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Otto SB, Servajean R, Lemopoulos A, Bitbol AF, Blokesch M. Interactions between pili affect the outcome of bacterial competition driven by the type VI secretion system. Curr Biol 2024; 34:2403-2417.e9. [PMID: 38749426 DOI: 10.1016/j.cub.2024.04.041] [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: 10/26/2023] [Revised: 04/09/2024] [Accepted: 04/22/2024] [Indexed: 06/06/2024]
Abstract
The bacterial type VI secretion system (T6SS) is a widespread, kin-discriminatory weapon capable of shaping microbial communities. Due to the system's dependency on contact, cellular interactions can lead to either competition or kin protection. Cell-to-cell contact is often accomplished via surface-exposed type IV pili (T4Ps). In Vibrio cholerae, these T4Ps facilitate specific interactions when the bacteria colonize natural chitinous surfaces. However, it has remained unclear whether and, if so, how these interactions affect the bacterium's T6SS-mediated killing. In this study, we demonstrate that pilus-mediated interactions can be harnessed by T6SS-equipped V. cholerae to kill non-kin cells under liquid growth conditions. We also show that the naturally occurring diversity of pili determines the likelihood of cell-to-cell contact and, consequently, the extent of T6SS-mediated competition. To determine the factors that enable or hinder the T6SS's targeted reduction of competitors carrying pili, we developed a physics-grounded computational model for autoaggregation. Collectively, our research demonstrates that T4Ps involved in cell-to-cell contact can impose a selective burden when V. cholerae encounters non-kin cells that possess an active T6SS. Additionally, our study underscores the significance of T4P diversity in protecting closely related individuals from T6SS attacks through autoaggregation and spatial segregation.
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Affiliation(s)
- Simon B Otto
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Richard Servajean
- Laboratory of Computational Biology and Theoretical Biophysics, Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Alexandre Lemopoulos
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland
| | - Anne-Florence Bitbol
- Laboratory of Computational Biology and Theoretical Biophysics, Institute of Bioengineering, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland; SIB Swiss Institute of Bioinformatics, 1015 Lausanne, Switzerland
| | - Melanie Blokesch
- Laboratory of Molecular Microbiology, Global Health Institute, School of Life Sciences, École Polytechnique Fédérale de Lausanne (EPFL), 1015 Lausanne, Switzerland.
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2
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Hong Y, Qin J, Totsika M. A conditional nature for the synthetical lethality between defects in lipid and peptidoglycan biosynthesis. Proc Natl Acad Sci U S A 2023; 120:e2318882120. [PMID: 38109534 PMCID: PMC10756204 DOI: 10.1073/pnas.2318882120] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2023] Open
Affiliation(s)
- Yaoqin Hong
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, QLD4006, Australia
- Max Planck Queensland Centre, Queensland University of Technology, QLD4006, Australia
| | - Jilong Qin
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, QLD4006, Australia
| | - Makrina Totsika
- Centre for Immunology and Infection Control, School of Biomedical Sciences, Queensland University of Technology, QLD4006, Australia
- Max Planck Queensland Centre, Queensland University of Technology, QLD4006, Australia
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3
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Allgood SC, Su CC, Crooks AL, Meyer CT, Zhou B, Betterton MD, Barbachyn MR, Yu EW, Detweiler CS. Bacterial efflux pump modulators prevent bacterial growth in macrophages and under broth conditions that mimic the host environment. mBio 2023; 14:e0249223. [PMID: 37921493 PMCID: PMC10746280 DOI: 10.1128/mbio.02492-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2023] [Accepted: 09/21/2023] [Indexed: 11/04/2023] Open
Abstract
New approaches for combating microbial infections are needed. One strategy for disrupting pathogenesis involves developing compounds that interfere with bacterial virulence. A critical molecular determinant of virulence for Gram-negative bacteria are efflux pumps of the resistance-nodulation-division family, which includes AcrAB-TolC. We previously identified small molecules that bind AcrB, inhibit AcrAB-TolC, and do not appear to damage membranes. These efflux pump modulators (EPMs) were discovered in an in-cell screening platform called SAFIRE (Screen for Anti-infectives using Fluorescence microscopy of IntracellulaR Enterobacteriaceae). SAFIRE identifies compounds that disrupt the growth of a Gram-negative human pathogen, Salmonella enterica serotype Typhimurium (S. Typhimurium), in macrophages. We used medicinal chemistry to iteratively design ~200 EPM35 analogs and test them for activity in SAFIRE, generating compounds with nanomolar potency. Analogs were demonstrated to bind AcrB in a substrate binding pocket by cryo-electron microscopy. Despite having amphipathic structures, the EPM analogs do not disrupt membrane voltage, as monitored by FtsZ localization to the cell septum. The EPM analogs had little effect on bacterial growth in standard Mueller Hinton Broth. However, under broth conditions that mimic the micro-environment of the macrophage phagosome, acrAB is required for growth, the EPM analogs are bacteriostatic, and the EPM analogs increase the potency of antibiotics. These data suggest that under macrophage-like conditions, the EPM analogs prevent the export of a toxic bacterial metabolite(s) through AcrAB-TolC. Thus, compounds that bind AcrB could disrupt infection by specifically interfering with the export of bacterial toxic metabolites, host defense factors, and/or antibiotics.IMPORTANCEBacterial efflux pumps are critical for resistance to antibiotics and for virulence. We previously identified small molecules that inhibit efflux pumps (efflux pump modulators, EPMs) and prevent pathogen replication in host cells. Here, we used medicinal chemistry to increase the activity of the EPMs against pathogens in cells into the nanomolar range. We show by cryo-electron microscopy that these EPMs bind an efflux pump subunit. In broth culture, the EPMs increase the potency (activity), but not the efficacy (maximum effect), of antibiotics. We also found that bacterial exposure to the EPMs appear to enable the accumulation of a toxic metabolite that would otherwise be exported by efflux pumps. Thus, inhibitors of bacterial efflux pumps could interfere with infection not only by potentiating antibiotics, but also by allowing toxic waste products to accumulate within bacteria, providing an explanation for why efflux pumps are needed for virulence in the absence of antibiotics.
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Affiliation(s)
- Samual C. Allgood
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Chih-Chia Su
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Amy L. Crooks
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
| | - Christian T. Meyer
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
- Chemical and Biological Engineering, University of Colorado Boulder, Boulder, Colorado, USA
- Duet Biosystems, Nashville, Tennessee, USA
- Antimicrobial Research Consortium (ARC) Labs, Boulder, Colorado, USA
| | - Bojun Zhou
- Department of Physics, University of Colorado, Boulder, Colorado, USA
| | - Meredith D. Betterton
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
- Department of Physics, University of Colorado, Boulder, Colorado, USA
- Center for Computational Biology, Flatiron Institute, New York, New York, USA
| | | | - Edward W. Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
| | - Corrella S. Detweiler
- Molecular, Cellular, and Developmental Biology, University of Colorado Boulder, Boulder, Colorado, USA
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4
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Allgood SC, Su CC, Crooks AL, Meyer CT, Zhou B, Betterton MD, Barbachyn MR, Yu EW, Detweiler CS. Bacterial Efflux Pump Modulators Prevent Bacterial Growth in Macrophages and Under Broth Conditions that Mimic the Host Environment. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.20.558466. [PMID: 37786697 PMCID: PMC10541609 DOI: 10.1101/2023.09.20.558466] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/04/2023]
Abstract
New approaches for combatting microbial infections are needed. One strategy for disrupting pathogenesis involves developing compounds that interfere with bacterial virulence. A critical molecular determinant of virulence for Gram-negative bacteria are efflux pumps of the resistance-nodulation-division (RND) family, which includes AcrAB-TolC. We previously identified small molecules that bind AcrB, inhibit AcrAB-TolC, and do not appear to damage membranes. These efflux pump modulators (EPMs) were discovered in an in-cell screening platform called SAFIRE (Screen for Anti-infectives using Fluorescence microscopy of IntracellulaR Enterobacteriaceae). SAFIRE identifies compounds that disrupt the growth of a Gram-negative human pathogen, Salmonella enterica serotype Typhimurium (S. Typhimurium) in macrophages. We used medicinal chemistry to iteratively design ~200 EPM35 analogs and test them for activity in SAFIRE, generating compounds with nanomolar potency. Analogs were demonstrated to bind AcrB in a substrate binding pocket by cryo-electron microscopy (cryo-EM). Despite having amphipathic structures, the EPM analogs do not disrupt membrane voltage, as monitored by FtsZ localization to the cell septum. The EPM analogs had little effect on bacterial growth in standard Mueller Hinton Broth. However, under broth conditions that mimic the micro-environment of the macrophage phagosome, acrAB is required for growth, the EPM analogs are bacteriostatic, and increase the potency of antibiotics. These data suggest that under macrophage-like conditions the EPM analogs prevent the export of a toxic bacterial metabolite(s) through AcrAB-TolC. Thus, compounds that bind AcrB could disrupt infection by specifically interfering with the export of bacterial toxic metabolites, host defense factors, and/or antibiotics.
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Affiliation(s)
- Samual C Allgood
- Molecular, Cellular Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Chih-Chia Su
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Amy L Crooks
- Molecular, Cellular Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
| | - Christian T Meyer
- Molecular, Cellular Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- Chemical and Biological Engineering, University of Colorado Boulder, Boulder, CO, USA
- Duet Biosystems, Nashville, TN, USA
- Antimicrobial Research Consortium (ARC) Labs, Boulder, CO, USA
| | - Bojun Zhou
- Department of Physics, University of Colorado, Boulder, CO, USA
| | - Meredith D Betterton
- Molecular, Cellular Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
- Department of Physics, University of Colorado, Boulder, CO, USA
- Center for Computational Biology, Flatiron Institute, New York, NY, USA
| | | | - Edward W Yu
- Department of Pharmacology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
- Cleveland Center for Membrane and Structural Biology, Case Western Reserve University School of Medicine, Cleveland, OH 44106, USA
| | - Corrella S Detweiler
- Molecular, Cellular Developmental Biology, University of Colorado Boulder, Boulder, CO, USA
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5
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Glover G, Voliotis M, Łapińska U, Invergo BM, Soanes D, O'Neill P, Moore K, Nikolic N, Petrov PG, Milner DS, Roy S, Heesom K, Richards TA, Tsaneva-Atanasova K, Pagliara S. Nutrient and salt depletion synergistically boosts glucose metabolism in individual Escherichia coli cells. Commun Biol 2022; 5:385. [PMID: 35444215 PMCID: PMC9021252 DOI: 10.1038/s42003-022-03336-6] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2022] [Accepted: 03/30/2022] [Indexed: 12/16/2022] Open
Abstract
The interaction between a cell and its environment shapes fundamental intracellular processes such as cellular metabolism. In most cases growth rate is treated as a proximal metric for understanding the cellular metabolic status. However, changes in growth rate might not reflect metabolic variations in individuals responding to environmental fluctuations. Here we use single-cell microfluidics-microscopy combined with transcriptomics, proteomics and mathematical modelling to quantify the accumulation of glucose within Escherichia coli cells. In contrast to the current consensus, we reveal that environmental conditions which are comparatively unfavourable for growth, where both nutrients and salinity are depleted, increase glucose accumulation rates in individual bacteria and population subsets. We find that these changes in metabolic function are underpinned by variations at the translational and posttranslational level but not at the transcriptional level and are not dictated by changes in cell size. The metabolic response-characteristics identified greatly advance our fundamental understanding of the interactions between bacteria and their environment and have important ramifications when investigating cellular processes where salinity plays an important role.
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Affiliation(s)
- Georgina Glover
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - Margaritis Voliotis
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
| | - Urszula Łapińska
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Brandon M Invergo
- Translational Research Exchange at Exeter, University of Exeter, Exeter, UK
| | - Darren Soanes
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Paul O'Neill
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Karen Moore
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Nela Nikolic
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Institute of Science and Technology Austria, 3400, Klosterneuburg, Austria
| | - Peter G Petrov
- Department of Physics and Astronomy, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK
| | - David S Milner
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Sumita Roy
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK
| | - Kate Heesom
- University of Bristol Proteomics Facility, University Walk, Bristol, BS8 1TD, UK
| | - Thomas A Richards
- Department of Zoology, University of Oxford, 11a Mansfield Road, Oxford, OX1 3SZ, UK
| | - Krasimira Tsaneva-Atanasova
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK
- Department of Mathematics, University of Exeter, Stocker Road, Exeter, UK
- Department of Bioinformatics and Mathematical Modelling, Institute of Biophysics and Biomedical Engineering, Bulgarian Academy of Sciences, 105 Acad. G. Bonchev Str., 1113, Sofia, Bulgaria
| | - Stefano Pagliara
- Living Systems Institute, University of Exeter, Stocker Road, Exeter, EX4 4QD, UK.
- Biosciences, University of Exeter, Stocker Road, Exeter, EX4 4Q, UK.
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6
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Lang Y, Shah NR, Tao X, Reeve SM, Zhou J, Moya B, Sayed ARM, Dharuman S, Oyer JL, Copik AJ, Fleischer BA, Shin E, Werkman C, Basso KB, Lucas DD, Sutaria DS, Mégroz M, Kim TH, Loudon-Hossler V, Wright A, Jimenez-Nieves RH, Wallace MJ, Cadet KC, Jiao Y, Boyce JD, LoVullo ED, Schweizer HP, Bonomo RA, Bharatham N, Tsuji BT, Landersdorfer CB, Norris MH, Shin BS, Louie A, Balasubramanian V, Lee RE, Drusano GL, Bulitta JB. Combating Multidrug-Resistant Bacteria by Integrating a Novel Target Site Penetration and Receptor Binding Assay Platform Into Translational Modeling. Clin Pharmacol Ther 2021; 109:1000-1020. [PMID: 33576025 PMCID: PMC10662281 DOI: 10.1002/cpt.2205] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2020] [Revised: 02/08/2021] [Accepted: 02/08/2021] [Indexed: 12/26/2022]
Abstract
Multidrug-resistant bacteria are causing a serious global health crisis. A dramatic decline in antibiotic discovery and development investment by pharmaceutical industry over the last decades has slowed the adoption of new technologies. It is imperative that we create new mechanistic insights based on latest technologies, and use translational strategies to optimize patient therapy. Although drug development has relied on minimal inhibitory concentration testing and established in vitro and mouse infection models, the limited understanding of outer membrane permeability in Gram-negative bacteria presents major challenges. Our team has developed a platform using the latest technologies to characterize target site penetration and receptor binding in intact bacteria that inform translational modeling and guide new discovery. Enhanced assays can quantify the outer membrane permeability of β-lactam antibiotics and β-lactamase inhibitors using multiplex liquid chromatography tandem mass spectrometry. While β-lactam antibiotics are known to bind to multiple different penicillin-binding proteins (PBPs), their binding profiles are almost always studied in lysed bacteria. Novel assays for PBP binding in the periplasm of intact bacteria were developed and proteins identified via proteomics. To characterize bacterial morphology changes in response to PBP binding, high-throughput flow cytometry and time-lapse confocal microscopy with fluorescent probes provide unprecedented mechanistic insights. Moreover, novel assays to quantify cytosolic receptor binding and intracellular drug concentrations inform target site occupancy. These mechanistic data are integrated by quantitative and systems pharmacology modeling to maximize bacterial killing and minimize resistance in in vitro and mouse infection models. This translational approach holds promise to identify antibiotic combination dosing strategies for patients with serious infections.
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Affiliation(s)
- Yinzhi Lang
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Nirav R. Shah
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Jansen R&D, Johnson & Johnson, Spring House, Pennsylvania, USA
| | - Xun Tao
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Genentech USA,Inc., South San Francisco, California, USA
| | - Stephanie M. Reeve
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jieqiang Zhou
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Bartolome Moya
- Servicio de Microbiología and Unidad de Investigación, Hospital Universitario Son Espases, Instituto de Investigación Sanitaria Illes Balears (IdISBa), Palma de Mallorca, Spain
| | - Alaa R. M. Sayed
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Department of Chemistry, Faculty of Science, Fayoum University, Fayoum, Egypt
| | - Suresh Dharuman
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Jeremiah L. Oyer
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Alicja J. Copik
- Burnett School of Biomedical Sciences, College of Medicine, University of Central Florida, Orlando, Florida, USA
| | - Brett A. Fleischer
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Eunjeong Shin
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Carolin Werkman
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Kari B. Basso
- Department of Chemistry, University of Florida, Gainesville, Florida, USA
| | - Deanna Deveson Lucas
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Dhruvitkumar S. Sutaria
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
- Present address: Genentech USA,Inc., South San Francisco, California, USA
| | - Marianne Mégroz
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Tae Hwan Kim
- College of Pharmacy, Catholic University of Daegu, Gyeongsan, Gyeongbuk, Korea
| | - Victoria Loudon-Hossler
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Amy Wright
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Rossie H. Jimenez-Nieves
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Miranda J. Wallace
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - Keisha C. Cadet
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - Yuanyuan Jiao
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
| | - John D. Boyce
- Infection and Immunity Program, Department of Microbiology, Monash Biomedicine Discovery Institute, Monash University, Melbourne, Victoria, Australia
| | - Eric D. LoVullo
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Herbert P. Schweizer
- Pathogen and Microbiome Institute, Northern Arizona University, Flagstaff, Arizona, USA
| | - Robert A. Bonomo
- Research Service and GRECC, Louis Stokes Cleveland Department of Veterans Affairs Medical Center, Cleveland, Ohio, USA
- Department of Medicine, Pharmacology, Molecular Biology and Microbiology, Biochemistry and Proteomics and Bioinformatics, Case Western Reserve University School of Medicine, Cleveland, Ohio, USA
- CWRU-Cleveland VAMC Center for Antimicrobial Resistance and Epidemiology (Case VA CARES), Cleveland, Ohio, USA
| | - Nagakumar Bharatham
- BUGWORKS Research India Pvt. Ltd., Centre for Cellular & Molecular Platforms, National Centre for Biological Sciences, Bengaluru, Karnataka, India
| | - Brian T. Tsuji
- Laboratory for Antimicrobial Pharmacodynamics, University at Buffalo, Buffalo, New York, USA
| | - Cornelia B. Landersdorfer
- Drug Delivery, Disposition, and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
- Centre for Medicine Use and Safety, Monash Institute of Pharmaceutical Sciences, Monash University, Melbourne, Victoria, Australia
| | - Michael H. Norris
- Spatial Epidemiology and Ecology Research Laboratory, Department of Geography and the Emerging Pathogens Institute, University of Florida, Gainesville, Florida, USA
| | - Beom Soo Shin
- School of Pharmacy, Sungkyunkwan University, Suwon, Gyeonggi-do, Korea
| | - Arnold Louie
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - Venkataraman Balasubramanian
- BUGWORKS Research India Pvt. Ltd., Centre for Cellular & Molecular Platforms, National Centre for Biological Sciences, Bengaluru, Karnataka, India
| | - Richard E. Lee
- Department of Chemical Biology and Therapeutics, St. Jude Children’s Research Hospital, Memphis, Tennessee, USA
| | - George L. Drusano
- Institute for Therapeutic Innovation, College of Medicine, University of Florida, Orlando, Florida, USA
| | - Jürgen B. Bulitta
- Department of Pharmacotherapy and Translational Research, College of Pharmacy, University of Florida, Orlando, Florida, USA
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7
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Harris KA, Odzer NB, Breaker RR. Disruption of the OLE ribonucleoprotein complex causes magnesium toxicity in Bacillus halodurans. Mol Microbiol 2019; 112:1552-1563. [PMID: 31461569 DOI: 10.1111/mmi.14379] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/22/2019] [Indexed: 12/26/2022]
Abstract
OLE RNAs represent an unusual class of bacterial noncoding RNAs common in Gram-positive anaerobes. The OLE RNA of the alkaliphile Bacillus halodurans is highly expressed and naturally interacts with at least two RNA-binding proteins called OapA and OapB. The phenotypes of the corresponding knockouts include growth inhibition when exposed to ethanol or other short-chain alcohols or when incubated at modestly reduced temperatures (e.g. 20°C). Intriguingly, the OapA 'PM1' mutant, which carries two amino acid changes to a highly conserved region, yields a dominant-negative phenotype that causes more severe growth defects under these same stress conditions. Herein, we report that the PM1 strain also exhibits extreme sensitivity to elevated Mg2+ concentrations, beginning as low as 2 mM. Suppressor mutants predominantly map to genes for aconitate hydratase and isocitrate dehydrogenase, which are expected to alter cellular citrate concentrations. Citrate reduces the severity of the Mg2+ toxicity phenotype, but neither the genomic mutations nor the addition of citrate to the medium overcomes ethanol toxicity or temperature sensitivity. These findings reveal that OLE RNA and its protein partners are involved in biochemical responses under several stress conditions, wherein the unusual sensitivity to Mg2+ can be independently suppressed by specific genomic mutations.
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Affiliation(s)
- Kimberly A Harris
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA.,Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Nicole B Odzer
- Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA
| | - Ronald R Breaker
- Howard Hughes Medical Institute, Yale University, New Haven, CT, USA.,Department of Molecular, Cellular and Developmental Biology, Yale University, New Haven, CT, USA.,Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, USA
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8
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Widya M, Pasutti WD, Sachdeva M, Simmons RL, Tamrakar P, Krucker T, Six DA. Development and Optimization of a Higher-Throughput Bacterial Compound Accumulation Assay. ACS Infect Dis 2019; 5:394-405. [PMID: 30624052 DOI: 10.1021/acsinfecdis.8b00299] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The Gram-negative bacterial permeability barrier, coupled with efflux, raises formidable challenges to antibiotic drug discovery. The absence of efficient assays to determine compound penetration into the cell and impact of efflux makes the process resource-intensive, small-scale, and lacking much success. Here, we present BacPK: a label-free, solid phase extraction-mass spectrometry (SPE-MS)-based assay that measures total cellular compound accumulation in Escherichia coli. The BacPK assay is a 96-well accumulation assay that takes advantage of 9 s/sample SPE-MS throughput. This enables the analysis of each compound in a four-point dose-response in isogenic strain pairs along with a no-cell control and 16-point external standard curve, all in triplicate. To validate the assay, differences in accumulation were examined for tetracycline (Tet) and two analogs, confirming that close analogs can differ greatly in accumulation. Tet cellular accumulation was also compared for isogenic strains exhibiting Tet resistance due to the expression of an efflux pump (TetA) or ribosomal protection protein (TetM), confirming only TetA affected cellular Tet accumulation. Finally, using a diverse set of antibacterial compounds, we confirmed the assay's ability to quantify differences in accumulation for isogenic strain pairs with efflux or permeability alterations that are consistent with differences in susceptibility seen for the compounds.
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9
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Hong Y, Moon Y, Choi T, Jung H, Yang S, Ahn J, Joo J, Park K, Kim Y, Bhatia SK, Lee YK, Yang Y. Enhanced production of glutaric acid by NADH oxidase and GabD‐reinforced bioconversion from
l
‐lysine. Biotechnol Bioeng 2018; 116:333-341. [DOI: 10.1002/bit.26869] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 10/13/2018] [Accepted: 10/26/2018] [Indexed: 12/19/2022]
Affiliation(s)
- Yun‐Gi Hong
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Yu‐Mi Moon
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Tae‐Rim Choi
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Hye‐Rim Jung
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Soo‐Yeon Yang
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Jung‐Oh Ahn
- Biotechnology Process Engineering Center, Korea Research Institute Bioscience Biotechnology, GwahangnoYuseong‐Gu Daejeon Republic of Korea
| | - Jeong‐Chan Joo
- Bio‐based Chemistry Research CenterAdvanced Convergent Chemistry Division, Korea Research Institute of Chemical Technology, Gajeong‐roYuseong‐gu Daejeon Republic of Korea
| | - Kyungmoon Park
- Department of Biological and Chemical EngineeringHongik University, Sejong, JochiwonSejong Republic of Korea
| | - Yun‐Gon Kim
- Department of Chemical EngineeringSoongsil University, Sang‐doro, Dongjak‐guSeoul South Korea
| | - Shashi Kant Bhatia
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
| | - Yoo Kyung Lee
- Division of Life SciencesKorea Polar Research InstituteIncheon Republic of Korea
| | - Yung‐Hun Yang
- Department of Biological EngineeringCollege of Engineering, Konkuk UniversitySeoul Republic of Korea
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10
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Nabergoj D, Modic P, Podgornik A. Effect of bacterial growth rate on bacteriophage population growth rate. Microbiologyopen 2018; 7:e00558. [PMID: 29195013 PMCID: PMC5911998 DOI: 10.1002/mbo3.558] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2017] [Revised: 10/12/2017] [Accepted: 10/13/2017] [Indexed: 01/15/2023] Open
Abstract
It is important to understand how physiological state of the host influence propagation of bacteriophages (phages), due to the potential higher phage production needs in the future. In our study, we tried to elucidate the effect of bacterial growth rate on adsorption constant (δ), latent period (L), burst size (b), and bacteriophage population growth rate (λ). As a model system, a well-studied phage T4 and Escherichia coli K-12 as a host was used. Bacteria were grown in a continuous culture operating at dilution rates in the range between 0.06 and 0.98 hr-1 . It was found that the burst size increases linearly from 8 PFU·cell-1 to 89 PFU·cell-1 with increase in bacteria growth rate. On the other hand, adsorption constant and latent period were both decreasing from 2.6∙10-9 ml·min-1 and 80 min to reach limiting values of 0.5 × 10-9 ml·min-1 and 27 min at higher growth rates, respectively. Both trends were mathematically described with Michaelis-Menten based type of equation and reasons for such form are discussed. By applying selected equations, a mathematical equation for prediction of bacteriophage population growth rate as a function of dilution rate was derived, reaching values around 8 hr-1 at highest dilution rate. Interestingly, almost identical description can be obtained using much simpler Monod type equation and possible reasons for this finding are discussed.
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Affiliation(s)
- Dominik Nabergoj
- Center of Excellence for BiosensorsInstrumentation and Process Control ‐ COBIKAjdovščinaSlovenia
| | - Petra Modic
- Faculty of Chemistry and Chemical TechnologyUniversity of LjubljanaLjubljanaSlovenia
| | - Aleš Podgornik
- Center of Excellence for BiosensorsInstrumentation and Process Control ‐ COBIKAjdovščinaSlovenia
- Faculty of Chemistry and Chemical TechnologyUniversity of LjubljanaLjubljanaSlovenia
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11
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Nabergoj D, Kuzmić N, Drakslar B, Podgornik A. Effect of dilution rate on productivity of continuous bacteriophage production in cellstat. Appl Microbiol Biotechnol 2018. [DOI: 10.1007/s00253-018-8893-9] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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12
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Chong ZS, Woo WF, Chng SS. Osmoporin OmpC forms a complex with MlaA to maintain outer membrane lipid asymmetry in Escherichia coli. Mol Microbiol 2015; 98:1133-46. [PMID: 26314242 DOI: 10.1111/mmi.13202] [Citation(s) in RCA: 89] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 08/24/2015] [Indexed: 12/21/2022]
Abstract
Gram-negative bacteria can survive in harsh environments in part because the asymmetric outer membrane (OM) hinders the entry of toxic compounds. Lipid asymmetry is established by having phospholipids (PLs) confined to the inner leaflet of the membrane and lipopolysaccharides (LPS) to the outer leaflet. Perturbation of OM lipid asymmetry, characterized by PL accumulation in the outer leaflet, disrupts proper LPS packing and increases membrane permeability. The multi-component Mla system prevents PL accumulation in the outer leaflet of the OM via an unknown mechanism. Here, we demonstrate that in Escherichia coli, the Mla system maintains OM lipid asymmetry with the help of osmoporin OmpC. We show that the OM lipoprotein MlaA interacts specifically with OmpC and OmpF. This interaction is sufficient to localize MlaA lacking its lipid anchor to the OM. Removing OmpC, but not OmpF, causes accumulation of PLs in the outer leaflet of the OM in stationary phase, as was previously observed for MlaA. We establish that OmpC is an additional component of the Mla system; the OmpC-MlaA complex may function to remove PLs directly from the outer leaflet to maintain OM lipid asymmetry. Our work reveals a novel function for the general diffusion channel OmpC in lipid transport.
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Affiliation(s)
- Zhi-Soon Chong
- Department of Chemistry, National University of Singapore, Singapore, 117543
| | - Wei-Fen Woo
- Department of Chemistry, National University of Singapore, Singapore, 117543
| | - Shu-Sin Chng
- Department of Chemistry, National University of Singapore, Singapore, 117543.,Singapore Center on Environmental Life Sciences Engineering (SCELSE), National University of Singapore, Singapore, 117456
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13
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Wang H, Bastian SEP, Lawrence A, Howarth GS. Factors Derived From Escherichia Coli Nissle 1917, Grown in Different Growth Media, Enhance Cell Death in a Model of 5-Fluorouracil-Induced Caco-2 Intestinal Epithelial Cell Damage. Nutr Cancer 2015; 67:316-26. [DOI: 10.1080/01635581.2015.990570] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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14
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Ford DC, Joshua GWP, Wren BW, Oyston PCF. The importance of the magnesium transporter MgtB for virulence of Yersinia pseudotuberculosis and Yersinia pestis. MICROBIOLOGY-SGM 2014; 160:2710-2717. [PMID: 25234474 DOI: 10.1099/mic.0.080556-0] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Mg(2+) has been shown to be an important signal controlling gene regulation via the PhoPQ two-component regulatory system for a range of Gram-negative bacteria, including Yersinia pestis and Yersinia pseudotuberculosis. The magnesium ion transporter MgtB is part of the complex PhoPQ regulon, being upregulated in response to low Mg(2+). Despite the presence of other Mg(2+) transport systems in Yersinia, inactivation of mgtB had a significant effect on the ability of the bacteria to scavenge this crucial ion. Whereas inactivation of PhoPQ is reported to adversely affect intracellular survival, we show that Y. pestis and Y. pseudotuberculosis ΔmgtB mutants survived equally as well as the respective parent strain within macrophages, although they were more sensitive to killing in the Galleria model of infection. Surprisingly, despite MgtB being only one member of the Mg(2+) stimulon and PhoPQ controlling the expression levels of a range of genes including mgtB, the Yersinia ΔmgtB mutants were more highly attenuated than the equivalent Yersinia ΔphoP mutants in mouse models of infection. MgtB may be a suitable target for development of novel antimicrobials, and investigation of its role may help elucidate the contribution of this component of the PhoPQ regulon to pathogenesis.
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Affiliation(s)
- Donna C Ford
- Biomedical Sciences, Dstl Porton Down, Salisbury SP4 0JQ, UK
| | - George W P Joshua
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
| | - Brendan W Wren
- Department of Infectious and Tropical Diseases, London School of Hygiene and Tropical Medicine, London WC1E 7HT, UK
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15
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Puentes-Téllez PE, Hansen MA, Sørensen SJ, van Elsas JD. Adaptation and heterogeneity of Escherichia coli MC1000 growing in complex environments. Appl Environ Microbiol 2013; 79:1008-17. [PMID: 23204426 PMCID: PMC3568559 DOI: 10.1128/aem.02920-12] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2012] [Accepted: 11/26/2012] [Indexed: 01/22/2023] Open
Abstract
In a study aiming to assess bacterial evolution in complex growth media, we evaluated the long-term adaptive response of Escherichia coli MC1000 in Luria-Bertani (LB) medium. Seven parallel populations were founded and followed over 150 days in sequential batch cultures under three different oxygen conditions (defined environments), and 19 evolved forms were isolated. The emergence of forms with enhanced fitness was evident in competition experiments of all evolved forms versus the ancestral strain. The evolved forms were then subjected to phenotypic and genomic analyses relative to the ancestor. Profound changes were found in their phenotypes as well as whole-genome sequences. Interestingly, considerable heterogeneity was found at the intrapopulational level. However, consistently occurring parallel adaptive responses were found across all populations. The evolved forms all contained a mutation in galR, a repressor of the galactose operon. Concomitantly, the new forms revealed enhanced growth on galactose as well as galactose-containing disaccharides. This response was likely driven by the LB medium.
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16
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Cathelicidin antimicrobial peptide expression is not induced or required for bacterial clearance during salmonella enterica infection of human monocyte-derived macrophages. Infect Immun 2012; 80:3930-8. [PMID: 22927052 DOI: 10.1128/iai.00672-12] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is able to resist antimicrobial peptide killing by induction of the PhoP-PhoQ and PmrA-PmrB two-component systems and the lipopolysaccharide (LPS) modifications they mediate. Murine cathelin-related antimicrobial peptide (CRAMP) has been reported to inhibit S. Typhimurium growth in vitro and in vivo. We hypothesize that infection of human monocyte-derived macrophages (MDMs) with Salmonella enterica serovar Typhi and S. Typhimurium will induce human cathelicidin antimicrobial peptide (CAMP) production, and exposure to LL-37 (processed, active form of CAMP/hCAP18) will lead to upregulation of PmrAB-mediated LPS modifications and increased survival in vivo. Unlike in mouse macrophages, in which CRAMP is upregulated during infection, camp gene expression was not induced in human MDMs infected with S. Typhi or S. Typhimurium. Upon infection, intracellular levels of ΔphoPQ, ΔpmrAB, and PhoP(c) S. Typhi decreased over time but were not further inhibited by the vitamin D(3)-induced increase in camp expression. MDMs infected with wild-type (WT) S. Typhi or S. Typhimurium released similar levels of proinflammatory cytokines; however, the LPS modification mutant strains dramatically differed in MDM-elicited cytokine levels. Overall, these findings indicate that camp is not induced during Salmonella infection of MDMs nor is key to Salmonella intracellular clearance. However, the cytokine responses from MDMs infected with WT or LPS modification mutant strains differ significantly, indicating a role for LPS modifications in altering the host inflammatory response. Our findings also suggest that S. Typhi and S. Typhimurium elicit different proinflammatory responses from MDMs, despite being capable of adding similar modifications to their LPS structures.
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Abstract
Gram-negative bacteria characteristically are surrounded by an additional membrane layer, the outer membrane. Although outer membrane components often play important roles in the interaction of symbiotic or pathogenic bacteria with their host organisms, the major role of this membrane must usually be to serve as a permeability barrier to prevent the entry of noxious compounds and at the same time to allow the influx of nutrient molecules. This review summarizes the development in the field since our previous review (H. Nikaido and M. Vaara, Microbiol. Rev. 49:1-32, 1985) was published. With the discovery of protein channels, structural knowledge enables us to understand in molecular detail how porins, specific channels, TonB-linked receptors, and other proteins function. We are now beginning to see how the export of large proteins occurs across the outer membrane. With our knowledge of the lipopolysaccharide-phospholipid asymmetric bilayer of the outer membrane, we are finally beginning to understand how this bilayer can retard the entry of lipophilic compounds, owing to our increasing knowledge about the chemistry of lipopolysaccharide from diverse organisms and the way in which lipopolysaccharide structure is modified by environmental conditions.
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Affiliation(s)
- Hiroshi Nikaido
- Department of Molecular and Cell Biology, University of California, Berkeley, California 94720-3202, USA.
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18
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Yuasa J, Nakagawa Y, Kotani Y, Shimohata A, Matsuyama T. Pseudomonas aeruginosa under Phosphorus-Poor Culture Conditions: Phospholipid-Poor Bacterial Membranes, and Susceptibility to Antibacterial Chemicals, High Temperature and Low pH. Microbes Environ 2002. [DOI: 10.1264/jsme2.2002.75] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Junko Yuasa
- Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University
| | - Yoji Nakagawa
- Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University
| | - Yoshifumi Kotani
- Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University
| | - Atsushi Shimohata
- Department of Applied Biological Chemistry, Faculty of Agriculture, Niigata University
| | - Tohey Matsuyama
- Department of Infectious Disease Control and International Medicine, Niigata University Graduate School of Medical and Dental Sciences
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19
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Taylor CJ, Anderson AJ, Wilkinson SG. Phenotypic variation of lipid composition in Burkholderia cepacia: a response to increased growth temperature is a greater content of 2-hydroxy acids in phosphatidylethanolamine and ornithine amide lipid. MICROBIOLOGY (READING, ENGLAND) 1998; 144 ( Pt 7):1737-1745. [PMID: 9695908 DOI: 10.1099/00221287-144-7-1737] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Burkholderia cepacia produces an unusual range of polar lipids, which includes two forms each of phosphatidylethanolamine (PE) and ornithine amide lipid (OL), differing in the presence or absence of 2-hydroxy fatty acids. By using chemostat cultures in chemically defined media, variations in the lipid content and the proportions of individual lipids have been studied as a function of (a) growth temperature, (b) growth rate and (c) growth-limiting nutrient (carbon, magnesium, phosphorus or oxygen). Total cellular lipid in carbon-limited cultures was lowest at high growth temperatures and low growth rates. Increases in growth temperature over the range 25-40 degrees C led to increases in the proportions of molecular species of PE and OL containing 2-hydroxy acids, without changing the PE:OL ratio. Growth temperature did not alter the balance between neutral and acidic lipids, but the contribution of phosphatidylglycerol to the latter increased with rising growth temperature and growth rate. Pigmentation of cells and the presence of flagella were also temperature-dependent. Change in growth rate also affected the PE:OL ratio and the extent to which monoenoic acids were replaced by their cyclopropane derivatives. Whereas similar lipid profiles were found for carbon-, magnesium- and oxygen-limited cultures, ornithine amides were the only polar lipids detected in phosphorus-limited cells.
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Affiliation(s)
- Catherine J Taylor
- Departments of Chemistry, University of Hull, Hull HU6 7RX, UK
- Departments of Chemistry and Biological Sciences, University of HullHull HU6 7RXUK
| | | | - Stephen G Wilkinson
- Departments of Chemistry and Biological Sciences, University of HullHull HU6 7RXUK
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20
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Wee S, Dowding JM, Nadakavukaren MJ, Wilkinson BJ. Characterization of cell surface material removed by water and NaCl washing of Paracoccus denitrificans grown under conditions of divalent cation deficiency and sufficiency. Antonie Van Leeuwenhoek 1994; 65:35-9. [PMID: 8060122 DOI: 10.1007/bf00878277] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Paracoccus denitrificans grown on complex medium deficient in Mg2+ and Ca2+ are rendered lysozyme susceptible by washing with NaCl, whereas cells grown in a succinate-salts medium (Mg2+ and Ca2+ sufficient) or complex medium supplemented with Mg(2+)+Ca2+ are not. The material released by water washing of cells grown on complex medium and complex medium supplemented with Mg2+ and Ca2+ was characterized by a high protein content. There was a high lipid: protein ratio and an appreciable amount of 3-deoxyoctulosonic acid in the material released by NaCl washing of cells grown under all conditions, indicating release of outer membrane material. The lipid ornithine: lipid phosphorous ratios of NaCl wash from cells grown on complex medium and complex medium supplemented with Mg2+ and Ca2+ were 0.54 and 0.34, respectively. Although NaCl washing removed outer membrane material from cells grown under all conditions, only divalent cation deficient cells were rendered lysozyme susceptible. This might be explained by the increased outer membrane ornithine-containing lipid to phospholipid ratio in these cells yielding a more permeable outer membrane.
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Affiliation(s)
- S Wee
- Department of Biological Sciences, Illinois State University, Normal 61761
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21
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Abstract
The outer membrane of gram-negative bacteria provides the cell with an effective permeability barrier against external noxious agents, including antibiotics, but is itself a target for antibacterial agents such as polycations and chelators. Both groups of agents weaken the molecular interactions of the lipopolysaccharide constituent of the outer membrane. Various polycations are able, at least under certain conditions, to bind to the anionic sites of lipopolysaccharide. Many of these disorganize and cross the outer membrane and render it permeable to drugs which permeate the intact membrane very poorly. These polycations include polymyxins and their derivatives, protamine, polymers of basic amino acids, compound 48/80, insect cecropins, reptilian magainins, various cationic leukocyte peptides (defensins, bactenecins, bactericidal/permeability-increasing protein, and others), aminoglycosides, and many more. However, the cationic character is not the sole determinant required for the permeabilizing activity, and therefore some of the agents are much more effective permeabilizers than others. They are useful tools in studies in which the poor permeability of the outer membrane poses problems. Some of them undoubtedly have a role as natural antibiotic substances, and they or their derivatives might have some potential as pharmaceutical agents in antibacterial therapy as well. Also, chelators (such as EDTA, nitrilotriacetic acid, and sodium hexametaphosphate), which disintegrate the outer membrane by removing Mg2+ and Ca2+, are effective and valuable permeabilizers.
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Affiliation(s)
- M Vaara
- Department of Bacteriology and Immunology, University of Helsinki, Finland
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22
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Abstract
The outer membrane of gram-negative bacteria provides the cell with an effective permeability barrier against external noxious agents, including antibiotics, but is itself a target for antibacterial agents such as polycations and chelators. Both groups of agents weaken the molecular interactions of the lipopolysaccharide constituent of the outer membrane. Various polycations are able, at least under certain conditions, to bind to the anionic sites of lipopolysaccharide. Many of these disorganize and cross the outer membrane and render it permeable to drugs which permeate the intact membrane very poorly. These polycations include polymyxins and their derivatives, protamine, polymers of basic amino acids, compound 48/80, insect cecropins, reptilian magainins, various cationic leukocyte peptides (defensins, bactenecins, bactericidal/permeability-increasing protein, and others), aminoglycosides, and many more. However, the cationic character is not the sole determinant required for the permeabilizing activity, and therefore some of the agents are much more effective permeabilizers than others. They are useful tools in studies in which the poor permeability of the outer membrane poses problems. Some of them undoubtedly have a role as natural antibiotic substances, and they or their derivatives might have some potential as pharmaceutical agents in antibacterial therapy as well. Also, chelators (such as EDTA, nitrilotriacetic acid, and sodium hexametaphosphate), which disintegrate the outer membrane by removing Mg2+ and Ca2+, are effective and valuable permeabilizers.
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Affiliation(s)
- M Vaara
- Department of Bacteriology and Immunology, University of Helsinki, Finland
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23
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Chine-Te-Chien, Shetty K, Mortimer M, Orser CS. Calcium-induced salt tolerance inRhizobium leguminosarumbiovarviciaestrain C124b. FEMS Microbiol Lett 1991. [DOI: 10.1111/j.1574-6968.1991.tb04443.x-i1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022] Open
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24
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Asselineau J. Bacterial lipids containing amino acids or peptides linked by amide bonds. FORTSCHRITTE DER CHEMIE ORGANISCHER NATURSTOFFE = PROGRESS IN THE CHEMISTRY OF ORGANIC NATURAL PRODUCTS. PROGRES DANS LA CHIMIE DES SUBSTANCES ORGANIQUES NATURELLES 1991; 56:1-85. [PMID: 2050312 DOI: 10.1007/978-3-7091-9084-5_1] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/30/2022]
Affiliation(s)
- J Asselineau
- Centre de Recherche de Biochimie et Génétique Cellulaires, Toulouse, France
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25
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Busse MD, Bottomley PJ. Growth and Nodulation Responses of
Rhizobium meliloti
to Water Stress Induced by Permeating and Nonpermeating Solutes. Appl Environ Microbiol 1989; 55:2431-6. [PMID: 16348021 PMCID: PMC203100 DOI: 10.1128/aem.55.10.2431-2436.1989] [Citation(s) in RCA: 59] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Isolates of
Rhizobium meliloti
, representing antigenically distinct indigenous serogroups 31 and 17, were grown in yeast extract-mannitol broth (YEM) containing NaCl or polyethylene glycol (PEG) to provide external water potentials ranging from −0.15 to −1.5 MPa. Several differences were found between representatives of the two groups in their abilities to adapt to water stress induced by the nonpermeating solute PEG. At potentials below −0.5 MPa, strain 31 had a lower specific growth rate than strain 17 and an irregular cell morphology. In contrast, neither growth nor cell morphology of either strain was affected significantly over the same range of water potentials created by a permeating solute, NaCl. Despite the superior growth of strain 17 at the low water potentials imposed by PEG, upshock of water-stressed cells (−1.0 MPa; PEG) into normal YEM (−0.15 MPa) resulted in a faster recovery of growth by strain 31 than by strain 17. Different responses of the two strains to a water potential increase were also revealed in nodulation studies. Strain 31 required significantly fewer days to nodulate alfalfa than strain 17 did when the strains were transferred from YEM with PEG at −1.0 MPa onto the roots of alfalfa seedlings in plant growth medium (−0.1 MPa). The addition of supplemental calcium (0.1 mM) to growth medium with PEG (−1.0 MPa) reduced the differences between strains in their responses to water stress. The severe growth restriction and morphological abnormalities shown by strain 31 were corrected, and the prolonged recovery time shown by water-stressed cells (−1.0 MPa; PEG) of strain 17 upon transfer to normal YEM was shortened. The latter strain also nodulated earlier and more rapidly after growth in PEG medium at −1.0 MPa in the presence of supplemental calcium ions. These results indicate that the efficacy of osmoregulation can vary among strains of the same species and that the mechanism of osmoregulation may differ depending on the nature of the water stress.
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Affiliation(s)
- M D Busse
- Departments of Soil Science and Microbiology, Oregon State University, Corvallis, Oregon 97331-3804
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26
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Vaara M, Jaakkola J. Sodium hexametaphosphate sensitizes Pseudomonas aeruginosa, several other species of Pseudomonas, and Escherichia coli to hydrophobic drugs. Antimicrob Agents Chemother 1989; 33:1741-7. [PMID: 2511800 PMCID: PMC172748 DOI: 10.1128/aac.33.10.1741] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Many gram-negative bacteria are known to be remarkably resistant to hydrophobic noxious agents by virtue of their outer membranes (OM). We investigated, by using four different assay methods, the ability of sodium hexametaphosphate (HMP) to disrupt this OM barrier. (i) In the growth inhibition assay, HMP was found to sensitize strains of Pseudomonas aeruginosa to all the hydrophobic probes tested (rifampin, fusidic acid, dactinomycin, sodium dodecyl sulfate, and Triton X-100). A concentration of 0.3% HMP decreased the MICs of the probes by a factor of approximately 10, and maximally even a 30-fold sensitization was found with 1% HMP. (ii) In the bactericidal assay, 0.3% HMP decreased the MBC of the hydrophobic probe rifampin by a factor of approximately 30. (iii) In the bacteriolytic assay, 0.1% HMP sensitized the target bacteria to lysis by sodium dodecyl sulfate and Triton X-100. (iv) In the fluorescent-probe binding assay, HMP drastically enhanced the binding of fluorescent N-phenyl naphthylamine to the membranes of the target cells. In addition to P. aeruginosa, P. fluorescens, P. putida, P. fragi, and Escherichia coli were susceptible to the OM permeability-increasing action of HMP, while P. cepacia was resistant.
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Affiliation(s)
- M Vaara
- Department of Bacteriology and Immunology, University of Helsinki, Finland
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