit to biofilms. The initial stage of this transition is underpinned by a stress-induced multilayer formation, emerging from a biophysical mechanism reminiscent of motility-induced phase separation (MIPS). The physical nature of the process suggests that stressors which suppress the expansion of swarms would induce biofilm formation. Indeed, a simple physical barrier also induces a swarm-to-biofilm transition. Based on the gained insight, we propose a strategy of antibiotic treatment to inhibit the transition from swarms to biofilms by targeting the localized phase transition.
Collapse
Affiliation(s)
- Iago Grobas
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom
| | - Marco Polin
- Warwick Medical School, Universityof Warwick, Coventry, United Kingdom.,Centre for Mechanochemical Cell Biology, University of Warwick, Coventry, United Kingdom.,Physics Department, University of Warwick, Coventry, United Kingdom.,Mediterranean Institute for Advanced Studies (IMEDEA UIB-CSIC), C/ Miquel Marqués, Balearic Islands, Spain
| | - Munehiro Asally
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry, United Kingdom.,Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, United Kingdom.,School of Life Sciences, University of Warwick, Coventry, United Kingdom
| |
Collapse
|
12
|
Bell J, Araujo G, Tang JX. Discovery of oscillations in rotational speed of body-tethered Caulobacter crescentus. Phys Rev E 2021; 102:062416. [PMID: 33466088 DOI: 10.1103/physreve.102.062416] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Accepted: 11/09/2020] [Indexed: 11/07/2022]
Abstract
Swarmer cells of Caulobacter crescentus have been found to tether to glass at a point on the cell body. The rolling of the freely rotating flagellum near the glass surface causes the cell body to rotate. We describe the discovery of damped oscillations in the rotational speed of these cell bodies. We show that the damped oscillations are robust over multiple cells and that they depend more on the cell's accumulated rotation angle than on time. We also find that their phase is determined by the moment the flagellar motor changes the direction of its rotation. The oscillations occur only for one direction of cell rotation, when the flagellum is in pulling mode. We discuss possible explanations for these oscillations, including fluctuations in flagellar motor torque and periodic changes in flagellar orientation, and illustrate both of these cases using simplified computer models. Finally, we present the hypothesis that the oscillations are the result of fluctuations in the proton motive force, initiated by a sudden change in proton current that occurs when the motor switches rotation direction.
Collapse
Affiliation(s)
- Jordan Bell
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - George Araujo
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| | - Jay X Tang
- Department of Physics, Brown University, Providence, Rhode Island 02912, USA
| |
Collapse
|
13
|
Bacterial flagellar motor as a multimodal biosensor. Methods 2020; 193:5-15. [PMID: 32640316 DOI: 10.1016/j.ymeth.2020.06.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Revised: 06/04/2020] [Accepted: 06/22/2020] [Indexed: 01/05/2023] Open
Abstract
Bacterial Flagellar Motor is one of nature's rare rotary molecular machines. It enables bacterial swimming and it is the key part of the bacterial chemotactic network, one of the best studied chemical signalling networks in biology, which enables bacteria to direct its movement in accordance with the chemical environment. The network can sense down to nanomolar concentrations of specific chemicals on the time scale of seconds. Motor's rotational speed is linearly proportional to the electrochemical gradients of either proton or sodium driving ions, while its direction is regulated by the chemotactic network. Recently, it has been discovered that motor is also a mechanosensor. Given these properties, we discuss the motor's potential to serve as a multifunctional biosensor and a tool for characterising and studying the external environment, the bacterial physiology itself and single molecular motor biophysics.
Collapse
|
14
|
Schofield Z, Meloni GN, Tran P, Zerfass C, Sena G, Hayashi Y, Grant M, Contera SA, Minteer SD, Kim M, Prindle A, Rocha P, Djamgoz MBA, Pilizota T, Unwin PR, Asally M, Soyer OS. Bioelectrical understanding and engineering of cell biology. J R Soc Interface 2020; 17:20200013. [PMID: 32429828 PMCID: PMC7276535 DOI: 10.1098/rsif.2020.0013] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2020] [Accepted: 04/17/2020] [Indexed: 02/07/2023] Open
Abstract
The last five decades of molecular and systems biology research have provided unprecedented insights into the molecular and genetic basis of many cellular processes. Despite these insights, however, it is arguable that there is still only limited predictive understanding of cell behaviours. In particular, the basis of heterogeneity in single-cell behaviour and the initiation of many different metabolic, transcriptional or mechanical responses to environmental stimuli remain largely unexplained. To go beyond the status quo, the understanding of cell behaviours emerging from molecular genetics must be complemented with physical and physiological ones, focusing on the intracellular and extracellular conditions within and around cells. Here, we argue that such a combination of genetics, physics and physiology can be grounded on a bioelectrical conceptualization of cells. We motivate the reasoning behind such a proposal and describe examples where a bioelectrical view has been shown to, or can, provide predictive biological understanding. In addition, we discuss how this view opens up novel ways to control cell behaviours by electrical and electrochemical means, setting the stage for the emergence of bioelectrical engineering.
Collapse
Affiliation(s)
- Zoe Schofield
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Gabriel N. Meloni
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Peter Tran
- Department of Chemical and Biological Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Christian Zerfass
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Giovanni Sena
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Yoshikatsu Hayashi
- Department of Biomedical Engineering, School of Biological Sciences, University of Reading, Reading RG6 6AH, UK
| | - Murray Grant
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Sonia A. Contera
- Clarendon Laboratory, Physics Department, University of Oxford, Parks Road, Oxford OX1 3PU, UK
| | - Shelley D. Minteer
- Department of Chemistry, University of Utah, 315 S 1400 E, Salt Lake City, Utah 84112, USA
| | - Minsu Kim
- Department of Physics, Emory University, Atlanta, GA 30322, USA
| | - Arthur Prindle
- Department of Chemical and Biological Engineering, Northwestern University, Chicago, IL 60611, USA
| | - Paulo Rocha
- Centre for Biosensors, Bioelectronics and Biodevices (C3Bio), Department of Electronic and Electrical Engineering, University of Bath, Claverton Down, Bath BA2 7AY, UK
| | - Mustafa B. A. Djamgoz
- Department of Life Sciences, Imperial College London, South Kensington Campus, London SW7 2AZ, UK
| | - Teuta Pilizota
- Systems and Synthetic Biology Centre and School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, Edinburgh EH9 3FF, UK
| | - Patrick R. Unwin
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- Department of Chemistry, University of Warwick, Coventry CV4 7AL, UK
| | - Munehiro Asally
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| | - Orkun S. Soyer
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, UK
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, UK
| |
Collapse
|
15
|
Boon N, Kaur M, Aziz A, Bradnick M, Shibayama K, Eguchi Y, Lund PA. The Signaling Molecule Indole Inhibits Induction of the AR2 Acid Resistance System in Escherichia coli. Front Microbiol 2020; 11:474. [PMID: 32351457 PMCID: PMC7174508 DOI: 10.3389/fmicb.2020.00474] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2020] [Accepted: 03/04/2020] [Indexed: 12/19/2022] Open
Abstract
Induction of the AR2 acid response system of Escherichia coli occurs at a moderately low pH (pH 5.5) and leads to high levels of resistance to pH levels below 2.5 in the presence of glutamate. Induction is mediated in part by the EvgAS two component system. Here, we show that the bacterial signaling molecule indole inhibits the induction of key promoters in the AR2 system and blocks the development of glutamate-dependent acid resistance. The addition of tryptophan, the precursor for indole biosynthesis, had the same effects, and this block was relieved in a tnaA mutant, which is unable to synthesize indole. Expression of a constitutively active EvgS protein was able to relieve the inhibition caused by indole, consistent with EvgS being inhibited directly or indirectly by indole. Indole had no effect on autophosphorylation of the isolated cytoplasmic domain of EvgS. This is consistent with a model where indole directly or indirectly affects the ability of EvgS to detect its inducing signal or to transduce this information across the cytoplasmic membrane. The inhibitory activity of indole on the AR2 system is not related to its ability to act as an ionophore, and, conversely, the ionophore CCCP had no effect on acid-induced AR2 promoter activity, showing that the proton motive force is unlikely to be a signal for induction of the AR2 system.
Collapse
Affiliation(s)
- Nathaniel Boon
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Manpreet Kaur
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Amina Aziz
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Morissa Bradnick
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| | - Kenta Shibayama
- Department of Science and Technology on Food Safety, Faculty of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Yoko Eguchi
- Department of Science and Technology on Food Safety, Faculty of Biology-Oriented Science and Technology, Kindai University, Wakayama, Japan
| | - Peter A Lund
- School of Biosciences and Institute of Microbiology and Infection, University of Birmingham, Birmingham, United Kingdom
| |
Collapse
|
16
|
Benarroch JM, Asally M. The Microbiologist’s Guide to Membrane Potential Dynamics. Trends Microbiol 2020; 28:304-314. [DOI: 10.1016/j.tim.2019.12.008] [Citation(s) in RCA: 69] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2019] [Revised: 11/25/2019] [Accepted: 12/09/2019] [Indexed: 10/25/2022]
|
17
|
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.
Collapse
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
| |
Collapse
|
18
|
Wang YK, Krasnopeeva E, Lin SY, Bai F, Pilizota T, Lo CJ. Comparison of Escherichia coli surface attachment methods for single-cell microscopy. Sci Rep 2019; 9:19418. [PMID: 31857669 PMCID: PMC6923479 DOI: 10.1038/s41598-019-55798-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 11/05/2019] [Indexed: 12/22/2022] Open
Abstract
For in vivo, single-cell imaging bacterial cells are commonly immobilised via physical confinement or surface attachment. Different surface attachment methods have been used both for atomic force and optical microscopy (including super resolution), and some have been reported to affect bacterial physiology. However, a systematic comparison of the effects these attachment methods have on the bacterial physiology is lacking. Here we present such a comparison for bacterium Escherichia coli, and assess the growth rate, size and intracellular pH of cells growing attached to different, commonly used, surfaces. We demonstrate that E. coli grow at the same rate, length and internal pH on all the tested surfaces when in the same growth medium. The result suggests that tested attachment methods can be used interchangeably when studying E. coli physiology.
Collapse
Affiliation(s)
- Yao-Kuan Wang
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Ekaterina Krasnopeeva
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK
| | - Ssu-Yuan Lin
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China
| | - Fan Bai
- Biodynamic Optical Imaging Center (BIOPIC), School of Life Sciences, Peking University, Beijing, 100871, China
| | - Teuta Pilizota
- Centre for Synthetic and Systems Biology, Institute of Cell Biology, School of Biological Sciences, University of Edinburgh, Alexander Crum Brown Road, EH9 3FF, Edinburgh, UK.
| | - Chien-Jung Lo
- Department of Physics and Graduate Institute of Biophysics, National Central University, Jhongli, Taiwan, 32001, Republic of China.
| |
Collapse
|
19
|
A General Workflow for Characterization of Nernstian Dyes and Their Effects on Bacterial Physiology. Biophys J 2019; 118:4-14. [PMID: 31810660 PMCID: PMC6950638 DOI: 10.1016/j.bpj.2019.10.030] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2019] [Revised: 10/08/2019] [Accepted: 10/18/2019] [Indexed: 12/22/2022] Open
Abstract
The electrical membrane potential (Vm) is one of the components of the electrochemical potential of protons across the biological membrane (proton motive force), which powers many vital cellular processes. Because Vm also plays a role in signal transduction, measuring it is of great interest. Over the years, a variety of techniques have been developed for the purpose. In bacteria, given their small size, Nernstian membrane voltage probes are arguably the favorite strategy, and their cytoplasmic accumulation depends on Vm according to the Nernst equation. However, a careful calibration of Nernstian probes that takes into account the tradeoffs between the ease with which the signal from the dye is observed and the dyes’ interactions with cellular physiology is rarely performed. Here, we use a mathematical model to understand such tradeoffs and apply the results to assess the applicability of the Thioflavin T dye as a Vm sensor in Escherichia coli. We identify the conditions in which the dye turns from a Vm probe into an actuator and, based on the model and experimental results, propose a general workflow for the characterization of Nernstian dye candidates.
Collapse
|
20
|
Pierce CJ, Osborne E, Mumper E, Lower BH, Lower SK, Sooryakumar R. Thrust and Power Output of the Bacterial Flagellar Motor: A Micromagnetic Tweezers Approach. Biophys J 2019; 117:1250-1257. [PMID: 31540710 DOI: 10.1016/j.bpj.2019.08.036] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2019] [Revised: 08/27/2019] [Accepted: 08/30/2019] [Indexed: 02/03/2023] Open
Abstract
One of the most common swimming strategies employed by microorganisms is based on the use of rotating helical filaments, called flagella, that are powered by molecular motors. Determining the physical properties of this propulsive system is crucial to understanding the behavior of these organisms. Furthermore, the ability to dynamically monitor the activity of the flagellar motor is a valuable indicator of the overall energetics of the cell. In this work, inherently magnetic bacteria confined in micromagnetic CoFe traps are used to directly and noninvasively determine the flagellar thrust force and swimming speed of motile cells. The technique permits determination of the ratio of propulsive force/swimming speed (the hydrodynamic resistance) and the power output of the flagellar motor for individual cells over extended time periods. Cells subjected to ultraviolet radiation are observed to experience exponential decays in power output as a function of exposure time. By noninvasively measuring thrust, velocity, and power output over time at a single-cell level, this technique can serve as the foundation for fundamental studies of bacterial hydrodynamics and also provides a novel, to our knowledge, tether-free probe of single-cell energetics over time.
Collapse
Affiliation(s)
| | - Emily Osborne
- Department of Physics, The Ohio State University, Columbus, Ohio
| | - Eric Mumper
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio
| | - Brian H Lower
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio
| | - Steven K Lower
- School of Environment and Natural Resources, The Ohio State University, Columbus, Ohio; School of Earth Sciences, The Ohio State University, Columbus, Ohio; Department of Microbial Infection and Immunity, The Ohio State University, Columbus, Ohio
| | | |
Collapse
|