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Cruz AAD, Cabeo M, Durán-Viseras A, Sampedro I, Llamas I. Interference of AHL signal production in the phytophatogen Pantoea agglomerans as a sustainable biological strategy to reduce its virulence. Microbiol Res 2024; 285:127781. [PMID: 38795406 DOI: 10.1016/j.micres.2024.127781] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2024] [Revised: 04/23/2024] [Accepted: 05/21/2024] [Indexed: 05/28/2024]
Abstract
Pantoea agglomerans is considered one of the most ubiquitous and versatile organisms that include strains that induce diseases in various crops and occasionally cause opportunistic infections in humans. To develop effective strategies to mitigate its impact on plant health and agricultural productivity, a comprehensive investigation is crucial for better understanding its pathogenicity. One proposed eco-friendly approach involves the enzymatic degradation of quorum sensing (QS) signal molecules like N-acylhomoserine lactones (AHLs), known as quorum quenching (QQ), offering potential treatment for such bacterial diseases. In this study the production of C4 and 3-oxo-C6HSL was identified in the plant pathogenic P. agglomerans CFBP 11141 and correlated to enzymatic activities such as amylase and acid phosphatase. Moreover, the heterologous expression of a QQ enzyme in the pathogen resulted in lack of AHLs production and the attenuation of the virulence by mean of drastically reduction of soft rot disease in carrots and cherry tomatoes. Additionally, the interference with the QS systems of P. agglomerans CFBP 11141 by two the plant growth-promoting and AHL-degrading bacteria (PGP-QQ) Pseudomonas segetis P6 and Bacillus toyonensis AA1EC1 was evaluated as a potential biocontrol approach for the first time. P. segetis P6 and B. toyonensis AA1EC1 demonstrated effectiveness in diminishing soft rot symptoms induced by P. agglomerans CFBP 11141 in both carrots and cherry tomatoes. Furthermore, the virulence of pathogen notably decreased when co-cultured with strain AA1EC1 on tomato plants.
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Affiliation(s)
- Alba Amaro-da Cruz
- Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, Granada 18071, Spain
| | - Mónica Cabeo
- Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, Granada 18071, Spain
| | - Ana Durán-Viseras
- Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, Granada 18071, Spain
| | - Inmaculada Sampedro
- Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, Granada 18071, Spain; Institute of Biotechnology, Biomedical Research Center (CIBM), University of Granada, Granada 18106, Spain.
| | - Inmaculada Llamas
- Department of Microbiology, Faculty of Pharmacy, Cartuja Campus, University of Granada, Granada 18071, Spain; Institute of Biotechnology, Biomedical Research Center (CIBM), University of Granada, Granada 18106, Spain.
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Faist H, Ankenbrand MJ, Sickel W, Hentschel U, Keller A, Deeken R. Opportunistic Bacteria of Grapevine Crown Galls Are Equipped with the Genomic Repertoire for Opine Utilization. Genome Biol Evol 2023; 15:evad228. [PMID: 38085065 PMCID: PMC10745273 DOI: 10.1093/gbe/evad228] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2023] [Indexed: 12/24/2023] Open
Abstract
Young grapevines (Vitis vinifera) suffer and eventually can die from the crown gall disease caused by the plant pathogen Allorhizobium vitis (Rhizobiaceae). Virulent members of A. vitis harbor a tumor-inducing plasmid and induce formation of crown galls due to the oncogenes encoded on the transfer DNA. The expression of oncogenes in transformed host cells induces unregulated cell proliferation and metabolic and physiological changes. The crown gall produces opines uncommon to plants, which provide an important nutrient source for A. vitis harboring opine catabolism enzymes. Crown galls host a distinct bacterial community, and the mechanisms establishing a crown gall-specific bacterial community are currently unknown. Thus, we were interested in whether genes homologous to those of the tumor-inducing plasmid coexist in the genomes of the microbial species coexisting in crown galls. We isolated 8 bacterial strains from grapevine crown galls, sequenced their genomes, and tested their virulence and opine utilization ability in bioassays. In addition, the 8 genome sequences were compared with 34 published bacterial genomes, including closely related plant-associated bacteria not from crown galls. Homologous genes for virulence and opine anabolism were only present in the virulent Rhizobiaceae. In contrast, homologs of the opine catabolism genes were present in all strains including the nonvirulent members of the Rhizobiaceae and non-Rhizobiaceae. Gene neighborhood and sequence identity of the opine degradation cluster of virulent and nonvirulent strains together with the results of the opine utilization assay support the important role of opine utilization for cocolonization in crown galls, thereby shaping the crown gall community.
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Affiliation(s)
- Hanna Faist
- Center for Health & Bioresources, Bioresources Unit, AIT Austrian Institute of Technology GmbH, Tulln 3430, Austria
- Julius-von-Sachs Institute for Biological Sciences, Molecular Plant Physiology and Biophysics, University of Würzburg, Würzburg 97082, Germany
| | - Markus J Ankenbrand
- Faculty of Biology, Center for Computational and Theoretical Biology, University of Würzburg, Würzburg 97074, Germany
| | - Wiebke Sickel
- Institute of Biodiversity, Thuenen-Institute of Biodiversity, Braunschweig 38116, Germany
| | - Ute Hentschel
- RD3 Marine Ecology, RU Marine Symbioses, GEOMAR Helmholtz Centre for Ocean Research Kiel, Kiel 24105, Germany
- Sektion Biologie, Christian-Albrechts University of Kiel, Kiel 24105, Germany
| | - Alexander Keller
- Cellular and Organismic Networks, Faculty of Biology, Ludwig-Maximilians-Universität München, Planegg-Martinsried 82152, Germany
| | - Rosalia Deeken
- Julius-von-Sachs Institute for Biological Sciences, Molecular Plant Physiology and Biophysics, University of Würzburg, Würzburg 97082, Germany
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Jin K, Tian N, da Silva Ferreira JF, Sandhu D, Xiao L, Gu M, Luo Y, Zhang X, Liu G, Liu Z, Huang J, Liu S. Comparative Transcriptome Analysis of Agrobacterium tumefaciens Reveals the Molecular Basis for the Recalcitrant Genetic Transformation of Camellia sinensis L. Biomolecules 2022; 12:688. [PMID: 35625616 PMCID: PMC9138961 DOI: 10.3390/biom12050688] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 05/06/2022] [Accepted: 05/09/2022] [Indexed: 11/17/2022] Open
Abstract
Tea (Camellia sinensis L.), an important economic crop, is recalcitrant to Agrobacterium-mediated transformation (AMT), which has seriously hindered the progress of molecular research on this species. The mechanisms leading to low efficiency of AMT in tea plants, related to the morphology, growth, and gene expression of Agrobacterium tumefaciens during tea-leaf explant infection, were compared to AMT of Nicotiana benthamiana leaves in the present work. Scanning electron microscopy (SEM) images showed that tea leaves induced significant morphological aberrations on bacterial cells and affected pathogen-plant attachment, the initial step of a successful AMT. RNA sequencing and transcriptomic analysis on Agrobacterium at 0, 3 and 4 days after leaf post-inoculation resulted in 762, 1923 and 1656 differentially expressed genes (DEGs) between the tea group and the tobacco group, respectively. The expressions of genes involved in bacterial fundamental metabolic processes, ATP-binding cassette (ABC) transporters, two-component systems (TCSs), secretion systems, and quorum sensing (QS) systems were severely affected in response to the tea-leaf phylloplane. Collectively, these results suggest that compounds in tea leaves, especially gamma-aminobutyrate (GABA) and catechins, interfered with plant-pathogen attachment, essential minerals (iron and potassium) acquisition, and quorum quenching (QQ) induction, which may have been major contributing factors to hinder AMT efficiency of the tea plant.
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Affiliation(s)
- Ke Jin
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Na Tian
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Jorge Freire da Silva Ferreira
- United States Salinity Laboratory, United States Department of Agriculture, Agricultural Research Service, Riverside, CA 92507, USA; (J.F.d.S.F.); (D.S.)
| | - Devinder Sandhu
- United States Salinity Laboratory, United States Department of Agriculture, Agricultural Research Service, Riverside, CA 92507, USA; (J.F.d.S.F.); (D.S.)
| | - Lizheng Xiao
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
| | - Meiyi Gu
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
| | - Yiping Luo
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Xiangqin Zhang
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Guizhi Liu
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Zhonghua Liu
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Jianan Huang
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
| | - Shuoqian Liu
- Department of Tea Science, College of Horticulture, Hunan Agricultural University, Changsha 410128, China; (K.J.); (N.T.); (L.X.); (M.G.)
- Key Laboratory of Tea Science of Ministry of Education, Hunan Agricultural University, Changsha 410128, China; (Y.L.); (X.Z.); (G.L.)
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Friends or Foes-Microbial Interactions in Nature. BIOLOGY 2021; 10:biology10060496. [PMID: 34199553 PMCID: PMC8229319 DOI: 10.3390/biology10060496] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Revised: 05/27/2021] [Accepted: 05/31/2021] [Indexed: 12/16/2022]
Abstract
Simple Summary Microorganisms like bacteria, archaea, fungi, microalgae, and viruses mostly form complex interactive networks within the ecosystem rather than existing as single planktonic cells. Interactions among microorganisms occur between the same species, with different species, or even among entirely different genera, families, or even domains. These interactions occur after environmental sensing, followed by converting those signals to molecular and genetic information, including many mechanisms and classes of molecules. Comprehensive studies on microbial interactions disclose key strategies of microbes to colonize and establish in a variety of different environments. Knowledge of the mechanisms involved in the microbial interactions is essential to understand the ecological impact of microbes and the development of dysbioses. It might be the key to exploit strategies and specific agents against different facing challenges, such as chronic and infectious diseases, hunger crisis, pollution, and sustainability. Abstract Microorganisms are present in nearly every niche on Earth and mainly do not exist solely but form communities of single or mixed species. Within such microbial populations and between the microbes and a eukaryotic host, various microbial interactions take place in an ever-changing environment. Those microbial interactions are crucial for a successful establishment and maintenance of a microbial population. The basic unit of interaction is the gene expression of each organism in this community in response to biotic or abiotic stimuli. Differential gene expression is responsible for producing exchangeable molecules involved in the interactions, ultimately leading to community behavior. Cooperative and competitive interactions within bacterial communities and between the associated bacteria and the host are the focus of this review, emphasizing microbial cell–cell communication (quorum sensing). Further, metagenomics is discussed as a helpful tool to analyze the complex genomic information of microbial communities and the functional role of different microbes within a community and to identify novel biomolecules for biotechnological applications.
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Mahavy CE, Duez P, ElJaziri M, Rasamiravaka T. African Plant-Based Natural Products with Antivirulence Activities to the Rescue of Antibiotics. Antibiotics (Basel) 2020; 9:antibiotics9110830. [PMID: 33228261 PMCID: PMC7699609 DOI: 10.3390/antibiotics9110830] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2020] [Revised: 11/14/2020] [Accepted: 11/16/2020] [Indexed: 12/14/2022] Open
Abstract
The worldwide emergence of antibiotic-resistant bacteria and the thread of widespread superbug infections have led researchers to constantly look for novel effective antimicrobial agents. Within the past two decades, there has been an increase in studies attempting to discover molecules with innovative properties against pathogenic bacteria, notably by disrupting mechanisms of bacterial virulence and/or biofilm formation which are both regulated by the cell-to-cell communication mechanism called ‘quorum sensing’ (QS). Certainly, targeting the virulence of bacteria and their capacity to form biofilms, without affecting their viability, may contribute to reduce their pathogenicity, allowing sufficient time for an immune response to infection and a reduction in the use of antibiotics. African plants, through their huge biodiversity, present a considerable reservoir of secondary metabolites with a very broad spectrum of biological activities, a potential source of natural products targeting such non-microbicidal mechanisms. The present paper aims to provide an overview on two main aspects: (i) succinct presentation of bacterial virulence and biofilm formation as well as their entanglement through QS mechanisms and (ii) detailed reports on African plant extracts and isolated compounds with antivirulence properties against particular pathogenic bacteria.
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Affiliation(s)
- Christian Emmanuel Mahavy
- Laboratory of Biotechnology and Microbiology, University of Antananarivo, BP 906 Antananarivo 101, Madagascar;
- Laboratory of Plant Biotechnology, Université Libre de Bruxelles, B-1050 Brussels, Belgium;
| | - Pierre Duez
- Unit of Therapeutic Chemistry and Pharmacognosy, University of Mons, 7000 Mons, Belgium;
| | - Mondher ElJaziri
- Laboratory of Plant Biotechnology, Université Libre de Bruxelles, B-1050 Brussels, Belgium;
| | - Tsiry Rasamiravaka
- Laboratory of Biotechnology and Microbiology, University of Antananarivo, BP 906 Antananarivo 101, Madagascar;
- Correspondence: ; Tel.: +261-32-61-903-38
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Chandrasekaran M, Lee JM, Ye BM, Jung SM, Kim J, Kim JW, Chun SC. Isolation and Characterization of Avirulent and Virulent Strains of Agrobacterium tumefaciens from Rose Crown Gall in Selected Regions of South Korea. PLANTS (BASEL, SWITZERLAND) 2019; 8:E452. [PMID: 31731525 PMCID: PMC6918265 DOI: 10.3390/plants8110452] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2019] [Revised: 10/18/2019] [Accepted: 10/24/2019] [Indexed: 01/22/2023]
Abstract
Agrobacterium tumefaciens is a plant pathogen that causes crown gall disease in various hosts across kingdoms. In the present study, five regions (Wonju, Jincheon, Taean, Suncheon, and Kimhae) of South Korea were chosen to isolate A. tumefaciens strains on roses and assess their opine metabolism (agrocinopine, nopaline, and octopine) genes based on PCR amplification. These isolated strains were confirmed as Agrobacterium using morphological, biochemical, and 16S rDNA analyses; and pathogenicity tests, including the growth characteristics of the white colony appearance on ammonium sulfate glucose minimal media, enzyme activities, 16S rDNA sequence alignment, and pathogenicity on tomato (Solanum lycopersicum). Carbon utilization, biofilm formation, tumorigenicity, and motility assays were performed to demarcate opine metabolism genes. Of 87 isolates, 18 pathogenic isolates were affirmative for having opine plasmid genes. Most of these isolates showed the presence of an agrocinopine type of carbon utilization. Two isolates showed nopaline types. However, none of these isolates showed octopine metabolic genes. The objectives of the present study were to isolate and confirm virulent strains from rose crown galls grown in the different regions of Korea and characterize their physiology and opine types. This is the first report to describe the absence of the octopine type inciting the crown gall disease of rose in South Korea.
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Affiliation(s)
- Murugesan Chandrasekaran
- Department of Food Science and Biotechnology, Sejong University, Gwangjin-gu, Seoul 05006, Korea;
| | - Jong Moon Lee
- Department of Environmental Health Science, Konkuk University, Gwangjin-gu, Seoul-143 701, Korea; (J.M.L.); (B.-M.Y.); (S.M.J.)
| | - Bee-Moon Ye
- Department of Environmental Health Science, Konkuk University, Gwangjin-gu, Seoul-143 701, Korea; (J.M.L.); (B.-M.Y.); (S.M.J.)
| | - So Mang Jung
- Department of Environmental Health Science, Konkuk University, Gwangjin-gu, Seoul-143 701, Korea; (J.M.L.); (B.-M.Y.); (S.M.J.)
| | - Jinwoo Kim
- Institute of Agriculture & Life Science and Division of Applied Life Science, Gyeongsang National University, Jinju 52828, Korea;
| | - Jin-Won Kim
- Department of Environmental Horticulture, University of Seoul, Seoul 02504, Korea;
| | - Se Chul Chun
- Department of Environmental Health Science, Konkuk University, Gwangjin-gu, Seoul-143 701, Korea; (J.M.L.); (B.-M.Y.); (S.M.J.)
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Kalia VC, Patel SKS, Kang YC, Lee JK. Quorum sensing inhibitors as antipathogens: biotechnological applications. Biotechnol Adv 2018; 37:68-90. [PMID: 30471318 DOI: 10.1016/j.biotechadv.2018.11.006] [Citation(s) in RCA: 185] [Impact Index Per Article: 30.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2018] [Revised: 10/19/2018] [Accepted: 11/18/2018] [Indexed: 12/20/2022]
Abstract
The mechanisms through which microbes communicate using signal molecules has inspired a great deal of research. Microbes use this exchange of information, known as quorum sensing (QS), to initiate and perpetuate infectious diseases in eukaryotic organisms, evading the eukaryotic defense system by multiplying and expressing their pathogenicity through QS regulation. The major issue to arise from such networks is increased bacterial resistance to antibiotics, resulting from QS-dependent mediation of the formation of biofilm, the induction of efflux pumps, and the production of antibiotics. QS inhibitors (QSIs) of diverse origins have been shown to act as potential antipathogens. In this review, we focus on the use of QSIs to counter diseases in humans as well as plants and animals of economic importance. We also discuss the challenges encountered in the potential applications of QSIs.
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Affiliation(s)
- Vipin Chandra Kalia
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea.
| | - Sanjay K S Patel
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea
| | - Yun Chan Kang
- Department of Materials Science and Engineering, Korea University, Anam-Dong, Seongbuk-Gu, Seoul 02841, Republic of Korea
| | - Jung-Kul Lee
- Department of Chemical Engineering, Konkuk University, Seoul 05029, Republic of Korea.
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Podlešáková K, Ugena L, Spíchal L, Doležal K, De Diego N. Phytohormones and polyamines regulate plant stress responses by altering GABA pathway. N Biotechnol 2018; 48:53-65. [PMID: 30048769 DOI: 10.1016/j.nbt.2018.07.003] [Citation(s) in RCA: 117] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/29/2017] [Revised: 06/20/2018] [Accepted: 07/21/2018] [Indexed: 11/16/2022]
Abstract
In plants, γ-aminobutyric acid (GABA) accumulates rapidly in response to environmental stress and variations in its endogenous concentration have been shown to affect plant growth. Exogenous application of GABA has also conferred higher stress tolerance by modulating the expression of genes involved in plant signalling, transcriptional regulation, hormone biosynthesis, reactive oxygen species production and polyamine metabolism. Plant hormones play critical roles in adaptation of plants to adverse environmental conditions through a sophisticated crosstalk among them. Several studies have provided evidence for the relationships between GABA, polyamines and hormones such as abscisic acid, cytokinins, auxins, gibberellins and ethylene, among others, focussing on the effect that one specific group of compounds exerts over the metabolic and signalling pathways of others. In this review, we bring together information obtained from plants exposed to several stress conditions and discuss the possible links among these different groups of molecules. The analysis supports the view that highly conserved pathways connect primary and secondary metabolism, with an overlap of regulatory functions related to stress responses and tolerance among phytohormones, amino acids and polyamines.
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Affiliation(s)
- Kateřina Podlešáková
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, CZ-78371, Czech Republic.
| | - Lydia Ugena
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, CZ-78371, Czech Republic.
| | - Lukáš Spíchal
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, CZ-78371, Czech Republic.
| | - Karel Doležal
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, CZ-78371, Czech Republic.
| | - Nuria De Diego
- Department of Chemical Biology and Genetics, Centre of the Region Haná for Biotechnological and Agricultural Research, Faculty of Science, Palacký University, Olomouc, CZ-78371, Czech Republic.
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Dessaux Y, Faure D. Quorum Sensing and Quorum Quenching in Agrobacterium: A "Go/No Go System"? Genes (Basel) 2018; 9:genes9040210. [PMID: 29659511 PMCID: PMC5924552 DOI: 10.3390/genes9040210] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 04/08/2018] [Accepted: 04/09/2018] [Indexed: 02/02/2023] Open
Abstract
The pathogen Agrobacterium induces gall formation on a wide range of dicotyledonous plants. In this bacteria, most pathogenicity determinants are borne on the tumour inducing (Ti) plasmid. The conjugative transfer of this plasmid between agrobacteria is regulated by quorum sensing (QS). However, processes involved in the disturbance of QS also occur in this bacteria under the molecular form of a protein, TraM, inhibiting the sensing of the QS signals, and two lactonases BlcC (AttM) and AiiB that degrade the acylhomoserine lactone (AHL) QS signal. In the model Agrobacteriumfabrum strain C58, several data, once integrated, strongly suggest that the QS regulation may not be reacting only to cell concentration. Rather, these QS elements in association with the quorum quenching (QQ) activities may constitute an integrated and complex “go/no go system” that finely controls the biologically costly transfer of the Ti plasmid in response to multiple environmental cues. This decision mechanism permits the bacteria to sense whether it is in a gall or not, in a living or decaying tumor, in stressed plant tissues, etc. In this scheme, the role of the lactonases selected and maintained in the course of Ti plasmid and agrobacterial evolution appears to be pivotal.
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Affiliation(s)
- Yves Dessaux
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Avenue de la terrasse, 91198 Gif sur Yvette CEDEX, France.
| | - Denis Faure
- Institute for Integrative Biology of the Cell (I2BC), CEA, CNRS, Univ. Paris-Sud, Université Paris-Saclay, Avenue de la terrasse, 91198 Gif sur Yvette CEDEX, France.
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10
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Barton IS, Fuqua C, Platt TG. Ecological and evolutionary dynamics of a model facultative pathogen: Agrobacterium and crown gall disease of plants. Environ Microbiol 2018; 20:16-29. [PMID: 29105274 PMCID: PMC5764771 DOI: 10.1111/1462-2920.13976] [Citation(s) in RCA: 38] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2017] [Revised: 10/20/2017] [Accepted: 10/25/2017] [Indexed: 01/09/2023]
Abstract
Many important pathogens maintain significant populations in highly disparate disease and non-disease environments. The consequences of this environmental heterogeneity in shaping the ecological and evolutionary dynamics of these facultative pathogens are incompletely understood. Agrobacterium tumefaciens, the causative agent for crown gall disease of plants has proven a productive model for many aspects of interactions between pathogens and their hosts and with other microbes. In this review, we highlight how this past work provides valuable context for the use of this system to examine how heterogeneity and transitions between disease and non-disease environments influence the ecology and evolution of facultative pathogens. We focus on several features common among facultative pathogens, such as the physiological remodelling required to colonize hosts from environmental reservoirs and the consequences of competition with host and non-host associated microbiota. In addition, we discuss how the life history of facultative pathogens likely often results in ecological tradeoffs associated with performance in disease and non-disease environments. These pathogens may therefore have different competitive dynamics in disease and non-disease environments and are subject to shifting selective pressures that can result in pathoadaptation or the within-host spread of avirulent phenotypes.
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Affiliation(s)
- Ian S. Barton
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Clay Fuqua
- Department of Biology, Indiana University, Bloomington, IN, USA
| | - Thomas G. Platt
- Division of Biology, Kansas State University, Manhattan, KS, USA
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11
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Ma ZP, Lao YM, Jin H, Lin GH, Cai ZH, Zhou J. Diverse Profiles of AI-1 Type Quorum Sensing Molecules in Cultivable Bacteria from the Mangrove ( Kandelia obovata) Rhizosphere Environment. Front Microbiol 2016; 7:1957. [PMID: 27994584 PMCID: PMC5136546 DOI: 10.3389/fmicb.2016.01957] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2016] [Accepted: 11/22/2016] [Indexed: 11/25/2022] Open
Abstract
Mangrove rhizosphere environment harbors diverse populations of microbes, and some evidence showed that rhizobacteria behavior was regulated by quorum sensing (QS). Investigating the diverse profiles of QS molecules in mangrove ecosystems may shed light on the bacterial roles and lead to a better understanding of the symbiotic interactions between plants and microbes. The aims of the current study focus on identifying AI-1 type QS signals, i.e., acyl homoserine lactones (AHLs), in Kandelia obovata rhizosphere environment. Approximately 1200 rhizobacteria were screened and 184 strains (15.3%) tested were positive. Subsequent 16s rRNA gene sequencing and dereplication analyses identified 24 species from the positive isolates, which were affiliated to three different phyla, including Proteobacteria, Firmicutes, and Actinobacteria. Thin-layer chromatography separation of extracts revealed diverse AHL profiles and detected at least one active compound in the supernatant of these 24 cultivable AHL-producers. The active extracts from these bacterial isolates were further evaluated by ultra performance liquid chromatography-mass spectrometry, and the carbon side chain length ranged from C4 to C14. This is the first report on the diversity of AI-1 type auto-inducers in the mangrove plant K. obovata, and it is imperative to expand our knowledge of plant-bacteria interactions with respect to the maintenance of wetland ecosystem health.
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Affiliation(s)
- Zhi P Ma
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua UniversityShenzhen, China; Shenzhen Public Platform for Screening and Application of Marine Microbial ResourcesShenzhen, China
| | - Yong M Lao
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua UniversityShenzhen, China; Shenzhen Public Platform for Screening and Application of Marine Microbial ResourcesShenzhen, China
| | - Hui Jin
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua UniversityShenzhen, China; Shenzhen Public Platform for Screening and Application of Marine Microbial ResourcesShenzhen, China
| | - Guang H Lin
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua University Shenzhen, China
| | - Zhong H Cai
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua UniversityShenzhen, China; Shenzhen Public Platform for Screening and Application of Marine Microbial ResourcesShenzhen, China
| | - Jin Zhou
- The Division of Ocean Science and Technology, Graduate School at Shenzhen, Tsinghua UniversityShenzhen, China; Shenzhen Public Platform for Screening and Application of Marine Microbial ResourcesShenzhen, China
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12
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Wang XY, Zhou L, Yang J, Ji GH, He YW. The RpfB-Dependent Quorum Sensing Signal Turnover System Is Required for Adaptation and Virulence in Rice Bacterial Blight Pathogen Xanthomonas oryzae pv. oryzae. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2016; 29:220-30. [PMID: 26667598 DOI: 10.1094/mpmi-09-15-0206-r] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
Xanthomonas oryzae pv. oryzae, the bacterial blight pathogen of rice, produces diffusible signal factor (DSF) family quorum sensing signals to regulate virulence. The biosynthesis and perception of DSF family signals require components of the rpf (regulation of pathogenicity factors) cluster. In this study, we report that RpfB plays an essential role in DSF family signal turnover in X. oryzae pv. oryzae PXO99A. The production of DSF family signals was boosted by deletion of the rpfB gene and was abolished by its overexpression. The RpfC/RpfG-mediated DSF signaling system negatively regulates rpfB expression via the global transcription regulator Clp, whose activity is reversible in the presence of cyclic diguanylate monophosphate. These findings indicate that the DSF family signal turnover system in PXO99A is generally consistent with that in Xanthomonas campestris pv. campestris. Moreover, this study has revealed several specific roles of RpfB in PXO99A. First, the rpfB deletion mutant produced high levels of DSF family signals but reduced extracellular polysaccharide production, extracellular amylase activity, and attenuated pathogenicity. Second, the rpfB/rpfC double-deletion mutant was partially deficient in xanthomonadin production. Taken together, the RpfB-dependent DSF family signal turnover system is a conserved and naturally presenting signal turnover system in Xanthomonas spp., which plays unique roles in X. oryzae pv. oryzae adaptation and pathogenesis.
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Affiliation(s)
- Xing-Yu Wang
- 1 State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Lian Zhou
- 1 State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Jun Yang
- 2 College of Plant Protection, Yunnan Agricultural University, Kunming 650201, China
| | - Guang-Hai Ji
- 2 College of Plant Protection, Yunnan Agricultural University, Kunming 650201, China
| | - Ya-Wen He
- 1 State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
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13
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Abstract
Agrobacterium tumefaciens is a plant pathogen with the capacity to deliver a segment of oncogenic DNA carried on a large plasmid called the tumor-inducing or Ti plasmid to susceptible plant cells. A. tumefaciens belongs to the class Alphaproteobacteria, whose members include other plant pathogens (Agrobacterium rhizogenes), plant and insect symbionts (Rhizobium spp. and Wolbachia spp., respectively), human pathogens (Brucella spp., Bartonella spp., Rickettsia spp.), and nonpathogens (Caulobacter crescentus, Rhodobacter sphaeroides). Many species of Alphaproteobacteria carry large plasmids ranging in size from ∼100 kb to nearly 2 Mb. These large replicons typically code for functions essential for cell physiology, pathogenesis, or symbiosis. Most of these elements rely on a conserved gene cassette termed repABC for replication and partitioning, and maintenance at only one or a few copies per cell. The subject of this review is the ∼200-kb Ti plasmids carried by infectious strains of A. tumefaciens. We will summarize the features of this plasmid as a representative of the repABC family of megaplasmids. We will also describe novel features of this plasmid that enable A. tumefaciens cells to incite tumor formation in plants, sense and respond to an array of plant host and bacterial signal molecules, and maintain and disseminate the plasmid among populations of agrobacteria. At the end of this review, we will describe how this natural genetic engineer has been adapted to spawn an entire industry of plant biotechnology and review its potential for use in future therapeutic applications of plant and nonplant species.
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Abbott ZD, Flynn KJ, Byrne BG, Mukherjee S, Kearns DB, Swanson MS. csrT Represents a New Class of csrA-Like Regulatory Genes Associated with Integrative Conjugative Elements of Legionella pneumophila. J Bacteriol 2016; 198:553-64. [PMID: 26598366 PMCID: PMC4719454 DOI: 10.1128/jb.00732-15] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Accepted: 11/12/2015] [Indexed: 12/15/2022] Open
Abstract
UNLABELLED Bacterial evolution is accelerated by mobile genetic elements. To spread horizontally and to benefit the recipient bacteria, genes encoded on these elements must be properly regulated. Among the legionellae are multiple integrative conjugative elements (ICEs) that each encode a paralog of the broadly conserved regulator csrA. Using bioinformatic analyses, we deduced that specific csrA paralogs are coinherited with particular lineages of the type IV secretion system that mediates horizontal spread of its ICE, suggesting a conserved regulatory interaction. As a first step to investigate the contribution of csrA regulators to this class of mobile genetic elements, we analyzed here the activity of the csrA paralog encoded on Legionella pneumophila ICE-βox. Deletion of this gene, which we name csrT, had no observed effect under laboratory conditions. However, ectopic expression of csrT abrogated the protection to hydrogen peroxide and macrophage degradation that ICE-βox confers to L. pneumophila. When ectopically expressed, csrT also repressed L. pneumophila flagellin production and motility, a function similar to the core genome's canonical csrA. Moreover, csrT restored the repression of motility to csrA mutants of Bacillus subtilis, a finding consistent with the predicted function of CsrT as an mRNA binding protein. Since all known ICEs of legionellae encode coinherited csrA-type IV secretion system pairs, we postulate that CsrA superfamily proteins regulate ICE activity to increase their horizontal spread, thereby expanding L. pneumophila versatility. IMPORTANCE ICEs are mobile DNA elements whose type IV secretion machineries mediate spread among bacterial populations. All surveyed ICEs within the Legionella genus also carry paralogs of the essential life cycle regulator csrA. It is striking that the csrA loci could be classified into distinct families based on either their sequence or the subtype of the adjacent type IV secretion system locus. To investigate whether ICE-encoded csrA paralogs are bona fide regulators, we analyzed ICE-βox as a model system. When expressed ectopically, its csrA paralog inhibited multiple ICE-βox phenotypes, as well as the motility of not only Legionella but also Bacillus subtilis. Accordingly, we predict that CsrA regulators equip legionellae ICEs to promote their spread via dedicated type IV secretion systems.
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Affiliation(s)
- Zachary D Abbott
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Kaitlin J Flynn
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Brenda G Byrne
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | | | - Daniel B Kearns
- Department of Biology, Indiana University, Bloomington, Indiana, USA
| | - Michele S Swanson
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
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15
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Succinic Semialdehyde Promotes Prosurvival Capability of Agrobacterium tumefaciens. J Bacteriol 2016; 198:930-40. [PMID: 26755630 DOI: 10.1128/jb.00373-15] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2015] [Accepted: 12/10/2015] [Indexed: 01/25/2023] Open
Abstract
UNLABELLED Succinic semialdehyde (SSA), an important metabolite of γ-aminobutyric acid (GABA), is a ligand of the repressor AttJ regulating the expression of the attJ-attKLM gene cluster in the plant pathogen Agrobacterium tumefaciens. While the response of A. tumefaciens to GABA and the function of attKLM have been extensively studied, genetic and physiological responses of A. tumefaciens to SSA remain unknown. In combination with microarray and genetic approaches, this study sets out to explore new roles of the SSA-AttJKLM regulatory mechanism during bacterial infection. The results showed that SSA plays a key role in regulation of several bacterial activities, including C4-dicarboxylate utilization, nitrate assimilation, and resistance to oxidative stress. Interestingly, while the SSA relies heavily on the functional AttKLM in mediating nitrate assimilation and oxidative stress resistance, the compound could regulate utilization of C4-dicarboxylates independent of AttJKLM. We further provide evidence that SSA controls C4-dicarboxylate utilization through induction of an SSA importer and that disruption of attKLM attenuates the tumorigenicity of A. tumefaciens. Taken together, these findings indicate that SSA could be a potent plant signal which, together with AttKLM, plays a vital role in promoting the bacterial prosurvival abilities during infection. IMPORTANCE Agrobacterium tumefaciens is a plant pathogen causing crown gall diseases and has been well known as a powerful tool for plant genetic engineering. During the long history of microbe-host interaction, A. tumefaciens has evolved the capabilities of recognition and response to plant-derived chemical metabolites. Succinic semialdehyde (SSA) is one such metabolite. Previous results have demonstrated that SSA functions to activate a quorum-quenching mechanism and thus to decrease the level of quorum-sensing signals, thereby avoiding the elicitation of a plant defense. Here, we studied the effect of SSA on gene expression at a genome-wide level and reported that SSA also promotes bacterial survival during infection. These findings provide a new insight on the biological significance of chemical signaling between agrobacteria and plant hosts.
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D101 is critical for the function of AttJ, a repressor of quorum quenching system in Agrobacterium tumefaciens. J Microbiol 2015; 53:623-32. [PMID: 26231372 DOI: 10.1007/s12275-015-5100-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2015] [Revised: 06/03/2015] [Accepted: 06/29/2015] [Indexed: 10/23/2022]
Abstract
The quorum quenching system of Agrobacterium tumefaciens is specifically activated upon entering the stationary phase. Evidence has shown that this system includes two key components: the IclR-type transcriptional factor AttJ (also named as BlcR) and the AHL-lactonase AttM (also named as BlcC). At exponential phase, AttJ binds to the promoter region of attM and thus suppresses the expression of attM. At stationary phase, however, the small molecule SSA directly binds to AttJ and relieves its inhibition of AttJ and thereby triggers the expression of attM. While the regulation of AttM has been extensively investigated, little is known about the regulation of AttJ. In this study, we demonstrated the D101 amino acid of AttJ is essential for the AttJ function. In vitro, the variant protein of AttJD101H appeared to be readily aggregated. In vivo, the D101H mutation in AttJ entirely abolished the inhibitory activity of AttJ and overexpressed attM in A. tumefaciens A6. In addition, D101H mutation led to an overexpression of attJ, indicating an auto-regulatory mechanism for the attJ regulation. Put together, these findings demonstrate that D101 is an important amino acid for the transcription activity of AttJ and the transcription of attJ is regulated by a negative feedback loop. These results expand previous biochemical characterization of AttJ and provide new mechanistic insights into the regulation of quorum quenching in A. tumefaciens.
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17
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Koraimann G, Wagner MA. Social behavior and decision making in bacterial conjugation. Front Cell Infect Microbiol 2014; 4:54. [PMID: 24809026 PMCID: PMC4010749 DOI: 10.3389/fcimb.2014.00054] [Citation(s) in RCA: 87] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2014] [Accepted: 04/09/2014] [Indexed: 01/05/2023] Open
Abstract
Bacteria frequently acquire novel genes by horizontal gene transfer (HGT). HGT through the process of bacterial conjugation is highly efficient and depends on the presence of conjugative plasmids (CPs) or integrated conjugative elements (ICEs) that provide the necessary genes for DNA transmission. This review focuses on recent advancements in our understanding of ssDNA transfer systems and regulatory networks ensuring timely and spatially controlled DNA transfer (tra) gene expression. As will become obvious by comparing different systems, by default, tra genes are shut off in cells in which conjugative elements are present. Only when conditions are optimal, donor cells—through epigenetic alleviation of negatively acting roadblocks and direct stimulation of DNA transfer genes—become transfer competent. These transfer competent cells have developmentally transformed into specialized cells capable of secreting ssDNA via a T4S (type IV secretion) complex directly into recipient cells. Intriguingly, even under optimal conditions, only a fraction of the population undergoes this transition, a finding that indicates specialization and cooperative, social behavior. Thereby, at the population level, the metabolic burden and other negative consequences of tra gene expression are greatly reduced without compromising the ability to horizontally transfer genes to novel bacterial hosts. This undoubtedly intelligent strategy may explain why conjugative elements—CPs and ICEs—have been successfully kept in and evolved with bacteria to constitute a major driving force of bacterial evolution.
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Affiliation(s)
- Günther Koraimann
- Institute of Molecular Biosciences, University of Graz Graz, Austria
| | - Maria A Wagner
- Max von Pettenkofer-Institut, Ludwig-Maximilians-Universität München Munich, Germany
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18
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Lang J, Planamente S, Mondy S, Dessaux Y, Moréra S, Faure D. Concerted transfer of the virulence Ti plasmid and companion At plasmid in the Agrobacterium tumefaciens-induced plant tumour. Mol Microbiol 2013; 90:1178-89. [PMID: 24118167 DOI: 10.1111/mmi.12423] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/01/2013] [Indexed: 01/28/2023]
Abstract
The plant pathogen Agrobacterium tumefaciens C58 harbours three independent type IV secretion (T4SS) machineries. T4SST-DNA promotes the transfer of the T-DNA to host plant cells, provoking tumour development and accumulation of opines such as nopaline and agrocinopines. T4SSpTi and T4SSpAt control the bacterial conjugation of the Ti and At plasmids respectively. Expression of T4SSpTi is controlled by the agrocinopine-responsive transcriptional repressor AccR. In this work, we compared the genome-wide transcriptional profile of the wild-type A. tumefaciens strain C58 with that of its accR KO-mutant to delineate the AccR regulon. In addition to the genes that encode agrocinopine catabolism and T4SSpTi , we found that AccR also regulated genes coding for nopaline catabolism and T4SSpAt . Further opine detection and conjugation assays confirmed the enhancement of nopaline consumption and At plasmid conjugation frequency in accR. Moreover, co-regulation of the T4SSpTi and T4SSpAt correlated with the co-transfer of the At and Ti plasmids both in vitro and in plant tumours. Finally, unlike T4SSpTi , T4SSpAt activation does not require quorum-sensing. Overall this study highlights the regulatory interplays between opines, At and Ti plasmids that contribute to a concerted dissemination of the two replicons in bacterial populations colonizing the plant tumour.
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Affiliation(s)
- Julien Lang
- Centre National de la Recherche Scientifique, Institut des Sciences du Végétal, UPR2355, 1, Avenue de la Terrasse, 91198, Gif-sur-Yvette, France
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19
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March Rosselló GA, Eiros Bouza JM. [Quorum sensing in bacteria and yeast]. Med Clin (Barc) 2013; 141:353-7. [PMID: 23622893 DOI: 10.1016/j.medcli.2013.02.031] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2012] [Revised: 02/01/2013] [Accepted: 02/21/2013] [Indexed: 12/31/2022]
Abstract
Bacterial sets are complex dynamic systems, which interact with each other and through the interaction, bacteria coexist, collaborate, compete and share information in a coordinated manner. A way of bacterial communication is quorum sensing. Through this mechanism the bacteria can recognize its concentration in a given environment and they can decide the time at which the expression of a particular set of genes should be started for developing a specific and simultaneous response. The result of these interconnections raises properties that cannot be explained from a single isolated bacterial cell.
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20
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Planamente S, Moréra S, Faure D. In planta fitness-cost of the Atu4232-regulon encoding for a selective GABA-binding sensor in Agrobacterium. Commun Integr Biol 2013; 6:e23692. [PMID: 23710277 PMCID: PMC3656012 DOI: 10.4161/cib.23692] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2012] [Revised: 01/21/2013] [Accepted: 01/21/2013] [Indexed: 12/01/2022] Open
Abstract
GABA (gamma-aminobutyric acid) mediates cell-to-cell communication in eukaryotes and interspecies communication in host-microbe interactions. Agrobacterium tumefaciens induces the development of plant tumor in which GABA accumulates. Two periplasmic binding proteins Atu2422 and Atu4243 and their appropriate ABC-transporter are involved in the binding and importation of GABA. The structure of the selective GABA-binding Atu4243 reveals a GABA conformation similar to a proposed model of GABA bound to the mammalian GABAC receptor. The A. tumefaciens atu4243 mutant is affected for GABA uptake, aggressiveness on plant host and GABA-induced degradation of the quorum-sensing signal, hence for horizontal transfer of the tumor-inducing plasmid. Here, we report that a de-repression of atu4243 and its co-regulated neighbor genes affect the fitness of A. tumefaciens during tumor colonization. Atu4243-orthologs are present in several species of the Agrobacterium genus. This addendum highlights the recent data on the GABA transport in the A. tumefaciens plant-pathogen.
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Affiliation(s)
- Sara Planamente
- Institut des Sciences du Végétal (ISV); CNRS; Gif-sur-Yvette, France ; Laboratoire d'Enzymologie et Biochimie Structurales (LEBS); CNRS; Gif-sur-Yvette, France
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21
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22
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Afriat-Jurnou L, Jackson CJ, Tawfik DS. Reconstructing a missing link in the evolution of a recently diverged phosphotriesterase by active-site loop remodeling. Biochemistry 2012; 51:6047-55. [PMID: 22809311 DOI: 10.1021/bi300694t] [Citation(s) in RCA: 112] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Only decades after the introduction of organophosphate pesticides, bacterial phosphotriesterases (PTEs) have evolved to catalyze their degradation with remarkable efficiency. Their closest known relatives, lactonases, with promiscuous phosphotriasterase activity, dubbed PTE-like lactonases (PLLs), share only 30% sequence identity and also differ in the configuration of their active-site loops. PTE was therefore presumed to have evolved from a yet unknown PLL whose primary activity was the hydrolysis of quorum sensing homoserine lactones (HSLs) (Afriat et al. (2006) Biochemistry 45, 13677-13686). However, how PTEs diverged from this presumed PLL remains a mystery. In this study we investigated loop remodeling as a means of reconstructing a homoserine lactonase ancestor that relates to PTE by few mutational steps. Although, in nature, loop remodeling is a common mechanism of divergence of enzymatic functions, reproducing this process in the laboratory is a challenge. Structural and phylogenetic analyses enabled us to remodel one of PTE's active-site loops into a PLL-like configuration. A deletion in loop 7, combined with an adjacent, highly epistatic, point mutation led to the emergence of an HSLase activity that is undetectable in PTE (k(cat)/K(M) values of up to 2 × 10(4)). The appearance of the HSLase activity was accompanied by only a minor decrease in PTE's paraoxonase activity. This specificity change demonstrates the potential role of bifunctional intermediates in the divergence of new enzymatic functions and highlights the critical contribution of loop remodeling to the rapid divergence of new enzyme functions.
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Affiliation(s)
- Livnat Afriat-Jurnou
- Department of Biological Chemistry, The Weizmann Institute of Science, Rehovot 76100, Israel
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23
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Applications of small molecule activators and inhibitors of quorum sensing in Gram-negative bacteria. Trends Microbiol 2012; 20:449-58. [PMID: 22771187 DOI: 10.1016/j.tim.2012.06.003] [Citation(s) in RCA: 136] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2012] [Revised: 06/08/2012] [Accepted: 06/13/2012] [Indexed: 01/23/2023]
Abstract
Quorum sensing is a form of intercellular communication used by many species of bacteria that facilitates concerted interactions between the cells comprising a population. The phenotypes regulated by quorum sensing are extremely diverse, with many having a significant impact upon healthcare, agriculture, and the environment. Consequently there has been significant interest in developing methods to manipulate this signalling process and recent years have witnessed significant theoretical and practical developments. A wide range of small molecule modulators of quorum sensing systems has been discovered, providing an expansive chemical toolbox for the study and modulation of this signalling mechanism. In this review, a selection of recent case studies which illustrate the value of both activators and inhibitors of quorum sensing in Gram-negative bacteria are discussed.
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Quorum quenching revisited--from signal decays to signalling confusion. SENSORS 2012; 12:4661-96. [PMID: 22666051 PMCID: PMC3355433 DOI: 10.3390/s120404661] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/28/2012] [Revised: 03/23/2012] [Accepted: 03/26/2012] [Indexed: 12/12/2022]
Abstract
In a polymicrobial community, while some bacteria are communicating with neighboring cells (quorum sensing), others are interrupting the communication (quorum quenching), thus creating a constant arms race between intercellular communication. In the past decade, numerous quorum quenching enzymes have been found and initially thought to inactivate the signalling molecules. Though this is widely accepted, the actual roles of these quorum quenching enzymes are now being uncovered. Recent evidence extends the role of quorum quenching to detoxification or metabolism of signalling molecules as food and energy source; this includes “signalling confusion”, a term coined in this paper to refer to the phenomenon of non-destructive modification of signalling molecules. While quorum quenching has been explored as a novel anti-infective therapy targeting, quorum sensing evidence begins to show the development of resistance against quorum quenching.
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25
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Wilms I, Voss B, Hess WR, Leichert LI, Narberhaus F. Small RNA-mediated control of the Agrobacterium tumefaciens GABA binding protein. Mol Microbiol 2011; 80:492-506. [PMID: 21320185 DOI: 10.1111/j.1365-2958.2011.07589.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Wounded plants activate a complex defence programme in response to Agrobacterium tumefaciens. They synthesize the non-proteinogenic amino acid γ-aminobutyric acid (GABA), which stimulates degradation of the quorum sensing signal N-(3-oxo-octanoyl) homoserine lactone. GABA is transported into A. tumefaciens via an ABC transporter dependent on the periplasmic binding protein Atu2422. We demonstrate that expression of atu2422 and two other ABC transporter genes is downregulated by the conserved small RNA (sRNA) AbcR1 (for ABC regulator). AbcR1 is encoded in tandem with another sRNA, which is similar in sequence and structure. Both sRNAs accumulate during stationary phase but only the absence of AbcR1 resulted in significant accumulation of Atu2422 and increased GABA import. AbcR1 inhibits initiation of atu2422 translation by masking its Shine-Dalgarno sequence and thereby reduces stability of the atu2422 transcript. It is the first described bacterial sRNA that controls uptake of a plant-generated signalling molecule. Given that similar sRNAs and ABC transporter genes are present in various Rhizobiaceae and in Brucella, it is likely that such sRNA-mediated control impacts a number of host-microbe interactions.
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Affiliation(s)
- Ina Wilms
- Lehrstuhl für Biologie der Mikroorganismen Medizinisches Proteom-Center, Ruhr-Universität Bochum, 44780 Bochum, Germany
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26
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Gamma-caprolactone stimulates growth of quorum-quenching Rhodococcus populations in a large-scale hydroponic system for culturing Solanum tuberosum. Res Microbiol 2011; 162:945-50. [PMID: 21288487 DOI: 10.1016/j.resmic.2011.01.010] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2010] [Accepted: 01/03/2011] [Indexed: 11/23/2022]
Abstract
Bacteria degrading quorum sensing (QS) signals have been proposed as biocontrol agents able to quench QS-dependent expression of virulence symptoms caused by Pectobacterium on potato plants. We report here that gamma-caprolactone (GCL) treatment stimulated growth of the native QS-degrading bacterial community in an industrial plant hydroponic system for culturing Solanum tuberosum. Post-GCL treatment, QS-degrading bacteria were mainly identified as Rhodococcus isolates, while Agrobacterium isolates dominated under similar untreated conditions. Most of the assayed Rhodococcus isolates exhibited efficient biocontrol activity for protecting potato tubers. Analytical chemistry approach revealed the rapid degradation of GCL introduced in the plant cultures.
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Zhu H, Wang SX, Zhang SS, Cao CX. Inhibiting Effect of Bioactive Metabolites Produced by Mushroom Cultivation on Bacterial Quorum Sensing-Regulated Behaviors. Chemotherapy 2011; 57:292-7. [DOI: 10.1159/000329525] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2010] [Accepted: 03/01/2011] [Indexed: 11/19/2022]
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Abstract
Isolated, clonal populations of cells are rarely found in nature. The emergent properties of microbial consortia present a challenge for the systems approach to biology, as chances for competition, communication, or collaboration multiply with the number of interacting agents. This review focuses on recent work on intercourse within biofilms, among quorum-sensing populations, and between cross-feeding metabolic cooperators. New tools from synthetic biology allow microbial interactions to be designed and tightly controlled, creating valuable model systems. We address both natural and synthetic partnerships, with an emphasis on how system behaviors derive from the properties of their components. Essential features of microbial biology arose in the context of a very mixed culture and cannot be understood without unscrambling it.
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Affiliation(s)
- Edwin H Wintermute
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts 02115, USA
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29
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Planamente S, Vigouroux A, Mondy S, Nicaise M, Faure D, Moréra S. A conserved mechanism of GABA binding and antagonism is revealed by structure-function analysis of the periplasmic binding protein Atu2422 in Agrobacterium tumefaciens. J Biol Chem 2010; 285:30294-303. [PMID: 20630861 DOI: 10.1074/jbc.m110.140715] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Bacterial periplasmic binding proteins (PBPs) and eukaryotic PBP-like domains (also called as Venus flytrap modules) of G-protein-coupled receptors are involved in extracellular GABA perception. We investigated the structural and functional basis of ligand specificity of the PBP Atu2422, which is implicated in virulence and transport of GABA in the plant pathogen Agrobacterium tumefaciens. Five high-resolution x-ray structures of Atu2422 liganded to GABA, Pro, Ala, and Val and of point mutant Atu2422-F77A liganded to Leu were determined. Structural analysis of the ligand-binding site revealed two essential residues, Phe(77) and Tyr(275), the implication of which in GABA signaling and virulence was confirmed using A. tumefaciens cells expressing corresponding Atu2422 mutants. Phe(77) restricts ligand specificity to α-amino acids with a short lateral chain, which act as antagonists of GABA signaling in A. tumefaciens. Tyr(275) specifically interacts with the GABA γ-amino group. Conservation of these two key residues in proteins phylogenetically related to Atu2422 brought to light a subfamily of PBPs in which all members could bind GABA and short α-amino acids. This work led to the identification of a fingerprint sequence and structural features for defining PBPs that bind GABA and its competitors and revealed their occurrence among host-interacting proteobacteria.
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Affiliation(s)
- Sara Planamente
- Laboratoire d'Enzymologie et Biochimie Structurales, Institut des Sciences du Végétal, CNRS, Avenue de la Terrasse, 91198 Gif-sur-Yvette, France
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