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Serizawa T, Yamaguchi S, Sugiura K, Marten R, Yamamoto A, Hata Y, Sawada T, Tanaka H, Tanaka M. Antibacterial Synthetic Nanocelluloses Synergizing with a Metal-Chelating Agent. ACS APPLIED BIO MATERIALS 2024; 7:246-255. [PMID: 37967519 PMCID: PMC10792664 DOI: 10.1021/acsabm.3c00846] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2023] [Revised: 11/02/2023] [Accepted: 11/02/2023] [Indexed: 11/17/2023]
Abstract
Antibacterial materials composed of biodegradable and biocompatible constituents that are produced via eco-friendly synthetic strategies will become an attractive alternative to antibiotics to combat antibiotic-resistant bacteria. In this study, we demonstrated the antibacterial properties of nanosheet-shaped crystalline assemblies of enzymatically synthesized aminated cellulose oligomers (namely, surface-aminated synthetic nanocelluloses) and their synergy with a metal-chelating antibacterial agent, ethylenediaminetetraacetic acid (EDTA). Growth curves and colony counting assays revealed that the surface-aminated cellulose assemblies had an antibacterial effect against Gram-negative Escherichia coli (E. coli). The cationic assemblies appeared to destabilize the cell wall of E. coli through electrostatic interactions with anionic lipopolysaccharide (LPS) molecules on the outer membrane. The antibacterial properties were significantly enhanced by the concurrent use of EDTA, which potentially removed metal ions from LPS molecules, resulting in synergistic bactericidal effects. No antibacterial activity of the surface-aminated cellulose assemblies was observed against Gram-positive Staphylococcus aureus even in the presence of EDTA, further supporting the contribution of electrostatic interactions between the cationic assemblies and anionic LPS to the activity against Gram-negative bacteria. Analysis using quartz crystal microbalance with dissipation monitoring revealed the attractive interaction of the surface-aminated cellulose assembly with LPS Ra monolayers artificially produced on the device substrate.
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Affiliation(s)
- Takeshi Serizawa
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Saeko Yamaguchi
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Kai Sugiura
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Ramona Marten
- Physical
Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, Heidelberg D69120, Germany
- Center
for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
| | - Akihisa Yamamoto
- Center
for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
| | - Yuuki Hata
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Toshiki Sawada
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Hiroshi Tanaka
- Department
of Chemical Science and Engineering, School of Materials and Chemical
Technology, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8550, Japan
| | - Motomu Tanaka
- Physical
Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, Heidelberg D69120, Germany
- Center
for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
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2
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Furikado I, Habe T, Inoue S, Tanaka M. Thermodynamics and Viscoelastic Property of Interface Unravel Combined Functions of Cationic Surfactant and Aromatic Alcohol against Gram-Negative Bacteria. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37289662 DOI: 10.1021/acs.langmuir.3c00862] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipopolysaccharides (LPSs), the major constituents of the outer membranes of Gram-negative bacteria, play a key role in protecting bacteria against antibiotics and antibacterial agents. In this study, we investigated how a mixture of cationic surfactants and aromatic alcohols, the base materials of widely used sanitizers, synergistically act on LPSs purified from Escherichia coli using isothermal titration calorimetry (ITC), surface tension measurements, and quartz crystal microbalance with dissipation (QCM-D). ITC data measured in the absence of Ca2+ ions showed the coexistence of exothermic and endothermic processes. The exotherm can be interpreted as the electrostatic binding of the cationic surfactant to the negatively charged LPS membrane surface, whereas the endotherm indicates the hydrophobic interaction between the hydrocarbon chains of the surfactants and LPSs. In the presence of Ca2+ ions, only an exothermic reaction was observed by ITC, and no entropically driven endotherm could be detected. Surface tension experiments further revealed that the co-adsorption of surfactants and LPS was synergistic, while that of surfactants and alcohol was negatively synergistic. Moreover, the QCM-D data indicated that the LPS membrane remained intact when the alcohol alone was added to the system. Intriguingly, the LPS membrane became highly susceptible to the combination of cationic surfactants and aromatic alcohols in the absence of Ca2+ ions. The obtained data provide thermodynamic and mechanical insights into the synergistic function of surfactants and alcohols in sanitation, which will enable the identification of the optimal combination of small molecules for a high hygiene level for the post-pandemic society.
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Affiliation(s)
- Ippei Furikado
- Analytical Science Research Laboratories, Kao Corporation, 1334, Minato, Wakayama-shi, Wakayama 640-8580, Japan
| | - Taichi Habe
- Analytical Science Research Laboratories, Kao Corporation, 1334, Minato, Wakayama-shi, Wakayama 640-8580, Japan
| | - Shigeto Inoue
- Analytical Science Research Laboratories, Kao Corporation, 1334, Minato, Wakayama-shi, Wakayama 640-8580, Japan
| | - Motomu Tanaka
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg University, Heidelberg 69120, Germany
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto 606-8501, Japan
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3
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Castelletto V, Seitsonen J, Hamley IW. Effect of Glycosylation on Self-Assembly of Lipid A Lipopolysaccharides in Aqueous Solutions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023. [PMID: 37289534 DOI: 10.1021/acs.langmuir.3c00828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipopolysaccharides (LPSs) based on lipid A produced by bacteria are of interest due to their bioactivity in stimulating immune responses, as are simpler synthetic components or analogues. Here, the self-assembly in water of two monodisperse lipid A derivatives based on simplified bacterial LPS structures is examined and compared to that of a native Escherichia coli LPS using small-angle X-ray scattering and cryogenic transmission electron microscopy. The critical aggregation concentration is obtained from fluorescence probe experiments, and conformation is probed using circular dichroism spectroscopy. The E. coli LPS is found to form wormlike micelles, whereas the synthetic analogues bearing six lipid chains and with four or two saccharide head groups (Kdo2-lipid A and monophosphoryl lipid A) self-assemble into nanosheets or vesicles, respectively. These observations are rationalized by considering the surfactant packing parameter.
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Affiliation(s)
- Valeria Castelletto
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, U.K
| | - Jani Seitsonen
- Nanomicroscopy Center, Aalto University, Puumiehenkuja 2, Espoo FIN-02150, Finland
| | - Ian W Hamley
- School of Chemistry, Food Biosciences and Pharmacy, University of Reading, Whiteknights, Reading RG6 6AD, U.K
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4
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Madhu M, Krishna Kumar AS, Lu CY, Tseng WL. Peptide-modified carbon dot aggregates for ultrasensitive detection of lipopolysaccharide through aggregation-induced emission enhancement. Talanta 2023; 253:123851. [PMID: 36108518 DOI: 10.1016/j.talanta.2022.123851] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2022] [Revised: 08/06/2022] [Accepted: 08/12/2022] [Indexed: 12/13/2022]
Abstract
This study fabricated yellow-emitting CDs (Y-CDs) by hydrothermal treatment of citric acid and urea and applied them as a fluorescence turn-on platform for sensitive and selective detection of lipopolysaccharide (LPS) based on the non-shifted AIEE of peptide-stabilized CD aggregates. The designed peptide (named K3) consisting of aggregation-active and LPS-recognition units triggered the aggregation of Y-CDs, switching on their fluorescence through the blue-shifted AIEE process. The formed K3-stabilized Y-CD aggregates (K3-YCDAs) specifically interacted with LPS at neutral pH, demonstrating that the sequence of the decorated peptide was highly connected with their selectivity and sensitivity. The K3-YCDAs provided a fast response time (within 5 min) to detect LPS with a quantification range of 0.5-100.0 nM and a limit of detection (LOD, signal-to-noise ratio of 3) of 300.0 pM. By integrating ultrafiltration membranes as a concentration device with K3-YCDAs as a sensing probe, the LOD for LPS was further reduced to 3.0 pM. The determination of picomolar levels of plasma LPS by the K3-YCDAs coupled to the centrifugation ultrafiltration was demonstrated to fall within the specificity range of clinical interest for sepsis patients. Also, the K3-YCDAs served as a fluorescent probe to selectively image and quantify E. coli cells. The distinct advantages of the K3-YCDAs for LPS include fast response time, wide linear range, low detection limit, and excellent selectivity compared to previously reported sensors.
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Affiliation(s)
- Manivannan Madhu
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lienhai Rd., Kaohsiung, 80424, Taiwan
| | - A Santhana Krishna Kumar
- Faculty of Geology, Geophysics and Environmental Protection, AGH University of Science and Technology, Poland
| | - Chi-Yu Lu
- School of Pharmacy, Kaohsiung Medical University, No. 100, Shiquan 1st Road, Sanmin District, Kaohsiung, 80708, Taiwan
| | - Wei-Lung Tseng
- Department of Chemistry, National Sun Yat-sen University, No. 70 Lienhai Rd., Kaohsiung, 80424, Taiwan; School of Pharmacy, College of Pharmacy, Kaohsiung Medical University, No.100, Shiquan 1st Rd., 80708, Kaohsiung, Taiwan.
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5
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Abstract
This review focuses on nonlytic outer membrane vesicles (OMVs), a subtype of bacterial extracellular vesicles (BEVs) produced by Gram-negative organisms focusing on the mechanisms of their biogenesis, cargo, and function. Throughout, we highlight issues concerning the characterization of OMVs and distinguishing them from other types of BEVs. We also highlight the shortcomings of commonly used methodologies for the study of BEVs that impact the interpretation of their functionality and suggest solutions to standardize protocols for OMV studies.
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Affiliation(s)
| | - Simon R. Carding
- Quadram Institute Bioscience, Norwich, United Kingdom
- Norwich Medical School, University of East Anglia, Norwich, United Kingdom
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6
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Stephan MS, Dunsing V, Pramanik S, Chiantia S, Barbirz S, Robinson T, Dimova R. Biomimetic asymmetric bacterial membranes incorporating lipopolysaccharides. Biophys J 2022:S0006-3495(22)03927-3. [PMID: 36523159 DOI: 10.1016/j.bpj.2022.12.017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2022] [Revised: 11/30/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Gram-negative bacteria are equipped with a cell wall that contains a complex matrix of lipids, proteins, and glycans, which form a rigid layer protecting bacteria from the environment. Major components of this outer membrane are the high-molecular weight and amphiphilic lipopolysaccharides (LPSs). They form the extracellular part of a heterobilayer with phospholipids. Understanding LPS properties within the outer membrane is therefore important to develop new antimicrobial strategies. Model systems, such as giant unilamellar vesicles (GUVs), provide a suitable platform for exploring membrane properties and interactions. However, LPS molecules contain large polysaccharide parts that confer high water solubility, which makes LPS incorporation in artificial membranes difficult; this hindrance is exacerbated for LPS with long polysaccharide chains, i.e., the smooth LPS. Here, a novel emulsification step of the inverted emulsion method is introduced to incorporate LPS in the outer or the inner leaflet of GUVs, exclusively. We developed an approach to determine the LPS content on individual GUVs and quantify membrane asymmetry. The asymmetric membranes with outer leaflet LPS show incorporations of 1-16 mol % smooth LPS (corresponding to 16-79 wt %), while vesicles with inner leaflet LPS reach coverages of 2-7 mol % smooth LPS (28-60 wt %). Diffusion coefficient measurements in the obtained GUVs showed that increasing LPS concentrations in the membranes resulted in decreased diffusivity.
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Affiliation(s)
| | - Valentin Dunsing
- Aix-Marseille Université, CNRS, IBDM, Turing Center for Living Systems, Marseille, France; University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Shreya Pramanik
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Salvatore Chiantia
- University of Potsdam, Institute of Biochemistry and Biology, Potsdam, Germany
| | - Stefanie Barbirz
- Department Humanmedizin, MSB Medical School Berlin, Berlin, Germany
| | - Tom Robinson
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
| | - Rumiana Dimova
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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7
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New antimicrobial peptide-antibiotic combination strategy for Pseudomonas aeruginosa inactivation. Biointerphases 2022; 17:041002. [PMID: 35922283 DOI: 10.1116/6.0001981] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Novel antimicrobials or new treatment strategies are urgently needed to treat Pseudomonas aeruginosa (P. aeruginosa) related infections and especially to address the problem of antibiotic resistance. We propose a novel strategy that combines the human antimicrobial peptide (AMP) LL37 with different antibiotics to find synergistic AMP-antibiotic combinations against P. aeruginosa strains in vitro. Our results showed that LL37 exhibited synergistic inhibitory and bactericidal effects against P. aeruginosa strains PAO1 and PA103 when combined with the antibiotics vancomycin, azithromycin, polymyxin B, and colistin. In addition, LL37 caused strong outer membrane permeabilization, as demonstrated through measurement of an increased uptake of the fluorescent probe N-phenyl-1-naphthylamine. The membrane permeabilization effects appear to explain why it was easier to rescue the effectiveness of the antibiotic toward the bacteria because the outer membrane of P. aeruginosa exhibits barrier function for antibiotics. Furthermore, the change in the zeta potential was measured for P. aeruginosa strains with the addition of LL37. Zeta potentials for P. aeruginosa strains PAO1 and PA103 were -40.9 and -10.9 mV, respectively. With the addition of LL37, negative zeta potentials were gradually neutralized. We found that positively charged LL37 can interact with and neutralize the negatively charged bacterial outer membrane through electrostatic interactions, and the process of neutralization is believed to have contributed to the increase in outer membrane permeability. Finally, to further illustrate the relationship between outer membrane permeabilization and the uptake of antibiotics, we used LL37 to make the outer membrane of P. aeruginosa strains more permeable, and minimum inhibitory concentrations (MICs) for several antibiotics (colistin, gentamicin, polymyxin B, vancomycin, and azithromycin) were measured. The MICs decreased were twofold to fourfold, in general. For example, the MICs of azithromycin and vancomycin decreased more than fourfold when against P. aeruginosa strain PAO1, which were the greatest decrease of any of the antibiotics tested in this experiment. As for PA103, the MIC of polymyxin B2 decreased fourfold, which was the strongest decrease seen for any of the antibiotics tested in this experiment. The increased uptake of antibiotics not only demonstrates the barrier role of the outer membrane but also validates the mechanism of synergistic effects that we have proposed. These results indicate the great potential of an LL37-antibiotic combination strategy and provide possible explanations for the mechanisms behind this synergy.
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8
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Sun J, Rutherford ST, Silhavy TJ, Huang KC. Physical properties of the bacterial outer membrane. Nat Rev Microbiol 2022; 20:236-248. [PMID: 34732874 PMCID: PMC8934262 DOI: 10.1038/s41579-021-00638-0] [Citation(s) in RCA: 85] [Impact Index Per Article: 42.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 09/14/2021] [Indexed: 11/09/2022]
Abstract
It has long been appreciated that the Gram-negative outer membrane acts as a permeability barrier, but recent studies have uncovered a more expansive and versatile role for the outer membrane in cellular physiology and viability. Owing to recent developments in microfluidics and microscopy, the structural, rheological and mechanical properties of the outer membrane are becoming apparent across multiple scales. In this Review, we discuss experimental and computational studies that have revealed key molecular factors and interactions that give rise to the spatial organization, limited diffusivity and stress-bearing capacity of the outer membrane. These physical properties suggest broad connections between cellular structure and physiology, and we explore future prospects for further elucidation of the implications of outer membrane construction for cellular fitness and survival.
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Affiliation(s)
- Jiawei Sun
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Steven T. Rutherford
- Department of Infectious Diseases, Genentech Inc., South San Francisco, CA 94080, USA,To whom correspondence should be addressed: , ,
| | - Thomas J. Silhavy
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA,To whom correspondence should be addressed: , ,
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA. .,Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA. .,Chan Zuckerberg Biohub, San Francisco, CA, USA.
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9
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Paracini N, Schneck E, Imberty A, Micciulla S. Lipopolysaccharides at Solid and Liquid Interfaces: Models for Biophysical Studies of the Gram-negative Bacterial Outer Membrane. Adv Colloid Interface Sci 2022; 301:102603. [PMID: 35093846 DOI: 10.1016/j.cis.2022.102603] [Citation(s) in RCA: 22] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Revised: 01/14/2022] [Accepted: 01/15/2022] [Indexed: 11/18/2022]
Abstract
Lipopolysaccharides (LPSs) are a constitutive element of the cell envelope of Gram-negative bacteria, representing the main lipid in the external leaflet of their outer membrane (OM) lipid bilayer. These unique surface-exposed glycolipids play a central role in the interactions of Gram-negative organisms with their surrounding environment and represent a key element for protection against antimicrobials and the development of antibiotic resistance. The biophysical investigation of a wide range of different types of in vitro model membranes containing reconstituted LPS has revealed functional and structural properties of these peculiar membrane lipids, providing molecular-level details of their interaction with antimicrobial compounds. LPS assemblies reconstituted at interfaces represent a versatile tool to study the properties of the Gram-negative OM by exploiting several surface-sensitive techniques, in particular X-ray and neutron scattering, which can probe the structure of thin films with sub-nanometer resolution. This review provides an overview of different approaches employed to investigate structural and biophysical properties of LPS, focusing on studies on Langmuir monolayers of LPS at the air/liquid interface and a range of supported LPS-containing model membranes reconstituted at solid/liquid interfaces.
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Affiliation(s)
| | - Emanuel Schneck
- Physics Departent, Technische Universität Darmstadt, Darmstadt, Germany
| | - Anne Imberty
- Université Grenoble Alpes, CNRS, CERMAV, Grenoble, France
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10
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Acinetobacter baumannii Can Survive with an Outer Membrane Lacking Lipooligosaccharide Due to Structural Support from Elongasome Peptidoglycan Synthesis. mBio 2021; 12:e0309921. [PMID: 34844428 PMCID: PMC8630537 DOI: 10.1128/mbio.03099-21] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Gram-negative bacteria resist external stresses due to cell envelope rigidity, which is provided by two membranes and a peptidoglycan layer. The outer membrane (OM) surface contains lipopolysaccharide (LPS; contains O-antigen) or lipooligosaccharide (LOS). LPS/LOS are essential in most Gram-negative bacteria and may contribute to cellular rigidity. Acinetobacter baumannii is a useful tool for testing these hypotheses as it can survive without LOS. Previously, our group found that strains with naturally high levels of penicillin binding protein 1A (PBP1A) could not become LOS deficient unless the gene encoding it was deleted, highlighting the relevance of peptidoglycan biosynthesis and suggesting that high PBP1A levels were toxic during LOS deficiency. Transposon sequencing and follow-up analysis found that axial peptidoglycan synthesis by the elongasome and a peptidoglycan recycling enzyme, ElsL, were vital in LOS-deficient cells. The toxicity of high PBP1A levels during LOS deficiency was clarified to be due to a negative impact on elongasome function. Our data suggest that during LOS deficiency, the strength of the peptidoglycan specifically imparted by elongasome synthesis becomes essential, supporting that the OM and peptidoglycan contribute to cell rigidity.
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11
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Kutsch M, Coers J. Human guanylate binding proteins: nanomachines orchestrating host defense. FEBS J 2021; 288:5826-5849. [PMID: 33314740 PMCID: PMC8196077 DOI: 10.1111/febs.15662] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2020] [Revised: 11/27/2020] [Accepted: 12/07/2020] [Indexed: 02/06/2023]
Abstract
Disease-causing microorganisms not only breach anatomical barriers and invade tissues but also frequently enter host cells, nutrient-enriched environments amenable to support parasitic microbial growth. Protection from many infectious diseases is therefore reliant on the ability of individual host cells to combat intracellular infections through the execution of cell-autonomous defense programs. Central players in human cell-autonomous immunity are members of the family of dynamin-related guanylate binding proteins (GBPs). The importance of these interferon-inducible GTPases in host defense to viral, bacterial, and protozoan pathogens has been established for some time; only recently, cell biological and biochemical studies that largely focused on the prenylated paralogs GBP1, GBP2, and GBP5 have provided us with robust molecular frameworks for GBP-mediated immunity. Specifically, the recent characterization of GBP1 as a bona fide pattern recognition receptor for bacterial lipopolysaccharide (LPS) disrupting the integrity of bacterial outer membranes through LPS aggregation, the discovery of a link between hydrolysis-induced GMP production by GBP1 and inflammasome activation, and the classification of GBP2 and GBP5 as inhibitors of viral envelope glycoprotein processing via suppression of the host endoprotease furin have paved the way for a vastly improved conceptual understanding of the molecular mechanisms by which GBP nanomachines execute cell-autonomous immunity. The herein discussed models incorporate our current knowledge of the antimicrobial, proinflammatory, and biochemical properties of human GBPs and thereby provide testable hypotheses that will guide future studies into the intricacies of GBP-controlled host defense and their role in human disease.
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Affiliation(s)
- Miriam Kutsch
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 22710, USA
| | - Jörn Coers
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, North Carolina 22710, USA
- Department of Immunology, Duke University Medical Center, Durham, North Carolina 22710, USA
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12
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Jiang X, Sun Y, Yang K, Yuan B, Velkov T, Wang L, Li J. Coarse-grained simulations uncover Gram-negative bacterial defense against polymyxins by the outer membrane. Comput Struct Biotechnol J 2021; 19:3885-3891. [PMID: 34584634 PMCID: PMC8441625 DOI: 10.1016/j.csbj.2021.06.051] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2021] [Revised: 06/29/2021] [Accepted: 06/30/2021] [Indexed: 01/12/2023] Open
Abstract
A structural model of bacterial outer membrane (OM) was developed with Ra LPS. Free energy landscape was revealed for polymyxin interactions with the OM. LPS core sugars and calcium ions confer intrinsic resistance to antibiotics.
The outer membrane (OM) of Gram-negative bacteria is a formidable barrier against antibiotics. Understanding the structure and function of the OM is essential for the discovery of novel membrane-acting agents against multidrug-resistant Gram-negative pathogens. However, it remains challenging to obtain three-dimensional structure of bacterial membranes using crystallographic approaches, which has significantly hindered the elucidation of its interaction with antibiotics. Here, we developed an asymmetric OM model consisting of rough lipopolysaccharide (LPS) and three key types of phospholipids. Using coarse-grained molecular dynamics simulations, we investigated the interaction dynamics of LPS-containing OM with the polymyxins, a last-line class of antibiotics against Gram-negative ‘superbugs’. We discovered that polymyxin molecules spontaneously penetrated the OM core sugar region where most were trapped before entering the lipid A region. Examination of the free energy profile of polymyxin penetration revealed a major free energy barrier at the LPS inner core and lipid A interface. Further analysis revealed calcium ions predominantly distributed in the inner core region and mediated extensive cross-linking interactions between LPS molecules, thereby inhibiting the penetration of polymyxins into the hydrophobic region of the OM. Collectively, our results provide novel mechanistic insights into an intrinsic defense of Gram-negative bacteria to polymyxins and may help identify new antimicrobial targets.
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Affiliation(s)
- Xukai Jiang
- National Glycoengineering Research Center, Shandong University, Qingdao, China.,Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Melbourne, Australia
| | - Yuliang Sun
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou, China
| | - Kai Yang
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou, China
| | - Bing Yuan
- Center for Soft Condensed Matter Physics and Interdisciplinary Research & School of Physical Science and Technology, Soochow University, Suzhou, China
| | - Tony Velkov
- Department of Pharmacology and Therapeutics, The University of Melbourne, Melbourne, Australia
| | - Lushan Wang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Jian Li
- Biomedicine Discovery Institute, Infection & Immunity Program, Department of Microbiology, Monash University, Melbourne, Australia
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13
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Nourbakhsh S, Yu L, Ha BY. Modeling the Protective Role of Bacterial Lipopolysaccharides against Membrane-Rupturing Peptides. J Phys Chem B 2021; 125:8839-8854. [PMID: 34319722 DOI: 10.1021/acs.jpcb.1c02330] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Lipopolysaccharide (LPS) is a key surface component of Gram-negative bacteria, populating the outer layer of their outer membrane. A number of experimental studies highlight its protective role against harmful molecules such as antibiotics and antimicrobial peptides (AMPs). In this work, we present a theoretical model for describing the interaction between LPS and cationic antimicrobial peptides, which combines the following two key features. The polysaccharide part is viewed as forming a polymer brush, exerting an osmotic pressure on inclusions such as antimicrobial peptides. The charged groups on LPS (those in lipid A and the two Kdo groups in the inner core) form electrostatic binding sites for cationic AMPs or cations. Using the resulting model, we offer a quantitative picture of how the brush component enhances the protective role of LPS against magainin-like peptides, in the presence of divalent cations such as Mg2+. The LPS brush tends to diminish the interfacial binding of the peptides, at the lipid headgroup region, by about 30%. In the presence of 5 mM of Mg2+, the interfacial binding does not reach a threshold value for wild-type LPS, beyond which the LPS layer is ruptured, even though it does for LPS Re (the simplest form of LPS, lacking the brush part), as long as [AMP] ≤ 20 μM, where [AMP] is the concentration of AMPs. At a low concentration of Mg2+ (≈1 mM), however, a smaller [AMP] value (≳2 μM) is needed to reach the threshold coverage for wild-type LPS. Our results also suggest that the interfacial binding of peptides is insensitive to their possible weak interaction with the surrounding brush chains.
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Affiliation(s)
- Shokoofeh Nourbakhsh
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Liu Yu
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bae-Yeun Ha
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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14
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Garner EC. Toward a Mechanistic Understanding of Bacterial Rod Shape Formation and Regulation. Annu Rev Cell Dev Biol 2021; 37:1-21. [PMID: 34186006 DOI: 10.1146/annurev-cellbio-010521-010834] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
One of the most common bacterial shapes is a rod, yet we have a limited understanding of how this simple shape is constructed. While only six proteins are required for rod shape, we are just beginning to understand how they self-organize to build the micron-sized enveloping structures that define bacterial shape out of nanometer-sized glycan strains. Here, we detail and summarize the insights gained over the last 20 years into this complex problem that have been achieved with a wide variety of different approaches. We also explain and compare both current and past models of rod shape formation and maintenance and then highlight recent insights into how the Rod complex might be regulated. Expected final online publication date for the Annual Review of Cell and Developmental Biology, Volume 37 is October 2021. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Ethan C Garner
- Department of Molecular and Cellular Biology, Harvard University, Cambridge, Massachusetts, USA;
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15
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Lee C, Dommer AC, Schiffer JM, Amaro RE, Grassian VH, Prather KA. Cation-Driven Lipopolysaccharide Morphological Changes Impact Heterogeneous Reactions of Nitric Acid with Sea Spray Aerosol Particles. J Phys Chem Lett 2021; 12:5023-5029. [PMID: 34024101 DOI: 10.1021/acs.jpclett.1c00810] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Lipopolysaccharides (LPS) in sea spray aerosol (SSA) particles have recently been shown to undergo heterogeneous reactions with HNO3 in the atmosphere. Here, we integrate theory and experiment to further investigate how the most abundant sea salt cations, Na+, Mg2+, and Ca2+, impact HNO3 reactions with LPS-containing SSA particles. Aerosol reaction flow tube studies show that heterogeneous reactions of SSA particles with divalent cation (Mg2+ and Ca2+) and LPS signatures were less reactive with HNO3 than those dominated by monovalent cations (Na+). All-atom molecular dynamics simulations of model LPS aggregates suggest that divalent cations cross-link the oligosaccharide chains to increase molecular aggregation and rigidity, which changes the particle phase and morphology, decreases water diffusion, and consequently decreases the reactive uptake of HNO3. This study provides new insight into how complex chemical interactions between ocean-derived salts and biogenic organic species can impact the heterogeneous reactivity of SSA particles.
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Affiliation(s)
- Christopher Lee
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, United States
| | - Abigail C Dommer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Jamie M Schiffer
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Rommie E Amaro
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Vicki H Grassian
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
| | - Kimberly A Prather
- Scripps Institution of Oceanography, University of California San Diego, La Jolla, California 92037, United States
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, California 92093, United States
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16
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Kutsch M, González-Prieto C, Lesser CF, Coers J. The GBP1 microcapsule interferes with IcsA-dependent septin cage assembly around Shigella flexneri. Pathog Dis 2021; 79:6246431. [PMID: 33885766 DOI: 10.1093/femspd/ftab023] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Accepted: 04/08/2021] [Indexed: 12/20/2022] Open
Abstract
Many cytosolic bacterial pathogens hijack the host actin polymerization machinery to form actin tails that promote direct cell-to-cell spread, enabling these pathogens to avoid extracellular immune defenses. However, these pathogens are still susceptible to intracellular cell-autonomous immune responses that restrict bacterial actin-based motility. Two classes of cytosolic antimotility factors, septins and guanylate-binding proteins (GBPs), have recently been established to block actin tail formation by the human-adapted bacterial pathogen Shigella flexneri. Both septin cages and GBP1 microcapsules restrict S. flexneri cell-to-cell spread by blocking S. flexneri actin-based motility. While septins assemble into cage-like structures around immobile S. flexneri, GBP1 forms microcapsules around both motile and immobile bacteria. The interplay between these two defense programs remains elusive. Here, we demonstrate that GBP1 microcapsules block septin cage assembly, likely by interfering with the function of S. flexneri IcsA, the outer membrane protein that promotes actin-based motility, as this protein is required for septin cage formation. However, S. flexneri that escape from GBP1 microcapsules via the activity of IpaH9.8, a type III secreted effector that promotes the degradation of GBPs, are often captured within septin cages. Thus, our studies reveal how septin cages and GBP1 microcapsules represent complementary host cell antimotility strategies.
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Affiliation(s)
- Miriam Kutsch
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA
| | - Coral González-Prieto
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02115, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Cammie F Lesser
- Center for Bacterial Pathogenesis, Division of Infectious Diseases, Massachusetts General Hospital, Boston, MA 02115, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jörn Coers
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC 27710, USA.,Department of Immunology, Duke University Medical Center, Durham, NC 27710, USA
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17
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Gao L, Tan Y, Zhang W, Qi Q, Lu X. Cytophaga hutchinsonii SprA and SprT Are Essential Components of the Type IX Secretion System Required for Ca 2+ Acquisition, Cellulose Degradation, and Cell Motility. Front Microbiol 2021; 12:628555. [PMID: 33643255 PMCID: PMC7906972 DOI: 10.3389/fmicb.2021.628555] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2020] [Accepted: 01/21/2021] [Indexed: 11/13/2022] Open
Abstract
The type IX secretion system (T9SS) is a novel protein secretion system, which is found in and confined to the phylum Bacteroidetes. T9SS is involved in the secretion of virulence factors, cell surface adhesins, and complex biopolymer degrading enzymes to the cell surface or extracellular medium. Cytophaga hutchinsonii is a widely distributed bacterium, which is able to efficiently digest cellulose and rapidly glide along the solid surfaces. C. hutchinsonii has a full set of orthologs of T9SS components. However, the functions of most homologous proteins have not been verified. In C. hutchinsonii, CHU_0029 and CHU_2709 are similar in sequence to Flavobacterium johnsoniae T9SS components SprA and SprT, respectively. In this study, the single deletion mutants of chu_0029 (sprA) and chu_2709 (sprT) were obtained using a complex medium with the addition of Ca2+ and Mg2+. Single deletion of sprA or sprT resulted in defects in cellulose utilization and gliding motility. Moreover, the ΔsprA and ΔsprT mutants showed growth defects in Ca2+- and Mg2+-deficient media. The results of ICP-MS test showed that both the whole cell and intracellular concentrations of Ca2+ were dramatically reduced in the ΔsprA and ΔsprT mutants, indicating that SprA and SprT are both important for the assimilation of trace amount of Ca2+. While the assimilation of Mg2+ was not obviously influenced in the ΔsprA and ΔsprT mutants. Through proteomics analysis of the cell surface proteins of the wild type and mutants, we found that the ΔsprA and ΔsprT mutants were defective in secretion of the majority of T9SS substrates. Together, these results indicate that SprA and SprT are both essential components of C. hutchinsonii T9SS, which is required for protein secretion, Ca2+ acquisition, cellulose degradation, and gliding motility in C. hutchinsonii. Our study shed more light on the functions of SprA and SprT in T9SS, and further proved the link between the T9SS and Ca2+ uptake system.
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Affiliation(s)
- Lijuan Gao
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Yahong Tan
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Weican Zhang
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Qingsheng Qi
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
| | - Xuemei Lu
- State Key Laboratory of Microbial Technology, Shandong University, Qingdao, China
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18
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Cao P, Wall D. The Fluidity of the Bacterial Outer Membrane Is Species Specific: Bacterial Lifestyles and the Emergence of a Fluid Outer Membrane. Bioessays 2020; 42:e1900246. [PMID: 32363627 PMCID: PMC7392792 DOI: 10.1002/bies.201900246] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Revised: 03/23/2020] [Indexed: 01/17/2023]
Abstract
The outer membrane (OM) is an essential barrier that guards Gram-negative bacteria from diverse environmental insults. Besides functioning as a chemical gatekeeper, the OM also contributes towards the strength and stiffness of cells and allows them to sustain mechanical stress. Largely influenced by studies of Escherichia coli, the OM is viewed as a rigid barrier where OM proteins and lipopolysaccharides display restricted mobility. Here the discussion is extended to other bacterial species, with a focus on Myxococcus xanthus. In contrast to the rigid OM paradigm, myxobacteria possess a relatively fluid OM. It is concluded that the fluidity of the OM varies across environmental species, which is likely linked to their evolution and adaptation to specific ecological niches. Importantly, a fluid OM can endow bacteria with distinct functions for cell-cell and cell-environment interactions.
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Affiliation(s)
| | - Daniel Wall
- Department of Molecular Biology, University of Wyoming, 1000 E University Avenue, Laramie, WY, 82071, USA
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19
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Thoma J, Abuillan W, Furikado I, Habe T, Yamamoto A, Gierlich S, Kaufmann S, Brandenburg K, Gutsmann T, Konovalov O, Inoue S, Tanaka M. Specific localisation of ions in bacterial membranes unravels physical mechanism of effective bacteria killing by sanitiser. Sci Rep 2020; 10:12302. [PMID: 32704045 PMCID: PMC7378190 DOI: 10.1038/s41598-020-69064-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Accepted: 07/06/2020] [Indexed: 12/02/2022] Open
Abstract
Antimicrobial resistance is a major threat to public health. Although many commercial sanitisers contain a combination of cationic surfactants and aromatic alcohols, the physical mechanisms where these two substances bind to or how they disturb bacterial membranes are still largely unknown. In this study, we designed a well-defined model of Gram-negative bacteria surfaces based on the monolayer of lipopolysaccharides with uniform saccharide head groups. Since commonly used X-ray reflectivity is sensitive to changes in the thickness, roughness and electron density but is not sensitive to elements, we employed grazing incidence X-ray fluorescence. In the absence of Ca2+, cationic surfactants can penetrate into the membrane core with no extra support by disturbing the layer of K+ coupled to negatively charged saccharide head group at z = 17 Å from the air/chain interface. On the other hand, Ca2+ confined at z = 19 Å crosslink charged saccharides and prevent the incorporation of cationic surfactants. We found that the addition of nonlethal aromatic alcohols facilitate the incorporation of cationic surfactants by the significant roughening of the chain/saccharide interface. Combination of precise localisation of ions and molecular-level structural analysis quantitatively demonstrated the synegtestic interplay of ingredients to achieve a high antibacterial activity.
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Affiliation(s)
- Judith Thoma
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120, Heidelberg, Germany
| | - Wasim Abuillan
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120, Heidelberg, Germany.
| | - Ippei Furikado
- Analytical Science Research Laboratories, Kao Corporation, 1334 Minato, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Taichi Habe
- Analytical Science Research Laboratories, Kao Corporation, 1334 Minato, Wakayama, Wakayama Prefecture, 640-8580, Japan
| | - Akihisa Yamamoto
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto, 606-8501, Japan
| | - Simone Gierlich
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120, Heidelberg, Germany
| | - Stefan Kaufmann
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120, Heidelberg, Germany
| | - Klaus Brandenburg
- Research Center Borstel, Leibniz Lung Center, 23845, Borstel, Germany.,Brandenburg Antiinfektiva GmbH, 23845, Borstel, Germany
| | - Thomas Gutsmann
- Research Center Borstel, Leibniz Lung Center, 23845, Borstel, Germany
| | - Oleg Konovalov
- European Synchrotron Radiation Facility (ESRF), 38043, Grenoble, France
| | - Shigeto Inoue
- Analytical Science Research Laboratories, Kao Corporation, 1334 Minato, Wakayama, Wakayama Prefecture, 640-8580, Japan.
| | - Motomu Tanaka
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, University of Heidelberg, 69120, Heidelberg, Germany. .,Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto, 606-8501, Japan.
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20
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Kutsch M, Sistemich L, Lesser CF, Goldberg MB, Herrmann C, Coers J. Direct binding of polymeric GBP1 to LPS disrupts bacterial cell envelope functions. EMBO J 2020; 39:e104926. [PMID: 32510692 PMCID: PMC7327485 DOI: 10.15252/embj.2020104926] [Citation(s) in RCA: 84] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 04/27/2020] [Accepted: 04/29/2020] [Indexed: 12/13/2022] Open
Abstract
In the outer membrane of gram‐negative bacteria, O‐antigen segments of lipopolysaccharide (LPS) form a chemomechanical barrier, whereas lipid A moieties anchor LPS molecules. Upon infection, human guanylate binding protein‐1 (hGBP1) colocalizes with intracellular gram‐negative bacterial pathogens, facilitates bacterial killing, promotes activation of the lipid A sensor caspase‐4, and blocks actin‐driven dissemination of the enteric pathogen Shigella. The underlying molecular mechanism for hGBP1's diverse antimicrobial functions is unknown. Here, we demonstrate that hGBP1 binds directly to LPS and induces “detergent‐like” LPS clustering through protein polymerization. Binding of polymerizing hGBP1 to the bacterial surface disrupts the O‐antigen barrier, thereby unmasking lipid A, eliciting caspase‐4 recruitment, enhancing antibacterial activity of polymyxin B, and blocking the function of the Shigella outer membrane actin motility factor IcsA. These findings characterize hGBP1 as an LPS‐binding surfactant that destabilizes the rigidity of the outer membrane to exert pleiotropic effects on the functionality of gram‐negative bacterial cell envelopes.
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Affiliation(s)
- Miriam Kutsch
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA
| | - Linda Sistemich
- Department of Physical Chemistry I, Ruhr-University Bochum, Bochum, Germany
| | - Cammie F Lesser
- Division of Infectious Diseases, Center for Bacterial Pathogenesis, Massachusetts General Hospital, Boston, MA, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Marcia B Goldberg
- Division of Infectious Diseases, Center for Bacterial Pathogenesis, Massachusetts General Hospital, Boston, MA, USA.,Department of Microbiology, Blavatnik Institute, Harvard Medical School, Boston, MA, USA
| | - Christian Herrmann
- Department of Physical Chemistry I, Ruhr-University Bochum, Bochum, Germany
| | - Jörn Coers
- Department of Molecular Genetics and Microbiology, Duke University Medical Center, Durham, NC, USA.,Department of Immunology, Duke University Medical Center, Durham, NC, USA
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21
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Rahnamoun A, Kim K, Pedersen JA, Hernandez R. Ionic Environment Affects Bacterial Lipopolysaccharide Packing and Function. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:3149-3158. [PMID: 32069057 DOI: 10.1021/acs.langmuir.9b03162] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The interaction of lipopolysaccharides (LPS) with metal cations strongly affects the stability and function of the Gram-negative bacterial outer membrane. The sensitivity of deep rough (Re) LPS packing and function to the ionic environment, as affected by cation valency and ionic radius, has been determined using molecular dynamics simulations and Langmuir balance experiments. The degree of LPS aggregation within the LPS models in the presence of different cations is assessed by measuring the effective mean molecular area (Âm) of each LPS molecule projected onto the interfacial plane at the end of the equilibration. These results are compared to the LPS mean molecular area from experimental measurements in which the LPS monolayers are assembled at the air-water interface using a Langmuir film balance. We found that packing of the LPS arrays is sensitive to the ionic radius and ion valency of the cations present in solution during LPS array packing. Using enhanced sampling of the free energy for the intercalation of oligo(allylamine HCl) (OAH) into deep rough Salmonella enterica LPS bilayers, we obtained the affinity of the core section of LPS to OAH as a function of the nature of the metal cations present in solution. We found that packing of the solvated LPS bilayer models is sensitive to ionic radius and ion valency of the neutralizing cations. This further suggests that ion bridging and steric barriers rather than charge shielding are important factors in mitigating ligand intercalation under conditions with low ionic concentrations.
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Affiliation(s)
- Ali Rahnamoun
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Kyoungtea Kim
- Molecular and Environmental Toxicology Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Joel A Pedersen
- Molecular and Environmental Toxicology Program, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
- Departments of Soil Science, Chemistry, Civil & Environmental Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706, United States
| | - Rigoberto Hernandez
- Department of Chemistry, Johns Hopkins University, Baltimore, Maryland 21218, United States
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22
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Rojas ER. The Mechanical Properties of Bacteria and Why they Matter. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2020; 1267:1-14. [PMID: 32894474 DOI: 10.1007/978-3-030-46886-6_1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
I review recent techniques to measure the mechanical properties of bacterial cells and their subcellular components, and then discuss what these techniques have revealed about the constitutive mechanical properties of whole bacterial cells and subcellular material, as well as the molecular basis for these properties.
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Affiliation(s)
- Enrique R Rojas
- Department of Biology, New York University, New York, NY, USA.
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23
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Redeker C, Briscoe WH. Interactions between Mutant Bacterial Lipopolysaccharide (LPS-Ra) Surface Layers: Surface Vesicles, Membrane Fusion, and Effect of Ca 2+and Temperature. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2019; 35:15739-15750. [PMID: 31604373 DOI: 10.1021/acs.langmuir.9b02609] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Lipopolysaccharides (LPS) are a major component of the protective outer membrane of Gram-negative bacteria. Understanding how the solution conditions may affect LPS-containing membranes is important to optimizing the design of antibacterial agents (ABAs) which exploit electrostatic and hydrophobic interactions to disrupt the bacteria membrane. Here, interactions between surface layers of LPS (Ra mutants) in aqueous media have been studied using a surface force apparatus (SFA), exploring the effects of temperature and divalent Ca2+ cations. Complementary dynamic light scattering (DLS) characterization suggests that vesicle-like aggregates of diameter ∼28-80 nm are formed by LPS-Ra in aqueous media. SFA results show that LPS-Ra vesicles adsorb weakly onto mica in pure water at room temperature (RT) and the surface layers are readily squeezed out as the two surfaces approach each other. However, upon addition of calcium (Ca2+) cations at near physiological concentration (2.5 mM) at RT, LPS multilayers or deformed LPS liposomes on mica are observed, presumably due to bridging between LPS phosphate groups and between LPS phosphates and negatively charged mica mediated by Ca2+, with a hard wall repulsion at surface separation D0 ∼ 30-40 nm. At 40 °C, which is above the LPS-Ra β-α acyl chain melting temperature (Tm = 36 °C), fusion events between the surface layers under compression could be observed, evident from δD ∼ 8-10 nm steps in the force-distance profiles attributed to LPS-bilayers being squeezed out due to enhanced fluidity of the LPS acyl-chain, with a final hard wall surface separation D0 ∼ 8-10 nm corresponding to the thickness of a single bilayer confined between the surfaces. These unprecedented SFA results reveal intricate structural responses of LPS surface layers to temperature and Ca2+, with implications to our fundamental understanding of the structures and interactions of bacterial membranes.
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Affiliation(s)
- Christian Redeker
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
| | - Wuge H Briscoe
- School of Chemistry , University of Bristol , Cantock's Close, Bristol BS8 1TS , United Kingdom
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24
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Lakey JH. Recent advances in neutron reflectivity studies of biological membranes. Curr Opin Colloid Interface Sci 2019. [DOI: 10.1016/j.cocis.2019.02.012] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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25
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Rodriguez-Loureiro I, Latza VM, Fragneto G, Schneck E. Conformation of Single and Interacting Lipopolysaccharide Surfaces Bearing O-Side Chains. Biophys J 2019; 114:1624-1635. [PMID: 29642032 DOI: 10.1016/j.bpj.2018.02.014] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2017] [Revised: 02/08/2018] [Accepted: 02/13/2018] [Indexed: 10/17/2022] Open
Abstract
The outer surfaces of Gram-negative bacteria are composed of lipopolysaccharide (LPS) molecules exposing oligo- and polysaccharides to the aqueous environment. This unique, structurally complex biological interface is of great scientific interest as it mediates the interaction of bacteria with antimicrobial agents as well as with neighboring bacteria in colonies and biofilms. Structural studies on LPS surfaces, however, have so far dealt almost exclusively with rough mutant LPS of reduced molecular complexity and limited biological relevance. Here, by using neutron reflectometry, we structurally characterize planar monolayers of wild-type LPS from Escherichia coli O55:B5 featuring strain-specific O-side chains in the presence and absence of divalent cations and under controlled interaction conditions. The model used for the reflectivity analysis is self-consistent and based on the volume fraction profiles of all chemical components. The saccharide profiles are found to be bimodal, with dense inner oligosaccharides and more dilute, extended O-side chains. For interacting LPS monolayers, we establish the pressure-distance curve and determine the distance-dependent saccharide conformation.
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Affiliation(s)
| | - Victoria M Latza
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | - Giovanna Fragneto
- Large Scale Structures (LSS) Group, Institut Laue-Langevin, Grenoble, France
| | - Emanuel Schneck
- Biomaterials Department, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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26
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Micciulla S, Gerelli Y, Schneck E. Structure and Conformation of Wild-Type Bacterial Lipopolysaccharide Layers at Air-Water Interfaces. Biophys J 2019; 116:1259-1269. [PMID: 30878200 DOI: 10.1016/j.bpj.2019.02.020] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2018] [Revised: 02/13/2019] [Accepted: 02/21/2019] [Indexed: 10/27/2022] Open
Abstract
The outer membrane of Gram-negative bacteria is of great scientific interest because it mediates the action of antimicrobial agents. The membrane surface is composed of lipopolysaccharide (LPS) molecules with negatively charged oligosaccharide headgroups. To a certain fraction, LPSs additionally display linear polysaccharides termed O-side chains (OSCs). Structural studies on bacterial outer surfaces models, based on LPS monolayers at air-water interfaces, have so far dealt only with rough mutant LPSs lacking these OSCs. Here, we characterize monolayers of wild-type LPS from Escherichia coli O55:B5 featuring strain-specific OSCs in the presence of defined concentrations of monovalent and divalent ions. Pressure-area isotherms yield insight into in-plane molecular interactions and monolayer elastic moduli. Structural investigations by x-ray and neutron reflectometry reveal the saccharide conformation and allow quantifying the area per molecule and the fraction of LPS molecules carrying OSCs. The OSC conformation is satisfactorily described by the self-consistent field theory for end-grafted polymer brushes. The monolayers exhibit a significant structural response to divalent cations, which goes beyond generic electrostatic screening.
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Affiliation(s)
- Samantha Micciulla
- Institut Laue-Langevin, Grenoble, France; Max Planck Institute of Colloids and Interfaces, Potsdam, Germany
| | | | - Emanuel Schneck
- Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
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27
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Han K, Luo D, Zou Y, Dong S, Wan Z, Yang X. Modulation of Gut Microbiota by Soybean 7S Globulin Peptide That Involved Lipopolysaccharide-Peptide Interaction. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY 2019; 67:2201-2211. [PMID: 30719912 DOI: 10.1021/acs.jafc.8b07109] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Soybean protein exhibits nutritional significance for the control of metabolic syndrome, and evidence suggests that gut microbiota are implicated in the control of metabolic disorders. This study aimed to investigate the modulation of pepsin-released peptides of soybean 7S globulin on gut microbiota and possible association between changes of gut microbiota composition and lipopolysaccharide (LPS)-peptide interaction. In vitro fermentation experiments showed that the extension region (ER) fragments of soybean 7S globulin selectively suppressed proinflammatory Gram-negative bacteria. ER peptides also promoted the highest production of short-chain fatty acids (SCFAs), which were associated with increase of the relative abundance of Lachnospiraceae and Lactobacillaceae. Isothermal titration calorimetry (ITC) and Langmuir monolayer studies demonstrated that ER peptides exhibited high affinity to LPS in the presence of Ca2+ and developed into β-sheet-rich aggregate structures, thus weakening the stability of LPS monolayers. This finding supplies a possible explanation for improvement of the effects of soybean 7S globulin on metabolic disease.
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Affiliation(s)
- Kaining Han
- Research and Development Center of Food Proteins, Department of Food Science and Technology , South China University of Technology , Guangzhou 510640 , China
| | - Danyang Luo
- Research and Development Center of Food Proteins, Department of Food Science and Technology , South China University of Technology , Guangzhou 510640 , China
| | - Yuan Zou
- Department of Bioengineering, College of Food Science , South China Agricultural University , Guangzhou 510640 , China
| | - Shiyuan Dong
- College of Food Science and Engineering , Ocean University of China , Qingdao 266003 , China
| | - Zhili Wan
- Research and Development Center of Food Proteins, Department of Food Science and Technology , South China University of Technology , Guangzhou 510640 , China
| | - Xiaoquan Yang
- Research and Development Center of Food Proteins, Department of Food Science and Technology , South China University of Technology , Guangzhou 510640 , China
- Guangdong Province Key Laboratory for Green Processing of Natural Products and Product Safety , Guangzhou 510640 , China
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28
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Distribution of mechanical stress in the Escherichia coli cell envelope. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2018; 1860:2566-2575. [PMID: 30278180 DOI: 10.1016/j.bbamem.2018.09.020] [Citation(s) in RCA: 54] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/23/2018] [Revised: 09/14/2018] [Accepted: 09/26/2018] [Indexed: 01/05/2023]
Abstract
The cell envelope in Gram-negative bacteria comprises two distinct membranes with a cell wall between them. There has been a growing interest in understanding the mechanical adaptation of this cell envelope to the osmotic pressure (or turgor pressure), which is generated by the difference in the concentration of solutes between the cytoplasm and the external environment. However, it remains unexplored how the cell wall, the inner membrane (IM), and the outer membrane (OM) effectively protect the cell from this pressure by bearing the resulting surface tension, thus preventing the formation of inner membrane bulges, abnormal cell morphology, spheroplasts and cell lysis. In this study, we have used molecular dynamics (MD) simulations combined with experiments to resolve how and to what extent models of the IM, OM, and cell wall respond to changes in surface tension. We calculated the area compressibility modulus of all three components in simulations from tension-area isotherms. Experiments on monolayers mimicking individual leaflets of the IM and OM were also used to characterize their compressibility. While the membranes become softer as they expand, the cell wall exhibits significant strain stiffening at moderate to high tensions. We integrate these results into a model of the cell envelope in which the OM and cell wall share the tension at low turgor pressure (0.3 atm) but the tension in the cell wall dominates at high values (>1 atm).
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Liquid crystalline bacterial outer membranes are critical for antibiotic susceptibility. Proc Natl Acad Sci U S A 2018; 115:E7587-E7594. [PMID: 30037998 DOI: 10.1073/pnas.1803975115] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The outer membrane (OM) of Gram-negative bacteria is a robust, impermeable, asymmetric bilayer of outer lipopolysaccharides (LPSs) and inner phospholipids containing selective pore proteins which confer on it the properties of a molecular sieve. This structure severely limits the variety of antibiotic molecules effective against Gram-negative pathogens and, as antibiotic resistance has increased, so has the need to solve the OM permeability problem. Polymyxin B (PmB) represents those rare antibiotics which act directly on the OM and which offer a distinct starting point for new antibiotic development. Here we investigate PmB's interactions with in vitro OM models and show how the physical state of the lipid matrix of the OM is a critical factor in regulating the interaction with the antimicrobial peptide. Using neutron reflectometry and infrared spectroscopy, we reveal the structural and chemical changes induced by PmB on OM models of increasing complexity. In particular, only a tightly packed model reproduced the temperature-controlled disruption of the asymmetric lipid bilayer by PmB observed in vivo. By measuring the order of outer-leaflet LPS and inner-leaflet phospholipids, we show that PmB insertion is dependent on the phase transition of LPS from the gel to the liquid crystalline state. The demonstration of a lipid phase transition in the physiological temperature range also supports the hypothesis that bacteria grown at different temperatures adapt their LPS structures to maintain a homeoviscous OM.
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Rojas ER, Billings G, Odermatt PD, Auer GK, Zhu L, Miguel A, Chang F, Weibel DB, Theriot JA, Huang KC. The outer membrane is an essential load-bearing element in Gram-negative bacteria. Nature 2018; 559:617-621. [PMID: 30022160 PMCID: PMC6089221 DOI: 10.1038/s41586-018-0344-3] [Citation(s) in RCA: 317] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2016] [Accepted: 06/05/2018] [Indexed: 12/24/2022]
Abstract
Gram-negative bacteria possess a complex cell envelope that consists of a plasma membrane, a peptidoglycan cell wall and an outer membrane. The envelope is a selective chemical barrier1 that defines cell shape2 and allows the cell to sustain large mechanical loads such as turgor pressure3. It is widely believed that the covalently cross-linked cell wall underpins the mechanical properties of the envelope4,5. Here we show that the stiffness and strength of Escherichia coli cells are largely due to the outer membrane. Compromising the outer membrane, either chemically or genetically, greatly increased deformation of the cell envelope in response to stretching, bending and indentation forces, and induced increased levels of cell lysis upon mechanical perturbation and during L-form proliferation. Both lipopolysaccharides and proteins contributed to the stiffness of the outer membrane. These findings overturn the prevailing dogma that the cell wall is the dominant mechanical element within Gram-negative bacteria, instead demonstrating that the outer membrane can be stiffer than the cell wall, and that mechanical loads are often balanced between these structures.
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Affiliation(s)
- Enrique R Rojas
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
| | | | - Pascal D Odermatt
- Department of Bioengineering, Stanford University, Stanford, CA, USA
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, CA, USA
| | - George K Auer
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
| | - Lillian Zhu
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Amanda Miguel
- Department of Bioengineering, Stanford University, Stanford, CA, USA
| | - Fred Chang
- Department of Cell and Tissue Biology, University of California San Francisco, San Francisco, CA, USA
| | - Douglas B Weibel
- Department of Biomedical Engineering, University of Wisconsin-Madison, Madison, WI, USA
- Department of Biochemistry, University of Wisconsin-Madison, Madison, WI, USA
- Department of Chemistry, University of Wisconsin-Madison, Madison, WI, USA
| | - Julie A Theriot
- Department of Biochemistry, Stanford University School of Medicine, Stanford, CA, USA
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA
- Howard Hughes Medical Institute, Stanford, CA, USA
- Biophysics Program, Stanford University, Stanford, CA, USA
| | - Kerwyn Casey Huang
- Department of Bioengineering, Stanford University, Stanford, CA, USA.
- Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, CA, USA.
- Biophysics Program, Stanford University, Stanford, CA, USA.
- Chan Zuckerberg Biohub, San Francisco, CA, USA.
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Reich J, Tamura H, Nagaoka I, Motschmann H. Investigation of the kinetics and mechanism of low endotoxin recovery in a matrix for biopharmaceutical drug products. Biologicals 2018; 53:1-9. [DOI: 10.1016/j.biologicals.2018.04.001] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2016] [Revised: 04/06/2018] [Accepted: 04/09/2018] [Indexed: 11/24/2022] Open
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Antibiotic Hybrids: the Next Generation of Agents and Adjuvants against Gram-Negative Pathogens? Clin Microbiol Rev 2018. [PMID: 29540434 DOI: 10.1128/cmr.00077-17] [Citation(s) in RCA: 171] [Impact Index Per Article: 28.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022] Open
Abstract
The global incidence of drug-resistant Gram-negative bacillary infections has been increasing, and there is a dire need to develop novel strategies to overcome this problem. Intrinsic resistance in Gram-negative bacteria, such as their protective outer membrane and constitutively overexpressed efflux pumps, is a major survival weapon that renders them refractory to current antibiotics. Several potential avenues to overcome this problem have been at the heart of antibiotic drug discovery in the past few decades. We review some of these strategies, with emphasis on antibiotic hybrids either as stand-alone antibacterial agents or as adjuvants that potentiate a primary antibiotic in Gram-negative bacteria. Antibiotic hybrid is defined in this review as a synthetic construct of two or more pharmacophores belonging to an established agent known to elicit a desired antimicrobial effect. The concepts, advances, and challenges of antibiotic hybrids are elaborated in this article. Moreover, we discuss several antibiotic hybrids that were or are in clinical evaluation. Mechanistic insights into how tobramycin-based antibiotic hybrids are able to potentiate legacy antibiotics in multidrug-resistant Gram-negative bacilli are also highlighted. Antibiotic hybrids indeed have a promising future as a therapeutic strategy to overcome drug resistance in Gram-negative pathogens and/or expand the usefulness of our current antibiotic arsenal.
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Mielke S, Habe T, Veschgini M, Liu X, Yoshikawa K, Krafft MP, Tanaka M. Emergence of Strong Nonlinear Viscoelastic Response of Semifluorinated Alkane Monolayers. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2018; 34:2489-2496. [PMID: 29359940 DOI: 10.1021/acs.langmuir.7b03997] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
Viscoelasticity of monolayers of fluorocarbon/hydrocarbon tetrablock amphiphiles di(FnHm) ((CnF2n+1CH2)(Cm-2H2m-3)CH-CH(CnF2n+1CH2)(Cm-2H2m-3)) was characterized by interfacial dilational rheology under periodic oscillation of the moving barriers at the air/water interface. Because the frequency dispersion of the response function indicated that di(FnHm) form two-dimensional gels at the interface, the viscosity and elasticity of di(FnHm) were first analyzed with the classical Kelvin-Voigt model. However, the global shape of stress response functions clearly indicated the emergence of a nonlinearity even at very low surface pressures (π ≈ 5 mN/m) and small strain amplitudes (u0 = 1%). The Fourier-transformed response function of higher harmonics exhibited a clear increase in the intensity only from odd modes, corresponding to the nonlinear elastic component under reflection because of mirror symmetry. The emergence of strong nonlinear viscoelasticity of di(FnHm) at low surface pressures and strain amplitudes is highly unique compared to the nonlinear viscoelasticity of other surfactant systems reported previously, suggesting a large potential of such fluorocarbon/hydrocarbon molecules to modulate the mechanics of interfaces using the self-assembled domains of small molecules.
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Affiliation(s)
- Salomé Mielke
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Taichi Habe
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Mariam Veschgini
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
| | - Xianhe Liu
- Institut Charles Sadron (CNRS), University of Strasbourg , 67034 Strasbourg, France
| | - Kenichi Yoshikawa
- Faculty of Life and Medical Sciences, Doshisha University , 610-0321 Kyotanabe, Japan
| | - Marie Pierre Krafft
- Institut Charles Sadron (CNRS), University of Strasbourg , 67034 Strasbourg, France
| | - Motomu Tanaka
- Institute of Physical Chemistry, University of Heidelberg , 69120 Heidelberg, Germany
- Institute for Advanced Study, Kyoto University , 606-8501 Kyoto, Japan
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Smart M, Rajagopal A, Liu WK, Ha BY. Opposing effects of cationic antimicrobial peptides and divalent cations on bacterial lipopolysaccharides. Phys Rev E 2017; 96:042405. [PMID: 29347628 DOI: 10.1103/physreve.96.042405] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2017] [Indexed: 12/15/2022]
Abstract
The permeability of the bacterial outer membrane, enclosing Gram-negative bacteria, depends on the interactions of the outer, lipopolysaccharide (LPS) layer, with surrounding ions and molecules. We present a coarse-grained model for describing how cationic amphiphilic molecules (e.g., antimicrobial peptides) interact with and perturb the LPS layer in a biologically relevant medium, containing monovalent and divalent salt ions (e.g., Mg^{2+}). In our approach, peptide binding is driven by electrostatic and hydrophobic interactions and is assumed to expand the LPS layer, eventually priming it for disruption. Our results suggest that in parameter ranges of biological relevance (e.g., at micromolar concentrations) the antimicrobial peptide magainin 2 effectively disrupts the LPS layer, even though it has to compete with Mg^{2+} for the layer. They also show how the integrity of LPS is restored with an increasing concentration of Mg^{2+}. Using the approach, we make a number of predictions relevant for optimizing peptide parameters against Gram-negative bacteria and for understanding bacterial strategies to develop resistance against cationic peptides.
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Affiliation(s)
- Matthew Smart
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Aruna Rajagopal
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Wing-Ki Liu
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Bae-Yeun Ha
- Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
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Veschgini M, Habe T, Mielke S, Inoue S, Liu X, Krafft MP, Tanaka M. Existence of Two‐Dimensional Physical Gels even at Zero Surface Pressure at the Air/Water Interface: Rheology of Self‐Assembled Domains of Small Molecules. Angew Chem Int Ed Engl 2017; 56:12603-12607. [DOI: 10.1002/anie.201707009] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 08/09/2017] [Indexed: 11/09/2022]
Affiliation(s)
- Mariam Veschgini
- Physical Chemistry of Biosystems Heidelberg University Im Neuenheimer Feld 253 69120 Heidelberg Germany
| | - Taichi Habe
- Physical Chemistry of Biosystems Heidelberg University Im Neuenheimer Feld 253 69120 Heidelberg Germany
| | - Salomé Mielke
- Physical Chemistry of Biosystems Heidelberg University Im Neuenheimer Feld 253 69120 Heidelberg Germany
| | - Shigeto Inoue
- Physical Chemistry of Biosystems Heidelberg University Im Neuenheimer Feld 253 69120 Heidelberg Germany
| | - Xianhe Liu
- Institut Charles Sadron (CNRS) University of Strasbourg 23, rue du Loess 67034 Strasbourg France
| | - Marie Pierre Krafft
- Institut Charles Sadron (CNRS) University of Strasbourg 23, rue du Loess 67034 Strasbourg France
| | - Motomu Tanaka
- Physical Chemistry of Biosystems Heidelberg University Im Neuenheimer Feld 253 69120 Heidelberg Germany
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Existence of Two‐Dimensional Physical Gels even at Zero Surface Pressure at the Air/Water Interface: Rheology of Self‐Assembled Domains of Small Molecules. Angew Chem Int Ed Engl 2017. [DOI: 10.1002/ange.201707009] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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37
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Abstract
Cellular mechanical properties play an integral role in bacterial survival and adaptation. Historically, the bacterial cell wall and, in particular, the layer of polymeric material called the peptidoglycan were the elements to which cell mechanics could be primarily attributed. Disrupting the biochemical machinery that assembles the peptidoglycan (e.g., using the β-lactam family of antibiotics) alters the structure of this material, leads to mechanical defects, and results in cell lysis. Decades after the discovery of peptidoglycan-synthesizing enzymes, the mechanisms that underlie their positioning and regulation are still not entirely understood. In addition, recent evidence suggests a diverse group of other biochemical elements influence bacterial cell mechanics, may be regulated by new cellular mechanisms, and may be triggered in different environmental contexts to enable cell adaptation and survival. This review summarizes the contributions that different biomolecular components of the cell wall (e.g., lipopolysaccharides, wall and lipoteichoic acids, lipid bilayers, peptidoglycan, and proteins) make to Gram-negative and Gram-positive bacterial cell mechanics. We discuss the contribution of individual proteins and macromolecular complexes in cell mechanics and the tools that make it possible to quantitatively decipher the biochemical machinery that contributes to bacterial cell mechanics. Advances in this area may provide insight into new biology and influence the development of antibacterial chemotherapies.
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Affiliation(s)
- George K Auer
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
| | - Douglas B Weibel
- Department of Biomedical Engineering, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Biochemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States.,Department of Chemistry, University of Wisconsin-Madison , Madison, Wisconsin 53706, United States
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Higaki Y, Fröhlich B, Yamamoto A, Murakami R, Kaneko M, Takahara A, Tanaka M. Ion-Specific Modulation of Interfacial Interaction Potentials between Solid Substrates and Cell-Sized Particles Mediated via Zwitterionic, Super-Hydrophilic Poly(sulfobetaine) Brushes. J Phys Chem B 2017; 121:1396-1404. [DOI: 10.1021/acs.jpcb.6b11540] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Yuji Higaki
- Institute
for Materials Chemistry and Engineering, Kyushu University, 744
Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International
Institute for Carbon-Neutral Energy Research (WPI I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Benjamin Fröhlich
- Physical
Chemistry of Biosystems, University of Heidelberg, D69120 Heidelberg, Germany
| | - Akihisa Yamamoto
- Institute
for Integrated Cell-Material Sciences (WPI iCeMS), Kyoto University 606-8501 Kyoto, Japan
| | - Ryo Murakami
- Department
of Mechanical Engineering, Osaka University, 565-0871 Suita, Japan
| | - Makoto Kaneko
- Department
of Mechanical Engineering, Osaka University, 565-0871 Suita, Japan
| | - Atsushi Takahara
- Institute
for Materials Chemistry and Engineering, Kyushu University, 744
Motooka, Nishi-ku, Fukuoka 819-0395, Japan
- International
Institute for Carbon-Neutral Energy Research (WPI I2CNER), Kyushu University, 744 Motooka, Nishi-ku, Fukuoka 819-0395, Japan
| | - Motomu Tanaka
- Physical
Chemistry of Biosystems, University of Heidelberg, D69120 Heidelberg, Germany
- Institute
for Integrated Cell-Material Sciences (WPI iCeMS), Kyoto University 606-8501 Kyoto, Japan
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Santiago-Morales J, Amariei G, Letón P, Rosal R. Antimicrobial activity of poly(vinyl alcohol)-poly(acrylic acid) electrospun nanofibers. Colloids Surf B Biointerfaces 2016; 146:144-51. [DOI: 10.1016/j.colsurfb.2016.04.052] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Revised: 04/05/2016] [Accepted: 04/30/2016] [Indexed: 11/28/2022]
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40
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Molecular mechanisms of membrane targeting antibiotics. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2016; 1858:980-7. [DOI: 10.1016/j.bbamem.2015.10.018] [Citation(s) in RCA: 270] [Impact Index Per Article: 33.8] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/21/2015] [Revised: 10/07/2015] [Accepted: 10/23/2015] [Indexed: 01/17/2023]
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