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Cifuente JO, Colleoni C, Kalscheuer R, Guerin ME. Architecture, Function, Regulation, and Evolution of α-Glucans Metabolic Enzymes in Prokaryotes. Chem Rev 2024; 124:4863-4934. [PMID: 38606812 PMCID: PMC11046441 DOI: 10.1021/acs.chemrev.3c00811] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/13/2024]
Abstract
Bacteria have acquired sophisticated mechanisms for assembling and disassembling polysaccharides of different chemistry. α-d-Glucose homopolysaccharides, so-called α-glucans, are the most widespread polymers in nature being key components of microorganisms. Glycogen functions as an intracellular energy storage while some bacteria also produce extracellular assorted α-glucans. The classical bacterial glycogen metabolic pathway comprises the action of ADP-glucose pyrophosphorylase and glycogen synthase, whereas extracellular α-glucans are mostly related to peripheral enzymes dependent on sucrose. An alternative pathway of glycogen biosynthesis, operating via a maltose 1-phosphate polymerizing enzyme, displays an essential wiring with the trehalose metabolism to interconvert disaccharides into polysaccharides. Furthermore, some bacteria show a connection of intracellular glycogen metabolism with the genesis of extracellular capsular α-glucans, revealing a relationship between the storage and structural function of these compounds. Altogether, the current picture shows that bacteria have evolved an intricate α-glucan metabolism that ultimately relies on the evolution of a specific enzymatic machinery. The structural landscape of these enzymes exposes a limited number of core catalytic folds handling many different chemical reactions. In this Review, we present a rationale to explain how the chemical diversity of α-glucans emerged from these systems, highlighting the underlying structural evolution of the enzymes driving α-glucan bacterial metabolism.
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Affiliation(s)
- Javier O. Cifuente
- Instituto
Biofisika (UPV/EHU, CSIC), University of
the Basque Country, E-48940 Leioa, Spain
| | - Christophe Colleoni
- University
of Lille, CNRS, UMR8576-UGSF -Unité de Glycobiologie Structurale
et Fonctionnelle, F-59000 Lille, France
| | - Rainer Kalscheuer
- Institute
of Pharmaceutical Biology and Biotechnology, Heinrich Heine University, 40225 Dusseldorf, Germany
| | - Marcelo E. Guerin
- Structural
Glycobiology Laboratory, Department of Structural and Molecular Biology, Molecular Biology Institute of Barcelona (IBMB), Spanish
National Research Council (CSIC), Barcelona Science Park, c/Baldiri Reixac 4-8, Tower R, 08028 Barcelona, Catalonia, Spain
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2
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Totsline N, Kniel KE, Bais HP. Microgravity and evasion of plant innate immunity by human bacterial pathogens. NPJ Microgravity 2023; 9:71. [PMID: 37679341 PMCID: PMC10485020 DOI: 10.1038/s41526-023-00323-x] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 08/16/2023] [Indexed: 09/09/2023] Open
Abstract
Spaceflight microgravity and modeled-microgravity analogs (MMA) broadly alter gene expression and physiology in both pathogens and plants. Research elucidating plant and bacterial responses to normal gravity or microgravity has shown the involvement of both physiological and molecular mechanisms. Under true and simulated microgravity, plants display differential expression of pathogen-defense genes while human bacterial pathogens exhibit increased virulence, antibiotic resistance, stress tolerance, and reduced LD50 in animal hosts. Human bacterial pathogens including Salmonella enterica and E. coli act as cross-kingdom foodborne pathogens by evading and suppressing the innate immunity of plants for colonization of intracellular spaces. It is unknown if evasion and colonization of plants by human pathogens occurs under microgravity and if there is increased infection capability as demonstrated using animal hosts. Understanding the relationship between microgravity, plant immunity, and human pathogens could prevent potentially deadly outbreaks of foodborne disease during spaceflight. This review will summarize (1) alterations to the virulency of human pathogens under microgravity and MMA, (2) alterations to plant physiology and gene expression under microgravity and MMA, (3) suppression and evasion of plant immunity by human pathogens under normal gravity, (4) studies of plant-microbe interactions under microgravity and MMA. A conclusion suggests future study of interactions between plants and human pathogens under microgravity is beneficial to human safety, and an investment in humanity's long and short-term space travel goals.
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Affiliation(s)
- Noah Totsline
- Department of Plant and Soil Sciences, AP Biopharma, University of Delaware, Newark, DE, USA.
| | - Kalmia E Kniel
- Department of Animal and Food Sciences, University of Delaware, Newark, DE, USA
| | - Harsh P Bais
- Department of Plant and Soil Sciences, AP Biopharma, University of Delaware, Newark, DE, USA
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3
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Patel P, Nandi A, Verma SK, Kaushik N, Suar M, Choi EH, Kaushik NK. Zebrafish-based platform for emerging bio-contaminants and virus inactivation research. THE SCIENCE OF THE TOTAL ENVIRONMENT 2023; 872:162197. [PMID: 36781138 PMCID: PMC9922160 DOI: 10.1016/j.scitotenv.2023.162197] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2022] [Revised: 01/23/2023] [Accepted: 02/08/2023] [Indexed: 05/27/2023]
Abstract
Emerging bio-contaminants such as viruses have affected health and environment settings of every country. Viruses are the minuscule entities resulting in severe contagious diseases like SARS, MERS, Ebola, and avian influenza. Recent epidemic like the SARS-CoV-2, the virus has undergone mutations strengthen them and allowing to escape from the remedies. Comprehensive knowledge of viruses is essential for the development of targeted therapeutic and vaccination treatments. Animal models mimicking human biology like non-human primates, rats, mice, and rabbits offer competitive advantage to assess risk of viral infections, chemical toxins, nanoparticles, and microbes. However, their economic maintenance has always been an issue. Furthermore, the redundancy of experimental results due to aforementioned aspects is also in examine. Hence, exploration for the alternative animal models is crucial for risk assessments. The current review examines zebrafish traits and explores the possibilities to monitor emerging bio-contaminants. Additionally, a comprehensive picture of the bio contaminant and virus particle invasion and abatement mechanisms in zebrafish and human cells is presented. Moreover, a zebrafish model to investigate the emerging viruses such as coronaviridae and poxviridae has been suggested.
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Affiliation(s)
- Paritosh Patel
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea
| | - Aditya Nandi
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
| | - Suresh K Verma
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India; Condensed Matter Theory Group, Materials Theory Division, Department of Physics and Astronomy, Uppsala University, Box 516, SE-751 20 Uppsala, Sweden
| | - Neha Kaushik
- Department of Biotechnology, College of Engineering, The University of Suwon, 18323 Hwaseong, Republic of Korea
| | - Mrutyunjay Suar
- School of Biotechnology, KIIT University, Bhubaneswar 751024, Odisha, India
| | - Eun Ha Choi
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea.
| | - Nagendra Kumar Kaushik
- Plasma Bioscience Research Center, Department of Electrical and Biological Physics, Kwangwoon University, 01897 Seoul, South Korea.
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Kumari M, Swarupa P, Kesari KK, Kumar A. Microbial Inoculants as Plant Biostimulants: A Review on Risk Status. LIFE (BASEL, SWITZERLAND) 2022; 13:life13010012. [PMID: 36675961 PMCID: PMC9860928 DOI: 10.3390/life13010012] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 11/01/2022] [Revised: 12/12/2022] [Accepted: 12/13/2022] [Indexed: 12/24/2022]
Abstract
Modern agriculture systems are copiously dependent on agrochemicals such as chemical fertilizers and pesticides intended to increase crop production and yield. The indiscriminate use of these chemicals not only affects the growth of plants due to the accumulation of toxic compounds, but also degrades the quality and life-supporting properties of soil. There is a dire need to develop some green approach that can resolve these issues and restore soil fertility and sustainability. The use of plant biostimulants has emerged as an environmentally friendly and acceptable method to increase crop productivity. Biostimulants contain biological substances which may be capable of increasing or stimulating plant growth in an eco-friendly manner. They are mostly biofertilizers that provide nutrients and protect plants from environmental stresses such as drought and salinity. In contrast to the protection of crop products, biostimulants not only act on the plant's vigor but also do not respond to direct actions against pests or diseases. Plant biostimulants improve nutrient mobilization and uptake, tolerance to stress, and thus crop quality when applied to plants directly or in the rhizospheric region. They foster plant growth and development by positively affecting the crop life-cycle starting from seed germination to plant maturity. Legalized application of biostimulants causes no hazardous effects on the environment and primarily provides nutrition to plants. It nurtures the growth of soil microorganisms, which leads to enhanced soil fertility and also improves plant metabolism. Additionally, it may positively influence the exogenous microbes and alter the equilibrium of the microfloral composition of the soil milieu. This review frequently cites the characterization of microbial plant biostimulants that belong to either a high-risk group or are closely related to human pathogens such as Pueudomonas, Klebsiella, Enterobacter, Acinetobacter, etc. These related pathogens cause ailments including septicemia, gastroenteritis, wound infections, inflammation in the respiratory system, meningitis, etc., of varied severity under different conditions of health status such as immunocompromized and comorbidity. Thus it may attract the related concern to review the risk status of biostimulants for their legalized applications in agriculture. This study mainly emphasizes microbial plant biostimulants and their safe application concerns.
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Affiliation(s)
- Menka Kumari
- Department of Life Sciences, School of Natural Sciences, Central University of Jharkhand Cheri-Manatu, Kamre, Kanke, Rachi 835222, India
| | - Preeti Swarupa
- Department of Microbiology, Patna Women’s College, Patna 800001, India
| | - Kavindra Kumar Kesari
- Department of Bioproducts and Biosystems, School of Chemical Engineering, Aalto University, 02150 Espoo, Finland
- Department of Applied Physics, School of Science, Aalto University, 02150 Espoo, Finland
- Correspondence: or (K.K.K.); (A.K.)
| | - Anil Kumar
- Department of Life Sciences, School of Natural Sciences, Central University of Jharkhand Cheri-Manatu, Kamre, Kanke, Rachi 835222, India
- Correspondence: or (K.K.K.); (A.K.)
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Leonard SR, Simko I, Mammel MK, Richter TKS, Brandl MT. Seasonality, shelf life and storage atmosphere are main drivers of the microbiome and E. coli O157:H7 colonization of post-harvest lettuce cultivated in a major production area in California. ENVIRONMENTAL MICROBIOME 2021; 16:25. [PMID: 34930479 PMCID: PMC8686551 DOI: 10.1186/s40793-021-00393-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 11/30/2021] [Indexed: 05/10/2023]
Abstract
BACKGROUND Lettuce is linked to recurrent outbreaks of Shiga toxin-producing Escherichia coli (STEC) infections, the seasonality of which remains unresolved. Infections have occurred largely from processed lettuce, which undergoes substantial physiological changes during storage. We investigated the microbiome and STEC O157:H7 (EcO157) colonization of fresh-cut lettuce of two cultivars with long and short shelf life harvested in the spring and fall in California and stored in modified atmosphere packaging (MAP) at cold and warm temperatures. RESULTS Inoculated EcO157 declined significantly less on the cold-stored cultivar with short shelf life, while multiplying rapidly at 24 °C independently of cultivar. Metagenomic sequencing of the lettuce microbiome revealed that the pre-storage bacterial community was variable but dominated by species in the Erwiniaceae and Pseudomonadaceae. After cold storage, the microbiome composition differed between cultivars, with a greater relative abundance (RA) of Erwiniaceae and Yersiniaceae on the cultivar with short shelf life. Storage at 24 °C shifted the microbiome to higher RAs of Erwiniaceae and Enterobacteriaceae and lower RA of Pseudomonadaceae compared with 6 °C. Fall harvest followed by lettuce deterioration were identified by recursive partitioning as important factors associated with high EcO157 survival at 6 °C, whereas elevated package CO2 levels correlated with high EcO157 multiplication at 24 °C. EcO157 population change correlated with the lettuce microbiome during 6 °C storage, with fall microbiomes supporting the greatest EcO157 survival on both cultivars. Fall and spring microbiomes differed before and during storage at both temperatures. High representation of Pantoea agglomerans was a predictor of fall microbiomes, lettuce deterioration, and enhanced EcO157 survival at 6 °C. In contrast, higher RAs of Erwinia persicina, Rahnella aquatilis, and Serratia liquefaciens were biomarkers of spring microbiomes and lower EcO157 survival. CONCLUSIONS The microbiome of processed MAP lettuce evolves extensively during storage. Under temperature abuse, high CO2 promotes a lettuce microbiome enriched in taxa with anaerobic capability and EcO157 multiplication. In cold storage, our results strongly support a role for season and lettuce deterioration in EcO157 survival and microbiome composition, suggesting that the physiology and microbiomes of fall- and spring-harvested lettuce may contribute to the seasonality of STEC outbreaks associated with lettuce grown in coastal California.
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Affiliation(s)
- Susan R Leonard
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA
| | - Ivan Simko
- Crop Improvement and Protection Research Unit, US Department of Agriculture, Agricultural Research Service, Salinas, CA, USA
| | - Mark K Mammel
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA
| | - Taylor K S Richter
- Office of Applied Research and Safety Assessment, Center for Food Safety and Applied Nutrition, U.S. Food and Drug Administration, Laurel, MD, USA
| | - Maria T Brandl
- Produce Safety and Microbiology Research Unit, US Department of Agriculture, Agricultural Research Service, Albany, CA, USA.
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Keswani C, Prakash O, Bharti N, Vílchez JI, Sansinenea E, Lally RD, Borriss R, Singh SP, Gupta VK, Fraceto LF, de Lima R, Singh HB. Re-addressing the biosafety issues of plant growth promoting rhizobacteria. THE SCIENCE OF THE TOTAL ENVIRONMENT 2019; 690:841-852. [PMID: 31302549 DOI: 10.1016/j.scitotenv.2019.07.046] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/24/2019] [Revised: 07/02/2019] [Accepted: 07/03/2019] [Indexed: 05/21/2023]
Abstract
To promote agronomic sustainability, extensive research is being carried out globally, investigating biofertilizer development. Recently, it has been realized that some microorganisms used as biofertilizers behave as opportunistic pathogens and belong to the biosafety level 2 (BSL-2) classification. This poses serious risk to the environmental and human health. Evidence presented in various scientific forums is increasingly favoring the merits of using BSL-2 microorganisms as biofertilizers. In this review, we emphasize that partial characterization based on traditional microbiological approaches and small subunit rRNA gene sequences/conserved regions are insufficient for the characterization of biofertilizer strains. It is advised herein, that research and industrial laboratories developing biofertilizers for commercialization or environmental release must characterize microorganisms of interest using a multilateral polyphasic approach of microbial systematics. This will determine their risk group and biosafety characteristics before proceeding with formulation development and environmental application. It has also been suggested that microorganisms belonging to risk-group-1 and BSL-1 category should be used for formulation development and for field scale applications. While, BSL-2 microorganisms should be restricted for research using containment practices compliant with strict regulations.
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Affiliation(s)
- Chetan Keswani
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Om Prakash
- National Centre for Microbial Resource, National Centre for Cell Science, Pune 411007, India.
| | - Nidhi Bharti
- Department of Botany, Savitribai Phule Pune University, Pune 411007, India.
| | - Juan I Vílchez
- Department of Plant Growth Promotion Rhizobacteria, Plant Stress Centre for Biology (PSC), Chinese Academy of Sciences (CAS), Shanghai, China.
| | - Estibaliz Sansinenea
- Facultad de Ciencias Químicas, Benemerita Universidad Autonoma de Puebla, Puebla, Pue, Mexico.
| | - Richard D Lally
- Research Department, Alltech, 3031 Catnip Hill Road, Nicholasville, KY 40356, USA.
| | - Rainer Borriss
- Nord Reet UG Greifswald, Germany and Humboldt University, Berlin, Germany.
| | - Surya P Singh
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India.
| | - Vijai K Gupta
- Department of Chemistry and Biotechnology, School of Science, Tallinn University of Technology, Akadeemia tee 15, 12618 Tallinn, Estonia.
| | - Leonardo F Fraceto
- São Paulo State University (UNESP), Institute of Science and Technology, Avenida Três de Março, 511, Alto da Boa Vista, Sorocaba, São Paulo, Brazil.
| | - Renata de Lima
- LABiToN - LaboratóriodeAvaliaçãodeBioatividadeeToxicologiade Nanomateriais, University of Sorocaba, Rodovia Raposo Tavares, Sorocaba, São Paulo, Brazil.
| | - Harikesh B Singh
- Department of Mycology and Plant Pathology, Institute of Agriculture Sciences, Banaras Hindu University, Varanasi 221005, India.
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Duckweed (Lemna minor) and Alfalfa (Medicago sativa) as Bacterial Infection Model Systems. METHODS IN MOLECULAR BIOLOGY (CLIFTON, N.J.) 2018; 1898:191-198. [PMID: 30570734 DOI: 10.1007/978-1-4939-8940-9_16] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Alternative animal host models of bacterial infection have been developed which reproduce some of the disease conditions observed in higher animals. Analogously, plants are useful for modeling bacterial pathogenesis, in some cases revealing broadly conserved infection mechanisms. Similar to animals, plants have been shown to possess innate immune systems that respond to invading viruses, bacteria, and fungi. Plant infection models often yield results faster, are more convenient, and less expensive than many animal infection models. Here, we describe the use of two different plant-based infection models for the discovery of virulence genes and factors involved in bacterial pathogenesis.
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8
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Fernández M, Corral-Lugo A, Krell T. The plant compound rosmarinic acid induces a broad quorum sensing response in Pseudomonas aeruginosa PAO1. Environ Microbiol 2018; 20:4230-4244. [PMID: 30051572 DOI: 10.1111/1462-2920.14301] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Accepted: 05/28/2018] [Indexed: 02/05/2023]
Abstract
The interference of plant compounds with bacterial quorum sensing (QS) is a major mechanism through which plants and bacteria communicate. However, little is known about the modes of action and effects on signal integrity during this type of communication. We have recently shown that the plant compound rosmarinic acid (RA) specifically binds to the Pseudomonas aeruginosa RhlR QS receptor. To determine the effect of RA on expression patterns, we carried out global RNA-seq analysis. The results show that RA induces the expression of 128 genes, amongst which many virulence factor genes. RA triggers a broad QS response because 88% of the induced genes are known to be controlled by QS, and because RA stimulated genes were found to be involved in all four QS signalling systems within P. aeruginosa. This finding was confirmed through the analysis of transcriptional fusions transferred to wt and a rhlI/lasI double mutant. RA did not induce gene expression in the rhlI/lasI/rhlR triple mutant indicating that the effects observed are due to the RA-RhlR interaction. Furthermore, RA induced seven sRNAs that were all encoded in regions close to QS and/or RA induced genes. This work significantly enhances our understanding of plant bacteria interaction.
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Affiliation(s)
- Matilde Fernández
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Andrés Corral-Lugo
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
- Institut de Biologie Intégrative de la Cellule (I2BC), CNRS, Gif-Sur-Yvette, France
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
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9
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Yadav M, Rathore JS. TAome analysis of type-II toxin-antitoxin system from Xenorhabdus nematophila. Comput Biol Chem 2018; 76:293-301. [DOI: 10.1016/j.compbiolchem.2018.07.010] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2018] [Revised: 05/23/2018] [Accepted: 07/07/2018] [Indexed: 12/23/2022]
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10
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O'Brien S, Fothergill JL. The role of multispecies social interactions in shaping Pseudomonas aeruginosa pathogenicity in the cystic fibrosis lung. FEMS Microbiol Lett 2018; 364:3958795. [PMID: 28859314 PMCID: PMC5812498 DOI: 10.1093/femsle/fnx128] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Accepted: 07/11/2017] [Indexed: 02/07/2023] Open
Abstract
Pseudomonas aeruginosa is a major pathogen in the lungs of cystic fibrosis (CF) patients. However, it is now recognised that a diverse microbial community exists in the airways comprising aerobic and anaerobic bacteria as well as fungi and viruses. This rich soup of microorganisms provides ample opportunity for interspecies interactions, particularly when considering secreted compounds. Here, we discuss how P. aeruginosa-secreted products can have community-wide effects, with the potential to ultimately shape microbial community dynamics within the lung. We focus on three well-studied traits associated with worsening clinical outcome in CF: phenazines, siderophores and biofilm formation, and discuss how secretions can shape interactions between P. aeruginosa and other commonly encountered members of the lung microbiome: Staphylococcus aureus, the Burkholderia cepacia complex, Candida albicans and Aspergillus fumigatus. These interactions may shape the evolutionary trajectory of P. aeruginosa while providing new opportunities for therapeutic exploitation of the CF lung microbiome.
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Affiliation(s)
- Siobhán O'Brien
- Center for Adaptation to a Changing Environment (ACE), ETH Zürich, 8092 Zürich, Switzerland.,Department of Biology, University of York, Wentworth Way, York YO10 5DD, UK
| | - Joanne L Fothergill
- Institute of Infection and Global Health, University of Liverpool, 8 West Derby Street, Liverpool L69 7B3, UK
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Padhi S, Dias I, Korn VL, Bennett JW. Pseudogymnoascus destructans: Causative Agent of White-Nose Syndrome in Bats Is Inhibited by Safe Volatile Organic Compounds. J Fungi (Basel) 2018; 4:jof4020048. [PMID: 29642609 PMCID: PMC6023378 DOI: 10.3390/jof4020048] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2018] [Revised: 03/27/2018] [Accepted: 04/03/2018] [Indexed: 01/12/2023] Open
Abstract
White-nose syndrome (WNS) is caused by Pseudogymnoascus destructans, a psychrophilic fungus that infects hibernating bats and has caused a serious decline in some species. Natural aroma compounds have been used to control growth of fungal food storage pathogens, so we hypothesized that a similar strategy could work for control of P. destructans. The effectiveness of exposure to low concentrations of the vapor phase of four of these compounds was tested on mycelial plugs and conidiospores at temperatures of 5, 10 and 15 °C. Here we report the efficacy of vapor phase mushroom alcohol (1-octen-3-ol) for inhibiting mycelial and conidiospore growth of P. destructans at 0.4 and 0.8 µmol/mL and demonstrate that the R enantiomer of this compound is more effective than the S enantiomer, supporting the finding that biological systems can be sensitive to stereochemistry. Further, we report that vapor phase leaf aldehyde (trans-2-hexenal), a common aroma compound associated with cut grass odors and also the major volatile compound in extra virgin olive oil, is more effective than mushroom alcohol. At 0.05 µmol/mL, trans-2-hexenal is fungicidal to both conidiospores and mycelia of P. destructans.
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Affiliation(s)
- Sally Padhi
- Department of Plant Biology, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901, USA.
| | - Itamar Dias
- Department of Plant Biology, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901, USA.
| | - Victoria L Korn
- Department of Plant Biology, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901, USA.
| | - Joan W Bennett
- Department of Plant Biology, Rutgers University, 59 Dudley Road, New Brunswick, NJ 08901, USA.
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12
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Reboud E, Basso P, Maillard AP, Huber P, Attrée I. Exolysin Shapes the Virulence of Pseudomonas aeruginosa Clonal Outliers. Toxins (Basel) 2017; 9:toxins9110364. [PMID: 29120408 PMCID: PMC5705979 DOI: 10.3390/toxins9110364] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2017] [Revised: 10/30/2017] [Accepted: 11/02/2017] [Indexed: 12/12/2022] Open
Abstract
Bacterial toxins are important weapons of toxicogenic pathogens. Depending on their origin, structure and targets, they show diverse mechanisms of action and effects on eukaryotic cells. Exolysin is a secreted 170 kDa pore-forming toxin employed by clonal outliers of Pseudomonas aeruginosa providing to some strains a hyper-virulent behaviour. This group of strains lacks the major virulence factor used by classical strains, the Type III secretion system. Here, we review the structural features of the toxin, the mechanism of its secretion and the effects of the pore formation on eukaryotic cells.
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Affiliation(s)
- Emeline Reboud
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, 17 rue des Martyrs, CEA-Grenoble, 38054 Grenoble, France.
| | - Pauline Basso
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, 17 rue des Martyrs, CEA-Grenoble, 38054 Grenoble, France.
| | - Antoine P Maillard
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, 17 rue des Martyrs, CEA-Grenoble, 38054 Grenoble, France.
| | - Philippe Huber
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, 17 rue des Martyrs, CEA-Grenoble, 38054 Grenoble, France.
| | - Ina Attrée
- CNRS-ERL5261, INSERM, U1036, CEA, Bacterial Pathogenesis and Cellular Responses, Biosciences and Biotechnology Institute of Grenoble, University Grenoble Alpes, 17 rue des Martyrs, CEA-Grenoble, 38054 Grenoble, France.
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13
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Biron D, Nedelkov D, Missé D, Holzmuller P. Proteomics and Host–Pathogen Interactions. GENETICS AND EVOLUTION OF INFECTIOUS DISEASES 2017. [PMCID: PMC7149668 DOI: 10.1016/b978-0-12-799942-5.00011-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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14
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Martín-Mora D, Ortega A, Reyes-Darias JA, García V, López-Farfán D, Matilla MA, Krell T. Identification of a Chemoreceptor in Pseudomonas aeruginosa That Specifically Mediates Chemotaxis Toward α-Ketoglutarate. Front Microbiol 2016; 7:1937. [PMID: 27965656 PMCID: PMC5126104 DOI: 10.3389/fmicb.2016.01937] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 11/17/2016] [Indexed: 12/21/2022] Open
Abstract
Pseudomonas aeruginosa is an ubiquitous pathogen able to infect humans, animals, and plants. Chemotaxis was found to be associated with the virulence of this and other pathogens. Although established as a model for chemotaxis research, the majority of the 26 P. aeruginosa chemoreceptors remain functionally un-annotated. We report here the identification of PA5072 (named McpK) as chemoreceptor for α-ketoglutarate (αKG). High-throughput thermal shift assays and isothermal titration calorimetry studies (ITC) of the recombinant McpK ligand binding domain (LBD) showed that it recognizes exclusively α-ketoglutarate. The ITC analysis indicated that the ligand bound with positive cooperativity (Kd1 = 301 μM, Kd2 = 81 μM). McpK is predicted to possess a helical bimodular (HBM) type of LBD and this and other studies suggest that this domain type may be associated with the recognition of organic acids. Analytical ultracentrifugation (AUC) studies revealed that McpK-LBD is present in monomer-dimer equilibrium. Alpha-KG binding stabilized the dimer and dimer self-dissociation constants of 55 μM and 5.9 μM were derived for ligand-free and αKG-bound forms of McpK-LBD, respectively. Ligand-induced LBD dimer stabilization has been observed for other HBM domain containing receptors and may correspond to a general mechanism of this protein family. Quantitative capillary chemotaxis assays demonstrated that P. aeruginosa showed chemotaxis to a broad range of αKG concentrations with maximal responses at 500 μM. Deletion of the mcpK gene reduced chemotaxis over the entire concentration range to close to background levels and wild type like chemotaxis was recovered following complementation. Real-time PCR studies indicated that the presence of αKG does not modulate mcpK expression. Since αKG is present in plant root exudates it was investigated whether the deletion of mcpK altered maize root colonization. However, no significant changes with respect to the wild type strain were observed. The existence of a chemoreceptor specific for αKG may be due to its central metabolic role as well as to its function as signaling molecule. This work expands the range of known chemoreceptor types and underlines the important physiological role of chemotaxis toward tricarboxylic acid cycle intermediates.
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Affiliation(s)
- David Martín-Mora
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Alvaro Ortega
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - José A Reyes-Darias
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Vanina García
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Diana López-Farfán
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Miguel A Matilla
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas Granada, Spain
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15
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Pletzer D, Braun Y, Weingart H. Swarming motility is modulated by expression of the putative xenosiderophore transporter SppR-SppABCD in Pseudomonas aeruginosa PA14. Antonie van Leeuwenhoek 2016; 109:737-53. [PMID: 26995781 DOI: 10.1007/s10482-016-0675-8] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2015] [Accepted: 03/03/2016] [Indexed: 12/14/2022]
Abstract
In the present study, we characterised the putative peptide ABC transporter SppABCD, which is co-transcribed with the TonB-dependent receptor SppR in Pseudomonas aeruginosa PA14. However, our data show that this transporter complex is not involved in the uptake of peptides. The fact that the TonB-dependent receptor SppR is regulated by an iron starvation ECF sigma factor suggested that this transporter is probably involved in the uptake of xenosiderophores. Therefore, we screened culture supernatants of 23 siderophore-producing bacteria for their ability to induce the expression of the SppR-regulating ECF sigma factor. However, none of them had an effect on the expression of this ECF sigma factor. Since the spp operon is not expressed under standard laboratory conditions, we overexpressed it from plasmids in PA14, which led to an impairment of its swarming motility on semisolid agar. Since we excluded the possibility that the uptake of a culture medium component was responsible for the observed phenotype, we hypothesize that the Spp transport system is involved in the uptake of a compound from the periplasmic space or a compound secreted by P. aeruginosa. Furthermore, we found that rhamnolipid synthesis was decreased while biofilm and exopolysaccharide synthesis was slightly increased upon overexpression of the spp operon. Moreover, we observed an impact of spp overexpression on regulation of genes involved in siderophore and phenazine biosynthesis.
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Affiliation(s)
- Daniel Pletzer
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany.
- R.E.W. Hancock Laboratory, Department of Microbiology and Immunology, University of British Columbia, Vancouver, Canada.
| | - Yvonne Braun
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
| | - Helge Weingart
- Department of Life Sciences and Chemistry, Jacobs University Bremen, Bremen, Germany
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16
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Corral-Lugo A, Daddaoua A, Ortega A, Espinosa-Urgel M, Krell T. Rosmarinic acid is a homoserine lactone mimic produced by plants that activates a bacterial quorum-sensing regulator. Sci Signal 2016; 9:ra1. [PMID: 26732761 DOI: 10.1126/scisignal.aaa8271] [Citation(s) in RCA: 69] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2023]
Abstract
Quorum sensing is a bacterial communication mechanism that controls genes, enabling bacteria to live as communities, such as biofilms. Homoserine lactone (HSL) molecules function as quorum-sensing signals for Gram-negative bacteria. Plants also produce previously unidentified compounds that affect quorum sensing. We identified rosmarinic acid as a plant-derived compound that functioned as an HSL mimic. In vitro assays showed that rosmarinic acid bound to the quorum-sensing regulator RhlR of Pseudomonas aeruginosa PAO1 and competed with the bacterial ligand N-butanoyl-homoserine lactone (C4-HSL). Furthermore, rosmarinic acid stimulated a greater increase in RhlR-mediated transcription in vitro than that of C4-HSL. In P. aeruginosa, rosmarinic acid induced quorum sensing-dependent gene expression and increased biofilm formation and the production of the virulence factors pyocyanin and elastase. Because P. aeruginosa PAO1 infection induces rosmarinic acid secretion from plant roots, our results indicate that rosmarinic acid secretion is a plant defense mechanism to stimulate a premature quorum-sensing response. P. aeruginosa is a ubiquitous pathogen that infects plants and animals; therefore, identification of rosmarinic acid as an inducer of premature quorum-sensing responses may be useful in agriculture and inform human therapeutic strategies.
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Affiliation(s)
- Andrés Corral-Lugo
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain
| | - Abdelali Daddaoua
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain
| | - Alvaro Ortega
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain
| | - Manuel Espinosa-Urgel
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008 Granada, Spain.
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17
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Cui J, Jin J, Chaudhary AS, Hsieh YH, Zhang H, Dai C, Damera K, Chen W, Tai PC, Wang B. Design, Synthesis and Evaluation of Triazole-Pyrimidine Analogues as SecA Inhibitors. ChemMedChem 2016; 11:43-56. [PMID: 26607404 PMCID: PMC4778717 DOI: 10.1002/cmdc.201500447] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2015] [Indexed: 01/15/2023]
Abstract
SecA, a key component of the bacterial Sec-dependent secretion pathway, is an attractive target for the development of new antimicrobial agents. Through a combination of virtual screening and experimental exploration of the surrounding chemical space, we identified a hit bistriazole SecA inhibitor, SCA-21, and studied a series of analogues by systematic dissections of the core scaffold. Evaluation of these analogues allowed us to establish an initial structure-activity relationship in SecA inhibition. The best compounds in this group are potent inhibitors of SecA-dependent protein-conducting channel activity and protein translocation activity at low- to sub-micromolar concentrations. They also have minimal inhibitory concentration (MIC) values against various strains of bacteria that correlate well with the SecA and protein translocation inhibition data. These compounds are effective against methicillin-resistant Staphylococcus aureus strains with various levels of efflux pump activity, indicating the capacity of SecA inhibitors to null the effect of multidrug resistance. Results from studies of drug-affinity-responsive target stability and protein pull-down assays are consistent with SecA as a target for these compounds.
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Affiliation(s)
- Jianmei Cui
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Jinshan Jin
- Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA
| | | | - Ying-hsin Hsieh
- Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA
| | - Hao Zhang
- Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA
| | - Chaofeng Dai
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Krishna Damera
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Weixuan Chen
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA
| | - Phang C Tai
- Department of Biology, Center for Biotechnology and Drug Design, Center for Diagnostics and Therapeutics, Georgia State University, Atlanta, GA, 30303, USA.
| | - Binghe Wang
- Department of Chemistry, Georgia State University, Atlanta, GA, 30303, USA.
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18
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Reyes-Darias JA, García V, Rico-Jiménez M, Corral-Lugo A, Lesouhaitier O, Juárez-Hernández D, Yang Y, Bi S, Feuilloley M, Muñoz-Rojas J, Sourjik V, Krell T. Specific gamma-aminobutyrate chemotaxis in pseudomonads with different lifestyle. Mol Microbiol 2015; 97:488-501. [PMID: 25921834 DOI: 10.1111/mmi.13045] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/26/2015] [Indexed: 02/02/2023]
Abstract
The PctC chemoreceptor of Pseudomonas aeruginosa mediates chemotaxis with high specificity to gamma-aminobutyric acid (GABA). This compound is present everywhere in nature and has multiple functions, including being a human neurotransmitter or plant signaling compound. Because P. aeruginosa is ubiquitously distributed in nature and able to infect and colonize different hosts, the physiological relevance of GABA taxis is unclear, but it has been suggested that bacterial attraction to neurotransmitters may enhance virulence. We report the identification of McpG as a specific GABA chemoreceptor in non-pathogenic Pseudomonas putida KT2440. As with PctC, GABA was found to bind McpG tightly. The analysis of chimeras comprising the PctC and McpG ligand-binding domains fused to the Tar signaling domain showed very high GABA sensitivities. We also show that PctC inactivation does not alter virulence in Caenorhabditis elegans. Significant amounts of GABA were detected in tomato root exudates, and deletion of mcpG reduced root colonization that requires chemotaxis through agar. The C. elegans data and the detection of a GABA receptor in non-pathogenic species indicate that GABA taxis may not be related to virulence in animal systems but may be of importance in the context of colonization and infection of plant roots by soil-dwelling pseudomonads.
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Affiliation(s)
- Jose Antonio Reyes-Darias
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain
| | - Vanina García
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain
| | - Miriam Rico-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain
| | - Andrés Corral-Lugo
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain
| | - Olivier Lesouhaitier
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université Rouen, 55 rue Saint Germain, 27000, Evreux, France
| | - Dalia Juárez-Hernández
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, 72570, Puebla, Mexico
| | - Yiling Yang
- Max Planck Institute for Terrestrial Microbiology & LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 10, D-35043, Marburg, Germany.,Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Shuangyu Bi
- Max Planck Institute for Terrestrial Microbiology & LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 10, D-35043, Marburg, Germany.,Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Marc Feuilloley
- Laboratory of Microbiology Signals and Microenvironnement LMSM, EA 4312, Normandie Université, Université Rouen, 55 rue Saint Germain, 27000, Evreux, France
| | - Jesús Muñoz-Rojas
- Laboratorio de Ecología Molecular Microbiana, Centro de Investigaciones en Ciencias Microbiológicas-Instituto de Ciencias, Benemérita Universidad Autónoma de Puebla, Ciudad Universitaria, 72570, Puebla, Mexico
| | - Victor Sourjik
- Max Planck Institute for Terrestrial Microbiology & LOEWE Research Center for Synthetic Microbiology (SYNMIKRO), Karl-von-Frisch Strasse 10, D-35043, Marburg, Germany.,Zentrum für Molekulare Biologie der Universität Heidelberg, DKFZ-ZMBH Alliance, Im Neuenheimer Feld 282, D-69120, Heidelberg, Germany
| | - Tino Krell
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/Prof. Albareda, 1, 18008, Granada, Spain
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19
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Ortega-González M, Sánchez de Medina F, Molina-Santiago C, López-Posadas R, Pacheco D, Krell T, Martínez-Augustin O, Abdelali D. Fructooligosacharides reduce Pseudomonas aeruginosa PAO1 pathogenicity through distinct mechanisms. PLoS One 2014; 9:e85772. [PMID: 24465697 PMCID: PMC3899050 DOI: 10.1371/journal.pone.0085772] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Accepted: 12/06/2013] [Indexed: 12/15/2022] Open
Abstract
Pseudomonas aeruginosa is ubiquitously present in the environment and acts as an opportunistic pathogen on humans, animals and plants. We report here the effects of the prebiotic polysaccharide inulin and its hydrolysed form FOS on this bacterium. FOS was found to inhibit bacterial growth of strain PAO1, while inulin did not affect growth rate or yield in a significant manner. Inulin stimulated biofilm formation, whereas a dramatic reduction of the biofilm formation was observed in the presence of FOS. Similar opposing effects were observed for bacterial motility, where FOS inhibited the swarming and twitching behaviour whereas inulin caused its stimulation. In co-cultures with eukaryotic cells (macrophages) FOS and, to a lesser extent, inulin reduced the secretion of the inflammatory cytokines IL-6, IL-10 and TNF-α. Western blot experiments indicated that the effects mediated by FOS in macrophages are associated with a decreased activation of the NF-κB pathway. Since FOS and inulin stimulate pathway activation in the absence of bacteria, the FOS mediated effect is likely to be of indirect nature, such as via a reduction of bacterial virulence. Further, this modulatory effect is observed also with the highly virulent ptxS mutated strain. Co-culture experiments of P. aeruginosa with IEC18 eukaryotic cells showed that FOS reduces the concentration of the major virulence factor, exotoxin A, suggesting that this is a possible mechanism for the reduction of pathogenicity. The potential of these compounds as components of antibacterial and anti-inflammatory cocktails is discussed.
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Affiliation(s)
- Mercedes Ortega-González
- Department of Biochemistry and Molecular Biology II, Centre of networked Biomedical Research about Hepatic and Digestive Diseases, School of Pharmacy, University of Granada, Granada, Spain
| | - Fermín Sánchez de Medina
- Departments of Pharmacology, Centre of networked Biomedical Research about Hepatic and Digestive Diseases, School of Pharmacy, University of Granada, Granada, Spain
| | - Carlos Molina-Santiago
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, Spain
| | - Rocío López-Posadas
- Departments of Pharmacology, Centre of networked Biomedical Research about Hepatic and Digestive Diseases, School of Pharmacy, University of Granada, Granada, Spain
| | - Daniel Pacheco
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, Spain
| | - Tino Krell
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, Spain
| | - Olga Martínez-Augustin
- Department of Biochemistry and Molecular Biology II, Centre of networked Biomedical Research about Hepatic and Digestive Diseases, School of Pharmacy, University of Granada, Granada, Spain
| | - Daddaoua Abdelali
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, C/Profesor Albareda 1, Granada, Spain
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20
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Baldini RL, Starkey M, Rahme LG. Assessing Pseudomonas virulence with the nonmammalian host model: Arabidopsis thaliana. Methods Mol Biol 2014; 1149:689-697. [PMID: 24818943 DOI: 10.1007/978-1-4939-0473-0_53] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
The popular plant model, Arabidopsis thaliana, has been used to successfully identify novel Pseudomonas aeruginosa genes that are involved in virulence. These genes have also been shown to be important for mammalian infection, demonstrating that this bacterium has a conserved set of virulence factors with broad range. This chapter describes using A. thaliana as a plant model for P. aeruginosa infection and describes obtaining the plants, preparing the inoculum, infecting the leaves, and collecting and interpreting the data. This protocol allows for both a qualitative assessment of symptoms and a quantitative measurement of the bacterial growth inside the leaves.
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Affiliation(s)
- Regina L Baldini
- Departamento de Bioquímica, Instituto de Química, Universidade de São Paulo, São Paulo, Brazil
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21
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Common duckweed (Lemna minor) is a versatile high-throughput infection model for the Burkholderia cepacia complex and other pathogenic bacteria. PLoS One 2013; 8:e80102. [PMID: 24223216 PMCID: PMC3819297 DOI: 10.1371/journal.pone.0080102] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2013] [Accepted: 10/07/2013] [Indexed: 01/05/2023] Open
Abstract
Members of the Burkholderia cepacia complex (Bcc) have emerged in recent decades as problematic pulmonary pathogens of cystic fibrosis (CF) patients, with severe infections progressing to acute necrotizing pneumonia and sepsis. This study presents evidence that Lemna minor (Common duckweed) is useful as a plant model for the Bcc infectious process, and has potential as a model system for bacterial pathogenesis in general. To investigate the relationship between Bcc virulence in duckweed and Galleria mellonella (Greater wax moth) larvae, a previously established Bcc infection model, a duckweed survival assay was developed and used to determine LD50 values. A strong correlation (R2 = 0.81) was found between the strains’ virulence ranks in the two infection models, suggesting conserved pathways in these vastly different hosts. To broaden the application of the duckweed model, enteropathogenic Escherichia coli (EPEC) and five isogenic mutants with previously established LD50 values in the larval model were tested against duckweed, and a strong correlation (R2 = 0.93) was found between their raw LD50 values. Potential virulence factors in B. cenocepacia K56-2 were identified using a high-throughput screen against single duckweed plants. In addition to the previously characterized antifungal compound (AFC) cluster genes, several uncharacterized genes were discovered including a novel lysR regulator, a histidine biosynthesis gene hisG, and a gene located near the gene encoding the recently characterized virulence factor SuhBBc. Finally, to demonstrate the utility of this model in therapeutic applications, duckweed was rescued from Bcc infection by treating with bacteriophage at 6-h intervals. It was observed that phage application became ineffective at a timepoint that coincided with a sharp increase in bacterial invasion of plant tissue. These results indicate that common duckweed can serve as an effective infection model for the investigation of bacterial virulence factors and therapeutic strategies to combat them.
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22
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Ellison ML, Farrow JM, Farrow JM, Parrish W, Danell AS, Pesci EC. The transcriptional regulator Np20 is the zinc uptake regulator in Pseudomonas aeruginosa. PLoS One 2013; 8:e75389. [PMID: 24086521 PMCID: PMC3781045 DOI: 10.1371/journal.pone.0075389] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2013] [Accepted: 08/15/2013] [Indexed: 11/18/2022] Open
Abstract
Zinc is essential for all bacteria, but excess amounts of the metal can have toxic effects. To address this, bacteria have developed tightly regulated zinc uptake systems, such as the ZnuABC zinc transporter which is regulated by the Fur-like zinc uptake regulator (Zur). In Pseudomonas aeruginosa, a Zur protein has yet to be identified experimentally, however, sequence alignment revealed that the zinc-responsive transcriptional regulator Np20, encoded by np20 (PA5499), shares high sequence identity with Zur found in other bacteria. In this study, we set out to determine whether Np20 was functioning as Zur in P. aeruginosa. Using RT-PCR, we determined that np20 (hereafter known as zur) formed a polycistronic operon with znuC and znuB. Mutant strains, lacking the putative znuA, znuB, or znuC genes were found to grow poorly in zinc deplete conditions as compared to wild-type strain PAO1. Intracellular zinc concentrations in strain PAO-Zur (Δzur) were found to be higher than those for strain PAO1, further implicating the zur as the zinc uptake regulator. Reporter gene fusions and real time RT-PCR revealed that transcription of znuA was repressed in a zinc-dependent manner in strain PAO1, however zinc-dependent transcriptional repression was alleviated in strain PAO-Zur, suggesting that the P. aeruginosa Zur homolog (ZurPA) directly regulates expression of znuA. Electrophoretic mobility shift assays also revealed that recombinant ZurPA specifically binds to the promoter region of znuA and does not bind in the presence of the zinc chelator N,N',N-tetrakis(2-pyridylmethyl) ethylenediamine (TPEN). Taken together, these data support the notion that Np20 is the P. aeruginosa Zur, which regulates the transcription of the genes encoding the high affinity ZnuABC zinc transport system.
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Affiliation(s)
- Matthew L Ellison
- Department of Microbiology and Immunology, East Carolina University, Greenville, North Carolina, United State of America ; Department of Biology and Chemistry, Morehead State University, Morehead, Kentucky, United State of America
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23
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Daddaoua A, Krell T, Ramos JL. Transcriptional control by two interacting regulatory proteins: identification of the PtxS binding site at PtxR. Nucleic Acids Res 2013; 41:10150-6. [PMID: 24019239 PMCID: PMC3905896 DOI: 10.1093/nar/gkt773] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
The PtxS and PtxR regulators control the expression of the glucose dehydrogenase genes from the Pgad promoter in Pseudomonas aeruginosa. These regulators bind to their cognate operators, that are separated by ∼50 nt, within the promoter region and interact with each other creating a DNA-loop that prevents RNA polymerase promoter access. Binding of the 2-ketogluconate effector to PtxS caused PtxS/PtxR complex dissociation and led to the dissolution of the repression loop facilitating the entry of the RNA polymerase and enabling the transcription of the gad gene. We have identified a hydrophobic surface patch on the PtxR putative surface that was hypothesized to correspond to the binding site for PtxS. Two surface-exposed residues in this patch, V173 and W269, were replaced by alanine. Isothermal titration calorimetry assays showed that PtxS does not interact with the mutant variants of PtxR. Electrophoretic mobility shift assay and DNAase I footprinting assays proved that both regulators bind to their target operators and that failure to interact with each other prevented the formation of the DNA-loop. In vitro transcription showed that PtxS per se is sufficient to inhibit transcription from the Pgad promoter, but that affinity of PtxS for its effector is modulated by PtxR.
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Affiliation(s)
- Abdelali Daddaoua
- Department of Environmental Protection, Consejo Superior de Investigaciones Científicas, Estación Experimental del Zaidín, Calle Profesor Albareda 1, E-18008 Granada, Spain
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Menezes-Costa A, Machado-Ferreira E, Voloch CM, Bonvicino CR, Seuánez HN, Leoncini O, Soares CAG. Identification of bacterial infection in neotropical primates. MICROBIAL ECOLOGY 2013; 66:471-478. [PMID: 23797292 DOI: 10.1007/s00248-013-0257-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2013] [Accepted: 06/10/2013] [Indexed: 06/02/2023]
Abstract
Emerging infectious diseases usually arise from wild animal populations. In the present work, we performed a screening for bacterial infection in natural populations of New World primates. The blood cell bulk DNAs from 181 individuals of four Platyrrhini genera were PCR screened for eubacterial 16S rRNA genes. Bacteria were detected and identified in 13 distinct individuals of Alouatta belzebul, Alouatta caraya, and Cebus apella monkeys from geographically distant regions in the states of Mato Grosso and Pará, Brazil. Sequence analyses showed that these Platyrrhini bacteria are closely related not only to human pathogens Pseudomonas spp. but also to Pseudomonas simiae and sheep-Acari infecting Pseudomonas spp. The identified Pseudomonas possibly represents a group of bacteria circulating in natural monkey populations.
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Affiliation(s)
- Andre Menezes-Costa
- Laboratório de Genética Molecular de Eucariontes e Simbiontes, Departamento de Genética, Instituto de Biologia, Universidade Federal do Rio de Janeiro, Ilha do Fundão, CCS, Bloco A, Lab. A2-120, Rio de Janeiro, RJ, CEP 21944-970, Brazil
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25
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Rico-Jiménez M, Muñoz-Martínez F, García-Fontana C, Fernandez M, Morel B, Ortega A, Ramos JL, Krell T. Paralogous chemoreceptors mediate chemotaxis towards protein amino acids and the non-protein amino acid gamma-aminobutyrate (GABA). Mol Microbiol 2013; 88:1230-43. [PMID: 23650915 DOI: 10.1111/mmi.12255] [Citation(s) in RCA: 82] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 05/06/2013] [Indexed: 01/31/2023]
Abstract
The paralogous receptors PctA, PctB and PctC of Pseudomonas aeruginosa were reported to mediate chemotaxis to amino acids, intermediates of amino acid metabolism and chlorinated hydrocarbons. We show that the recombinant ligand binding regions (LBRs) of PctA, PctB and PctC bind 17, 5 and 2 l-amino acids respectively. In addition, PctC-LBR recognized GABA but not any other structurally related compound. l-Gln, one of the three amino acids that is not recognized by PctA-LBR, was the most tightly binding ligand to PctB suggesting that PctB has evolved to mediate chemotaxis primarily towards l-Gln. Bacteria were efficiently attracted to l-Gln and GABA, but mutation of pctB and pctC, respectively, abolished chemoattraction. The physiological relevance of taxis towards GABA is proposed to reside in an interaction with plants. LBRs were predicted to adopt double PDC (PhoQ/DcuS/CitA) like structures and site-directed mutagenesis studies showed that ligands bind to the membrane-distal module. Analytical ultracentrifugation studies have shown that PctA-LBR and PctB-LBR are monomeric in the absence and presence of ligands, which is in contrast to the enterobacterial receptors that require sensor domain dimers for ligand recognition.
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Affiliation(s)
- Miriam Rico-Jiménez
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, C/ Prof. Albareda, 1, 18008, Granada, Spain
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Kumar A, Munder A, Aravind R, Eapen SJ, Tümmler B, Raaijmakers JM. Friend or foe: genetic and functional characterization of plant endophytic Pseudomonas aeruginosa. Environ Microbiol 2012; 15:764-79. [PMID: 23171326 DOI: 10.1111/1462-2920.12031] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2012] [Revised: 10/16/2012] [Accepted: 10/19/2012] [Indexed: 01/02/2023]
Abstract
Endophytic Pseudomonas aeruginosa strain BP35 was originally isolated from black pepper grown in the rain forest in Kerala, India. Strain PaBP35 was shown to provide significant protection to black pepper against infections by Phytophthora capsici and Radopholus similis. For registration and implementation in disease management programmes, several traits of PaBP35 were investigated including its endophytic behaviour, biocontrol activity, phylogeny and toxicity to mammals. The results showed that PaBP35 efficiently colonized black pepper shoots and displayed a typical spatiotemporal pattern in its endophytic movement with concomitant suppression of Phytophthora rot. Confocal laser scanning microscopy revealed high populations of PaBP35::gfp2 inside tomato plantlets, supporting its endophytic behaviour in other plant species. Polyphasic approaches to genotype PaBP35, including BOX-PCR, recN sequence analysis, multilocus sequence typing and comparative genome hybridization analysis, revealed its uniqueness among P. aeruginosa strains representing clinical habitats. However, like other P. aeruginosa strains, PaBP35 exhibited resistance to antibiotics, grew at 25-41°C and produced rhamnolipids and phenazines. PaBP35 displayed strong type II secretion effectors-mediated cytotoxicity on mammalian A549 cells. Coupled with pathogenicity in a murine airway infection model, we conclude that this plant endophytic strain is as virulent as clinical P. aeruginosa strains. Safety issues related to the selection of plant endophytic bacteria for crop protection are discussed.
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Affiliation(s)
- A Kumar
- Laboratory of Phytopathology, Wageningen University, Wageningen, The Netherlands.
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Rada B, Leto TL. Pyocyanin effects on respiratory epithelium: relevance in Pseudomonas aeruginosa airway infections. Trends Microbiol 2012; 21:73-81. [PMID: 23140890 DOI: 10.1016/j.tim.2012.10.004] [Citation(s) in RCA: 195] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2012] [Revised: 10/03/2012] [Accepted: 10/05/2012] [Indexed: 01/26/2023]
Abstract
Pseudomonas aeruginosa (PA) uses several virulence factors to establish chronic respiratory infections in bronchiectasis, chronic obstructive pulmonary disease, and cystic fibrosis (CF) patients. One of its toxins, pyocyanin (PYO), is a redox-active pigment that is required for full virulence in animal models and has been detected in patients' airway secretions. PYO promotes virulence by interfering with several cellular functions in host cells including electron transport, cellular respiration, energy metabolism, gene expression, and innate immune mechanisms. This review summarizes recent advances in PYO biology with special attention to current views on its role in human airway infections and on its interactions with the first line of our airway defense, the respiratory epithelium.
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Affiliation(s)
- Balázs Rada
- University of Georgia, College of Veterinary Medicine, Department of Infectious Diseases, 501 DW Brooks Drive, Athens, GA 30602, USA
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Üstün Ş, Müller P, Palmisano R, Hensel M, Börnke F. SseF, a type III effector protein from the mammalian pathogen Salmonella enterica, requires resistance-gene-mediated signalling to activate cell death in the model plant Nicotiana benthamiana. THE NEW PHYTOLOGIST 2012; 194:1046-1060. [PMID: 22471508 DOI: 10.1111/j.1469-8137.2012.04124.x] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Type III effector proteins (T3Es) of many Gram-negative pathogenic bacteria manipulate highly conserved cellular processes, indicating conservation in virulence mechanisms during the infection of hosts of divergent evolutionary origin. In order to identify conserved effector functions, we used a cross-kingdom approach in which we expressed selected T3Es from the mammalian pathogen Salmonella enterica in leaves of Nicotiana benthamiana and searched for possible virulence or avirulence phenotypes. We show that the T3E SseF of S. enterica triggers hypersensitive response (HR)-like symptoms, a hallmark of effector-triggered immunity in plants, either when transiently expressed in leaves of N. benthamiana by Agrobacterium tumefaciens infiltration or when delivered by Xanthomonas campestris pv vesicatoria (Xcv) through the type III secretion system. The ability of SseF to elicit HR-like symptoms was lost upon silencing of suppressor of G2 allele of skp1 (SGT1), indicating that the S. enterica T3E is probably recognized by an R protein in N. benthamiana. Xcv translocating an AvrRpt2-SseF fusion protein was restricted in multiplication within leaves of N. benthamiana. Bacterial growth was not impaired but symptom development was rather accelerated in a compatible interaction with susceptible pepper (Capsicum annuum) plants. We conclude that the S. enterica T3E SseF is probably recognized by the plant immune system in N. benthamiana, resulting in effector-triggered immunity.
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Affiliation(s)
- Şuayib Üstün
- Department Biologie, Lehrstuhl für Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Petra Müller
- Infektionsbiologische Abteilung im Mikrobiologischen Institut, Universitätsklinikum Erlangen, Wasserturmstr. 3-5, 91054 Erlangen, Germany
| | - Ralf Palmisano
- Department Biologie, Lehrstuhl für Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
| | - Michael Hensel
- Infektionsbiologische Abteilung im Mikrobiologischen Institut, Universitätsklinikum Erlangen, Wasserturmstr. 3-5, 91054 Erlangen, Germany
| | - Frederik Börnke
- Department Biologie, Lehrstuhl für Biochemie, Friedrich Alexander Universität Erlangen-Nürnberg, Staudtstr. 5, 91058 Erlangen, Germany
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Barak JD, Schroeder BK. Interrelationships of food safety and plant pathology: the life cycle of human pathogens on plants. ANNUAL REVIEW OF PHYTOPATHOLOGY 2012; 50:241-66. [PMID: 22656644 DOI: 10.1146/annurev-phyto-081211-172936] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Bacterial food-borne pathogens use plants as vectors between animal hosts, all the while following the life cycle script of plant-associated bacteria. Similar to phytobacteria, Salmonella, pathogenic Escherichia coli, and cross-domain pathogens have a foothold in agricultural production areas. The commonality of environmental contamination translates to contact with plants. Because of the chronic absence of kill steps against human pathogens for fresh produce, arrival on plants leads to persistence and the risk of human illness. Significant research progress is revealing mechanisms used by human pathogens to colonize plants and important biological interactions between and among bacteria in planta. These findings articulate the difficulty of eliminating or reducing the pathogen from plants. The plant itself may be an untapped key to clean produce. This review highlights the life of human pathogens outside an animal host, focusing on the role of plants, and illustrates areas that are ripe for future investigation.
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Affiliation(s)
- Jeri D Barak
- Department of Plant Pathology, University of Wisconsin, Madison, Wisconsin 53706, USA.
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Abstract
An important environmental factor that determines the mode of motility adopted by Pseudomonas aeruginosa is the viscosity of the medium, often provided by adjusting agar concentrations in vitro. However, the viscous gel-like property of the mucus layer that overlays epithelial surfaces is largely due to the glycoprotein mucin. P. aeruginosa is known to swim within 0.3% (wt/vol) agar and swarm on the surface at 0.5% (wt/vol) agar with amino acids as a weak nitrogen source. When physiological concentrations or as little as 0.05% (wt/vol) mucin was added to the swimming agar, in addition to swimming, P. aeruginosa was observed to undergo highly accelerated motility on the surface of the agar. The surface motility colonies in the presence of mucin appeared to be circular, with a bright green center surrounded by a thicker white edge. While intact flagella were required for the surface motility in the presence of mucin, type IV pili and rhamnolipid production were not. Replacement of mucin with other wetting agents indicated that the lubricant properties of mucin might contribute to the surface motility. Based on studies with mutants, the quorum-sensing systems (las and rhl) and the orphan autoinducer receptor QscR played important roles in this form of surface motility. Transcriptional analysis of cells taken from the motility zone revealed the upregulation of genes involved in virulence and resistance. Based on these results, we suggest that mucin may be promoting a new or highly modified form of surface motility, which we propose should be termed “surfing.” An important factor that dictates the mode of motility adopted by P. aeruginosa is the viscosity of the medium, often provided by adjusting agar concentrations in vitro. However, the gel-like properties of the mucous layers that overlay epithelial surfaces, such as those of the lung, a major site of Pseudomonas infection, are contributed mostly by the production of the glycoprotein mucin. In this study, we added mucin to swimming media and found that it promoted the ability of P. aeruginosa to exhibit rapid surface motility. These motility colonies appeared in a circular form, with a bright green center surrounded by a thicker white edge. Interestingly, bacterial cells at the thick edge appeared piled up and lacked flagella, while cells at the motility center had flagella. Our data from various genetic and phenotypic studies suggest that mucin may be promoting a modified form of swarming or a novel form of surface motility in P. aeruginosa.
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Bevivino A, Pirone L, Pilkington R, Cifani N, Dalmastri C, Callaghan M, Ascenzioni F, McClean S. Interaction of environmental Burkholderia cenocepacia strains with cystic fibrosis and non-cystic fibrosis bronchial epithelial cells in vitro. MICROBIOLOGY-SGM 2012; 158:1325-1333. [PMID: 22322958 DOI: 10.1099/mic.0.056986-0] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
Burkholderia cenocepacia is an important human pathogen in patients with cystic fibrosis (CF). Non-clinical reservoirs may play a role in the acquisition of infection, so it is important to evaluate the pathogenic potential of environmental B. cenocepacia isolates. In this study, we investigated the interactions of two environmental B. cenocepacia strains (Mex1 and MCII-168) with two bronchial epithelial cell lines, 16HBE14o(-) and CFBE41o(-), which have a non-CF and a CF phenotype, respectively. The environmental strains showed a significantly lower level of invasion into both CF and non-CF cells in comparison with the clinical B. cenocepacia LMG16656(T) strain. Exposure of polarized CFBE41o(-) or 16HBE14o(-) cells to the environmental strains resulted in a significant reduction in transepithelial resistance (TER), comparable with that observed following exposure to the clinical strain. A different mechanism of tight junction disruption in CF versus non-CF epithelia was found. In the 16HBE41o(-) cells, the environmental strains resulted in a drop in TER without any apparent effect on tight junction proteins such as zonula occludens-1 (ZO-1). In contrast, in CF cells, the amount of ZO-1 and its localization were clearly altered by the presence of both the environmental strains, comparable with the effect of LMG16656. This study demonstrates that even if the environmental strains are significantly less invasive than the clinical strain, they have an effect on epithelial integrity comparable with that of the clinical strain. Finally, the tight junction regulatory protein ZO-1 appears to be more susceptible to the presence of environmental strains in CF cells than in cells which express a functional cystic fibrosis transmembrane regulator (CFTR).
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Affiliation(s)
- Annamaria Bevivino
- ENEA C.R. Casaccia - Technical Unit for Sustainable Development and Innovation of Agro-Industrial System, Via Anguillarese 301, 00123 Rome, Italy
| | - Luisa Pirone
- Department of Biology and Biotechnology 'C. Darwin', Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy.,ENEA C.R. Casaccia - Technical Unit for Sustainable Development and Innovation of Agro-Industrial System, Via Anguillarese 301, 00123 Rome, Italy
| | - Ruth Pilkington
- Centre of Microbial Host Interactions, Institute of Technology Tallaght, Old Blessington Road, Dublin 2, Ireland
| | - Noemi Cifani
- Department of Biology and Biotechnology 'C. Darwin', Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Claudia Dalmastri
- ENEA C.R. Casaccia - Technical Unit for Sustainable Development and Innovation of Agro-Industrial System, Via Anguillarese 301, 00123 Rome, Italy
| | - Máire Callaghan
- Centre of Applied Science for Health, Institute of Technology Tallaght, Old Blessington Road, Dublin 2, Ireland.,Centre of Microbial Host Interactions, Institute of Technology Tallaght, Old Blessington Road, Dublin 2, Ireland
| | - Fiorentina Ascenzioni
- Department of Biology and Biotechnology 'C. Darwin', Sapienza University of Rome, P.le Aldo Moro 5, 00185 Rome, Italy
| | - Siobhán McClean
- Centre of Applied Science for Health, Institute of Technology Tallaght, Old Blessington Road, Dublin 2, Ireland.,Centre of Microbial Host Interactions, Institute of Technology Tallaght, Old Blessington Road, Dublin 2, Ireland
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Kasozi DM, Gromer S, Adler H, Zocher K, Rahlfs S, Wittlin S, Fritz-Wolf K, Schirmer RH, Becker K. The bacterial redox signaller pyocyanin as an antiplasmodial agent: comparisons with its thioanalog methylene blue. Redox Rep 2011; 16:154-65. [PMID: 21888766 DOI: 10.1179/174329211x13049558293678] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
The quorum sensor and signalling molecule pyocyanin (PYO) contributes significantly to the pathophysiology of Pseudomonas aeruginosa infections. Comparison to phenothiazine drugs suggests that the antimalarial compound methylene blue (MB) can be regarded as a sulfur analog of PYO. This working hypothesis would explain why the synthetic drug MB behaves as a compound shaped in biological evolution. Here we report on redox-associated biological and biochemical properties of PYO in direct comparison to its synthetic analog MB. We quantitatively describe the reactivity of both compounds toward cellular reductants, the reactivity of their reduced leuco-forms towards O2, and their interactions with FAD-containing disulfide reductases. Furthermore, the interaction of PYO with human glutathione reductase was studied in structural detail by x-ray crystallography, showing that a single PYO molecule binds to the intersubunit cavity of the enzyme. Like MB, also PYO was also found to be active against blood schizonts of the malaria parasite P. falciparum in vitro. Furthermore, both compounds were active against the disease transmitting gametocyte forms of the parasites, which was systematically studied in vitro. As shown for mice, PYO is too toxic to be used as a drug. It may, however, have antimalarial activity in numerous human patients with concomitant Pseudomonas infections. MB, in contrast to PYO, is well tolerated and represents a promising agent for MB-based combination therapies against malaria. Current and future clinical studies can be guided by the comparisons between MB and PYO reported here. Additionally, it is of interest to study if and to what extent the protection from malaria in patients with cystic fibrosis or with severe wound infections is based on PYO produced by Pseudomonas species.
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Affiliation(s)
- D M Kasozi
- Interdisciplinary Research Center, Giessen, Germany
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Pérez-Mendoza D, Coulthurst SJ, Humphris S, Campbell E, Welch M, Toth IK, Salmond GPC. A multi-repeat adhesin of the phytopathogen, Pectobacterium atrosepticum, is secreted by a Type I pathway and is subject to complex regulation involving a non-canonical diguanylate cyclase. Mol Microbiol 2011; 82:719-33. [PMID: 21992096 DOI: 10.1111/j.1365-2958.2011.07849.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/24/2023]
Abstract
Cyclic diguanylate (c-di-GMP) is a second messenger controlling many important bacterial processes. The phytopathogen Pectobacterium atrosepticum SCRI1043 (Pba1043) possesses a Type I secretion system (T1SS) essential for the secretion of a proteinaceous multi-repeat adhesin (MRP) required for binding to the host plant. The genes encoding the MRP and the T1SS are tightly linked to genes encoding several putative c-di-GMP regulatory components. We show that c-di-GMP regulates secreted MRP levels in Pba1043 through the action of two genes encoding predicted diguanylate cyclase (DGC) and phosphodiesterase proteins (ECA3270 and ECA3271). Phenotypic analyses and quantification of c-di-GMP levels demonstrated that ECA3270 and ECA3271 regulate secreted MRP levels by increasing and decreasing, respectively, the intracellular levels of c-di-GMP. Moreover, ECA3270 represents the first active DGC reported to have an alternative active-site motif from the 'canonical' GG[D/E]EF. ECA3270 has an A-site motif of SGDEF and analysis of single amino acid replacements demonstrated that the first position of this motif can tolerate functional substitution. Serine in position one of the A-site is also observed in many other DGCs. Finally, another T1SS-linked regulator (ECA3265) also plays an important role in regulating secreted MRP, with an altered localization of MRP observed in an ECA3265 mutant background. Mutants defective in these three T1SS-linked regulators exhibit a reduction in root binding and virulence, confirming that this complex, finely tuned regulation system is crucial in the interaction with host plants.
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Galleria mellonella as model host for the trans-kingdom pathogen Fusarium oxysporum. Fungal Genet Biol 2011; 48:1124-9. [PMID: 21907298 DOI: 10.1016/j.fgb.2011.08.004] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2011] [Accepted: 08/24/2011] [Indexed: 11/23/2022]
Abstract
Fusarium oxysporum, the causal agent of vascular wilt disease, affects a wide range of plant species and can produce disseminated infections in humans. F. oxysporum f. sp. lycopersici isolate FGSC 9935 causes disease both on tomato plants and immunodepressed mice, making it an ideal model for the comparative analysis of fungal virulence on plant and animal hosts. Here we tested the ability of FGSC 9935 to cause disease in the greater wax moth Galleria mellonella, an invertebrate model host that is widely used for the study of microbial human pathogens. Injection of living but not of heat-killed microconidia into the hemocoel of G. mellonella larvae resulted in dose-dependent killing both at 30°C and at 37°C. Fluorescence microscopy of larvae inoculated with a F. oxysporum transformant expressing GFP revealed hyphal proliferation within the hemocoel, interaction with G. mellonella hemocytes, and colonization of the killed insects by the fungus. Fungal gene knockout mutants previously tested in the tomato and immunodepressed mouse systems displayed a good correlation in virulence between the Galleria and the mouse model. Thus, Galleria represents a useful non-vertebrate infection model for studying virulence mechanisms of F. oxysporum on animal hosts.
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35
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Barkovits K, Schubert B, Heine S, Scheer M, Frankenberg-Dinkel N. Function of the bacteriophytochrome BphP in the RpoS/Las quorum-sensing network of Pseudomonas aeruginosa. Microbiology (Reading) 2011; 157:1651-1664. [DOI: 10.1099/mic.0.049007-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
The bacterial phytochrome of Pseudomonas aeruginosa (PaBphP) is an in vitro-active red/far-red light sensor histidine kinase of a two-component regulatory system. Despite solid biochemical data, its function in this heterotrophic, opportunistic pathogen is still unknown. Previous studies established that the genes encoding the two necessary phytochrome components BphO, a chromophore-producing haem oxygenase, and BphP, the apo-phytochrome, are co-transcribed in a bicistronic operon. Transcription has been shown to be induced in the stationary phase and to be dependent on the alternative sigma factor RpoS. Here we show an additional regulation of bphP expression through the quorum-sensing (QS) regulator LasR. This regulation is also reflected in a combination of expression profile experiments and proteome analyses of wild-type and phytochrome-deficient strains. While PaBphP has a pleiotropic effect on global gene expression, 66 % of the downregulated genes in the phytochrome mutant display a link to the Las QS system. Most of these genes seem to be indirectly regulated by LasR through BphP and the unknown response regulator BphR. A model of phytochrome function within the Las QS network is presented.
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Affiliation(s)
- Katalin Barkovits
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Britta Schubert
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Sabrina Heine
- Physiology of Microorganisms, Ruhr-University Bochum, Universitaetsstr. 150, 44780 Bochum, Germany
| | - Maurice Scheer
- Institute for Microbiology, Technical University Braunschweig, 38106 Braunschweig, Germany
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Eberl L, Riedel K. Mining quorum sensing regulated proteins - Role of bacterial cell-to-cell communication in global gene regulation as assessed by proteomics. Proteomics 2011; 11:3070-85. [PMID: 21548094 DOI: 10.1002/pmic.201000814] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 01/20/2011] [Accepted: 02/17/2011] [Indexed: 12/31/2022]
Affiliation(s)
- Leo Eberl
- Department of Microbiology, Institute of Plant Biology, University of Zürich, Zurich, Switzerland
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Alagely A, Rajamani S, Teplitski M. Luminescent reporters and their applications for the characterization of signals and signal-mimics that alter LasR-mediated quorum sensing. Methods Mol Biol 2011; 692:113-30. [PMID: 21031308 DOI: 10.1007/978-1-60761-971-0_9] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023]
Abstract
In many pathogenic bacteria, quorum sensing (QS) controls expression of genes that are involved in virulence, production and resistance to antibiotics, formation and maintenance of microbial multicellular consortia on biotic and abiotic surfaces of medical and industrial importance. N-acyl homoserine lactones (AHL) are the best characterized quorum sensing signals in Gram-negative bacteria. Interference with AHL-mediated QS, therefore, is considered an attractive strategy for controlling virulence in pathogens. The search for AHL signals and their mimics has been facilitated by the development of sensitive bioassays, in which QS reporters luminesce in response to AHL signals. These bioassays have already led to the identification of dozens of compounds with QS modulating activities. The characterization of the mode of action of QS signals and their mimics requires follow-up biochemical studies. Here, we describe a set of luminescent reporters, which could be used in high, medium or low throughput format, for the discovery and validation of agonists or antagonists of the Las QS system of Pseudomonas aeruginosa. These nearly isogenic reporters contain truncations or point mutations in the AHL binding domain of the AHL receptor LasR, as well as mutations in the promoter for the gene encoding LasI AHL synthase. We also developed reporters for documenting the regulation of lasI and lasR promoters. The use of these reporters significantly streamlines identification and characterization of the Las QS signal agonists and antagonists prior to biochemical experiments. To test the usefulness of these reporters, we carried out bioassays with patulin, a known inhibitor of Las QS.
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Affiliation(s)
- Ali Alagely
- Soil and Water Sciences Department, Genetics Institute, Institute of Food and Agricultural Sciences (IFAS), University of Florida, Gainesville, FL, USA
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Mhedbi-Hajri N, Jacques MA, Koebnik R. Adhesion mechanisms of plant-pathogenic Xanthomonadaceae. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2011; 715:71-89. [PMID: 21557058 DOI: 10.1007/978-94-007-0940-9_5] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The family Xanthomonadaceae is a wide-spread family of bacteria belonging to the gamma subdivision of the Gram-negative proteobacteria, including the two plant-pathogenic genera Xanthomonas and Xylella, and the related genus Stenotrophomonas. Adhesion is a widely conserved virulence mechanism among Gram-negative bacteria, no matter whether they are human, animal or plant pathogens, since attachment to the host tissue is one of the key early steps of the bacterial infection process. Bacterial attachment to surfaces is mediated by surface structures that are anchored in the bacterial outer membrane and cover a broad group of fimbrial and non-fimbrial structures, commonly known as adhesins. In this chapter, we discuss recent findings on candidate adhesins of plant-pathogenic Xanthomonadaceae, including polysaccharidic (lipopolysaccharides, exopolysaccharides) and proteineous structures (chaperone/usher pili, type IV pili, autotransporters, two-partner-secreted and other outer membrane adhesins), their involvement in the formation of biofilms and their mode of regulation via quorum sensing. We then compare the arsenals of adhesins among different Xanthomonas strains and evaluate their mode of selection. Finally, we summarize the sparse knowledge on specific adhesin receptors in plants and the possible role of RGD motifs in binding to integrin-like plant molecules.
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Affiliation(s)
- Nadia Mhedbi-Hajri
- Pathologie Végétale (UMR077 INRA-Agrocampus Ouest-Université d'Angers), Beaucouzé, France.
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Kleter GA, Peijnenburg AACM, Aarts HJM. Health considerations regarding horizontal transfer of microbial transgenes present in genetically modified crops. J Biomed Biotechnol 2010; 2005:326-52. [PMID: 16489267 PMCID: PMC1364539 DOI: 10.1155/jbb.2005.326] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The potential effects of horizontal gene transfer on human health
are an important item in the safety assessment of genetically
modified organisms. Horizontal gene transfer from genetically
modified crops to gut microflora most likely occurs with
transgenes of microbial origin. The characteristics of microbial
transgenes other than antibiotic-resistance genes in
market-approved genetically modified crops are reviewed. These
characteristics include the microbial source, natural function,
function in genetically modified crops, natural prevalence,
geographical distribution, similarity to other microbial genes,
known horizontal transfer activity, selective conditions and
environments for horizontally transferred genes, and potential
contribution to pathogenicity and virulence in humans and animals.
The assessment of this set of data for each of the microbial genes
reviewed does not give rise to health concerns. We recommend
including the above-mentioned items into the premarket safety
assessment of genetically modified crops carrying transgenes other
than those reviewed in the present study.
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Affiliation(s)
- Gijs A Kleter
- RIKILT, Institute of Food Safety, Wageningen University and Research Center, Wageningen, The Netherlands.
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Robène-Soustrade I, Legrand D, Gagnevin L, Chiroleu F, Laurent A, Pruvost O. Multiplex nested PCR for detection of Xanthomonas axonopodis pv. allii from onion seeds. Appl Environ Microbiol 2010; 76:2697-703. [PMID: 20208024 PMCID: PMC2863456 DOI: 10.1128/aem.02697-09] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2009] [Accepted: 02/22/2010] [Indexed: 11/20/2022] Open
Abstract
Bacterial blight of onion (BBO) is an emerging disease that is present in many onion-producing areas. The causal agent, Xanthomonas axonopodis pv. allii, is seed transmitted. A reliable and sensitive diagnostic tool for testing seed health is needed. Detection of X. axonopodis pv. allii was achieved using a multiplex nested PCR assay developed using two randomly amplified polymorphic DNA (RAPD) and amplified fragment length polymorphism (AFLP) sequences corresponding to pilus assembly genes (pilW and pilX) and the avrRxv gene, respectively. The multiplex nested PCR was used with a large collection of X. axonopodis pv. allii strains pathogenic to onion and/or other Allium species isolated in different regions of the world. The internal primers used in the multiplex PCR assay directed amplification for all 86 X. axonopodis pv. allii strains tested, resulting in a 401-bp amplicon, a 444- to 447-bp amplicon, or both amplicons, depending on the strain. No amplification was obtained for 41 unrelated phytopathogenic bacteria and for 14 saprophytic bacteria commonly isolated from onion leaves and seeds. Most Xanthomonas strains also did not produce amplicons, except for nine strains classified in X. axonopodis genetic subgroup 9.1 or 9.2 and not pathogenic to onion. Nevertheless, sequence signatures distinguished most of these strains from X. axonopodis pv. allii. The assay detected X. axonopodis pv. allii in seed lots with contamination levels of 5 x 10(2) CFU g(-1) or higher. The sensitivity threshold of the multiplex nested PCR assay was found to be 1 infected seed in 27,340 seeds. This PCR-based assay should be useful for certifying that commercial seed lots are free of this important seed-borne pathogen.
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Affiliation(s)
- Isabelle Robène-Soustrade
- CIRAD, UMR Peuplements Végétaux et Bioagresseurs en Milieu Tropical CIRAD-Université de la Réunion, Pôle de Protection des Plantes, 7 chemin de l'Irat, Saint Pierre, La Réunion, France.
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Schmid M, Iversen C, Gontia I, Stephan R, Hofmann A, Hartmann A, Jha B, Eberl L, Riedel K, Lehner A. Evidence for a plant-associated natural habitat for Cronobacter spp. Res Microbiol 2009; 160:608-14. [DOI: 10.1016/j.resmic.2009.08.013] [Citation(s) in RCA: 100] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/22/2009] [Revised: 08/21/2009] [Accepted: 08/31/2009] [Indexed: 11/15/2022]
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Mikkelsen H, Ball G, Giraud C, Filloux A. Expression of Pseudomonas aeruginosa CupD fimbrial genes is antagonistically controlled by RcsB and the EAL-containing PvrR response regulators. PLoS One 2009; 4:e6018. [PMID: 19547710 PMCID: PMC2696094 DOI: 10.1371/journal.pone.0006018] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2009] [Accepted: 05/11/2009] [Indexed: 12/16/2022] Open
Abstract
Pseudomonas aeruginosa is a gram-negative pathogenic bacterium with a high adaptive potential that allows proliferation in a broad range of hosts or niches. It is also the causative agent of both acute and chronic biofilm-related infections in humans. Three cup gene clusters (cupA-C), involved in the assembly of cell surface fimbriae, have been shown to be involved in biofilm formation by the P. aeruginosa strains PAO1 or PAK. In PA14 isolates, a fourth cluster, named cupD, was identified within a pathogenicity island, PAPI-I, and may contribute to the higher virulence of this strain. Expression of the cupA genes is controlled by the HNS-like protein MvaT, whereas the cupB and cupC genes are under the control of the RocS1A1R two-component system. In this study, we show that cupD gene expression is positively controlled by the response regulator RcsB. As a consequence, CupD fimbriae are assembled on the cell surface, which results in a number of phenotypes such as a small colony morphotype, increased biofilm formation and decreased motility. These behaviors are compatible with the sessile bacterial lifestyle. The balance between planktonic and sessile lifestyles is known to be linked to the intracellular levels of c-di-GMP with high levels favoring biofilm formation. We showed that the EAL domain-containing PvrR response regulator counteracts the activity of RcsB on cupD gene expression. The action of PvrR is likely to involve c-di-GMP degradation through phosphodiesterase activity, confirming the key role of this second messenger in the balance between bacterial lifestyles. The regulatory network between RcsB and PvrR remains to be elucidated, but it stands as a potential model system to study how the equilibrium between the two lifestyles could be influenced by therapeutic agents that favor the planktonic lifestyle. This would render the pathogen accessible for the immune system or conventional antibiotic treatment.
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Affiliation(s)
- Helga Mikkelsen
- Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, South Kensington Campus, London, United Kingdom
| | - Geneviève Ball
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
| | - Caroline Giraud
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
| | - Alain Filloux
- Imperial College London, Division of Cell and Molecular Biology, Centre for Molecular Microbiology and Infection, South Kensington Campus, London, United Kingdom
- Laboratoire d'Ingénierie des Systèmes Macromoléculaires, UPR9027, CNRS-IBSM, Marseille, France
- * E-mail:
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Darsonval A, Darrasse A, Durand K, Bureau C, Cesbron S, Jacques MA. Adhesion and fitness in the bean phyllosphere and transmission to seed of Xanthomonas fuscans subsp. fuscans. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2009; 22:747-57. [PMID: 19445599 DOI: 10.1094/mpmi-22-6-0747] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/05/2023]
Abstract
Deciphering the mechanisms enabling plant-pathogenic bacteria to disperse, colonize, and survive on their hosts provides the necessary basis to set up new control methods. We evaluated the role of bacterial attachment and biofilm formation in host colonization processes for Xanthomonas fuscans subsp. fuscans on its host. This bacterium is responsible for the common bacterial blight of bean (Phaseolus vulgaris), a seedborne disease. The five adhesin genes (pilA, fhab, xadA1, xadA2, and yapH) identified in X. fuscans subsp. fuscans CFBP4834-R strain were mutated. All mutants were altered in their abilities to adhere to polypropylene or seed. PilA was involved in adhesion and transmission to seed, and mutation of pilA led to lower pathogenicity on bean. YapH was required for adhesion to seed, leaves, and abiotic surfaces but not for in planta transmission to seed or aggressiveness on leaves. Transmission to seed through floral structures did not require any of the known adhesins. Conversely, all mutants tested, except in yapH, were altered in their vascular transmission to seed. In conclusion, we showed that adhesins are implicated in the various processes leading to host phyllosphere colonization and transmission to seed by plant-pathogenic bacteria.
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Affiliation(s)
- A Darsonval
- UMR077 PaVé, INRA, 42, F-49071 Beaucouzé, France
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Pseudomonas aeruginosa infection of zebrafish involves both host and pathogen determinants. Infect Immun 2009; 77:1293-303. [PMID: 19168742 DOI: 10.1128/iai.01181-08] [Citation(s) in RCA: 119] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Zebrafish (Danio rerio) have a number of strengths as a host model for infection, including genetic tractability, a vertebrate immune system similar to that of mammals, ease and scale of laboratory handling, which allows analysis with reasonable throughput, and transparency, which facilitates visualization of the infection. With these advantages in mind, we examined whether zebrafish could be used to study Pseudomonas aeruginosa pathogenesis and found that infection of zebrafish embryos with live P. aeruginosa (PA14 or PAO1) by microinjection results in embryonic death, unlike infection with Escherichia coli or heat-killed P. aeruginosa, which has no effect. Similar to studies with mice, P. aeruginosa mutants deficient in type three secretion (pscD) or quorum sensing (lasR and mvfR) are attenuated in zebrafish embryos infected at 50 h postfertilization (hpf), a developmental stage when both macrophages and neutrophils are present. In contrast, embryos infected at 28 hpf, when only macrophages are initially present, succumb to lethal challenge with far fewer P. aeruginosa cells than those required for embryos infected at 50 hpf, are susceptible to infection with lasR and pscD deletion mutants, and are moderately resistant to infection with an mvfR mutant. Finally, we show that we can control the outcome of infection through the use of morpholinos, which allow us to shift immune cell numbers, or small molecules (antibiotics), which rescue embryos from lethal challenge. Thus, zebrafish are a novel host model that is well suited for studying the interactions among individual pathogenic functions of P. aeruginosa, the role of individual components of host immune defense, and small-molecule modulators of infection.
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Pirone L, Bragonzi A, Farcomeni A, Paroni M, Auriche C, Conese M, Chiarini L, Dalmastri C, Bevivino A, Ascenzioni F. Burkholderia cenocepacia strains isolated from cystic fibrosis patients are apparently more invasive and more virulent than rhizosphere strains. Environ Microbiol 2008; 10:2773-84. [PMID: 18643926 DOI: 10.1111/j.1462-2920.2008.01697.x] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Given the widespread presence of Burkholderia cenocepacia in the rhizosphere it is important to determine whether rhizosphere strains are pathogenic for cystic fibrosis patients or not. Eighteen B. cenocepacia strains of rhizosphere and clinical origin were typed by multi-locus sequence typing (MLST) analysis and compared for their ability to invade pulmonary epithelial cells and their virulence in a mouse model of airway infection. Although there was great variability, clinical strains were the most invasive in vitro. Almost all the rhizosphere and two clinical strains were defined as non-invasive, six clinical strains as invasive, and two strains of both clinical and environmental origin as indeterminate. Exposure of murine airways to clinical strains caused higher acute mortality than that seen after challenge with rhizosphere strains. Furthermore, both clinical and environmental strains were able to persist in the lungs of infected mice, with no significant differences in bacterial loads and localization 14 days after challenge. DNA dot blot analyses of AHL synthase, porin and amidase genes, which play a role in B. cenocepacia virulence, showed that they were present in B. cenocepacia strains irrespective of their origin. Overall, our results suggest that rhizosphere strains do not differ from clinical strains in some pathogenic traits.
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Affiliation(s)
- Luisa Pirone
- ENEA C.R. Casaccia - Department of Biotechnologies, Agroindustry and Protection of Health, Plant Genetics and Genomics Section, Rome, Italy
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Whipps JM, Hand P, Pink DA, Bending GD. Chapter 7 Human Pathogens and the Phyllosphere. ADVANCES IN APPLIED MICROBIOLOGY 2008; 64:183-221. [DOI: 10.1016/s0065-2164(08)00407-3] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Abstract
Cryptococcus spp. are potentially lethal fungal pathogens of humans and animals that are not easily communicable. In this issue of Cell Host & Microbe, Xue et al. describe sexual reproduction of Cryptococcus in association with plants and identify plant-derived mating stimulatory compounds. These results may have wide significance in explaining environmental sources of effective inoculum in human disease foci.
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Affiliation(s)
- Marina Nadal
- Department of Plant Pathology, University of Georgia, Athens, GA 30602-7274, USA
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Mehl HL, Epstein L. Fusarium solani species complex isolates conspecific with Fusarium solani f. sp. cucurbitae race 2 from naturally infected human and plant tissue and environmental sources are equally virulent on plants, grow at 37 degrees C and are interfertile. Environ Microbiol 2007; 9:2189-99. [PMID: 17686017 DOI: 10.1111/j.1462-2920.2007.01333.x] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
In a previous taxonomic study based on multilocus sequencing of Fusarium from clinical specimens and hospital environments, the most common lineage was Fusarium solani species complex group 1 (FSSC 1) which is conspecific with F. solani f. sp. cucurbitae race 2, a pathogen of cucurbit fruits. The aims of our study were to determine if clinical and environmental isolates of FSSC 1 are plant pathogens and members of the same biological species as cucurbit isolates, and to determine if all isolates can germinate, grow and sporulate at 37 degrees C. Isolates from the different sources did not differ in virulence on zucchini fruits. All FSSC 1 isolates were pathogenic and produced more rot than FSSC isolates from plant hosts other than cucurbits. Both mating types were found among isolates from each of the sources, and all isolates were sexually compatible with cucurbit isolates. All isolates germinated, grew and sporulated at 37 degrees C. This is the first report in which plant pathogenicity has been verified for a collection of human clinical isolates. Our data are consistent with the hypothesis that all FSSC 1 isolates, regardless of source, are a single biological species, equally virulent plant pathogens and tolerant of the human body temperature.
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Affiliation(s)
- Hillary L Mehl
- Department of Plant Pathology, University of California, Davis, CA 95616, USA
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van Baarlen P, van Belkum A, Thomma BPHJ. Disease induction by human microbial pathogens in plant-model systems: potential, problems and prospects. Drug Discov Today 2007; 12:167-73. [PMID: 17275738 DOI: 10.1016/j.drudis.2006.12.007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2006] [Accepted: 12/07/2006] [Indexed: 01/26/2023]
Abstract
Relatively simple eukaryotic model organisms such as the genetic model weed plant Arabidopsis thaliana possess an innate immune system that shares important similarities with its mammalian counterpart. In fact, some human pathogens infect Arabidopsis and cause overt disease with human symptomology. In such cases, decisive elements of the plant's immune system are likely to be targeted by the same microbial factors that are necessary for causing disease in humans. These similarities can be exploited to identify elementary microbial pathogenicity factors and their corresponding targets in a green host. This circumvents important cost aspects that often frustrate studies in humans or animal models and, in addition, results in facile ethical clearance.
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Affiliation(s)
- Peter van Baarlen
- Nijmegen Centre for Molecular Life Sciences (NCMLS), Radboud University, Nijmegen Medical Centre, Geert Grooteplein 26-28, 6525 GA Nijmegen, The Netherlands
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Anselme C, Vallier A, Balmand S, Fauvarque MO, Heddi A. Host PGRP gene expression and bacterial release in endosymbiosis of the weevil Sitophilus zeamais. Appl Environ Microbiol 2006; 72:6766-72. [PMID: 17021229 PMCID: PMC1610295 DOI: 10.1128/aem.00942-06] [Citation(s) in RCA: 67] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023] Open
Abstract
Intracellular symbiosis (endosymbiosis) with gram-negative bacteria is common in insects, yet little is known about how the host immune system perceives the endosymbionts and controls their growth and invasion without complete bacterial clearance. In this study, we have explored the expression of a peptidoglycan recognition protein gene of the weevil Sitophilus zeamais (wPGRP); an ortholog in Drosophila (i.e., PGRP-LB) was recently shown to downregulate the Imd pathway (A. Zaidman-Remy, M. Herve, M. Poidevin, S. Pili-Floury, M. S. Kim, D. Blanot, B. H. Oh, R. Ueda, D. Mengin-Lecreulx, and B. Lemaitre, Immunity 24:463-473, 2006). Insect challenges with bacteria have demonstrated that wPGRP is induced by gram-negative bacteria and that the level of induction depends on bacterial growth. Real-time reverse transcription-PCR quantification of the wPGRP gene transcript performed at different points in insect development has shown a high steady-state level in the bacteria-bearing organ (the bacteriome) of larvae and a high level of wPGRP up-regulation in the symbiotic nymphal phase. Concomitantly, during this stage fluorescence in situ hybridization has revealed an endosymbiont release from the host bacteriocytes. Together with the previously described high induction level of endosymbiont virulence genes at the nymphal phase (C. Dale, G. R. Plague, B. Wang, H. Ochman, and N. A. Moran, Proc. Natl. Acad. Sci. USA 99:12397-12402, 2002), these findings indicate that insect mutualistic relationships evolve through an interplay between bacterial virulence and host immune defense and that the host immunity engages the PGRP gene family in that interplay.
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Affiliation(s)
- Caroline Anselme
- Laboratoire de Biologie Fonctionnelle Insectes et Interactions (BF2I), UMR INRA/INSA de Lyon, Bât. Louis Pasteur, 20 Avenue Albert Einstein, 69621 Villeurbanne Cedex, France
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