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Rill A, Zhao L, Bode HB. Genetic toolbox for Photorhabdus and Xenorhabdus: pSEVA based heterologous expression systems and CRISPR/Cpf1 based genome editing for rapid natural product profiling. Microb Cell Fact 2024; 23:98. [PMID: 38561780 PMCID: PMC10983751 DOI: 10.1186/s12934-024-02363-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Accepted: 03/11/2024] [Indexed: 04/04/2024] Open
Abstract
BACKGROUND Bacteria of the genus Photorhabdus and Xenorhabdus are motile, Gram-negative bacteria that live in symbiosis with entomopathogenic nematodes. Due to their complex life cycle, they produce a large number of specialized metabolites (natural products) encoded in biosynthetic gene clusters (BGC). Genetic tools for Photorhabdus and Xenorhabdus have been rare and applicable to only a few strains. In the past, several tools have been developed for the activation of BGCs and the deletion of individual genes. However, these often have limited efficiency or are time consuming. Among the limitations, it is essential to have versatile expression systems and genome editing tools that could facilitate the practical work. RESULTS In the present study, we developed several expression vectors and a CRISPR-Cpf1 genome editing vector for genetic manipulations in Photorhabdus and Xenorhabdus using SEVA plasmids. The SEVA collection is based on modular vectors that allow exchangeability of different elements (e.g. origin of replication and antibiotic selection markers with the ability to insert desired sequences for different end applications). Initially, we tested different SEVA vectors containing the broad host range origins and three different resistance genes for kanamycin, gentamycin and chloramphenicol, respectively. We demonstrated that these vectors are replicative not only in well-known representatives, e.g. Photorhabdus laumondii TTO1, but also in other rarely described strains like Xenorhabdus sp. TS4. For our CRISPR/Cpf1-based system, we used the pSEVA231 backbone to delete not only small genes but also large parts of BGCs. Furthermore, we were able to activate and refactor BGCs to obtain high production titers of high value compounds such as safracin B, a semisynthetic precursor for the anti-cancer drug ET-743. CONCLUSIONS The results of this study provide new inducible expression vectors and a CRISPR/CPf1 encoding vector all based on the SEVA (Standard European Vector Architecture) collection, which can improve genetic manipulation and genome editing processes in Photorhabdus and Xenorhabdus.
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Affiliation(s)
- Alexander Rill
- Department of Natural Products in Organismic Interactions, Max-Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany
- Molecular Biotechnology, Department of Biosciences, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
- Department of Chemistry, Chemical Biology, Phillips University Marburg, 35043, Marburg, Germany
| | - Lei Zhao
- Molecular Biotechnology, Department of Biosciences, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany
- State Key Laboratory of Bio-organic and Natural Products Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai, 200032, China
| | - Helge B Bode
- Department of Natural Products in Organismic Interactions, Max-Planck Institute for Terrestrial Microbiology, 35043, Marburg, Germany.
- Molecular Biotechnology, Department of Biosciences, Goethe University Frankfurt, 60438, Frankfurt am Main, Germany.
- Department of Chemistry, Chemical Biology, Phillips University Marburg, 35043, Marburg, Germany.
- Center for Synthetic Microbiology (SYNMIKRO), Phillips University Marburg, 35043, Marburg, Germany.
- Senckenberg Gesellschaft für Naturforschung, 60325, Frankfurt, Germany.
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Lamichhane B, Mawad AMM, Saleh M, Kelley WG, Harrington PJ, Lovestad CW, Amezcua J, Sarhan MM, El Zowalaty ME, Ramadan H, Morgan M, Helmy YA. Salmonellosis: An Overview of Epidemiology, Pathogenesis, and Innovative Approaches to Mitigate the Antimicrobial Resistant Infections. Antibiotics (Basel) 2024; 13:76. [PMID: 38247636 PMCID: PMC10812683 DOI: 10.3390/antibiotics13010076] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Revised: 12/24/2023] [Accepted: 01/10/2024] [Indexed: 01/23/2024] Open
Abstract
Salmonella is a major foodborne pathogen and a leading cause of gastroenteritis in humans and animals. Salmonella is highly pathogenic and encompasses more than 2600 characterized serovars. The transmission of Salmonella to humans occurs through the farm-to-fork continuum and is commonly linked to the consumption of animal-derived food products. Among these sources, poultry and poultry products are primary contributors, followed by beef, pork, fish, and non-animal-derived food such as fruits and vegetables. While antibiotics constitute the primary treatment for salmonellosis, the emergence of antibiotic resistance and the rise of multidrug-resistant (MDR) Salmonella strains have highlighted the urgency of developing antibiotic alternatives. Effective infection management necessitates a comprehensive understanding of the pathogen's epidemiology and transmission dynamics. Therefore, this comprehensive review focuses on the epidemiology, sources of infection, risk factors, transmission dynamics, and the host range of Salmonella serotypes. This review also investigates the disease characteristics observed in both humans and animals, antibiotic resistance, pathogenesis, and potential strategies for treatment and control of salmonellosis, emphasizing the most recent antibiotic-alternative approaches for infection control.
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Affiliation(s)
- Bibek Lamichhane
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Asmaa M. M. Mawad
- Botany and Microbiology Department, Faculty of Science, Assiut University, Assiut 71516, Egypt
| | - Mohamed Saleh
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - William G. Kelley
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Patrick J. Harrington
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Cayenne W. Lovestad
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Jessica Amezcua
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Mohamed M. Sarhan
- Faculty of Pharmacy, King Salman International University (KSIU), Ras Sudr 8744304, Egypt
| | - Mohamed E. El Zowalaty
- Veterinary Medicine and Food Security Research Group, Medical Laboratory Sciences Program, Faculty of Health Sciences, Abu Dhabi Women’s Campus, Higher Colleges of Technology, Abu Dhabi 41012, United Arab Emirates
| | - Hazem Ramadan
- Hygiene and Zoonoses Department, Faculty of Veterinary Medicine, Mansoura University, Mansoura 35516, Egypt
| | - Melissa Morgan
- Department of Animal and Food Sciences, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
| | - Yosra A. Helmy
- Department of Veterinary Science, Martin-Gatton College of Agriculture, Food and Environment, University of Kentucky, Lexington, KY 40546, USA
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Escobar-Muciño E, Arenas-Hernández MMP, Luna-Guevara ML. Mechanisms of Inhibition of Quorum Sensing as an Alternative for the Control of E. coli and Salmonella. Microorganisms 2022; 10:microorganisms10050884. [PMID: 35630329 PMCID: PMC9143355 DOI: 10.3390/microorganisms10050884] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2022] [Revised: 04/08/2022] [Accepted: 04/10/2022] [Indexed: 02/05/2023] Open
Abstract
Quorum sensing (QS) is a process of cell–cell communication for bacteria such as E. coli and Salmonella that cause foodborne diseases, with the production, release, and detection of autoinducer (AI) molecules that participate in the regulation of virulence genes. All of these proteins are useful in coordinating collective behavior, the expression of virulence factors, and the pathogenicity of Gram-negative bacteria. In this work, we review the natural or synthetic inhibitor molecules of QS that inactivate the autoinducer and block QS regulatory proteins in E. coli and Salmonella. Furthermore, we describe mechanisms of QS inhibitors (QSIs) that act as competitive inhibitors, being a useful tool for preventing virulence gene expression through the downregulation of AI-2 production pathways and the disruption of signal uptake. In addition, we showed that QSIs have negative regulatory activity of genes related to bacterial biofilm formation on clinical artifacts, which confirms the therapeutic potential of QSIs in the control of infectious pathogens. Finally, we discuss resistance to QSIs, the design of next-generation QSIs, and how these molecules can be leveraged to provide a new antivirulence therapy to combat diseases caused by E. coli or Salmonella.
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Affiliation(s)
- Esmeralda Escobar-Muciño
- Posgrado en Microbiología, Centro de Investigación en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla C.P. 72570, Pue, Mexico;
| | - Margarita M. P. Arenas-Hernández
- Posgrado en Microbiología, Centro de Investigación en Ciencias Microbiológicas, Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla C.P. 72570, Pue, Mexico;
- Correspondence: (M.M.P.A.-H.); (M.L.L.-G.); Tel.: +52-(222)-191-06-00 (M.M.P.A.-H.); +52-(222)-352-31-25 (M.L.L.-G.)
| | - M. Lorena Luna-Guevara
- Colegío de Ingeniería en Alimentos, Facultad de Ingeniería Química, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, Puebla C.P. 72570, Pue, Mexico
- Correspondence: (M.M.P.A.-H.); (M.L.L.-G.); Tel.: +52-(222)-191-06-00 (M.M.P.A.-H.); +52-(222)-352-31-25 (M.L.L.-G.)
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Galante D, Manzulli V, Donatiello A, Fasanella A, Chirullo B, Francia M, Rondinone V, Serrecchia L, Pace L, Iatarola M, Tarantino M, Adone R. Production of a Bacillus anthracis Secretome with Suitable Characteristics as Antigen in a Complement Fixation Test. Life (Basel) 2022; 12:life12020312. [PMID: 35207599 PMCID: PMC8876820 DOI: 10.3390/life12020312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2022] [Revised: 02/15/2022] [Accepted: 02/16/2022] [Indexed: 11/22/2022] Open
Abstract
In this study, we cultured the Bacillus anthracis vaccine strain Sterne 34F2 in a medium containing EDTA, and we assessed the best conditions to inhibit the activity of zinc-dependent metalloproteases to obtain a secretome containing a high concentration of non-degraded PA (PA83), as evaluated by the SDS-PAGE analysis. Then, we used this secretome as the antigen in a Complement Fixation Test (CFT) to monitor the production of antibodies against PA83 in the sera of rabbits vaccinated with Sterne 34F2 and then infected with a B. anthracis virulent strain to evaluate the potency of the vaccine. The PAS-based CFT results were compared with those obtained by using a commercial ELISA kit. The two serological tests gave similar results in terms of specificity and sensitivity, as the kinetics of the antibodies production was very similar. The Sterne 34F2 vaccine induced an antibody response to PA83, whose titer was not inferior to 1:8 in PAS-based CFT and 42 kU/mL in PA83-based ELISA, respectively, in all vaccinated rabbits. Our opinion is that the PAS-based CFT can be successfully employed in humans and in animals for epidemiological retrospective studies or post-vaccination monitoring. We also suggest the use of our method to test the efficacy of veterinary anthrax vaccines.
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Affiliation(s)
- Domenico Galante
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
- Correspondence: ; Tel.: +39-0881786330
| | - Viviana Manzulli
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Adelia Donatiello
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Antonio Fasanella
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Barbara Chirullo
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (B.C.); (M.F.); (M.T.); (R.A.)
| | - Massimiliano Francia
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (B.C.); (M.F.); (M.T.); (R.A.)
| | - Valeria Rondinone
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Luigina Serrecchia
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Lorenzo Pace
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Michela Iatarola
- Istituto Zooprofilattico Sperimentale della Puglia e della Basilicata, Anthrax Reference Institute of Italy, Via Manfredonia 20, 71121 Foggia, Italy; (V.M.); (A.D.); (A.F.); (V.R.); (L.S.); (L.P.); (M.I.)
| | - Michela Tarantino
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (B.C.); (M.F.); (M.T.); (R.A.)
| | - Rosanna Adone
- Department of Food Safety, Nutrition and Veterinary Public Health, Istituto Superiore di Sanità, Viale Regina Elena 299, 00161 Rome, Italy; (B.C.); (M.F.); (M.T.); (R.A.)
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Jia Z, Luo Y, Wang D, Dinh QN, Lin S, Sharma A, Block EM, Yang M, Gu T, Pearlstein AJ, Yu H, Zhang B. Nondestructive multiplex detection of foodborne pathogens with background microflora and symbiosis using a paper chromogenic array and advanced neural network. Biosens Bioelectron 2021; 183:113209. [PMID: 33836430 DOI: 10.1016/j.bios.2021.113209] [Citation(s) in RCA: 16] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2021] [Revised: 03/11/2021] [Accepted: 03/28/2021] [Indexed: 01/04/2023]
Abstract
We have developed an inexpensive, standardized paper chromogenic array (PCA) integrated with a machine learning approach to accurately identify single pathogens (Listeria monocytogenes, Salmonella Enteritidis, or Escherichia coli O157:H7) or multiple pathogens (either in multiple monocultures, or in a single cocktail culture), in the presence of background microflora on food. Cantaloupe, a commodity with significant volatile organic compound (VOC) emission and large diverse populations of background microflora, was used as the model food. The PCA was fabricated from a paper microarray via photolithography and paper microfluidics, into which 22 chromogenic dye spots were infused and to which three red/green/blue color-standard dots were taped. When exposed to VOCs emitted by pathogens of interest, dye spots exhibited distinguishable color changes and pattern shifts, which were automatically segmented and digitized into a ΔR/ΔG/ΔB database. We developed an advanced deep feedforward neural network with a learning rate scheduler, L2 regularization, and shortcut connections. After training on the ΔR/ΔG/ΔB database, the network demonstrated excellent performance in identifying pathogens in single monocultures, multiple monocultures, and in cocktail culture, and in distinguishing them from the background signal on cantaloupe, providing accuracy of up to 93% and 91% under ambient and refrigerated conditions, respectively. With its combination of speed, reliability, portability, and low cost, this nondestructive approach holds great potential to significantly advance culture-free pathogen detection and identification on food, and is readily extendable to other food commodities with complex microflora.
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Affiliation(s)
- Zhen Jia
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Yaguang Luo
- Environmental Microbial and Food Safety Lab and Food Quality Lab, U.S. Department of Agriculture, Agricultural Research Service, Beltsville, 20705, MD, USA
| | - Dayang Wang
- Department of Electrical and Computer Engineering, University of Massachusetts, Lowell, 01854, MA, USA
| | - Quynh N Dinh
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Sophia Lin
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Arnav Sharma
- Department of Physiology and Neurobiology, University of Connecticut, Storrs, 06269, CT, USA
| | - Ethan M Block
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Manyun Yang
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Tingting Gu
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA
| | - Arne J Pearlstein
- Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, 61801, IL, USA
| | - Hengyong Yu
- Department of Electrical and Computer Engineering, University of Massachusetts, Lowell, 01854, MA, USA
| | - Boce Zhang
- Department of Biomedical and Nutritional Sciences, University of Massachusetts, Lowell, 01854, MA, USA.
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Simoska O, Stevenson KJ. Electrochemical sensors for rapid diagnosis of pathogens in real time. Analyst 2020; 144:6461-6478. [PMID: 31603150 DOI: 10.1039/c9an01747j] [Citation(s) in RCA: 67] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
Microbial infections remain the principal cause for high morbidity and mortality rates. While approximately 1400 human pathogens have been recognized, the majority of healthcare-associated infectious diseases are caused by only a few opportunistic pathogens (e.g., Pseudomonas aeruginosa, Staphylococcus aureus, Escherichia coli), which are associated with increased antibiotic and antimicrobial resistance. Rapid detection, reliable identification and real-time monitoring of these pathogens remain not only a scientific problem but also a practical challenge of vast importance, especially in tailoring effective treatment strategies. Although the development of vaccinations and antibacterial drug treatments are the leading research, progress, and implementation of early warning, quantitative systems indicative of confirming pathogen presence are necessary. Over the years, various approaches, such as conventional culturing, straining, molecular methods (e.g., polymerase chain reaction and immunological assays), microscopy-based and mass spectrometry techniques, have been employed to identify and quantify pathogenic agents. While being sensitive in some cases, these procedures are costly, time-consuming, mostly qualitative, and are indirect detection methods. A great challenge is therefore to develop rapid, highly sensitive, specific devices with adequate figures of merit to corroborate the presence of microbes and enable dynamic real-time measurements of metabolism. As an alternative, electrochemical sensor platforms have been developed as powerful quantitative tools for label-free detection of infection-related biomarkers with high sensitivity. This minireview is focused on the latest electrochemical-based approaches for pathogen sensing, putting them into the context of standard sensing methods, such as cell culturing, mass spectrometry, and fluorescent-based approaches. Description of the latest, impactful electrochemical sensors for pathogen detection will be presented. Recent breakthroughs will be highlighted, including the use of micro- and nano-electrode arrays for real-time detection of bacteria in polymicrobial infections and microfluidic devices for pathogen separation analysis. We will conclude with perspectives and outlooks to understand shortcomings in designing future sensing schemes. The need for high sensitivity and selectivity, low-cost implementation, fast detection, and screening increases provides an impetus for further development in electrochemical detectors for microorganisms and biologically relevant targets.
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Affiliation(s)
- Olja Simoska
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, TX 78712, USA
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Simoska O, Sans M, Eberlin LS, Shear JB, Stevenson KJ. Electrochemical monitoring of the impact of polymicrobial infections on Pseudomonas aeruginosa and growth dependent medium. Biosens Bioelectron 2019; 142:111538. [DOI: 10.1016/j.bios.2019.111538] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2019] [Revised: 07/16/2019] [Accepted: 07/24/2019] [Indexed: 01/04/2023]
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Simoska O, Sans M, Fitzpatrick MD, Crittenden CM, Eberlin LS, Shear JB, Stevenson KJ. Real-Time Electrochemical Detection of Pseudomonas aeruginosa Phenazine Metabolites Using Transparent Carbon Ultramicroelectrode Arrays. ACS Sens 2019; 4:170-179. [PMID: 30525472 DOI: 10.1021/acssensors.8b01152] [Citation(s) in RCA: 42] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Here, we use a recently developed electrochemical sensing platform of transparent carbon ultramicroelectrode arrays (T-CUAs) for the in vitro detection of phenazine metabolites from the opportunistic human pathogen Pseudomonas aeruginosa. Specifically, redox-active metabolites pyocyanin (PYO), 5-methylphenazine-1-carboxylic acid (5-MCA), and 1-hydroxyphenazine (OHPHZ) are produced by P. aeruginosa, which is commonly found in chronic wound infections and in the lungs of cystic fibrosis patients. As highly diffusible chemicals, PYO and other metabolites are extremely toxic to surrounding host cells and other competing microorganisms, thus their detection is of great importance as it could provide insights regarding P. aeruginosa virulence mechanisms. Phenazine metabolites are known to play important roles in cellular functions; however, very little is known about how their concentrations fluctuate and influence cellular behaviors over the course of infection and growth. Herein we report the use of easily assembled, low-cost electrochemical sensors that provide rapid response times, enhanced sensitivity, and high reproducibility. As such, these T-CUAs enable real-time electrochemical monitoring of PYO and another extremely reactive and distinct redox-active phenazine metabolite, 5-methylphenazine-1-carboxylic acid (5-MCA), from a highly virulent laboratory P. aeruginosa strain, PA14. In addition to quantifying phenazine metabolite concentrations, changes in phenazine dynamics are observed in the biosynthetic route for the production of PYO. Our quantitative results, over a 48-h period, show increasing PYO concentrations during the first 21 h of bacterial growth, after which PYO levels plateau and then slightly decrease. Additionally, we explore environmental effects on phenazine dynamics and PYO concentrations in two growth media, tryptic soy broth (TSB) and lysogeny broth (LB). The maximum concentrations of cellular PYO were determined to be 190 ± 5 μM and 150 ± 1 μM in TSB and LB, respectively. Finally, using desorption electrospray ionization (DESI) and nanoelectrospray ionization (nano-ESI) mass spectrometry we confirm the detection and identification of reactive phenazine metabolites.
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Affiliation(s)
- Olja Simoska
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Marta Sans
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Mignon D. Fitzpatrick
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Christopher M. Crittenden
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Livia S. Eberlin
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Jason B. Shear
- Department of Chemistry, University of Texas at Austin, 1 University Station, Stop A5300, Austin, Texas 78712, United States
| | - Keith J. Stevenson
- Center for Electrochemical Energy Storage, Skolkovo Institute of Science and Technology, 3 Nobel Street, Moscow 143026, Russia
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Anti-infective potential of a quorum modulatory polyherbal extract (panchvalkal) against certain pathogenic bacteria. J Ayurveda Integr Med 2018; 11:336-343. [PMID: 33012317 PMCID: PMC7527823 DOI: 10.1016/j.jaim.2017.10.012] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 10/05/2017] [Accepted: 10/22/2017] [Indexed: 11/20/2022] Open
Abstract
Background In view of the gravity of the problem of antimicrobial resistance among pathogenic bacteria against conventional bactericidal agents, investigation on alternative approaches to combat bacterial infections is warranted. Objective Current study aimed at investigating anti-infective potential of a polyherbal ayurvedic formulation namely panchvalkal against three different pathogenic bacteria. Materials and methods The panchvalkal formulation available as Pentaphyte P5® was tested for its possible in vitro quorum-modulatory potential against Chromobacterium violaceum, Serratia marcescens, and Staphylococcus aureus through broth dilution assay. Invivo efficacy was demonstrated employing Caenorhabditis elegans as the model host for test pathogens. Results This formulation was found to exert quorum-modulatory effect on C. violaceum, S. marcescens, and S. aureus at 250–750 μg/ml. Besides altering production of the quorum sensing-regulated pigments in these bacteria, the test formulation also had in vitro effect on antibiotic susceptibility, catalase activity and haemolytic potential of the pathogens. Invivo assay confirmed the protective effect of this panchvalkal formulation on C. elegans, when challenged with the pathogenic bacteria. Repeated exposure of S. aureus to panchvalkal did not induce resistance in this bacterium. Conclusion To the best of our awareness, this the first report on quorum-modulatory potential of panchvalkal formulation, validating the anti-infective potential and moderate prebiotic property of this polyherbal preparation.
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Hongman H, Yifang W, Gongliang Z, Yaolei Z, Longquan X, Hongshun H, Yue W, Meishan L. Effects of Sulfide Flavors on AHL-Mediated Quorum Sensing and Biofilm Formation of Hafnia alvei. J Food Sci 2018; 83:2550-2559. [PMID: 30221799 DOI: 10.1111/1750-3841.14345] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2018] [Revised: 08/01/2018] [Accepted: 08/17/2018] [Indexed: 12/21/2022]
Abstract
In this study, 10 different sulfide flavor compounds commonly used as food additives were screened for antiquorum-sensing activity. Among these, diallyl disulfide (DADS) and methyl 2-methyl-3-furyl disulfide (MMFDS) were found to exert the strongest inhibition against violacein production in Chromobacterium violaceum 026, the tested biosensor strain. DADS and MMFDS also inhibited the growth of Hafnia alvei H4, yielding MIC values of 48 and 41.6 mM, respectively. In addition, DADS and MMFDS also inhibited the ability of H. alvei H4 to produce acyl-homoserine lactone as demonstrated by the reduced level of C6-HSL in the supernatant of DADS-treated culture. At concentrations corresponding to 1/4 MIC, DADS, and MMFDS inhibited the swarming ability of H. alvei H4 by 73.50% and 76.43%, respectively, while having virtually no effect on cell growth. The same concentrations of DADS and MMFDS also completely inhibited the formation of biofilm. These antiquorum sensing effects of DADS and MMFDS involved changes in the expression of the quorum-sensing genes luxI and luxR. Quantitative RT-PCR analysis showed that the mRNA levels of both genes were significantly reduced by DADS and MMDFS at concentrations below their MICs. However, further test using a mutant strain of H. alvei lacking luxR (ΔluxR) revealed significant reduction in luxI mRNA level upon treatment of the strain with DADS or MMDFS, but no change in luxR mRNA level occurred when a luxI-lacking mutant (ΔluxI) was treated with these compounds. The result therefore suggested that the antiquorum-sensing effect of DADS and MMFDS against H. alvei H4 might operate mainly through the inhibition of luxI expression in the cells. PRACTICAL APPLICATION The sulfide flavors compounds used in this paper are commonly used in food processing in China and are listed in the national standard of Chinese food additives GB2760-2014. The application of sulfide flavors in food processing can enhance aroma and prevent food spoilage.
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Affiliation(s)
- Hou Hongman
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Wang Yifang
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Zhang Gongliang
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Zhu Yaolei
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Xu Longquan
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Hao Hongshun
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Wang Yue
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
| | - Lu Meishan
- Liaoning Key Lab for Aquatic Processing Quality and Safety, School of Food Science and Technology, Dalian Polytechnic University, Dalian, 116034, People's Republic of China
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11
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Yan H, Wang M, Sun F, Dandekar AA, Shen D, Li N. A Metabolic Trade-Off Modulates Policing of Social Cheaters in Populations of Pseudomonas aeruginosa. Front Microbiol 2018. [PMID: 29535700 PMCID: PMC5835063 DOI: 10.3389/fmicb.2018.00337] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa uses quorum sensing (QS) to regulate the production of public goods such as the secreted protease elastase. P. aeruginosa requires the LasI-LasR QS circuit to induce elastase and enable growth on casein as the sole carbon and energy source. The LasI-LasR system also induces a second QS circuit, the RhlI-RhlR system. During growth on casein, LasR-mutant social cheaters emerge, and this can lead to a population collapse. In a minimal medium containing ammonium sulfate as a nitrogen source, populations do not collapse, and cheaters and cooperators reach a stable equilibrium; however, without ammonium sulfate, cheaters overtake the cooperators and populations collapse. We show that ammonium sulfate enhances the activity of the RhlI-RhlR system in casein medium and this leads to increased production of cyanide, which serves to control levels of cheaters. This enhancement of cyanide production occurs because of a trade-off in the metabolism of glycine: exogenous ammonium ion inhibits the transformation of glycine to 5,10-methylenetetrahydrofolate through a reduction in the expression of the glycine cleavage genes gcvP1 and gcvP2, thereby increasing the availability of glycine as a substrate for RhlR-regulated hydrogen cyanide synthesis. Thus, environmental ammonia enhances cyanide production and stabilizes QS in populations of P. aeruginosa.
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Affiliation(s)
- Huicong Yan
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Meizhen Wang
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Feng Sun
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China
| | - Ajai A Dandekar
- Department of Microbiology, University of Washington, Seattle, WA, United States.,Department of Medicine, University of Washington, Seattle, WA, United States
| | - Dongsheng Shen
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
| | - Na Li
- School of Environmental Science and Engineering, Zhejiang Gongshang University, Hangzhou, China.,Zhejiang Provincial Key Laboratory of Solid Waste Treatment and Recycling, Hangzhou, China
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12
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Homogentisic acid γ-lactone suppresses the virulence factors of Pseudomonas aeruginosa by quenching its quorum sensing signal molecules. CHINESE CHEM LETT 2018. [DOI: 10.1016/j.cclet.2017.09.052] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
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13
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Blasche S, Kim Y, Oliveira AP, Patil KR. Model microbial communities for ecosystems biology. ACTA ACUST UNITED AC 2017. [DOI: 10.1016/j.coisb.2017.09.002] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
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14
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Modarresi F, Azizi O, Shakibaie MR, Motamedifar M, Mansouri S. Cloning and expression of quorum sensing N-acyl-homoserine synthase (LuxI) gene detected in Acinetobacter baumannii. IRANIAN JOURNAL OF MICROBIOLOGY 2016; 8:139-46. [PMID: 27307980 PMCID: PMC4906721 DOI: pmid/27307980] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Background and Objectives: In present study we aimed to clone the luxI gene encoding N-acyl-homoserine synthase detected in clinical isolates of Acinetobacter baumannii and study its expression in Escherichia coli transformants. Materials and Methods: Four A. baumannii hospital strains which demonstrated strong biofilm activity were selected in this investigation. The presence of luxI gene was detected using PCR technique. Purified PCR product DNA was initially cloned into pTG19 and transformed to E. coli DH5α. The gene was then recovered from agarose gel and ligated by T4 DNA ligase into pET28a expression vector using NdeI and XhoI enzymes. pET28a + luxI was transformed into E. coli BL21 (DE3). The luxI putative gene was further detected in the transformants by colony PCR. Expression of the luxI gene in the recombinant E. coli BL21 cells was studied by quantitative real time PCR (qRT-PCR) and the presence of N-acylhomoserine lactone (AHL) was checked by colorimetric assay and Fourier Transform Infra-Red (FT-IR) spectroscopy. Results: We successfully cloned AHL gene from A. baumannii strain 23 to pET28a expression vector. There was four fold increases in expression of luxI in the transformants (P ≤ 0.05). It was found that, strain 23 and the transformants showed highest amount of AHL activity (OD = 1.524). The FT-IR analysis indicated stretching C=O bond of the lactone ring and primary amides (N=H) at 1764.69 cm−1 and 1659.23 cm−1 respectively. Conclusion: From above results we concluded that, luxI in A. baumannii is indeed responsible for AHL production and not regulation and pET28a vector allows efficient AHL expression in E. coli BL21 transformants.
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Affiliation(s)
- Farzan Modarresi
- Department of Microbiology and Virology, Afzalipuor School of Medicine, Kerman, Iran
| | - Omid Azizi
- Department of Microbiology and Virology, Afzalipuor School of Medicine, Kerman, Iran
| | - Mohammad Reza Shakibaie
- Department of Microbiology and Virology, Afzalipuor School of Medicine, Kerman, Iran; Research Center for Infectious Diseases and Tropical Medicine, Kerman, Iran; Environmental Health Engineering Research Center, Kerman University of Medical Sciences, Kerman, Iran
| | - Mohammad Motamedifar
- Departments of Bacteriology and Virology, School of Medicine, Shiraz University of Medical Sciences, Shiraz, Iran
| | - Shahla Mansouri
- Department of Microbiology and Virology, Afzalipuor School of Medicine, Kerman, Iran
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15
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Enterococcal Sex Pheromones: Evolutionary Pathways to Complex, Two-Signal Systems. J Bacteriol 2016; 198:1556-1562. [PMID: 27021562 DOI: 10.1128/jb.00128-16] [Citation(s) in RCA: 45] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Gram-positive bacteria carry out intercellular communication using secreted peptides. Important examples of this type of communication are the enterococcal sex pheromone systems, in which the transfer of conjugative plasmids is controlled by intercellular signaling among populations of donors and recipients. This review focuses on the pheromone response system of the conjugative plasmid pCF10. The peptide pheromones regulating pCF10 transfer act by modulating the ability of the PrgX transcription factor to repress the transcription of an operon encoding conjugation functions. Many Gram-positive bacteria regulate important processes, including the production of virulence factors, biofilm formation, sporulation, and genetic exchange using peptide-mediated signaling systems. The key master regulators of these systems comprise the RRNPP (RggRap/NprR/PlcR/PrgX) family of intracellular peptide receptors; these regulators show conserved structures. While many RRNPP systems include a core module of two linked genes encoding the regulatory protein and its cognate signaling peptide, the enterococcal sex pheromone plasmids have evolved to a complex system that also recognizes a second host-encoded signaling peptide. Additional regulatory genes not found in most RRNPP systems also modulate signal production and signal import in the enterococcal pheromone plasmids. This review summarizes several structural studies that cumulatively demonstrate that the ability of three pCF10 regulatory proteins to recognize the same 7-amino-acid pheromone peptide arose by convergent evolution of unrelated proteins from different families. We also focus on the selective pressures and structure/function constraints that have driven the evolution of pCF10 from a simple, single-peptide system resembling current RRNPPs in other bacteria to the current complex inducible plasmid transfer system.
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16
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Novel reporter for identification of interference with acyl homoserine lactone and autoinducer-2 quorum sensing. Appl Environ Microbiol 2016; 81:1477-89. [PMID: 25527543 DOI: 10.1128/aem.03290-14] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Two reporter strains were established to identify novel biomolecules interfering with bacterial communication (quorum sensing [QS]). The basic design of these Escherichia coli-based systems comprises a gene encoding a lethal protein fused to promoters induced in the presence of QS signal molecules. Consequently, these E. coli strains are unable to grow in the presence of the respective QS signal molecules unless a nontoxic QS-interfering compound is present. The first reporter strain designed to detect autoinducer-2 (AI-2)-interfering activities (AI2-QQ.1) contained the E. coli ccdB lethal gene under the control of the E. coli lsrA promoter. The second reporter strain (AI1-QQ.1) contained the Vibrio fischeri luxI promoter fused to the ccdB gene to detect interference with acyl-homoserine lactones. Bacteria isolated from the surfaces of several marine eukarya were screened for quorum- quenching (QQ) activities using the established reporter systems AI1-QQ.1 and AI2-QQ.1. Out of 34 isolates, two interfered with acylated homoserine lactone (AHL) signaling, five interfered with AI-2 QS signaling, and 10 were demonstrated to interfere with both signal molecules. Open reading frames (ORFs) conferring QQ activity were identified for three selected isolates (Photobacterium sp., Pseudoalteromonas sp., and Vibrio parahaemolyticus). Evaluation of the respective heterologously expressed and purified QQ proteins confirmed their ability to interfere with the AHL and AI-2 signaling processes.
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17
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Bucio-Cano A, Reyes-Arellano A, Correa-Basurto J, Bello M, Torres-Jaramillo J, Salgado-Zamora H, Curiel-Quesada E, Peralta-Cruz J, Avila-Sorrosa A. Targeting quorum sensing by designing azoline derivatives to inhibit the N-hexanoyl homoserine lactone-receptor CviR: Synthesis as well as biological and theoretical evaluations. Bioorg Med Chem 2015; 23:7565-77. [PMID: 26654469 DOI: 10.1016/j.bmc.2015.10.046] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2015] [Revised: 10/23/2015] [Accepted: 10/31/2015] [Indexed: 10/22/2022]
Abstract
To counteract bacterial resistance, we investigated the interruption of quorum sensing mediated by non-classical bioisosteres of the N-hexanoyl homoserine lactone with an azoline core. For this purpose, a set of selected 2-substituted azolines was synthesized, establishing the basis for a new protocol to synthesize 2-amino imidazolines. The synthesized compounds were evaluated as inhibitors of violacein production in Chromobacterium violaceum. Theoretical studies on bioisostere-protein interactions were performed using CviR. The results show that some azolines decreased violacein production, suggesting an antiquorum sensing profile against Gram-negative bacteria. Docking and molecular dynamic simulations together with binding free energy calculations revealed the exact binding and inhibitory profiles. These theoretical results show relationship with the in vitro activity of the azoline series.
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Affiliation(s)
- Alejandro Bucio-Cano
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
| | - Alicia Reyes-Arellano
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico.
| | - José Correa-Basurto
- Instituto Politécnico Nacional, Escuela Superior de Medicina, Laboratorio de Modelado Molecular y Diseño de Fármacos, Campus Casco de Santo Tomás, 11340 México, D.F., Mexico
| | - Martiniano Bello
- Instituto Politécnico Nacional, Escuela Superior de Medicina, Laboratorio de Modelado Molecular y Diseño de Fármacos, Campus Casco de Santo Tomás, 11340 México, D.F., Mexico
| | - Jenifer Torres-Jaramillo
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
| | - Héctor Salgado-Zamora
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
| | - Everardo Curiel-Quesada
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
| | - Javier Peralta-Cruz
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
| | - Alcives Avila-Sorrosa
- Instituto Politécnico Nacional, Escuela Nacional de Ciencias Biológicas, Departamento de Química Orgánica, Campus Casco de Santo Tomás, Carpio y Plan de Ayala S/N, Colonia Santo Tomás, 11340 México, D.F., Mexico
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18
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Goo E, An JH, Kang Y, Hwang I. Control of bacterial metabolism by quorum sensing. Trends Microbiol 2015; 23:567-76. [DOI: 10.1016/j.tim.2015.05.007] [Citation(s) in RCA: 83] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 05/07/2015] [Accepted: 05/20/2015] [Indexed: 01/03/2023]
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19
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A Social Medium: ASM's 5th Cell-Cell Communication in Bacteria Meeting in Review. J Bacteriol 2015; 197:2084-2093. [PMID: 25917904 DOI: 10.1128/jb.00161-15] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The 5th American Society for Microbiology Conference on Cell-Cell Communication in Bacteria (CCCB-5), which convened from October 18 - 21, 2014 in San Antonio, Texas, highlighted recent advances in our understanding of microbial intercellular signaling. While the CCCB meetings arose from interests in pheromone signaling and quorum sensing, it was evident at CCCB-5 that the cell-cell communication field is continuing to mature, expanding into new areas and integrating cutting-edge technologies. In this review, we recap some of the research discussed at CCCB-5 as well as the questions that have arisen from it.
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20
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21
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Song XN, Qiu HB, Xiao X, Cheng YY, Li WW, Sheng GP, Li XY, Yu HQ. Determination of autoinducer-2 in biological samples by high-performance liquid chromatography with fluorescence detection using pre-column derivatization. J Chromatogr A 2014; 1361:162-8. [DOI: 10.1016/j.chroma.2014.07.103] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Revised: 07/29/2014] [Accepted: 07/31/2014] [Indexed: 12/21/2022]
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22
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Shulami S, Shenker O, Langut Y, Lavid N, Gat O, Zaide G, Zehavi A, Sonenshein AL, Shoham Y. Multiple regulatory mechanisms control the expression of the Geobacillus stearothermophilus gene for extracellular xylanase. J Biol Chem 2014; 289:25957-75. [PMID: 25070894 DOI: 10.1074/jbc.m114.592873] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
Geobacillus stearothermophilus T-6 produces a single extracellular xylanase (Xyn10A) capable of producing short, decorated xylo-oligosaccharides from the naturally branched polysaccharide, xylan. Gel retardation assays indicated that the master negative regulator, XylR, binds specifically to xylR operators in the promoters of xylose and xylan-utilization genes. This binding is efficiently prevented in vitro by xylose, the most likely molecular inducer. Expression of the extracellular xylanase is repressed in medium containing either glucose or casamino acids, suggesting that carbon catabolite repression plays a role in regulating xynA. The global transcriptional regulator CodY was shown to bind specifically to the xynA promoter region in vitro, suggesting that CodY is a repressor of xynA. The xynA gene is located next to an uncharacterized gene, xynX, that has similarity to the NIF3 (Ngg1p interacting factor 3)-like protein family. XynX binds specifically to a 72-bp fragment in the promoter region of xynA, and the expression of xynA in a xynX null mutant appeared to be higher, indicating that XynX regulates xynA. The specific activity of the extracellular xylanase increases over 50-fold during early exponential growth, suggesting cell density regulation (quorum sensing). Addition of conditioned medium to fresh and low cell density cultures resulted in high expression of xynA, indicating that a diffusible extracellular xynA density factor is present in the medium. The xynA density factor is heat-stable, sensitive to proteases, and was partially purified using reverse phase liquid chromatography. Taken together, these results suggest that xynA is regulated by quorum-sensing at low cell densities.
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Affiliation(s)
- Smadar Shulami
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Ofer Shenker
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Yael Langut
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Noa Lavid
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Orit Gat
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Galia Zaide
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Arie Zehavi
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
| | - Abraham L Sonenshein
- the Department of Molecular Biology and Microbiology, Tufts University School of Medicine, Boston, Massachusetts 02111
| | - Yuval Shoham
- From the Department of Biotechnology and Food Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel and
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23
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Shong J, Collins CH. Quorum sensing-modulated AND-gate promoters control gene expression in response to a combination of endogenous and exogenous signals. ACS Synth Biol 2014; 3:238-46. [PMID: 24175658 DOI: 10.1021/sb4000965] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
We have constructed and characterized two synthetic AND-gate promoters that require both a quorum-sensing (QS) signal and an exogenously added inducer to turn on gene expression. The engineered promoters, LEE and TTE, contain binding sites for the QS-dependent repressor, EsaR, and either LacI or TetR, and they are induced by an acyl-homoserine lactone (AHL) signal and IPTG or aTc. Although repression of both LEE and TTE by wild-type EsaR was observed, induction of gene expression at physiologically relevant concentrations of AHL required the use of an EsaR variant with higher signal sensitivity. Gene expression from both LEE and TTE was shown to require both signal molecules, and gene expression above background levels was not observed with either signal alone. We added endogenous production of AHL to evaluate the ability of the promoters to function in a QS-dependent manner and observed that gene expression increased as a function of cell density only in the presence of exogenously added IPTG or aTc. Cell-cell communication-dependent AND-gate behaviors were demonstrated using an agar plate assay, where cells containing the engineered promoters were shown to respond to AHL produced by a second E. coli strain only in the presence of exogenously added IPTG or aTc. The promoters described in this work demonstrate that EsaR and its target DNA sequence can be used to engineer new promoters to respond to cell density or cell-cell communication. Further, the AND-gate promoters described here may serve as a template for new regulatory systems that integrate QS and the presence of key metabolites or other environmental cues to enable dynamic changes in gene expression for metabolic engineering applications.
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Affiliation(s)
- Jasmine Shong
- Department of Chemical
and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Center for Biotechnology
and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
| | - Cynthia H. Collins
- Department of Chemical
and Biological Engineering, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Center for Biotechnology
and Interdisciplinary Studies, Rensselaer Polytechnic Institute, 110 8th Street, Troy New York 12180 United States of America
- Department of Biology, Rensselaer Polytechnic Institute, 110 8th Street, Troy New
York 12180 United States of America
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Lang J, Faure D. Functions and regulation of quorum-sensing in Agrobacterium tumefaciens. FRONTIERS IN PLANT SCIENCE 2014; 5:14. [PMID: 24550924 PMCID: PMC3907764 DOI: 10.3389/fpls.2014.00014] [Citation(s) in RCA: 60] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/30/2013] [Accepted: 01/12/2014] [Indexed: 05/05/2023]
Abstract
In Agrobacterium tumefaciens, horizontal transfer and vegetative replication of oncogenic Ti plasmids involve a cell-to-cell communication process called quorum-sensing (QS). The determinants of the QS-system belong to the LuxR/LuxI class. The LuxI-like protein TraI synthesizes N-acyl-homoserine lactone molecules which act as diffusible QS-signals. Beyond a threshold concentration, these molecules bind and activate the LuxR-like transcriptional regulator TraR, thereby initiating the QS-regulatory pathway. For the last 20 years, A. tumefaciens has stood as a prominent model in the understanding of the LuxR/LuxI type of QS systems. A number of studies also unveiled features which are unique to A. tumefaciens QS, some of them being directly related to the phytopathogenic lifestyle of the bacteria. In this review, we will present the current knowledge of QS in A. tumefaciens at both the genetic and molecular levels. We will also describe how interactions with plant host modulate the QS pathway of A. tumefaciens, and discuss what could be the advantages for the agrobacteria to use such a tightly regulated QS-system to disseminate the Ti plasmids.
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Affiliation(s)
| | - Denis Faure
- *Correspondence: Denis Faure, Institut des Sciences du Végétal, UPR2355, Centre National de la Recherche Scientifique, 1 Avenue de la Terrasse, 91 198 Gif-sur-Yvette, France e-mail:
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25
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Katharios-Lanwermeyer S, Xi C, Jakubovics NS, Rickard AH. Mini-review: Microbial coaggregation: ubiquity and implications for biofilm development. BIOFOULING 2014; 30:1235-1251. [PMID: 25421394 DOI: 10.1080/08927014.2014.976206] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Coaggregation is the specific recognition and adherence of genetically distinct microorganisms. Because most biofilms are polymicrobial communities, there is potential for coaggregation to play an integral role in spatiotemporal biofilm development and the moderation of biofilm community composition. However, understanding of the mechanisms contributing to coaggregation and the relevance of coaggregation to biofilm ecology is at a very early stage. The purpose of this review is to highlight recent advances in the understanding of microbial coaggregation within different environments and to describe the possible ecological ramifications of such interactions. Bacteria that coaggregate with many partner species within different environments will be highlighted, including oral streptococci and oral bridging organisms such as fusobacteria, as well as the freshwater sphingomonads and acinetobacters. Irrespective of environment, it is proposed that coaggregation is essential for the orchestrated development of multi-species biofilms.
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Affiliation(s)
- S Katharios-Lanwermeyer
- a Department of Environmental Health Sciences , University of Michigan , Ann Arbor , MI , USA
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Redox interactions between structurally different alkylresorcinols and iron(III) in aqueous media: frozen-solution 57Fe Mössbauer spectroscopic studies, redox kinetics and quantum chemical evaluation of the alkylresorcinol reactivities. Struct Chem 2013. [DOI: 10.1007/s11224-013-0367-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
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Modulation of the Bacillus anthracis secretome by the immune inhibitor A1 protease. J Bacteriol 2013; 196:424-35. [PMID: 24214942 DOI: 10.1128/jb.00690-13] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
The Bacillus anthracis secretome includes protective antigen, lethal factor, and edema factor, which are the components of anthrax toxin, and other proteins with known or potential roles in anthrax disease. Immune inhibitor A1 (InhA1) is a secreted metalloprotease that is unique to pathogenic members of the Bacillus genus and has been associated with cleavage of host proteins during infection. Here, we report the effect of InhA1 on the B. anthracis secretome. Differential in-gel electrophoresis of proteins present in culture supernatants from a parent strain and an isogenic inhA1-null mutant revealed multiple differences. Of the 1,340 protein spots observed, approximately one-third were less abundant and one-third were more abundant in the inhA1 secretome than in the parent strain secretome. Proteases were strongly represented among those proteins exhibiting a 9-fold or greater change. InhA1 purified from a B. anthracis culture supernatant directly cleaved each of the anthrax toxin proteins as well as an additional secreted protease, Npr599. The conserved zinc binding motif HEXXH of InhA1 (HEYGH) was critical for its proteolytic activity. Our data reveal that InhA1 directly and indirectly modulates the form and/or abundance of over half of all the secreted proteins of B. anthracis. The proteolytic activity of InhA1 on established secreted virulence factors, additional proteases, and other secreted proteins suggests that this major protease plays an important role in virulence not only by cleaving mammalian substrates but also by modulating the B. anthracis secretome itself.
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Proteomic analysis of the quorum-sensing regulon in Pantoea stewartii and identification of direct targets of EsaR. Appl Environ Microbiol 2013; 79:6244-52. [PMID: 23913428 DOI: 10.1128/aem.01744-13] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The proteobacterium Pantoea stewartii subsp. stewartii causes Stewart's wilt disease in maize when it colonizes the xylem and secretes large amounts of stewartan, an exopolysaccharide. The success of disease pathogenesis lies in the timing of bacterial virulence factor expression through the different stages of infection. Regulation is achieved through a quorum-sensing (QS) system consisting of the acyl-homoserine lactone (AHL) synthase, EsaI, and the transcription regulator EsaR. At low cell densities, EsaR represses transcription of itself and of rcsA, an activator of the stewartan biosynthesis operon; it also activates esaS, which encodes a small RNA (sRNA). Repression or activation ceases at high cell densities when EsaI synthesizes sufficient levels of the AHL ligand N-3-oxo-hexanoyl-L-homoserine lactone to bind and inactivate EsaR. This study aims to identify other genes activated or repressed by EsaR during the QS response. Proteomic analysis identified a QS regulon of more than 30 proteins. Electrophoretic mobility shift assays of promoters of genes encoding differentially expressed proteins distinguished direct targets of EsaR from indirect targets. Additional quantitative reverse transcription-PCR (qRT-PCR) and DNA footprinting analysis established that EsaR directly regulates the promoters of dkgA, glpF, and lrhA. The proteins encoded by dkgA, glpF, and lrhA are a 2,5-diketogluconate reductase, glycerol facilitator, and transcriptional regulator of chemotaxis and motility, respectively, indicating a more global QS response in P. stewartii than previously recognized.
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Chu W, Liu Y, Jiang Y, Zhu W, Zhuang X. Production of N-acyl Homoserine Lactones and Virulence Factors of Waterborne Aeromonas hydrophila. Indian J Microbiol 2013; 53:264-8. [PMID: 24426120 DOI: 10.1007/s12088-013-0381-4] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Accepted: 02/25/2013] [Indexed: 12/01/2022] Open
Abstract
Aeromonads are inhabitants of aquatic ecosystems and are described as being involved in intestinal disturbances and other infections. The purpose of this study was to investigate the production of N-acyl-homoserine lactone (AHL) signal molecules and some virulence factors, including hemolysins, proteases, extracellular nucleases production and cytotoxicity by waterborne Aeromonas hydrophila. A total of 24 strains isolated from fresh-water or diseased fish were used in the study. The majority A.hydrophila strains produce two AHL molecules (21/24), one is N-butanoyl homoserine lactone (BHL), and the other is N-hexanoyl homoserine lactone (HHL) according to thin-layer chromatography analysis. Among the virulence factors tested, more than 83 % of the isolates produced β haemolysin when inoculated on sheep blood agar, only 50 % of the isolates displayed DNase activity, 75 % of the isolates shown proteolytic activity on skimmed milk plate, and cytotoxic activity was detected in 20 of 24 of the isolates. The strains producing AHLs possessed one or more virulence factors. In conclusion, the production of quorum sensing signal molecules is common among the strains that we examined, and there seems to some relationships between quorum sensing signal production and virulence factors in A. hydrophila.
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Affiliation(s)
- Weihua Chu
- Department of Microbiology, School of Life Science & Technology, China Pharmaceutical University, No. 24 Tongjiaxiang Road, 210009 Nanjing, People's Republic of China
| | - Yongwang Liu
- College of Veterinary Medicine, Nanjing Agricultural University, 210095 Nanjing, People's Republic of China
| | - Yan Jiang
- Jiangsu Entry-Exit Inspection and Quarantine Buearu, 210001 Nanjing, People's Republic of China
| | - Wei Zhu
- Department of Microbiology, School of Life Science & Technology, China Pharmaceutical University, No. 24 Tongjiaxiang Road, 210009 Nanjing, People's Republic of China
| | - Xiyi Zhuang
- Department of Microbiology, School of Life Science & Technology, China Pharmaceutical University, No. 24 Tongjiaxiang Road, 210009 Nanjing, People's Republic of China
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McFall-Ngai M, Hadfield MG, Bosch TCG, Carey HV, Domazet-Lošo T, Douglas AE, Dubilier N, Eberl G, Fukami T, Gilbert SF, Hentschel U, King N, Kjelleberg S, Knoll AH, Kremer N, Mazmanian SK, Metcalf JL, Nealson K, Pierce NE, Rawls JF, Reid A, Ruby EG, Rumpho M, Sanders JG, Tautz D, Wernegreen JJ. Animals in a bacterial world, a new imperative for the life sciences. Proc Natl Acad Sci U S A 2013; 110:3229-36. [PMID: 23391737 PMCID: PMC3587249 DOI: 10.1073/pnas.1218525110] [Citation(s) in RCA: 1561] [Impact Index Per Article: 141.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
In the last two decades, the widespread application of genetic and genomic approaches has revealed a bacterial world astonishing in its ubiquity and diversity. This review examines how a growing knowledge of the vast range of animal-bacterial interactions, whether in shared ecosystems or intimate symbioses, is fundamentally altering our understanding of animal biology. Specifically, we highlight recent technological and intellectual advances that have changed our thinking about five questions: how have bacteria facilitated the origin and evolution of animals; how do animals and bacteria affect each other's genomes; how does normal animal development depend on bacterial partners; how is homeostasis maintained between animals and their symbionts; and how can ecological approaches deepen our understanding of the multiple levels of animal-bacterial interaction. As answers to these fundamental questions emerge, all biologists will be challenged to broaden their appreciation of these interactions and to include investigations of the relationships between and among bacteria and their animal partners as we seek a better understanding of the natural world.
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Affiliation(s)
- Margaret McFall-Ngai
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706
| | | | - Thomas C. G. Bosch
- Zoological Institute, Christian-Albrechts-University, D-24098 Kiel, Germany
| | - Hannah V. Carey
- Department of Comparative Biosciences, University of Wisconsin, Madison, WI 53706
| | | | - Angela E. Douglas
- Department of Entomology and Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853
| | - Nicole Dubilier
- Max Planck Institute for Marine Microbiology, Symbiosis Group, D-28359 Bremen, Germany
| | - Gerard Eberl
- Lymphoid Tissue Development Unit, Institut Pasteur, 75724 Paris, France
| | - Tadashi Fukami
- Department of Biology, Stanford University, Stanford, CA 94305
| | - Scott F. Gilbert
- Biotechnology Institute, University of Helsinki, Helsinki 00014, Finland
| | - Ute Hentschel
- Julius-von-Sachs Institute, University of Wuerzburg, D-97082 Wuezburg, Germany
| | - Nicole King
- Molecular and Cell Biology, University of California, Berkeley, CA 94720
| | - Staffan Kjelleberg
- Singapore Centre on Environmental Life Sciences Engineering, Nanyang Technological University, Singapore 637551, and Centre for Marine Bio-Innovation and School of Biotechnology and Biomolecular Sciences, University of New South Wales, Sydney 2052, Australia
| | | | - Natacha Kremer
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706
| | | | | | - Kenneth Nealson
- Department of Earth Sciences, University of Southern California, Los Angeles, CA 90089
| | - Naomi E. Pierce
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | - John F. Rawls
- Cell Biology and Physiology, University of North Carolina, Chapel Hill, NC 27599
| | - Ann Reid
- American Academy of Microbiology, Washington, DC 20036
| | - Edward G. Ruby
- Department of Medical Microbiology and Immunology, University of Wisconsin, Madison, WI 53706
| | - Mary Rumpho
- Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT 06269
| | - Jon G. Sanders
- Department of Organismic and Evolutionary Biology, Harvard University, Cambridge, MA 02138
| | - Diethard Tautz
- Department of Evolutionary Genetics, Max Planck Institute for Evolutionary Biology, D-24306 Plön, Germany; and
| | - Jennifer J. Wernegreen
- Nicholas School and Institute for Genome Sciences and Policy, Duke University, Durham, NC 27708
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31
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Nadell CD, Bucci V, Drescher K, Levin SA, Bassler BL, Xavier JB. Cutting through the complexity of cell collectives. Proc Biol Sci 2013; 280:20122770. [PMID: 23363630 DOI: 10.1098/rspb.2012.2770] [Citation(s) in RCA: 104] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Via strength in numbers, groups of cells can influence their environments in ways that individual cells cannot. Large-scale structural patterns and collective functions underpinning virulence, tumour growth and bacterial biofilm formation are emergent properties of coupled physical and biological processes within cell groups. Owing to the abundance of factors influencing cell group behaviour, deriving general principles about them is a daunting challenge. We argue that combining mechanistic theory with theoretical ecology and evolution provides a key strategy for clarifying how cell groups form, how they change in composition over time, and how they interact with their environments. Here, we review concepts that are critical for dissecting the complexity of cell collectives, including dimensionless parameter groups, individual-based modelling and evolutionary theory. We then use this hybrid modelling approach to provide an example analysis of the evolution of cooperative enzyme secretion in bacterial biofilms.
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Affiliation(s)
- Carey D Nadell
- Department of Molecular Biology, Princeton University, Princeton, NJ 08544, USA.
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Gillings MR. Evolutionary consequences of antibiotic use for the resistome, mobilome and microbial pangenome. Front Microbiol 2013; 4:4. [PMID: 23386843 PMCID: PMC3560386 DOI: 10.3389/fmicb.2013.00004] [Citation(s) in RCA: 144] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2012] [Accepted: 01/03/2013] [Indexed: 12/16/2022] Open
Abstract
The widespread use and abuse of antibiotic therapy has evolutionary and ecological consequences, some of which are only just beginning to be examined. One well known consequence is the fixation of mutations and lateral gene transfer (LGT) events that confer antibiotic resistance. Sequential selection events, driven by different classes of antibiotics, have resulted in the assembly of diverse resistance determinants and mobile DNAs into novel genetic elements of ever-growing complexity and flexibility. These novel plasmids, integrons, and genomic islands have now become fixed at high frequency in diverse cell lineages by human antibiotic use. Consequently they can be regarded as xenogenetic pollutants, analogous to xenobiotic compounds, but with the critical distinction that they replicate rather than degrade when released to pollute natural environments. Antibiotics themselves must also be regarded as pollutants, since human production overwhelms natural synthesis, and a major proportion of ingested antibiotic is excreted unchanged into waste streams. Such antibiotic pollutants have non-target effects, raising the general rates of mutation, recombination, and LGT in all the microbiome, and simultaneously providing the selective force to fix such changes. This has the consequence of recruiting more genes into the resistome and mobilome, and of increasing the overlap between these two components of microbial genomes. Thus the human use and environmental release of antibiotics is having second order effects on the microbial world, because these small molecules act as drivers of bacterial evolution. Continued pollution with both xenogenetic elements and the selective agents that fix such elements in populations has potentially adverse consequences for human welfare.
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Affiliation(s)
- Michael R Gillings
- Department of Biological Sciences, Macquarie University Sydney, NSW, Australia
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Stacy DM, Le Quement ST, Hansen CL, Clausen JW, Tolker-Nielsen T, Brummond JW, Givskov M, Nielsen TE, Blackwell HE. Synthesis and biological evaluation of triazole-containing N-acyl homoserine lactones as quorum sensing modulators. Org Biomol Chem 2012; 11:938-54. [PMID: 23258305 DOI: 10.1039/c2ob27155a] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Many bacterial species are capable of assessing their local population densities through a cell-cell signaling mechanism termed quorum sensing (QS). This intercellular communication process is mediated by small molecule or peptide ligands and their cognate protein receptors. Numerous pathogens use QS to initiate virulence once they achieve a threshold cell number on a host. Consequently, approaches to intercept QS have attracted considerable attention as potential anti-infective therapies. Our interest in the development of small molecule tools to modulate QS pathways motivated us to evaluate triazole-containing analogs of natural N-acyl L-homoserine lactone (AHL) signals as non-native QS agonists and antagonists in Gram-negative bacteria. We synthesized 72 triazole derivatives of five broad structure types in high yields and purities using efficient Cu(I)-catalyzed azide-alkyne couplings. These compounds were evaluated for their ability to activate or inhibit two QS receptors from two prevalent pathogens - LasR from Pseudomonas aeruginosa and AbaR from Acinetobacter baumannii- using bacterial reporter strains. Several triazole derivatives were identified that were capable of strongly modulating the activity of LasR and AbaR. These compounds represent a new and synthetically accessible class of AHL analogs, and could find utility as chemical tools to study QS and its role in bacterial virulence.
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Affiliation(s)
- Danielle M Stacy
- Department of Chemistry, University of Wisconsin-Madison, 1101 University Ave., Madison, WI 53706, USA
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Ryan GT, Wei Y, Winans SC. A LuxR-type repressor of Burkholderia cenocepacia inhibits transcription via antiactivation and is inactivated by its cognate acylhomoserine lactone. Mol Microbiol 2012; 87:94-111. [PMID: 23136852 DOI: 10.1111/mmi.12085] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/29/2012] [Indexed: 11/30/2022]
Abstract
Burkholderia cenocepacia is an opportunistic human pathogen that encodes two LuxI-type acylhomoserine lactone (AHL) synthases and three LuxR-type AHL receptors. Of these, cepI and cepR form a cognate synthase/receptor pair, as do cciI and cciR, while cepR2 lacks a genetically linked AHL synthase gene. Another group showed that a cepR2 mutant overexpressed a cluster of linked genes that appear to direct the production of a secondary metabolite. We found that these same genes were upregulated by octanoylhomoserine lactone (OHL), which is synthesized by CepI. These data suggest that several cepR2-linked promoters are repressed by CepR2 and that CepR2 is antagonized by OHL. Fusions of two divergent promoters to lacZ were used to confirm these hypotheses, and promoter resections and DNase I footprinting assays revealed a single CepR2 binding site between the two promoters. This binding site lies well upstream of both promoters, suggesting an unusual mode of repression. Adjacent to the cepR2 gene is a gene that we designate cepS, which encodes an AraC-type transcription factor. CepS is essential for expression of both promoters, regardless of the CepR2 status or OHL concentration. CepS therefore acts downstream of CepR2, and CepR2 appears to function as a CepS antiactivator.
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Affiliation(s)
- Gina T Ryan
- Department of Microbiology, Cornell University, Ithaca, NY 14853, USA
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Balasubramanian D, Schneper L, Kumari H, Mathee K. A dynamic and intricate regulatory network determines Pseudomonas aeruginosa virulence. Nucleic Acids Res 2012; 41:1-20. [PMID: 23143271 PMCID: PMC3592444 DOI: 10.1093/nar/gks1039] [Citation(s) in RCA: 313] [Impact Index Per Article: 26.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Pseudomonas aeruginosa is a metabolically versatile bacterium that is found in a wide range of biotic and abiotic habitats. It is a major human opportunistic pathogen causing numerous acute and chronic infections. The critical traits contributing to the pathogenic potential of P. aeruginosa are the production of a myriad of virulence factors, formation of biofilms and antibiotic resistance. Expression of these traits is under stringent regulation, and it responds to largely unidentified environmental signals. This review is focused on providing a global picture of virulence gene regulation in P. aeruginosa. In addition to key regulatory pathways that control the transition from acute to chronic infection phenotypes, some regulators have been identified that modulate multiple virulence mechanisms. Despite of a propensity for chaotic behaviour, no chaotic motifs were readily observed in the P. aeruginosa virulence regulatory network. Having a ‘birds-eye’ view of the regulatory cascades provides the forum opportunities to pose questions, formulate hypotheses and evaluate theories in elucidating P. aeruginosa pathogenesis. Understanding the mechanisms involved in making P. aeruginosa a successful pathogen is essential in helping devise control strategies.
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Affiliation(s)
- Deepak Balasubramanian
- Department of Biological Sciences, College of Arts and Science, Florida International University, Miami, FL 33199, USA
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36
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Stacy DM, Welsh MA, Rather PN, Blackwell HE. Attenuation of quorum sensing in the pathogen Acinetobacter baumannii using non-native N-Acyl homoserine lactones. ACS Chem Biol 2012; 7:1719-28. [PMID: 22853441 DOI: 10.1021/cb300351x] [Citation(s) in RCA: 88] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Many bacterial pathogens use quorum sensing (QS) to control virulence. As a result, the development of methods to intercept QS has attracted significant interest as a potential anti-infective therapy. Acinetobacter baumannii has emerged as a pan-drug-resistant pathogen and displays a remarkable ability to persist in hospital settings despite desiccation and antimicrobial treatment. Recent studies have shown that A. baumannii QS mutants have limited motility and fail to form mature biofilms; these phenotypes are linked to its ability to persist on biotic and abiotic surfaces and increase its pathogenicity. A. baumannii uses N-(3-hydroxydodecanoyl)-l-homoserine lactone (OH-dDHL) and its putative cognate receptor, AbaR, for QS. We sought to identify non-native ligands capable of blocking or promoting AbaR activity in A. baumannii for use as chemical probes to modulate QS phenotypes in this pathogen. We screened a focused library of synthetic, non-native N-acyl homoserine lactones (AHLs) to identify such compounds, and several highly potent antagonists and agonists were uncovered, with IC(50) and EC(50) values in the low micromolar range, respectively. The strongest AbaR antagonists largely contained aromatic acyl groups, whereas the AbaR agonists closely resembled OH-dDHL. Notably, the 10 most potent AbaR antagonists also strongly inhibited A. baumannii motility, and five antagonists reduced biofilm formation in A. baumannii by up to 40%. The discovery of these compounds is significant, as they represent, to our knowledge, the first non-native modulators of QS in A. baumannii to be reported and could find utility as new tools to study the role and timing of QS phenotypes in A. baumannii infections.
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Affiliation(s)
- Danielle M. Stacy
- Department of Chemistry, University of Madison−Wisconsin, 1101 University
Ave., Madison, Wisconsin 53706, United States
| | - Michael A. Welsh
- Department of Chemistry, University of Madison−Wisconsin, 1101 University
Ave., Madison, Wisconsin 53706, United States
| | - Philip N. Rather
- Department of Microbiology and
Immunology, Emory University School of Medicine, 3001 Rollins Research Center, Atlanta, Georgia 30322, United States
- Research Service, Veterans Affairs Medical Center, 1670 Clairmont Rd.,
Decatur, Georgia 30033, United States
| | - Helen E. Blackwell
- Department of Chemistry, University of Madison−Wisconsin, 1101 University
Ave., Madison, Wisconsin 53706, United States
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