51
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Paternò GM, Bondelli G, Lanzani G. Bringing Microbiology to Light: Toward All-Optical Electrophysiology in Bacteria. Bioelectricity 2021; 3:136-142. [PMID: 34476389 DOI: 10.1089/bioe.2021.0008] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The observation of neuron-like behavior in bacteria, such as the occurrence of electric spiking and extended bioelectric signaling, points to the role of membrane dynamics in prokaryotes. Electrophysiology of bacteria, however, has been overlooked for long time, due to the difficulties in monitoring bacterial bioelectric phenomena with those probing techniques that are commonly used for eukaryotes. Optical technologies can allow a paradigm shift in the field of electrophysiology of bacteria, as they would permit to elicit and monitor signaling rapidly, remotely, and with high spatiotemporal precision. In this perspective, we discuss about the potentiality of light interrogation methods in microbiology, encouraging the development of all-optical electrophysiology of bacteria.
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Affiliation(s)
| | - Gaia Bondelli
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy.,Physics Department, Politecnico di Milano, Milano, Italy
| | - Guglielmo Lanzani
- Center for Nanoscience and Technology, Istituto Italiano di Tecnologia, Milano, Italy.,Physics Department, Politecnico di Milano, Milano, Italy
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52
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Wu D, Qi W, Nie W, Lu Z, Ye Y, Li J, Sun T, Zhu Y, Cheng H, Wang X. BacFlash signals acid-resistance gene expression in bacteria. Cell Res 2021; 31:703-712. [PMID: 33159153 PMCID: PMC8169942 DOI: 10.1038/s41422-020-00431-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Accepted: 10/14/2020] [Indexed: 11/08/2022] Open
Abstract
Intracellular pH (pHi) homeostasis is crucial for cellular functions and signal transduction across all kingdoms of life. In particular, bacterial pHi homeostasis is important for physiology, ecology, and pathogenesis. Here we report an exquisite bacterial acid-resistance (AR) mechanism in which proton leak elicits a pre-emptive AR response. A single bacterial cell undergoes quantal electrochemical excitation, termed "BacFlash", which consists of membrane depolarization, transient pHi rise, and bursting production of reactive oxygen species. BacFlash ignition is dictated by acid stress in the form of proton leak across the plasma membrane and the rate of BacFlash occurrence is reversely correlated with the pHi buffering capacity. Through genome-wide screening, we further identify the ATP synthase Fo complex subunit a as the putative proton sensor for BacFlash biogenesis. Importantly, persistent BacFlash hyperactivity activates transcription of a panel of key AR genes and predisposes the cells to survive imminent extreme acid stress. These findings demonstrate a prototypical coupling between electrochemical excitation and nucleoid gene expression in prokaryotes.
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Affiliation(s)
- Di Wu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Wenfeng Qi
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Wei Nie
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
- Research Unit of Mitochondria in Brain Diseases, Chinese Academy of Medical Sciences, PKU-Nanjing Institute of Translational Medicine, Nanjing, Jiangsu, China
| | - Zhengyuan Lu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Yongxin Ye
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Jinghang Li
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Tao Sun
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
| | - Yufei Zhu
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China
- Research Unit of Mitochondria in Brain Diseases, Chinese Academy of Medical Sciences, PKU-Nanjing Institute of Translational Medicine, Nanjing, Jiangsu, China
| | - Heping Cheng
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China.
- Research Unit of Mitochondria in Brain Diseases, Chinese Academy of Medical Sciences, PKU-Nanjing Institute of Translational Medicine, Nanjing, Jiangsu, China.
| | - Xianhua Wang
- State Key Laboratory of Membrane Biology, Beijing Key Laboratory of Cardiometabolic Molecular Medicine, Peking-Tsinghua Center for Life Sciences, Institute of Molecular Medicine, Peking University, Beijing, 100871, China.
- Research Unit of Mitochondria in Brain Diseases, Chinese Academy of Medical Sciences, PKU-Nanjing Institute of Translational Medicine, Nanjing, Jiangsu, China.
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53
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Abstract
Bacteria are electrically powered organisms; cells maintain an electrical potential across their plasma membrane as a source of free energy to drive essential processes. In recent years, however, bacterial membrane potential has been increasingly recognized as dynamic. Those dynamics have been implicated in diverse physiological functions and behaviors, including cell division and cell-to-cell signaling. In eukaryotic cells, such dynamics play major roles in coupling bioelectrical stimuli to changes in internal cell states. Neuroscientists and physiologists have established detailed molecular pathways that transduce eukaryotic membrane potential dynamics to physiological and gene expression responses. We are only just beginning to explore these intracellular responses to bioelectrical activity in bacteria. In this review, we summarize progress in this area, including evidence of gene expression responses to stimuli from electrodes and mechanically induced membrane potential spikes. We argue that the combination of provocative results, missing molecular detail, and emerging tools makes the investigation of bioelectrically induced long-term intracellular responses an important and rewarding effort in the future of microbiology.
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Affiliation(s)
- Joshua M Jones
- Department of Biology, Boston University, Boston, Massachusetts, USA.,Department of Physics, Boston University, Boston, Massachusetts, USA.,Biological Design Center, Boston University, Boston, Massachusetts, USA
| | - Joseph W Larkin
- Department of Biology, Boston University, Boston, Massachusetts, USA.,Department of Physics, Boston University, Boston, Massachusetts, USA.,Biological Design Center, Boston University, Boston, Massachusetts, USA
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54
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Kralj JM. Finding the Spark. Bioelectricity 2021; 3:143-146. [PMID: 34476390 DOI: 10.1089/bioe.2021.0017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
It began, as with many good things, at a happy hour. Adam Cohen, a young assistant professor asked whether rhodopsins could be used to optically sense voltage. In the heady days of 2009, channel rhodopsin had just been unveiled as a voltage actuator in neurons. Adam had the insight to question whether rhodopsins could be run in reverse; could optical changes in a protein relay the cellular voltage state using light? This was one of the earliest lessons I learned under his mentorship, and the first piece of advice in this retrospective-turning a scientific question or statement on its head can be the basis for many fantastic research projects.
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Affiliation(s)
- Joel M Kralj
- BioFrontiers and MCDB Department, University of Colorado-Boulder, Boulder, Colorado, USA
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55
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Machine Learning Establishes Single-Cell Calcium Dynamics as an Early Indicator of Antibiotic Response. Microorganisms 2021; 9:microorganisms9051000. [PMID: 34063175 PMCID: PMC8148219 DOI: 10.3390/microorganisms9051000] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2021] [Revised: 04/28/2021] [Accepted: 04/30/2021] [Indexed: 11/17/2022] Open
Abstract
Changes in bacterial physiology necessarily precede cell death in response to antibiotics. Herein we investigate the early disruption of Ca2+ homeostasis as a marker for antibiotic response. Using a machine learning framework, we quantify the temporal information encoded in single-cell Ca2+ dynamics. We find Ca2+ dynamics distinguish kanamycin sensitive and resistant cells before changes in gross cell phenotypes such as cell growth or protein stability. The onset time (pharmacokinetics) and probability (pharmacodynamics) of these aberrant Ca2+ dynamics are dose and time-dependent, even at the resolution of single-cells. Of the compounds profiled, we find Ca2+ dynamics are also an indicator of Polymyxin B activity. In Polymyxin B treated cells, we find aberrant Ca2+ dynamics precedes the entry of propidium iodide marking membrane permeabilization. Additionally, we find modifying membrane voltage and external Ca2+ concentration alters the time between these aberrant dynamics and membrane breakdown suggesting a previously unappreciated role of Ca2+ in the membrane destabilization during Polymyxin B treatment. In conclusion, leveraging live, single-cell, Ca2+ imaging coupled with machine learning, we have demonstrated the discriminative capacity of Ca2+ dynamics in identifying antibiotic-resistant bacteria.
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56
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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.
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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
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57
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Eckhart KE, Arnold AM, Starvaggi FA, Sydlik SA. Tunable, bacterio-instructive scaffolds made from functional graphenic materials. Biomater Sci 2021; 9:2467-2479. [PMID: 33404025 DOI: 10.1039/d0bm01471k] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023]
Abstract
The balance of bacterial populations in the human body is critical for human health. Researchers have aimed to control bacterial populations using antibiotic substrates. However, antibiotic materials that non-selectively kill bacteria can compromise health by eliminating beneficial bacteria, which leaves the body vulnerable to colonization by harmful pathogens. Due to their chemical tunablity and unique surface properties, graphene oxide (GO)-based materials - termed "functional graphenic materials" (FGMs) - have been previously designed to be antibacterial but have the capacity to actively adhere and instruct probiotics to maintain human health. Numerous studies have demonstrated that negatively and positively charged surfaces influence bacterial adhesion through electrostatic interactions with the negatively charged bacterial surface. We found that tuning the surface charge of FGMs provides an avenue to control bacterial attachment without compromising vitality. Using E. coli as a model organism for Gram-negative bacteria, we demonstrate that negatively charged Claisen graphene (CG), a reduced and carboxylated FGM, is bacterio-repellent through electrostatic repulsion with the bacterial surface. Though positively charged poly-l-lysine (PLL) is antibacterial when free in solution by inserting into the bacterial cell wall, here, we found that covalent conjugation of PLL to CG (giving PLLn-G) masks the antimicrobial activity of PLL by restricting polypeptide mobility. This allows the immobilized positive charge of the PLLn-Gs to be leveraged for E. coli adhesion through electrostatic attraction. We identified the magnitude of positive charge of the PLLn-G conjugates, which is modulated by the length of the PLL peptide, as an important parameter to tune the balance between the opposing forces of bacterial adhesion and proliferation. We also tested adhesion of Gram-positive B. subtilis to these FGMs and found that the effect of FGM charge is less pronounced. B. subtilis adheres nondiscriminatory to all FGMs, regardless of charge, but adhesion is scarce and localized. Overall, this work demonstrates that FGMs can be tuned to selectively control bacterial response, paving the way for future development of FGM-based biomaterials as bacterio-instructive scaffolds through careful design of FGM surface chemistry.
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Affiliation(s)
- Karoline E Eckhart
- Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
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58
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Stautz J, Hellmich Y, Fuss MF, Silberberg JM, Devlin JR, Stockbridge RB, Hänelt I. Molecular Mechanisms for Bacterial Potassium Homeostasis. J Mol Biol 2021; 433:166968. [PMID: 33798529 DOI: 10.1016/j.jmb.2021.166968] [Citation(s) in RCA: 55] [Impact Index Per Article: 18.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2021] [Revised: 03/11/2021] [Accepted: 03/22/2021] [Indexed: 10/21/2022]
Abstract
Potassium ion homeostasis is essential for bacterial survival, playing roles in osmoregulation, pH homeostasis, regulation of protein synthesis, enzyme activation, membrane potential adjustment and electrical signaling. To accomplish such diverse physiological tasks, it is not surprising that a single bacterium typically encodes several potassium uptake and release systems. To understand the role each individual protein fulfills and how these proteins work in concert, it is important to identify the molecular details of their function. One needs to understand whether the systems transport ions actively or passively, and what mechanisms or ligands lead to the activation or inactivation of individual systems. Combining mechanistic information with knowledge about the physiology under different stress situations, such as osmostress, pH stress or nutrient limitation, one can identify the task of each system and deduce how they are coordinated with each other. By reviewing the general principles of bacterial membrane physiology and describing the molecular architecture and function of several bacterial K+-transporting systems, we aim to provide a framework for microbiologists studying bacterial potassium homeostasis and the many K+-translocating systems that are still poorly understood.
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Affiliation(s)
- Janina Stautz
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Yvonne Hellmich
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Michael F Fuss
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jakob M Silberberg
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany
| | - Jason R Devlin
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States
| | - Randy B Stockbridge
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, MI, United States.
| | - Inga Hänelt
- Institute of Biochemistry, Goethe University Frankfurt, Frankfurt am Main, Germany.
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59
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Abstract
All living cells interact dynamically with a constantly changing world. Eukaryotes, in particular, evolved radically new ways to sense and react to their environment. These advances enabled new and more complex forms of cellular behaviour in eukaryotes, including directional movement, active feeding, mating, and responses to predation. But what are the key events and innovations during eukaryogenesis that made all of this possible? Here we describe the ancestral repertoire of eukaryotic excitability and discuss five major cellular innovations that enabled its evolutionary origin. The innovations include a vastly expanded repertoire of ion channels, the emergence of cilia and pseudopodia, endomembranes as intracellular capacitors, a flexible plasma membrane and the relocation of chemiosmotic ATP synthesis to mitochondria, which liberated the plasma membrane for more complex electrical signalling involved in sensing and reacting. We conjecture that together with an increase in cell size, these new forms of excitability greatly amplified the degrees of freedom associated with cellular responses, allowing eukaryotes to vastly outperform prokaryotes in terms of both speed and accuracy. This comprehensive new perspective on the evolution of excitability enriches our view of eukaryogenesis and emphasizes behaviour and sensing as major contributors to the success of eukaryotes. This article is part of the theme issue 'Basal cognition: conceptual tools and the view from the single cell'.
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Affiliation(s)
- Kirsty Y. Wan
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
| | - Gáspár Jékely
- Living Systems Institute, University of Exeter, Stocker Road, Exeter EX4 4QD, UK
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60
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Genome-Wide Functional Screen for Calcium Transients in Escherichia coli Identifies Increased Membrane Potential Adaptation to Persistent DNA Damage. J Bacteriol 2021; 203:JB.00509-20. [PMID: 33199283 DOI: 10.1128/jb.00509-20] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/07/2020] [Indexed: 12/12/2022] Open
Abstract
Calcium plays numerous critical roles in signaling and homeostasis in eukaryotic cells. Far less is known about calcium signaling in bacteria than in eukaryotic cells, and few genes controlling influx and efflux have been identified. Previous work in Escherichia coli showed that calcium influx was induced by voltage depolarization, which was enhanced by mechanical stimulation, which suggested a role in bacterial mechanosensation. To identify proteins and pathways affecting calcium handling in bacteria, we designed a live-cell screen to monitor calcium dynamics in single cells across a genome-wide knockout panel in E. coli The screen measured cells from the Keio collection of knockouts and quantified calcium transients across the population. Overall, we found 143 gene knockouts that decreased levels of calcium transients and 32 gene knockouts that increased levels of transients. Knockouts of proteins involved in energy production and regulation appeared, as expected, as well as knockouts of proteins of a voltage sink, F1Fo-ATPase. Knockouts of exopolysaccharide and outer membrane synthesis proteins showed reduced transients which refined our model of electrophysiology-mediated mechanosensation. Additionally, knockouts of proteins associated with DNA repair had reduced calcium transients and voltage. However, acute DNA damage did not affect voltage, and the results suggested that only long-term adaptation to DNA damage decreased membrane potential and calcium transients. Our work showed a distinct separation between the acute and long-term DNA damage responses in bacteria, which also has implications for mitochondrial DNA damage in eukaryotes.IMPORTANCE All eukaryotic cells use calcium as a critical signaling molecule. There is tantalizing evidence that bacteria also use calcium for cellular signaling, but much less is known about the molecular actors and physiological roles. To identify genes regulating cytoplasmic calcium in Escherichia coli, we created a single-cell screen for modulators of calcium dynamics. The genes uncovered in this screen helped refine a model for voltage-mediated bacterial mechanosensation. Additionally, we were able to more carefully dissect the mechanisms of adaptation to long-term DNA damage, which has implications for both bacteria and mitochondria in the face of unrepaired DNA.
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61
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Setting the Stage: Genes Controlling Mechanosensation and Ca 2+ Signaling in Escherichia coli. J Bacteriol 2021; 203:JB.00595-20. [PMID: 33199281 DOI: 10.1128/jb.00595-20] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Although mechanistic understanding of calcium signaling in bacteria remains inchoate, current evidence clearly links Ca2+ signaling with membrane potential and mechanosensation. Adopting a radically new approach, Luder et al. scanned the Keio collection of Escherichia coli gene knockouts (R. Luder, G. N. Bruni, and J. M. Kralj, J Bacteriol 203:e00509-20, 2021, https://doi.org/10.1128/JB.00509-20) to identify mutations that cause changes in Ca2+ transients. They identify genes associating Ca2+ signaling with outer membrane biogenesis, proton motive force, and, surprisingly, long-term DNA damage. Their work has major implications for electrophysiological communication between bacteria and their environment.
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62
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Gleco S, Noussi T, Jude A, Reddy P, Kirste R, Collazo R, LaJeunesse D, Ivanisevic A. Oxidative Stress Transcriptional Responses of Escherichia coli at GaN Interfaces. ACS APPLIED BIO MATERIALS 2020; 3:9073-9081. [DOI: 10.1021/acsabm.0c01299] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Sara Gleco
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Theophraste Noussi
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina Greensboro, Greensboro, North Carolina 27402-6170, United States
| | - Akamu Jude
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina Greensboro, Greensboro, North Carolina 27402-6170, United States
| | - Pramod Reddy
- Adroit Materials, 2054 Kildaire Farm Road, Suite 205, Cary, North Carolina 27518, United States
| | - Ronny Kirste
- Adroit Materials, 2054 Kildaire Farm Road, Suite 205, Cary, North Carolina 27518, United States
| | - Ramón Collazo
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Dennis LaJeunesse
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina Greensboro, Greensboro, North Carolina 27402-6170, United States
| | - Albena Ivanisevic
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
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63
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Grobas I, Bazzoli DG, Asally M. Biofilm and swarming emergent behaviours controlled through the aid of biophysical understanding and tools. Biochem Soc Trans 2020; 48:2903-2913. [PMID: 33300966 PMCID: PMC7752047 DOI: 10.1042/bst20200972] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2020] [Revised: 10/28/2020] [Accepted: 10/29/2020] [Indexed: 02/06/2023]
Abstract
Bacteria can organise themselves into communities in the forms of biofilms and swarms. Through chemical and physical interactions between cells, these communities exhibit emergent properties that individual cells alone do not have. While bacterial communities have been mainly studied in the context of biochemistry and molecular biology, recent years have seen rapid advancements in the biophysical understanding of emergent phenomena through physical interactions in biofilms and swarms. Moreover, new technologies to control bacterial emergent behaviours by physical means are emerging in synthetic biology. Such technologies are particularly promising for developing engineered living materials (ELM) and devices and controlling contamination and biofouling. In this minireview, we overview recent studies unveiling physical and mechanical cues that trigger and affect swarming and biofilm development. In particular, we focus on cell shape, motion and density as the key parameters for mechanical cell-cell interactions within a community. We then showcase recent studies that use physical stimuli for patterning bacterial communities, altering collective behaviours and preventing biofilm formation. Finally, we discuss the future potential extension of biophysical and bioengineering research on microbial communities through computational modelling and deeper investigation of mechano-electrophysiological coupling.
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Affiliation(s)
- Iago Grobas
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K
- Warwick Medical School, University of Warwick, Coventry CV4 7AL, U.K
| | - Dario G. Bazzoli
- School of Chemical Engineering, University of Birmingham, Birmingham B15 2TT, U.K
| | - Munehiro Asally
- School of Life Sciences, University of Warwick, Coventry CV4 7AL, U.K
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry CV4 7AL, U.K
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry CV4 7AL, U.K
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64
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Are antibacterial effects of non-antibiotic drugs random or purposeful because of a common evolutionary origin of bacterial and mammalian targets? Infection 2020; 49:569-589. [PMID: 33325009 PMCID: PMC7737717 DOI: 10.1007/s15010-020-01547-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2020] [Accepted: 10/28/2020] [Indexed: 01/09/2023]
Abstract
Purpose Advances in structural biology, genetics, bioinformatics, etc. resulted in the availability of an enormous pool of information enabling the analysis of the ancestry of pro- and eukaryotic genes and proteins. Methods This review summarizes findings of structural and/or functional homologies of pro- and eukaryotic enzymes catalysing analogous biological reactions because of their highly conserved active centres so that non-antibiotics interacted with bacterial targets. Results Protease inhibitors such as staurosporine or camostat inhibited bacterial serine/threonine or serine/tyrosine protein kinases, serine/threonine phosphatases, and serine/threonine kinases, to which penicillin-binding-proteins are linked, so that these drugs synergized with β-lactams, reverted aminoglycoside-resistance and attenuated bacterial virulence. Calcium antagonists such as nitrendipine or verapamil blocked not only prokaryotic ion channels but interacted with negatively charged bacterial cell membranes thus disrupting membrane energetics and inducing membrane stress response resulting in inhibition of P-glycoprotein such as bacterial pumps thus improving anti-mycobacterial activities of rifampicin, tetracycline, fluoroquinolones, bedaquilin and imipenem-activity against Acinetobacter spp. Ciclosporine and tacrolimus attenuated bacterial virulence. ACE-inhibitors like captopril interacted with metallo-β-lactamases thus reverting carbapenem-resistance; prokaryotic carbonic anhydrases were inhibited as well resulting in growth impairment. In general, non-antibiotics exerted weak antibacterial activities on their own but synergized with antibiotics, and/or reverted resistance and/or attenuated virulence. Conclusions Data summarized in this review support the theory that prokaryotic proteins represent targets for non-antibiotics because of a common evolutionary origin of bacterial- and mammalian targets resulting in highly conserved active centres of both, pro- and eukaryotic proteins with which the non-antibiotics interact and exert antibacterial actions.
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65
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Wu Q, Bai Y, Li W, Congdon EE, Liu W, Lin Y, Ji C, Gan WB, Sigurdsson EM. Increased neuronal activity in motor cortex reveals prominent calcium dyshomeostasis in tauopathy mice. Neurobiol Dis 2020; 147:105165. [PMID: 33166699 DOI: 10.1016/j.nbd.2020.105165] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2020] [Revised: 11/01/2020] [Accepted: 11/03/2020] [Indexed: 12/25/2022] Open
Abstract
Perturbed neuronal Ca2+ homeostasis is implicated in Alzheimer's disease, which has primarily been demonstrated in mice with amyloid-β deposits but to a lesser and more variable extent in tauopathy models. In this study, we injected AAV to express Ca2+ indicator in layer II/III motor cortex neurons and measured neuronal Ca2+ activity by two photon imaging in awake transgenic JNPL3 tauopathy and wild-type mice. Various biochemical measurements were conducted in postmortem mouse brains for mechanistic insight and a group of animals received two intravenous injections of a tau monoclonal antibody spaced by four days to test whether the Ca2+ dyshomeostasis was related to pathological tau protein. Under running conditions, we found abnormal neuronal Ca2+ activity in tauopathy mice compared to age-matched wild-type mice with higher frequency of Ca2+ transients, lower amplitude of peak Ca2+ transients and lower total Ca2+ activity in layer II/III motor cortex neurons. While at resting conditions, only Ca2+ frequency was increased. Brain levels of soluble pathological tau correlated better than insoluble tau levels with the degree of Ca2+ dysfunction in tauopathy mice. Furthermore, tau monoclonal antibody 4E6 partially rescued Ca2+ activity abnormalities in tauopathy mice after two intravenous injections and decreased soluble pathological tau protein within the brain. This correlation and antibody effects strongly suggest that the neuronal Ca2+ dyshomeostasis is causally linked to pathological tau protein. These findings also reveal more pronounced neuronal Ca2+ dysregulation in tauopathy mice than previously reported by two-photon imaging that can be partially corrected with an acute tau antibody treatment.
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Affiliation(s)
- Qian Wu
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America.
| | - Yang Bai
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Skirball Institute, 550 First Avenue, New York, NY 10016, United States of America.
| | - Wei Li
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Skirball Institute, 550 First Avenue, New York, NY 10016, United States of America
| | - Erin E Congdon
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America.
| | - Wenke Liu
- New York University Grossman School of Medicine, Department of Psychiatry, 550 First Avenue, New York, NY 10016, United States of America.
| | - Yan Lin
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America.
| | - Changyi Ji
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America.
| | - Wen-Biao Gan
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Skirball Institute, 550 First Avenue, New York, NY 10016, United States of America.
| | - Einar M Sigurdsson
- New York University Grossman School of Medicine, Department of Neuroscience and Physiology, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; New York University Grossman School of Medicine, Neuroscience Institute, Science Building, 435 East 30th Street, New York, NY 10016, United States of America; Department of Psychiatry, New York University Grossman School of Medicine, New York, NY 10016, United States of America.
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66
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Nava AR, Mauricio N, Sanca AJ, Domínguez DC. Evidence of Calcium Signaling and Modulation of the LmrS Multidrug Resistant Efflux Pump Activity by Ca 2 + Ions in S. aureus. Front Microbiol 2020; 11:573388. [PMID: 33193178 PMCID: PMC7642317 DOI: 10.3389/fmicb.2020.573388] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2020] [Accepted: 09/14/2020] [Indexed: 12/19/2022] Open
Abstract
Calcium ions (Ca2+) play a pivotal role in eukaryote cell signaling and regulate many physiological functions. Although a similar role for Ca2+ in prokaryotes has been difficult to demonstrate, there is increasing evidence for Ca2+ as a cell regulator in bacteria. The purpose of this study was to investigate Ca2+ signaling and the effect of Ca2+ on the Staphylococcus aureus multidrug resistant efflux pump LmrS. We hypothesized that antibiotics act by increasing Ca2+ concentrations, which in turn enhance the efflux activity of LmrS. These Ca2+ transients were measured by luminometry in response to various antibiotics by using the photoprotein aequorin reconstituted within live bacterial cells. Efflux associated with LmrS was measured by the increase in fluorescence due to the loss of ethidium bromide (EtBr) from both S. aureus cells and from E. coli cells in which the lmrs gene of S. aureus was expressed. We found that addition of antibiotics to cells generated unique cytosolic Ca2+ transients and that addition of CaCl2 to cells enhanced EtBr efflux whereas addition of Ca2+ chelators or efflux pump inhibitors significantly decreased EtBr efflux from cells. We conclude that antibiotics induce a Ca2+ mediated response through transients in cytosolic Ca2+, which then stimulates LmrS efflux pump.
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Affiliation(s)
- Amy R Nava
- Department of Interdisciplinary Health Sciences, The University of Texas at El Paso, El Paso, TX, United States
| | - Natalia Mauricio
- Biology Department, El Paso Community College, El Paso, TX, United States
| | - Angel J Sanca
- Biological Sciences Department, The University of Texas at El Paso, El Paso, TX, United States
| | - Delfina C Domínguez
- Department of Interdisciplinary Health Sciences, The University of Texas at El Paso, El Paso, TX, United States.,Clinical Laboratory Science Program/Department of Public Health Sciences, The University of Texas at El Paso, El Paso, TX, United States
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67
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Gleco S, Reddy P, Kirste R, Collazo R, LaJeunesse D, Ivanisevic A. Modulating the Stress Response of E. coli at GaN Interfaces Using Surface Charge, Surface Chemistry, and Genetic Mutations. ACS APPLIED BIO MATERIALS 2020; 3:7211-7218. [DOI: 10.1021/acsabm.0c01007] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Affiliation(s)
- Sara Gleco
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Pramod Reddy
- Adroit Materials, 2054 Kildaire Farm Road, Suite 205, Cary, North Carolina 27518, United States
| | - Ronny Kirste
- Adroit Materials, 2054 Kildaire Farm Road, Suite 205, Cary, North Carolina 27518, United States
| | - Ramón Collazo
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
| | - Dennis LaJeunesse
- Department of Nanoscience, Joint School of Nanoscience and Nanoengineering, University of North Carolina Greensboro, Greensboro, North Carolina 27401, United States
| | - Albena Ivanisevic
- Department of Materials Science and Engineering, North Carolina State University, Raleigh, North Carolina 27695, United States
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68
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Khan F, Pham DTN, Tabassum N, Oloketuyi SF, Kim YM. Treatment strategies targeting persister cell formation in bacterial pathogens. Crit Rev Microbiol 2020; 46:665-688. [DOI: 10.1080/1040841x.2020.1822278] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
Affiliation(s)
- Fazlurrahman Khan
- Institute of Food Science, Pukyong National University, Busan, Korea
| | - Dung Thuy Nguyen Pham
- Department of Food Science and Technology, Pukyong National University, Busan, Korea
| | - Nazia Tabassum
- Industrial Convergence Bionix Engineering, Pukyong National University, Busan, Korea
| | | | - Young-Mog Kim
- Institute of Food Science, Pukyong National University, Busan, Korea
- Department of Food Science and Technology, Pukyong National University, Busan, Korea
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69
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Kimkes TEP, Heinemann M. How bacteria recognise and respond to surface contact. FEMS Microbiol Rev 2020; 44:106-122. [PMID: 31769807 PMCID: PMC7053574 DOI: 10.1093/femsre/fuz029] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2019] [Accepted: 11/23/2019] [Indexed: 12/27/2022] Open
Abstract
Bacterial biofilms can cause medical problems and issues in technical systems. While a large body of knowledge exists on the phenotypes of planktonic and of sessile cells in mature biofilms, our understanding of what happens when bacteria change from the planktonic to the sessile state is still very incomplete. Fundamental questions are unanswered: for instance, how do bacteria sense that they are in contact with a surface, and what are the very initial cellular responses to surface contact. Here, we review the current knowledge on the signals that bacteria could perceive once they attach to a surface, the signal transduction systems that could be involved in sensing the surface contact and the cellular responses that are triggered as a consequence to surface contact ultimately leading to biofilm formation. Finally, as the main obstacle in investigating the initial responses to surface contact has been the difficulty to experimentally study the dynamic response of single cells upon surface attachment, we also review recent experimental approaches that could be employed to study bacterial surface sensing, which ultimately could lead to an improved understanding of how biofilm formation could be prevented.
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Affiliation(s)
- Tom E P Kimkes
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
| | - Matthias Heinemann
- Molecular Systems Biology, Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Nijenborgh 4, 9747 AG Groningen, the Netherlands
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70
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Bruni GN, Kralj JM. Membrane voltage dysregulation driven by metabolic dysfunction underlies bactericidal activity of aminoglycosides. eLife 2020; 9:58706. [PMID: 32748785 PMCID: PMC7406350 DOI: 10.7554/elife.58706] [Citation(s) in RCA: 38] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2020] [Accepted: 07/24/2020] [Indexed: 12/15/2022] Open
Abstract
Aminoglycosides are broad-spectrum antibiotics whose mechanism of action is under debate. It is widely accepted that membrane voltage potentiates aminoglycoside activity, which is ascribed to voltage-dependent drug uptake. In this paper, we measured the response of Escherichia coli treated with aminoglycosides and discovered that the bactericidal action arises not from the downstream effects of voltage-dependent drug uptake, but rather directly from dysregulated membrane potential. In the absence of voltage, aminoglycosides are taken into cells and exert bacteriostatic effects by inhibiting translation. However, cell killing was immediate upon re-polarization. The hyperpolarization arose from altered ATP flux, which induced a reversal of the F1Fo-ATPase to hydrolyze ATP and generated the deleterious voltage. Heterologous expression of an ATPase inhibitor completely eliminated bactericidal activity, while loss of the F-ATPase reduced the electrophysiological response to aminoglycosides. Our data support a model of voltage-induced death, and separates aminoglycoside bacteriostasis and bactericide in E. coli.
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Affiliation(s)
- Giancarlo Noe Bruni
- BioFrontiers Institute and the Department of Molecular, Cellular, Developmental Biology, University of Colorado Boulder, Boulder, United States
| | - Joel M Kralj
- BioFrontiers Institute and the Department of Molecular, Cellular, Developmental Biology, University of Colorado Boulder, Boulder, United States
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71
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Yang CY, Bialecka-Fornal M, Weatherwax C, Larkin JW, Prindle A, Liu J, Garcia-Ojalvo J, Süel GM. Encoding Membrane-Potential-Based Memory within a Microbial Community. Cell Syst 2020; 10:417-423.e3. [PMID: 32343961 PMCID: PMC7286314 DOI: 10.1016/j.cels.2020.04.002] [Citation(s) in RCA: 58] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/16/2019] [Revised: 02/13/2020] [Accepted: 04/02/2020] [Indexed: 12/29/2022]
Abstract
Cellular membrane potential plays a key role in the formation and retrieval of memories in the metazoan brain, but it remains unclear whether such memory can also be encoded in simpler organisms like bacteria. Here, we show that single-cell-level memory patterns can be imprinted in bacterial biofilms by light-induced changes in the membrane potential. We demonstrate that transient optical perturbations generate a persistent and robust potassium-channel-mediated change in the membrane potential of bacteria within the biofilm. The light-exposed cells respond in an anti-phase manner, relative to unexposed cells, to both natural and induced oscillations in extracellular ion concentrations. This anti-phase response, which persists for hours following the transient optical stimulus, enables a direct single-cell resolution visualization of spatial memory patterns within the biofilm. The ability to encode robust and persistent membrane-potential-based memory patterns could enable computations within prokaryotic communities and suggests a parallel between neurons and bacteria.
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Affiliation(s)
- Chih-Yu Yang
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Maja Bialecka-Fornal
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Colleen Weatherwax
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Joseph W Larkin
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA
| | - Arthur Prindle
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; Department of Biochemistry and Molecular Genetics, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611, USA
| | - Jintao Liu
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; Center for Infectious Diseases Research and Tsinghua-Peking Center for Life Sciences, School of Medicine, Tsinghua University, Beijing 100084, People's Republic of China
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, Barcelona Biomedical Research Park, Barcelona 08003, Spain
| | - Gürol M Süel
- Division of Biological Sciences, University of California, San Diego, Pacific Hall Room 2225B, Mail Code 0347, 9500 Gilman Drive, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093-0380, USA.
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72
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The E. coli transcription factor GrlA is regulated by subcellular compartmentalization and activated in response to mechanical stimuli. Proc Natl Acad Sci U S A 2020; 117:9519-9528. [PMID: 32277032 DOI: 10.1073/pnas.1917500117] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a foodborne pathogen that colonizes the gastrointestinal tract and has evolved intricate mechanisms to sense and respond to the host environment. Upon the sensation of chemical and physical cues specific to the host's intestinal environment, locus of enterocyte effacement (LEE)-encoded virulence genes are activated and promote intestinal colonization. The LEE transcriptional activator GrlA mediates EHEC's response to mechanical cues characteristic of the intestinal niche, including adhesive force that results from bacterial adherence to epithelial cells and fluid shear that results from intestinal motility and transit. GrlA expression and release from its inhibitor GrlR was not sufficient to induce virulence gene transcription; mechanical stimuli were required for GrlA activation. The exact mechanism of GrlA activation, however, remained unknown. We isolated GrlA mutants that activate LEE transcription, independent of applied mechanical stimuli. In nonstimulated EHEC, wild-type GrlA associates with cardiolipin membrane domains via a patch of basic C-terminal residues, and this membrane sequestration is disrupted in EHEC that expresses constitutively active GrlA mutants. GrlA transitions from an inactive, membrane-associated state and relocalizes to the cytoplasm in response to mechanical stimuli, allowing GrlA to bind and activate the LEE1 promoter. GrlA expression and its relocalization in response to mechanical stimuli are required for optimal virulence regulation and colonization of the host intestinal tract during infection. These data suggest a posttranslational regulatory mechanism of the mechanosensor GrlA, whereby virulence gene expression can be rapidly fine-tuned in response to the highly dynamic spatiotemporal mechanical profile of the gastrointestinal tract.
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73
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Copley SD. The physical basis and practical consequences of biological promiscuity. Phys Biol 2020; 17:10.1088/1478-3975/ab8697. [PMID: 32244231 PMCID: PMC9291633 DOI: 10.1088/1478-3975/ab8697] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Proteins interact with metabolites, nucleic acids, and other proteins to orchestrate the myriad catalytic, structural and regulatory functions that support life from the simplest microbes to the most complex multicellular organisms. These molecular interactions are often exquisitely specific, but never perfectly so. Adventitious "promiscuous" interactions are ubiquitous due to the thousands of macromolecules and small molecules crowded together in cells. Such interactions may perturb protein function at the molecular level, but as long as they do not compromise organismal fitness, they will not be removed by natural selection. Although promiscuous interactions are physiologically irrelevant, they are important because they can provide a vast reservoir of potential functions that can provide the starting point for evolution of new functions, both in nature and in the laboratory.
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Affiliation(s)
- Shelley D Copley
- Department of Molecular, Cellular and Developmental Biology and Cooperative Institute for Research in Environmental Sciences, University of Colorado Boulder, Boulder, Colorado, UNITED STATES
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74
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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]
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75
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Mechanical regulation of photosynthesis in cyanobacteria. Nat Microbiol 2020; 5:757-767. [PMID: 32203409 DOI: 10.1038/s41564-020-0684-2] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2019] [Accepted: 02/04/2020] [Indexed: 12/17/2022]
Abstract
Photosynthetic organisms regulate their responses to many diverse stimuli in an effort to balance light harvesting with utilizable light energy for carbon fixation and growth (source-sink regulation). This balance is critical to prevent the formation of reactive oxygen species that can lead to cell death. However, investigating the molecular mechanisms that underlie the regulation of photosynthesis in cyanobacteria using ensemble-based measurements remains a challenge due to population heterogeneity. Here, to address this problem, we used long-term quantitative time-lapse fluorescence microscopy, transmission electron microscopy, mathematical modelling and genetic manipulation to visualize and analyse the growth and subcellular dynamics of individual wild-type and mutant cyanobacterial cells over multiple generations. We reveal that mechanical confinement of actively growing Synechococcus sp. PCC 7002 cells leads to the physical disassociation of phycobilisomes and energetic decoupling from the photosynthetic reaction centres. We suggest that the mechanical regulation of photosynthesis is a critical failsafe that prevents cell expansion when light and nutrients are plentiful, but when space is limiting. These results imply that cyanobacteria must convert a fraction of the available light energy into mechanical energy to overcome frictional forces in the environment, providing insight into the regulation of photosynthesis and how microorganisms navigate their physical environment.
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76
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Blee JA, Roberts IS, Waigh TA. Membrane potentials, oxidative stress and the dispersal response of bacterial biofilms to 405 nm light. Phys Biol 2020; 17:036001. [PMID: 32050190 DOI: 10.1088/1478-3975/ab759a] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The majority of chronic infections are caused by biofilms, which have higher levels of antibiotic resistance than planktonic growth. Violet-blue 405 nm light has recently emerged as a novel bactericide, but limited studies have been conducted on its effectiveness against biofilms. We found that in response to 405 nm light both Pseudomonas aeruginosa and Bacillus subtilis biofilms exhibited cell dispersal and membrane potential hyperpolarisations. The response to 405 nm light depended on the stage of biofilm growth. The use of reactive oxygen species scavengers reduced membrane hyperpolarisation and biofilm dispersal in response to 405 nm light. This is the first time that membrane potential hyperpolarisations have been linked with photooxidative stress in bacteria and with biofilm dispersal. These results provide a new insight into the role of membrane potentials in the bacterial stress response and could be used in the development of 405 nm light based biofilm treatments.
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Affiliation(s)
- J A Blee
- Division of Infection, Lydia Becker Institute of Immunology and Inflammation Immunity & Respiratory Medicine, Immunity & Respiratory Medicine, School of Biological Sciences, University of Manchester, Oxford Road, M13 9PT, United Kingdom. Biological Physics, Department of Physics and Astronomy, School of Natural Sciences, University of Manchester, Oxford Road, M13 9PL, United Kingdom. Photon Science Institute, Alan Turing Building, University of Manchester, Oxford Road, M13 9PL, United Kingdom
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77
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Designing heterotropically activated allosteric conformational switches using supercharging. Proc Natl Acad Sci U S A 2020; 117:5291-5297. [PMID: 32098845 DOI: 10.1073/pnas.1916046117] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Heterotropic allosteric activation of protein function, in which binding of one ligand thermodynamically activates the binding of another, different ligand or substrate, is a fundamental control mechanism in metabolism and as such has been a long-aspired capability in protein design. Here we show that greatly increasing the magnitude of a protein's net charge using surface supercharging transforms that protein into an allosteric ligand- and counterion-gated conformational molecular switch. To demonstrate this we first modified the designed helical bundle hemoprotein H4, creating a highly charged protein which both unfolds reversibly at low ionic strength and undergoes the ligand-induced folding transition commonly observed in signal transduction by intrinsically disordered proteins in biology. As a result of the high surface-charge density, ligand binding to this protein is allosterically activated up to 1,300-fold by low concentrations of divalent cations and the polyamine spermine. To extend this process further using a natural protein, we similarly modified Escherichia coli cytochrome b 562 and the resulting protein behaves in a like manner. These simple model systems not only establish a set of general engineering principles which can be used to convert natural and designed soluble proteins into allosteric molecular switches useful in biodesign, sensing, and synthetic biology, the behavior we have demonstrated--functional activation of supercharged intrinsically disordered proteins by low concentrations of multivalent ions--may be a control mechanism utilized by Nature which has yet to be appreciated.
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78
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La Edwards C, Malyshev D, Stratford JP, Asally M. Rapid Detection of Proliferative Bacteria by Electrical Stimulation. Bio Protoc 2020; 10:e3508. [PMID: 33654734 DOI: 10.21769/bioprotoc.3508] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Revised: 11/26/2019] [Accepted: 12/26/2019] [Indexed: 11/02/2022] Open
Abstract
Detecting live bacteria is an important task for antimicrobial susceptibility testing (AST) in the medical sector and for quality-monitoring in biological industries. Current methods for live-bacteria detection suffer limitations in speed or sensitivity. In a recent paper, we reported that electrical response dynamics in membrane potential enable single-cell rapid detection of live bacteria. The electrical response can be observed within a minute after electrical stimulation. Thus, it has potential in accelerating AST and the monitoring of biological samples. This method also enables experiments for biophysical and microbiological investigations into bacterial electrophysiology. With the hope that more researchers, scientists and engineers will use electrical stimulation for their assays, here we detail each step of the electrical stimulation experiment.
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Affiliation(s)
- Conor La Edwards
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, The United Kingdom
| | - Dmitry Malyshev
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, The United Kingdom
| | - James P Stratford
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, The United Kingdom
| | - Munehiro Asally
- School of Life Sciences, University of Warwick, Coventry, CV4 7AL, The United Kingdom
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79
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Mechanomicrobiology: how bacteria sense and respond to forces. Nat Rev Microbiol 2020; 18:227-240. [DOI: 10.1038/s41579-019-0314-2] [Citation(s) in RCA: 99] [Impact Index Per Article: 24.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2019] [Indexed: 12/26/2022]
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80
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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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81
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King MM, Kayastha BB, Franklin MJ, Patrauchan MA. Calcium Regulation of Bacterial Virulence. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1131:827-855. [PMID: 31646536 DOI: 10.1007/978-3-030-12457-1_33] [Citation(s) in RCA: 31] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
Calcium (Ca2+) is a universal signaling ion, whose major informational role shaped the evolution of signaling pathways, enabling cellular communications and responsiveness to both the intracellular and extracellular environments. Elaborate Ca2+ regulatory networks have been well characterized in eukaryotic cells, where Ca2+ regulates a number of essential cellular processes, ranging from cell division, transport and motility, to apoptosis and pathogenesis. However, in bacteria, the knowledge on Ca2+ signaling is still fragmentary. This is complicated by the large variability of environments that bacteria inhabit with diverse levels of Ca2+. Yet another complication arises when bacterial pathogens invade a host and become exposed to different levels of Ca2+ that (1) are tightly regulated by the host, (2) control host defenses including immune responses to bacterial infections, and (3) become impaired during diseases. The invading pathogens evolved to recognize and respond to the host Ca2+, triggering the molecular mechanisms of adhesion, biofilm formation, host cellular damage, and host-defense resistance, processes enabling the development of persistent infections. In this review, we discuss: (1) Ca2+ as a determinant of a host environment for invading bacterial pathogens, (2) the role of Ca2+ in regulating main events of host colonization and bacterial virulence, and (3) the molecular mechanisms of Ca2+ signaling in bacterial pathogens.
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Affiliation(s)
- Michelle M King
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA
| | - Biraj B Kayastha
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA
| | - Michael J Franklin
- Department of Microbiology and Center for Biofilm Engineering, Montana State University, Bozeman, MT, USA
| | - Marianna A Patrauchan
- Department of Microbiology and Molecular Genetics, Oklahoma State University, Stillwater, OK, USA.
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Fernandes MM, Carvalho EO, Lanceros-Mendez S. Electroactive Smart Materials: Novel Tools for Tailoring Bacteria Behavior and Fight Antimicrobial Resistance. Front Bioeng Biotechnol 2019; 7:277. [PMID: 31681752 PMCID: PMC6813912 DOI: 10.3389/fbioe.2019.00277] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 10/02/2019] [Indexed: 11/13/2022] Open
Abstract
Despite being very simple organisms, bacteria possess an outstanding ability to adapt to different environments. Their long evolutionary history, being exposed to vastly different physicochemical surroundings, allowed them to detect and respond to a wide range of signals including biochemical, mechanical, electrical, and magnetic ones. Taking into consideration their adapting mechanisms, it is expected that novel materials able to provide bacteria with specific stimuli in a biomimetic context may tailor their behavior and make them suitable for specific applications in terms of anti-microbial and pro-microbial approaches. This review maintains that electroactive smart materials will be a future approach to be explored in microbiology to obtain novel strategies for fighting the emergence of live threatening antibiotic resistance.
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Affiliation(s)
- Margarida M. Fernandes
- Centre of Biological Engineering, University of Minho, Braga, Portugal
- Centre of Physics, University of Minho, Braga, Portugal
| | - Estela O. Carvalho
- Centre of Biological Engineering, University of Minho, Braga, Portugal
- Centre of Physics, University of Minho, Braga, Portugal
| | - Senentxu Lanceros-Mendez
- BCMaterials, Basque Center for Materials, Applications and Nanostructures, UPV/EHU Science Park, Leioa, Spain
- Ikerbasque, Basque Foundation for Science, Bilbao, Spain
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83
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Cooperativity and Steep Voltage Dependence in a Bacterial Channel. Int J Mol Sci 2019; 20:ijms20184501. [PMID: 31514419 PMCID: PMC6770917 DOI: 10.3390/ijms20184501] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Revised: 09/02/2019] [Accepted: 09/04/2019] [Indexed: 11/17/2022] Open
Abstract
This paper reports on the discovery of a novel three-membrane channel unit exhibiting very steep voltage dependence and strong cooperative behavior. It was reconstituted into planar phospholipid membranes formed by the monolayer method and studied under voltage-clamp conditions. The behavior of the novel channel-former, isolated from Escherichia coli, is consistent with a linearly organized three-channel unit displaying steep voltage-gating (a minimum of 14 charges in the voltage sensor) that rivals that of channels in mammalian excitable membranes. The channels also display strong cooperativity in that closure of the first channel permits the second to close and closure of the second channel permits closure of the third. All three have virtually the same conductance and selectivity, and yet the first and third close at positive potentials whereas the second closes at negative potentials. Thus, is it likely that the second channel-former is oriented in the membrane in a direction opposite to that of the other two. This novel structure is named “triplin.” The extraordinary behavior of triplin indicates that it must have important and as yet undefined physiological roles.
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84
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Carvalho EO, Fernandes MM, Padrao J, Nicolau A, Marqués-Marchán J, Asenjo A, Gama FM, Ribeiro C, Lanceros-Mendez S. Tailoring Bacteria Response by Piezoelectric Stimulation. ACS APPLIED MATERIALS & INTERFACES 2019; 11:27297-27305. [PMID: 31267736 DOI: 10.1021/acsami.9b05013] [Citation(s) in RCA: 34] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Bacteria are simple organisms with a remarkable capacity for survival by adapting to different environments, which is a result of their long evolutionary history. Taking into consideration these adapting mechanisms, this work now investigates the effect of electrically active microenvironments on bacteria and on how this stimulation may trigger bacteria growth inhibition or proliferation. Electrical microenvironments are generated via stimulation of a piezoelectric polymer with a mechanical cue, thus developing an electrical response and a variation on the surface charge of the polymeric material. Specifically, Gram-positive Staphylococcus epidermidis and Gram-negative Escherichia coli were grown overnight under static and dynamic conditions on piezoelectric poly(vinylidene) fluoride (PVDF) films to further study bacteria behavior under: (i) the effect of the material surface charge in static conditions, (ii) the mechanical effect, and (iii) the piezoelectric effect, the last two performed under dynamic conditions. Bacteria viability in planktonic and biofilm forms was measured, and the microorganism morphology was characterized. Whereas E. coli responds little to any of the stimuli application, S. epidermidis growth can be regulated through the material surface charge and by the applied frequency. Positively charged PVDF induces bacterial growth inhibition in planktonic and adhered cells in static conditions, whereas antifouling properties are obtained when a mechanical or piezoelectric effect at 4 Hz stimuli is applied. By increasing the stimuli to 40 Hz, however, the adhesion of bacteria is promoted. In conclusion, the behavior of certain bacteria species is tailored through the application of piezoelectric materials, which provide sufficient mechanoelectrical stimuli for growth or inhibition of bacteria, allowing for the design of suitable anti- and promicrobial strategies. Such strategies are only found in studies related to mammalian cells, whereas in bacterial cells this type of stimuli are still unknown. Thus, this work provides one of the first insights on the effect of piezoelectric stimuli on bacterial cells.
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Affiliation(s)
- Estela O Carvalho
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
- Centre of Physics , University of Minho , Braga 4710-057 , Portugal
| | - Margarida M Fernandes
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
- Centre of Physics , University of Minho , Braga 4710-057 , Portugal
| | - Jorge Padrao
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
| | - Ana Nicolau
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
| | | | - Agustina Asenjo
- Instituto de Ciencia de Materiales de Madrid , CSIC , Madrid 28049 , Spain
| | - Francisco M Gama
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
| | - Clarisse Ribeiro
- Centre of Biological Engineering , University of Minho , Campus de Gualtar , Braga 4710-057 , Portugal
- Centre of Physics , University of Minho , Braga 4710-057 , Portugal
| | - Senentxu Lanceros-Mendez
- BCMaterials, Basque Center for Materials, Applications and Nanostructures , UPV/EHU Science Park , Leioa 48940 , Spain
- Ikerbasque, Basque Foundation for Science , Bilbao 48013 , Spain
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85
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Lee B, Lee DG. Synergistic antibacterial activity of gold nanoparticles caused by apoptosis-like death. J Appl Microbiol 2019; 127:701-712. [PMID: 31216601 DOI: 10.1111/jam.14357] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2019] [Revised: 06/11/2019] [Accepted: 06/14/2019] [Indexed: 01/06/2023]
Abstract
AIMS Metal nanoparticles are promising materials for the management of infectious diseases as known to have various antimicrobial activities in pathogenic micro-organisms. Among them, gold nanoparticles (AuNPs) are used in a wide range of fields such as photodynamic therapy, molecular diagnostics and drug delivery because of their unique physicochemical properties. However, little is known about the synergistic antibacterial activity and mechanism of AuNPs on pathogenic bacteria. METHODS AND RESULTS Combinations of AuNPs and cefotaxime and ciprofloxacin showed synergistic interaction against all Salmonella species, however the combination with kanamycin exhibited no interaction. We determined that AuNPs and in combinations with antibiotics exert its antibacterial effect through bacterial apoptosis-like death. AuNPs caused collapse of intracellular divalent cation homeostasis, and conventional antibiotics caused accumulation of reactive oxygen species, which induced apoptotic hallmarks such as membrane depolarization, caspase-like protein activation, cell filamentation and phosphatidylserine externalization. CONCLUSIONS The cation homeostasis disruption by AuNPs and the accumulation of reactive oxygen species by conventional antibiotics synergistically affected bacterial cell death and induced apoptosis-like death in Salmonella cells. SIGNIFICANCE AND IMPACT OF THE STUDY The synergistic activity between AuNPs and antibiotics propose that the AuNPs are a potential antibacterial agent and adjuvant for antimicrobial chemotherapy.
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Affiliation(s)
- B Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Korea
| | - D G Lee
- School of Life Sciences, BK21 Plus KNU Creative BioResearch Group, Kyungpook National University, Daegu, Korea
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86
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Sirec T, Benarroch JM, Buffard P, Garcia-Ojalvo J, Asally M. Electrical Polarization Enables Integrative Quality Control during Bacterial Differentiation into Spores. iScience 2019; 16:378-389. [PMID: 31226599 PMCID: PMC6586994 DOI: 10.1016/j.isci.2019.05.044] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2018] [Revised: 12/18/2018] [Accepted: 05/30/2019] [Indexed: 12/03/2022] Open
Abstract
Quality control of offspring is important for the survival of cells. However, the mechanisms by which quality of offspring cells may be checked while running genetic programs of cellular differentiation remain unclear. Here we investigated quality control during sporulating in Bacillus subtilis by combining single-cell time-lapse microscopy, molecular biology, and mathematical modeling. Our results revealed that the quality control via premature germination is coupled with the electrical polarization of outer membranes of developing forespores. The forespores that accumulate fewer cations on their surface are more likely to be aborted. This charge accumulation enables the projection of multi-dimensional information about the external environment and morphological development of the forespore into one-dimensional information of cation accumulation. We thus present a paradigm of cellular regulation by bacterial electrical signaling. Moreover, based on the insight we gain, we propose an electrophysiology-based approach of reducing the yield and quality of Bacillus endospores. Quality control during bacterial sporulation is coupled with cation accumulation Cation accumulation prevents premature germination Cation accumulation integrates information on morphological defects and environments Spores are less fit when sporulated with Thioflavin T
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Affiliation(s)
- Teja Sirec
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
| | - Jonatan M Benarroch
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK; Warwick Medical School, The University of Warwick, Coventry CV4 7AL, UK
| | - Pauline Buffard
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Munehiro Asally
- School of Life Sciences, The University of Warwick, Coventry CV4 7AL, UK; Warwick Integrative Synthetic Biology Centre, The University of Warwick, Coventry CV4 7AL, UK; Bio-electrical Engineering Innovation Hub, The University of Warwick, Coventry CV4 7AL, UK.
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87
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Hooper SL. Motor Evolution: Lit-Up Hydra Bare All. Curr Biol 2019; 29:R408-R410. [PMID: 31163142 DOI: 10.1016/j.cub.2019.04.050] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Whole-animal Hydra imaging shows that epitheliomuscular calcium influx dynamics and inter-cell progression speeds are very different for different behaviors. Hydra movements therefore likely arise from fast (ionotropic) and slow (metabotropic) neural mechanisms, and from interactions among the epitheliomuscular cells themselves.
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Affiliation(s)
- Scott L Hooper
- Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
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88
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Stratford JP, Edwards CLA, Ghanshyam MJ, Malyshev D, Delise MA, Hayashi Y, Asally M. Electrically induced bacterial membrane-potential dynamics correspond to cellular proliferation capacity. Proc Natl Acad Sci U S A 2019; 116:9552-9557. [PMID: 31000597 PMCID: PMC6511025 DOI: 10.1073/pnas.1901788116] [Citation(s) in RCA: 90] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Membrane-potential dynamics mediate bacterial electrical signaling at both intra- and intercellular levels. Membrane potential is also central to cellular proliferation. It is unclear whether the cellular response to external electrical stimuli is influenced by the cellular proliferative capacity. A new strategy enabling electrical stimulation of bacteria with simultaneous monitoring of single-cell membrane-potential dynamics would allow bridging this knowledge gap and further extend electrophysiological studies into the field of microbiology. Here we report that an identical electrical stimulus can cause opposite polarization dynamics depending on cellular proliferation capacity. This was demonstrated using two model organisms, namely Bacillus subtilis and Escherichia coli, and by developing an apparatus enabling exogenous electrical stimulation and single-cell time-lapse microscopy. Using this bespoke apparatus, we show that a 2.5-second electrical stimulation causes hyperpolarization in unperturbed cells. Measurements of intracellular K+ and the deletion of the K+ channel suggested that the hyperpolarization response is caused by the K+ efflux through the channel. When cells are preexposed to 400 ± 8 nm wavelength light, the same electrical stimulation depolarizes cells instead of causing hyperpolarization. A mathematical model extended from the FitzHugh-Nagumo neuron model suggested that the opposite response dynamics are due to the shift in resting membrane potential. As predicted by the model, electrical stimulation only induced depolarization when cells are treated with antibiotics, protonophore, or alcohol. Therefore, electrically induced membrane-potential dynamics offer a reliable approach for rapid detection of proliferative bacteria and determination of their sensitivity to antimicrobial agents at the single-cell level.
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Affiliation(s)
- James P Stratford
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, West Midlands, CV4 7AL,United Kingdom
| | - Conor L A Edwards
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
| | - Manjari J Ghanshyam
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
| | - Dmitry Malyshev
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
| | - Marco A Delise
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
| | - Yoshikatsu Hayashi
- Department of Biomedical Engineering, School of Biological Sciences, University of Reading, Reading, Berkshire, RG6 6AH, United Kingdom
| | - Munehiro Asally
- School of Life Sciences, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom;
- Warwick Integrative Synthetic Biology Centre, University of Warwick, Coventry, West Midlands, CV4 7AL,United Kingdom
- Bio-Electrical Engineering Innovation Hub, University of Warwick, Coventry, West Midlands, CV4 7AL, United Kingdom
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89
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Lee DYD, Galera-Laporta L, Bialecka-Fornal M, Moon EC, Shen Z, Briggs SP, Garcia-Ojalvo J, Süel GM. Magnesium Flux Modulates Ribosomes to Increase Bacterial Survival. Cell 2019; 177:352-360.e13. [PMID: 30853217 PMCID: PMC6814349 DOI: 10.1016/j.cell.2019.01.042] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2018] [Revised: 12/03/2018] [Accepted: 01/24/2019] [Indexed: 01/30/2023]
Abstract
Bacteria exhibit cell-to-cell variability in their resilience to stress, for example, following antibiotic exposure. Higher resilience is typically ascribed to "dormant" non-growing cellular states. Here, by measuring membrane potential dynamics of Bacillus subtilis cells, we show that actively growing bacteria can cope with ribosome-targeting antibiotics through an alternative mechanism based on ion flux modulation. Specifically, we observed two types of cellular behavior: growth-defective cells exhibited a mathematically predicted transient increase in membrane potential (hyperpolarization), followed by cell death, whereas growing cells lacked hyperpolarization events and showed elevated survival. Using structural perturbations of the ribosome and proteomic analysis, we uncovered that stress resilience arises from magnesium influx, which prevents hyperpolarization. Thus, ion flux modulation provides a distinct mechanism to cope with ribosomal stress. These results suggest new approaches to increase the effectiveness of ribosome-targeting antibiotics and reveal an intriguing connection between ribosomes and the membrane potential, two fundamental properties of cells.
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Affiliation(s)
- Dong-Yeon D Lee
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Leticia Galera-Laporta
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Maja Bialecka-Fornal
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Eun Chae Moon
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA
| | - Zhouxin Shen
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093-0380, USA
| | - Steven P Briggs
- Section of Cell and Developmental Biology, Division of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093-0380, USA
| | - Jordi Garcia-Ojalvo
- Department of Experimental and Health Sciences, Universitat Pompeu Fabra, 08003 Barcelona, Spain
| | - Gürol M Süel
- Molecular Biology Section, Division of Biological Sciences, University of California, San Diego, La Jolla, CA 92093, USA; San Diego Center for Systems Biology, University of California, San Diego, La Jolla, CA 92093-0380, USA; Center for Microbiome Innovation, University of California, San Diego, La Jolla, CA 92093-0380, USA.
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90
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Lee H, Lee DG. The Potential of Gold and Silver Antimicrobials: Nanotherapeutic Approach and Applications. Nanotheranostics 2019. [DOI: 10.1007/978-3-030-29768-8_8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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91
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Mei G, Mamaeva N, Ganapathy S, Wang P, DeGrip WJ, Rothschild KJ. Raman spectroscopy of a near infrared absorbing proteorhodopsin: Similarities to the bacteriorhodopsin O photointermediate. PLoS One 2018; 13:e0209506. [PMID: 30586409 PMCID: PMC6306260 DOI: 10.1371/journal.pone.0209506] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2018] [Accepted: 12/06/2018] [Indexed: 02/07/2023] Open
Abstract
Microbial rhodopsins have become an important tool in the field of optogenetics. However, effective in vivo optogenetics is in many cases severely limited due to the strong absorption and scattering of visible light by biological tissues. Recently, a combination of opsin site-directed mutagenesis and analog retinal substitution has produced variants of proteorhodopsin which absorb maximally in the near-infrared (NIR). In this study, UV-Visible-NIR absorption and resonance Raman spectroscopy were used to study the double mutant, D212N/F234S, of green absorbing proteorhodopsin (GPR) regenerated with MMAR, a retinal analog containing a methylamino modified β-ionone ring. Four distinct subcomponent absorption bands with peak maxima near 560, 620, 710 and 780 nm are detected with the NIR bands dominant at pH <7.3, and the visible bands dominant at pH 9.5. FT-Raman using 1064-nm excitation reveal two strong ethylenic bands at 1482 and 1498 cm-1 corresponding to the NIR subcomponent absorption bands based on an extended linear correlation between λmax and γC = C. This spectrum exhibits two intense bands in the fingerprint and HOOP mode regions that are highly characteristic of the O640 photointermediate from the light-adapted bacteriorhodopsin photocycle. In contrast, 532-nm excitation enhances the 560-nm component, which exhibits bands very similar to light-adapted bacteriorhodopsin and/or the acid-purple form of bacteriorhodopsin. Native GPR and its mutant D97N when regenerated with MMAR also exhibit similar absorption and Raman bands but with weaker contributions from the NIR absorbing components. Based on these results it is proposed that the NIR absorption in GPR-D212N/F234S with MMAR arises from an O-like chromophore, where the Schiff base counterion D97 is protonated and the MMAR adopts an all-trans configuration with a non-planar geometry due to twists in the conjugated polyene segment. This configuration is characterized by extensive charge delocalization, most likely involving nitrogens atoms in the MMAR chromophore.
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Affiliation(s)
- Gaoxiang Mei
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
| | - Natalia Mamaeva
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
| | - Srividya Ganapathy
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden UniversityAR Leiden, The Netherlands
| | - Peng Wang
- Bruker Corporation, Billerica, MA, United States of America
| | - Willem J. DeGrip
- Department of Biophysical Organic Chemistry, Leiden Institute of Chemistry, Leiden UniversityAR Leiden, The Netherlands
| | - Kenneth J. Rothschild
- Molecular Biophysics Laboratory, Photonics Center and Department of Physics, Boston University, Boston, Massachusetts, United States of America
- * E-mail:
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92
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Lee H, Lee DG. Gold nanoparticles induce a reactive oxygen species-independent apoptotic pathway in Escherichia coli. Colloids Surf B Biointerfaces 2018; 167:1-7. [DOI: 10.1016/j.colsurfb.2018.03.049] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2017] [Revised: 02/07/2018] [Accepted: 03/28/2018] [Indexed: 12/28/2022]
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93
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Zhang J, Lakowicz JR. A superior bright NIR luminescent nanoparticle preparation and indicating calcium signaling detection in cells and small animals. Cell Biosci 2018; 8:37. [PMID: 29928497 PMCID: PMC5987641 DOI: 10.1186/s13578-018-0235-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/21/2018] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Near-field fluorescence (NFF) effects were employed to develop a novel near-infrared (NIR) luminescent nanoparticle (LNP) with superior brightness. The LNP is used as imaging contrast agent for cellular and small animal imaging and furthermore suggested to use for detecting voltage-sensitive calcium in living cells and animals with high sensitivity. RESULTS NIR Indocyanine green (ICG) dye was conjugated with human serum albumin (HSA) followed by covalently binding to gold nanorod (AuNR). The AuNR displayed dual plasmons from transverse and longitudinal axis, and the longitudinal plasmon was localized at the NIR region which could efficiently couple with the excitation and emission of ICG dye leading to a largely enhanced NFF. The enhancement factor was measured to be about 16-fold using both ensemble and single nanoparticle spectral methods. As an imaging contrast agent, the ICG-HSA-Au complex (abbreviate as ICG-Au) was conjugated on HeLa cells and fluorescence cell images were recorded on a time-resolved confocal microscope. The emission signals of ICG-Au complexes were distinctly resolved as the individual spots that were observed over the cellular backgrounds due to their strong brightness as well as shortened lifetime. The LNPs were also tested to have a low cytotoxicity. The ICG-Au complexes were injected below the skin surface of mouse showing emission spots 5-fold brighter than those from the same amount of free ICG-HSA conjugates. CONCLUSIONS Based on the observations in this research, the excitation and emission of NIR ICG dyes were found to be able to sufficiently couple with the longitudinal plasmon of AuNRs leading to a largely enhanced NFF. Using the LNP with super-brightness as a contrast agent, the ICG-Au complex could be resolved from the background in the cell and small animal imaging. The novel NIR LNP has also a great potential for detection of voltage-gated calcium concentration in the cell and living animal with a high sensitivity.
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Affiliation(s)
- Jian Zhang
- Department of Biochemistry and Molecular Biology, Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201 USA
- Present Address: Vigene Biosciences Inc., 9430 Key W. Ave Suite 105, Rockville, MD 20850 USA
| | - Joseph. R. Lakowicz
- Department of Biochemistry and Molecular Biology, Center for Fluorescence Spectroscopy, University of Maryland School of Medicine, 725 West Lombard Street, Baltimore, MD 21201 USA
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