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Elias-Mordechai M, David N, Oren S, Georgia Pelah M, Jopp J, Fichtman B, Harel A, Berkovich R, Sal-Man N. A single filament biomechanical study of the enteropathogenic Escherichia coli Type III secretion system reveals a high elastic aspect ratio. NANOSCALE 2023; 15:15027-15037. [PMID: 37668452 DOI: 10.1039/d3nr01953e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/06/2023]
Abstract
Type III secretion systems (T3SSs) are syringe-like protein complexes used by some of the most harmful bacterial pathogens to infect host cells. While the T3SS filament, a long hollow conduit that bridges between bacteria and host cells, has been characterized structurally, very little is known about its physical properties. These filaments should endure shear and normal stresses imposed by the viscous mucosal flow during infection within the intestinal tract. We used atomic force microscopy (AFM) to probe the longitudinal and radial mechanical response of individual T3SS filaments by pulling on filaments extending directly from bacterial surfaces and later pressing into filaments that were detached from the bacteria. The measured longitudinal elastic moduli were higher by about two orders of magnitude than the radial elastic moduli. These proportions are commensurate with the role of the T3SS filament, which requires horizontal flexibility while maintaining its structural integrity to withstand intense stresses during infection.
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Affiliation(s)
- Moran Elias-Mordechai
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Nofar David
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Sonia Oren
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Maya Georgia Pelah
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
| | - Jürgen Jopp
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Boris Fichtman
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Amnon Harel
- Azrieli Faculty of Medicine, Bar-Ilan University, Safed, Israel
| | - Ronen Berkovich
- Department of Chemical Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
- The Ilse Katz Institute for Nanoscale Science and Technology, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Neta Sal-Man
- Department of Microbiology, Immunology, and Genetics, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel.
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2
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Patkowski JB, Dahlberg T, Amin H, Gahlot DK, Vijayrajratnam S, Vogel JP, Francis MS, Baker JL, Andersson M, Costa TRD. The F-pilus biomechanical adaptability accelerates conjugative dissemination of antimicrobial resistance and biofilm formation. Nat Commun 2023; 14:1879. [PMID: 37019921 PMCID: PMC10076315 DOI: 10.1038/s41467-023-37600-y] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 03/22/2023] [Indexed: 04/07/2023] Open
Abstract
Conjugation is used by bacteria to propagate antimicrobial resistance (AMR) in the environment. Central to this process are widespread conjugative F-pili that establish the connection between donor and recipient cells, thereby facilitating the spread of IncF plasmids among enteropathogenic bacteria. Here, we show that the F-pilus is highly flexible but robust at the same time, properties that increase its resistance to thermochemical and mechanical stresses. By a combination of biophysical and molecular dynamics methods, we establish that the presence of phosphatidylglycerol molecules in the F-pilus contributes to the structural stability of the polymer. Moreover, this structural stability is important for successful delivery of DNA during conjugation and facilitates rapid formation of biofilms in harsh environmental conditions. Thus, our work highlights the importance of F-pilus structural adaptations for the efficient spread of AMR genes in a bacterial population and for the formation of biofilms that protect against the action of antibiotics.
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Affiliation(s)
- Jonasz B Patkowski
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | - Tobias Dahlberg
- Department of Physics, Umeå University, 901 87, Umeå, Sweden
| | - Himani Amin
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK
| | | | - Sukhithasri Vijayrajratnam
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Joseph P Vogel
- Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, MO, 63110, USA
| | - Matthew S Francis
- Department of Molecular Biology, Umeå University, 901 87, Umeå, Sweden
| | - Joseph L Baker
- Department of Chemistry, The College of New Jersey, Ewing, NJ, 08628, USA.
| | | | - Tiago R D Costa
- MRC Centre for Molecular Bacteriology and Infection, Department of Life Sciences, Imperial College, London, SW7 2AZ, UK.
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3
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Munhoz DD, Richards AC, Santos FF, Mulvey MA, Piazza RMF. E. coli Common pili promote the fitness and virulence of a hybrid aEPEC/ExPEC strain within diverse host environments. Gut Microbes 2023; 15:2190308. [PMID: 36949030 PMCID: PMC10038029 DOI: 10.1080/19490976.2023.2190308] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/22/2022] [Accepted: 03/07/2023] [Indexed: 03/24/2023] Open
Abstract
Pathogenic subsets of Escherichia coli include diarrheagenic (DEC) strains that cause disease within the gut and extraintestinal pathogenic E. coli (ExPEC) strains that are linked with urinary tract infections, bacteremia, and other infections outside of intestinal tract. Among DEC strains is an emergent pathotype known as atypical enteropathogenic E. coli (aEPEC), which can cause severe diarrhea. Recent sequencing efforts revealed that some E. coli strains possess genetic features that are characteristic of both DEC and ExPEC isolates. BA1250 is a newly reclassified hybrid strain with characteristics of aEPEC and ExPEC. This strain was isolated from a child with diarrhea, but its genetic features indicate that it might have the capacity to cause disease at extraintestinal sites. The spectrum of adhesins encoded by hybrid strains like BA1250 are expected to be especially important in facilitating colonization of diverse niches. E. coli common pilus (ECP) is an adhesin expressed by many E. coli pathogens, but how it impacts hybrid strains has not been ascertained. Here, using zebrafish larvae as surrogate hosts to model both gut colonization and extraintestinal infections, we found that ECP can act as a multi-niche colonization and virulence factor for BA1250. Furthermore, our results indicate that ECP-related changes in activation of envelope stress response pathways may alter the fitness of BA1250. Using an in silico approach, we also delineated the broader repertoire of adhesins that are encoded by BA1250, and provide evidence that the expression of at least a few of these varies in the absence of functional ECP.
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Affiliation(s)
| | - Amanda C. Richards
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake, UT, USA
| | - Fernanda F. Santos
- Laboratório Alerta, Departamento de Medicina, Escola Paulista de Medicina, Universidade Federal de São Paulo, São Paulo, SP, Brazil
| | - Matthew A. Mulvey
- Division of Microbiology and Immunology, Department of Pathology, University of Utah, Salt Lake, UT, USA
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4
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Dahlberg T, Baker JL, Bullitt E, Andersson M. Unveiling molecular interactions that stabilize bacterial adhesion pili. Biophys J 2022; 121:2096-2106. [PMID: 35491503 PMCID: PMC9247471 DOI: 10.1016/j.bpj.2022.04.036] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Revised: 03/09/2022] [Accepted: 04/27/2022] [Indexed: 11/29/2022] Open
Abstract
Adhesion pili assembled by the chaperone-usher pathway are superelastic helical filaments on the surface of bacteria, optimized for attachment to target cells. Here, we investigate the biophysical function and structural interactions that stabilize P pili from uropathogenic bacteria. Using optical tweezers, we measure P pilus subunit-subunit interaction dynamics and show that pilus compliance is contour-length dependent. Atomic details of subunit-subunit interactions of pili under tension are shown using steered molecular dynamics (sMD) simulations. sMD results also indicate that the N-terminal "staple" region of P pili, which provides interactions with pilins that are four and five subunits away, significantly stabilizes the helical filament structure. These data are consistent with previous structural data, and suggest that more layer-to-layer interactions could compensate for the lack of a staple in type 1 pili. This study informs our understanding of essential structural and dynamic features of adhesion pili, supporting the hypothesis that the function of pili is critically dependent on their structure and biophysical properties.
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Affiliation(s)
| | - Joseph L Baker
- Department of Chemistry, The College of New Jersey, Ewing, New Jersey
| | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, Massachusetts.
| | - Magnus Andersson
- Department of Physics, Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research (UCMR), Umeå, Sweden.
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5
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Roghanian P, Zare Karizi S, Motamedi MJ, Kazemi R, Khoobbakht D, Amani J. Designing and determining immunogenicity of a recombinant protein due to producing a new vaccine against Enterotoxigenic Escherichia coli containing CfaE and CotD subunits. J Immunoassay Immunochem 2021; 42:525-542. [PMID: 33834940 DOI: 10.1080/15321819.2021.1906890] [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: 01/11/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) is one of the most common bacterial causes of mortalities in developing countries due to diarrhea. Since mucosal immune responses to CFs can prevent the disease, a chimeric protein containing ETEC's CFA/I (CfaE) tip subunits and CS2 (CotD) sub-structural units is developed to produce effective vaccine. Using bioinformatics tools, the chimeric construct was analyzed and then the optimized gene was synthesized and expressed in E. coli. The recombinant protein was expressed and purified by the Ni-NTA chromatography column and confirmed by anti-his tag antibody by western blotting. Mice were immunized with recombinant protein, and the IgG and IgA antibodies' titrations of the sera were analyzed by ELISA. In addition, the immunogenicity and protective efficacy against the live ETEC bacteria in the challenge test were determined. Western blot analysis verified the chimeric protein expression of CotD-CfaE. The outcome of ELISA was a substantial improvement in the IgG antibody titer in immunized mice. In a live ETEC challenge, the survival percentage of 30% was shown for immunized mice. The developed recombinant chimeric protein could be suggested as an effective component in producing an efficient vaccine against Enterotoxigenic E. coli with other crucial subunits, different immunization route, and other factors.
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Affiliation(s)
- Pooneh Roghanian
- Department of Genetics, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - Shohreh Zare Karizi
- Department of Genetics and Biotechnology, School of Biological Science, Varamin-Pishva, Branch Islamic Azad University, Varamin, Iran
| | | | | | - Dorna Khoobbakht
- Department of Genetics, Islamic Azad University, Science and Research Branch, Tehran, Iran
| | - Jafar Amani
- Applied Microbiology Research Center, Systems Biology and Poisonings Institute, Baqiyatallah University of Medical Sciences, Tehran, Iran
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6
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Baker JL, Dahlberg T, Bullitt E, Andersson M. Impact of an alpha helix and a cysteine-cysteine disulfide bond on the resistance of bacterial adhesion pili to stress. Proc Natl Acad Sci U S A 2021; 118:e2023595118. [PMID: 34011607 PMCID: PMC8166124 DOI: 10.1073/pnas.2023595118] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023] Open
Abstract
Escherichia coli express adhesion pili that mediate attachment to host cell surfaces and are exposed to body fluids in the urinary and gastrointestinal tracts. Pilin subunits are organized into helical polymers, with a tip adhesin for specific host binding. Pili can elastically unwind when exposed to fluid flow forces, reducing the adhesin load, thereby facilitating sustained attachment. Here we investigate biophysical and structural differences of pili commonly expressed on bacteria that inhabit the urinary and intestinal tracts. Optical tweezers measurements reveal that class 1a pili of uropathogenic E. coli (UPEC), as well as class 1b of enterotoxigenic E. coli (ETEC), undergo an additional conformational change beyond pilus unwinding, providing significantly more elasticity to their structure than ETEC class 5 pili. Examining structural and steered molecular dynamics simulation data, we find that this difference in class 1 pili subunit behavior originates from an α-helical motif that can unfold when exposed to force. A disulfide bond cross-linking β-strands in class 1 pili stabilizes subunits, allowing them to tolerate higher forces than class 5 pili that lack this covalent bond. We suggest that these extra contributions to pilus resiliency are relevant for the UPEC niche, since resident bacteria are exposed to stronger, more transient drag forces compared to those experienced by ETEC bacteria in the mucosa of the intestinal tract. Interestingly, class 1b ETEC pili include the same structural features seen in UPEC pili, while requiring lower unwinding forces that are more similar to those of class 5 ETEC pili.
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Affiliation(s)
- Joseph L Baker
- Department of Chemistry, The College of New Jersey, Ewing, NJ 08628;
| | | | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA 02118
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7
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Banerjee S, Chakraborty S, Sreepada A, Banerji D, Goyal S, Khurana Y, Haldar S. Cutting-Edge Single-Molecule Technologies Unveil New Mechanics in Cellular Biochemistry. Annu Rev Biophys 2021; 50:419-445. [PMID: 33646813 DOI: 10.1146/annurev-biophys-090420-083836] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Single-molecule technologies have expanded our ability to detect biological events individually, in contrast to ensemble biophysical technologies, where the result provides averaged information. Recent developments in atomic force microscopy have not only enabled us to distinguish the heterogeneous phenomena of individual molecules, but also allowed us to view up to the resolution of a single covalent bond. Similarly, optical tweezers, due to their versatility and precision, have emerged as a potent technique to dissect a diverse range of complex biological processes, from the nanomechanics of ClpXP protease-dependent degradation to force-dependent processivity of motor proteins. Despite the advantages of optical tweezers, the time scales used in this technology were inconsistent with physiological scenarios, which led to the development of magnetic tweezers, where proteins are covalently linked with the glass surface, which in turn increases the observation window of a single biomolecule from minutes to weeks. Unlike optical tweezers, magnetic tweezers use magnetic fields to impose torque, which makes them convenient for studying DNA topology and topoisomerase functioning. Using modified magnetic tweezers, researchers were able to discover the mechanical role of chaperones, which support their substrate proteinsby pulling them during translocation and assist their native folding as a mechanical foldase. In this article, we provide a focused review of many of these new roles of single-molecule technologies, ranging from single bond breaking to complex chaperone machinery, along with the potential to design mechanomedicine, which would be a breakthrough in pharmacological interventions against many diseases.
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Affiliation(s)
- Souradeep Banerjee
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Soham Chakraborty
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Abhijit Sreepada
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Devshuvam Banerji
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Shashwat Goyal
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Yajushi Khurana
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
| | - Shubhasis Haldar
- Department of Biological Sciences, Ashoka University, Sonipat, Haryana 131029, India;
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8
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Paul TJ, Strzelczyk AK, Feldhof MI, Schmidt S. Temperature-Switchable Glycopolymers and Their Conformation-Dependent Binding to Receptor Targets. Biomacromolecules 2020; 21:2913-2921. [DOI: 10.1021/acs.biomac.0c00676] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Affiliation(s)
- Tanja J. Paul
- Institute of Organic and Macromolecular Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, Dusseldorf 40225, Germany
| | - Alexander K. Strzelczyk
- Institute of Organic and Macromolecular Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, Dusseldorf 40225, Germany
| | - Melina I. Feldhof
- Institute of Organic and Macromolecular Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, Dusseldorf 40225, Germany
| | - Stephan Schmidt
- Institute of Organic and Macromolecular Chemistry, Heinrich-Heine-University Düsseldorf, Universitätsstraße 1, Dusseldorf 40225, Germany
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9
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Zheng W, Andersson M, Mortezaei N, Bullitt E, Egelman E. Cryo-EM structure of the CFA/I pilus rod. IUCRJ 2019; 6:815-821. [PMID: 31576215 PMCID: PMC6760452 DOI: 10.1107/s2052252519007966] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 06/03/2019] [Indexed: 05/04/2023]
Abstract
Enterotoxigenic Escherichia coli (ETEC) are common agents of diarrhea for travelers and a major cause of mortality in children in developing countries. To attach to intestinal cells ETEC express colonization factors, among them CFA/I, which are the most prevalent factors and are the archetypical representative of class 5 pili. The helical quaternary structure of CFA/I can be unwound under tensile force and it has been shown that this mechanical property helps bacteria to withstand shear forces from fluid motion. We report in this work the CFA/I pilus structure at 4.3 Å resolution from electron cryomicroscopy (cryo-EM) data, and report details of the donor strand complementation. The CfaB pilins modeled into the cryo-EM map allow us to identify the buried surface area between subunits, and these regions are correlated to quaternary structural stability in class 5 and chaperone-usher pili. In addition, from the model built using the EM structure we also predicted that residue 13 (proline) of the N-terminal β-strand could have a major impact on the filament's structural stability. Therefore, we used optical tweezers to measure and compare the stability of the quaternary structure of wild type CFA/I and a point-mutated CFA/I with a propensity for unwinding. We found that pili with this mutated CFA/I require a lower force to unwind, supporting our hypothesis that Pro13 is important for structural stability. The high-resolution CFA/I pilus structure presented in this work and the analysis of structural stability will be useful for the development of novel antimicrobial drugs that target adhesion pili needed for initial attachment and sustained adhesion of ETEC.
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Affiliation(s)
- Weili Zheng
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
| | | | | | - Esther Bullitt
- Physiology and Biophysics, Boston University School of Medicine, 700 Albany Street, Boston, MA 02118, USA
| | - Edward Egelman
- Department of Biochemistry and Molecular Genetics, University of Virginia, Charlottesville, VA, USA
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10
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Werneburg GT, Thanassi DG. Pili Assembled by the Chaperone/Usher Pathway in Escherichia coli and Salmonella. EcoSal Plus 2018; 8:10.1128/ecosalplus.ESP-0007-2017. [PMID: 29536829 PMCID: PMC5940347 DOI: 10.1128/ecosalplus.esp-0007-2017] [Citation(s) in RCA: 45] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2017] [Indexed: 12/12/2022]
Abstract
Gram-negative bacteria assemble a variety of surface structures, including the hair-like organelles known as pili or fimbriae. Pili typically function in adhesion and mediate interactions with various surfaces, with other bacteria, and with other types of cells such as host cells. The chaperone/usher (CU) pathway assembles a widespread class of adhesive and virulence-associated pili. Pilus biogenesis by the CU pathway requires a dedicated periplasmic chaperone and integral outer membrane protein termed the usher, which forms a multifunctional assembly and secretion platform. This review addresses the molecular and biochemical aspects of the CU pathway in detail, focusing on the type 1 and P pili expressed by uropathogenic Escherichia coli as model systems. We provide an overview of representative CU pili expressed by E. coli and Salmonella, and conclude with a discussion of potential approaches to develop antivirulence therapeutics that interfere with pilus assembly or function.
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Affiliation(s)
- Glenn T. Werneburg
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
| | - David G. Thanassi
- Department of Molecular Genetics and Microbiology, Stony Brook University, Stony Brook, NY, USA
- Center for Infectious Diseases, Stony Brook University, Stony Brook, NY, USA
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11
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Abstract
Escherichia coli bacterial cells produce multiple types of adhesion pili that mediate cell-cell and cell-host attachments. These pili (also called 'fimbriae') are large biopolymers that are comprised of subunits assembled via a sophisticated micro-machinery into helix-like structures that are anchored in the bacterial outer membrane. They are commonly essential for initiation of disease and thus provide a potential target for antibacterial prevention and treatment. To develop new therapeutics for disease prevention and treatment we need to understand the molecular mechanisms and the direct role of adhesion pili during pathogenesis. These helix-like pilus structures possess fascinating and unique biomechanical properties that have been thoroughly investigated using high-resolution imaging techniques, force spectroscopy and fluid flow chambers. In this chapter, we first discuss the structure of pili and the micro-machinery responsible for the assembly process. Thereafter, we present methods for measurement of the biomechanics of adhesion pili, including optical tweezers. Data demonstrate unique biomechanical properties of pili that allow bacteria to sustain binding during in vivo fluid shear forces. We thereafter summarize the current biomechanical findings related to adhesion pili and show that pili biomechanical properties are niche-specific. That is, the data suggest that there is an organ-specific adaptation of pili that facilitates infection of the bacteria's target tissue. Thus, pilus biophysical properties are an important part of Escherichia coli pathogenesis, allowing bacteria to overcome hydrodynamic challenges in diverse environments.
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Affiliation(s)
| | - Esther Bullitt
- Department of Physiology & Biophysics, Boston University School of Medicine, Boston, MA, USA.
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Even C, Marlière C, Ghigo JM, Allain JM, Marcellan A, Raspaud E. Recent advances in studying single bacteria and biofilm mechanics. Adv Colloid Interface Sci 2017; 247:573-588. [PMID: 28754382 DOI: 10.1016/j.cis.2017.07.026] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2017] [Revised: 07/18/2017] [Accepted: 07/18/2017] [Indexed: 12/15/2022]
Abstract
Bacterial biofilms correspond to surface-associated bacterial communities embedded in hydrogel-like matrix, in which high cell density, reduced diffusion and physico-chemical heterogeneity play a protective role and induce novel behaviors. In this review, we present recent advances on the understanding of how bacterial mechanical properties, from single cell to high-cell density community, determine biofilm tri-dimensional growth and eventual dispersion and we attempt to draw a parallel between these properties and the mechanical properties of other well-studied hydrogels and living systems.
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13
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14
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Antibodies Damage the Resilience of Fimbriae, Causing Them To Be Stiff and Tangled. J Bacteriol 2016; 199:JB.00665-16. [PMID: 27795330 DOI: 10.1128/jb.00665-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 10/12/2016] [Indexed: 01/23/2023] Open
Abstract
As adhesion fimbriae are a major virulence factor for many pathogenic Gram-negative bacteria, they are also potential targets for antibodies. Fimbriae are commonly required for initiating the colonization that leads to disease, and their success as adhesion organelles lies in their ability to both initiate and sustain bacterial attachment to epithelial cells. The ability of fimbriae to unwind and rewind their helical filaments presumably reduces their detachment from tissue surfaces with the shear forces that accompany significant fluid flow. Therefore, the disruption of functional fimbriae by inhibiting this resilience should have high potential for use as a vaccine to prevent disease. In this study, we show that two characteristic biomechanical features of fimbrial resilience, namely, the extension force and the extension length, are significantly altered by the binding of antibodies to fimbriae. The fimbriae that were studied are normally expressed on enterotoxigenic Escherichia coli, which are a major cause of diarrheal disease. This alteration in biomechanical properties was observed with bivalent polyclonal antifimbrial antibodies that recognize major pilin subunits but not with the Fab fragments of these antibodies. Thus, we propose that the mechanism by which bound antibodies disrupt the uncoiling of natural fimbria under force is by clamping together layers of the helical filament, thereby increasing their stiffness and reducing their resilience during fluid flow. In addition, we propose that antibodies tangle fimbriae via bivalent binding, i.e., by binding to two individual fimbriae and linking them together. Use of antibodies to disrupt physical properties of fimbriae may be generally applicable to the large number of Gram-negative bacteria that rely on these surface-adhesion molecules as an essential virulence factor. IMPORTANCE Our study shows that the resiliency of colonization factor antigen I (CFA/I) and coli surface antigen 2 (CS2) fimbriae, which are current targets for vaccine development, can be compromised significantly in the presence of antifimbrial antibodies. It is unclear how the humoral immune system specifically interrupts infection after the attachment of enterotoxigenic Escherichia coli (ETEC) to the epithelial surface. Our study indicates that immunoglobulins, in addition to their well-documented role in adaptive immunity, can mechanically damage the resilience of fimbriae of surface-attached ETEC, thereby revealing a new mode of action. Our data suggest a mechanism whereby antibodies coat adherent and free-floating bacteria to impede fimbrial resilience. Further elucidation of this possible mechanism is likely to inform the development and refinement of preventive vaccines against ETEC diarrhea.
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15
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Theory for nonlinear dynamic force spectroscopy. EUROPEAN BIOPHYSICS JOURNAL: EBJ 2016; 46:225-233. [PMID: 27461369 PMCID: PMC5346443 DOI: 10.1007/s00249-016-1158-6] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 07/01/2016] [Accepted: 07/11/2016] [Indexed: 11/25/2022]
Abstract
Dynamic force spectroscopy (DFS) is an experimental technique that is commonly used to assess information on the strength, energy landscape, and lifetime of noncovalent bio-molecular interactions. DFS traditionally requires an applied force that increases linearly with time so that the bio-complex under investigation is exposed to a constant loading rate. However, tethers or polymers can modulate the applied force in a nonlinear manner. For example, bacterial adhesion pili and polymers with worm-like chain properties are structures that show nonlinear force responses. In these situations, the theory for traditional DFS cannot be readily applied. In this work, we expand the theory for DFS to also include nonlinear external forces while still maintaining compatibility with the linear DFS theory. To validate the theory, we modeled a bio-complex expressed on a stiff, an elastic, and a worm-like chain polymer, using Monte Carlo methods, and assessed the corresponding rupture force spectra. It was found that the nonlinear DFS (NLDFS) theory correctly predicted the numerical results. We also present a protocol suggesting an experimental approach and analysis method of the data to estimate the bond length and the thermal off-rate.
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16
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Zakrisson J, Singh B, Svenmarker P, Wiklund K, Zhang H, Hakobyan S, Ramstedt M, Andersson M. Detecting Bacterial Surface Organelles on Single Cells Using Optical Tweezers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2016; 32:4521-9. [PMID: 27088225 DOI: 10.1021/acs.langmuir.5b03845] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/20/2023]
Abstract
Bacterial cells display a diverse array of surface organelles that are important for a range of processes such as intercellular communication, motility and adhesion leading to biofilm formation, infections, and bacterial spread. More specifically, attachment to host cells by Gram-negative bacteria are mediated by adhesion pili, which are nanometers wide and micrometers long fibrous organelles. Since these pili are significantly thinner than the wavelength of visible light, they cannot be detected using standard light microscopy techniques. At present, there is no fast and simple method available to investigate if a single cell expresses pili while keeping the cell alive for further studies. In this study, we present a method to determine the presence of pili on a single bacterium. The protocol involves imaging the bacterium to measure its size, followed by predicting the fluid drag based on its size using an analytical model, and thereafter oscillating the sample while a single bacterium is trapped by an optical tweezer to measure its effective fluid drag. Comparison between the predicted and the measured fluid drag thereby indicate the presence of pili. Herein, we verify the method using polymer coated silica microspheres and Escherichia coli bacteria expressing adhesion pili. Our protocol can in real time and within seconds assist single cell studies by distinguishing between piliated and nonpiliated bacteria.
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Affiliation(s)
- Johan Zakrisson
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Bhupender Singh
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Pontus Svenmarker
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Krister Wiklund
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Hanqing Zhang
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Shoghik Hakobyan
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Madeleine Ramstedt
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
| | - Magnus Andersson
- Department of Physics, and ‡Department of Chemistry, Umeå University , 901 87 Umeå, Sweden
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Castelain M, Duviau MP, Canette A, Schmitz P, Loubière P, Cocaign-Bousquet M, Piard JC, Mercier-Bonin M. The Nanomechanical Properties of Lactococcus lactis Pili Are Conditioned by the Polymerized Backbone Pilin. PLoS One 2016; 11:e0152053. [PMID: 27010408 PMCID: PMC4806873 DOI: 10.1371/journal.pone.0152053] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Accepted: 03/08/2016] [Indexed: 12/16/2022] Open
Abstract
Pili produced by Lactococcus lactis subsp. lactis are putative linear structures consisting of repetitive subunits of the major pilin PilB that forms the backbone, pilin PilA situated at the distal end of the pilus, and an anchoring pilin PilC that tethers the pilus to the peptidoglycan. We determined the nanomechanical properties of pili using optical-tweezers force spectroscopy. Single pili were exposed to optical forces that yielded force-versus-extension spectra fitted using the Worm-Like Chain model. Native pili subjected to a force of 0–200 pN exhibit an inextensible, but highly flexible ultrastructure, reflected by their short persistence length. We tested a panel of derived strains to understand the functional role of the different pilins. First, we found that both the major pilin PilB and sortase C organize the backbone into a full-length organelle and dictate the nanomechanical properties of the pili. Second, we found that both PilA tip pilin and PilC anchoring pilin were not essential for the nanomechanical properties of pili. However, PilC maintains the pilus on the bacterial surface and may play a crucial role in the adhesion- and biofilm-forming properties of L. lactis.
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Affiliation(s)
- Mickaël Castelain
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
- * E-mail:
| | - Marie-Pierre Duviau
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
| | - Alexis Canette
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Philippe Schmitz
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
| | - Pascal Loubière
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
| | - Muriel Cocaign-Bousquet
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
| | - Jean-Christophe Piard
- Micalis Institute, INRA, AgroParisTech, Université Paris-Saclay, 78350, Jouy-en-Josas, France
| | - Muriel Mercier-Bonin
- Université de Toulouse, INSA, UPS, INP, LISBP, 135 Avenue de Rangueil, F-31077, Toulouse, France
- INRA, UMR792 Ingénierie des Systèmes Biologiques et des Procédés, F-31400, Toulouse, France
- CNRS, UMR5504, F-31400, Toulouse, France
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