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Yin F, Hu Y, Bu Z, Liu Y, Zhang H, Hu Y, Xue Y, Li S, Tan C, Chen X, Li L, Zhou R, Huang Q. Genome-wide identification of genes critical for in vivo fitness of multi-drug resistant porcine extraintestinal pathogenic Escherichia coli by transposon-directed insertion site sequencing using a mouse infection model. Virulence 2023; 14:2158708. [PMID: 36537189 PMCID: PMC9828833 DOI: 10.1080/21505594.2022.2158708] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Extraintestinal pathogenic Escherichia coli (ExPEC) is an important zoonotic pathogen. Recently, ExPEC has been reported to be an emerging problem in pig farming. However, the mechanism of pathogenicity of porcine ExPEC remains to be revealed. In this study, we constructed a transposon (Tn) mutagenesis library covering Tn insertion in over 72% of the chromosome-encoded genes of a virulent and multi-drug resistant porcine ExPEC strain PCN033. By using a mouse infection model, a transposon-directed insertion site sequencing (TraDIS) assay was performed to identify in vivo fitness factors. By comparing the Tn insertion frequencies between the input Tn library and the recovered library from different organs, 64 genes were identified to be involved in fitness during systemic infection. 15 genes were selected and individual gene deletion mutants were constructed. The in vivo fitness was evaluated by using a competitive infection assay. Among them, ΔfimG was significantly outcompeted by the WT strain in vivo and showed defective adhesion to host cells. rfa which was involved in lipopolysaccharide biosynthesis was shown to be critical for in vivo fitness which may have resulted from its role in the resistance to serum killing. In addition, several metabolic genes including fepB, sdhC, fepG, gltS, dcuA, ccmH, ddpD, narU, glpD, malM, and yabL and two regulatory genes metJ and baeS were shown as important determinants of in vivo fitness of porcine ExPEC. Collectively, this study performed a genome-wide screening for in vivo fitness factors which will be important for understanding the pathogenicity of porcine ExPEC.
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Affiliation(s)
- Fan Yin
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yan Hu
- College of Animal Sciences & Technology, Huazhong Agricultural University, Wuhan, China
| | - Zixuan Bu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yuying Liu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Hui Zhang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Yawen Hu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Ying Xue
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Shaowen Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China
| | - Chen Tan
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Ministry of Science and Technology, International Research Center for Animal Disease, Wuhan, China
| | - Xiabing Chen
- Institute of Animal Husbandry and Veterinary Science, Wuhan Academy of Agricultural Science and Technology, Wuhan, China
| | - Lu Li
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Ministry of Science and Technology, International Research Center for Animal Disease, Wuhan, China
| | - Rui Zhou
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Ministry of Science and Technology, International Research Center for Animal Disease, Wuhan, China,The HZAU-HVSEN Institute, Wuhan, China,CONTACT Rui Zhou
| | - Qi Huang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Cooperative Innovation Center for Sustainable Pig Production, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, China,Ministry of Science and Technology, International Research Center for Animal Disease, Wuhan, China,Qi Huang
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2
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Yu S, Kang J, Chung EH, Lee Y. Disruption of the metC Gene Affects Methionine Biosynthesis in Pectobacterium carotovorum subsp. carotovorum Pcc21 and Reduces Soft-Rot Disease. THE PLANT PATHOLOGY JOURNAL 2023; 39:62-74. [PMID: 36760050 PMCID: PMC9929172 DOI: 10.5423/ppj.oa.09.2022.0135] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 11/28/2022] [Accepted: 11/28/2022] [Indexed: 06/18/2023]
Abstract
Plant pathogenic Pectobacterium species cause severe soft rot/blackleg diseases in many economically important crops worldwide. Pectobacterium utilizes plant cell wall degrading enzymes (PCWDEs) as the main virulence determinants for its pathogenicity. In this study, we screened a random mutant, M29 is a transposon insertion mutation in the metC gene encoding cystathionine β-lyase that catalyzes cystathionine to homocysteine at the penultimate step in methionine biosynthesis. M29 became a methionine auxotroph and resulted in growth defects in methionine-limited conditions. Impaired growth was restored with exogenous methionine or homocysteine rather than cystathionine. The mutant exhibited reduced soft rot symptoms in Chinese cabbages and potato tubers, maintaining activities of PCWDEs and swimming motility. The mutant was unable to proliferate in both Chinese cabbages and potato tubers. The reduced virulence was partially restored by a complemented strain or 100 µM of methionine, whereas it was fully restored by the extremely high concentration (1 mM). Our transcriptomic analysis showed that genes involved in methionine biosynthesis or transporter were downregulated in the mutant. Our results demonstrate that MetC is important for methionine biosynthesis and transporter and influences its virulence through Pcc21 multiplication in plant hosts.
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Affiliation(s)
- Seonmi Yu
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Jihee Kang
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
| | - Eui-Hwan Chung
- Department of Plant Biotechnology, Korea University, Seoul 02841,
Korea
| | - Yunho Lee
- Department of Food Science and Biotechnology, CHA University, Pocheon 11160,
Korea
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3
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Matilla MA, Monson RE, Murphy A, Schicketanz M, Rawlinson A, Duncan C, Mata J, Leeper F, Salmond GPC. Solanimycin: Biosynthesis and Distribution of a New Antifungal Antibiotic Regulated by Two Quorum-Sensing Systems. mBio 2022; 13:e0247222. [PMID: 36214559 PMCID: PMC9765074 DOI: 10.1128/mbio.02472-22] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2022] [Accepted: 09/02/2022] [Indexed: 11/20/2022] Open
Abstract
The increasing emergence of drug-resistant fungal infections has necessitated a search for new compounds capable of combating fungal pathogens of plants, animals, and humans. Microorganisms represent the main source of antibiotics with applicability in agriculture and in the clinic, but many aspects of their metabolic potential remain to be explored. This report describes the discovery and characterization of a new antifungal compound, solanimycin, produced by a hybrid polyketide/nonribosomal peptide (PKS/NRPS) system in Dickeya solani, the enterobacterial pathogen of potato. Solanimycin was active against a broad range of plant-pathogenic fungi of global economic concern and the human pathogen Candida albicans. The genomic cluster responsible for solanimycin production was defined and analyzed to identify the corresponding biosynthetic proteins, which include four multimodular PKS/NRPS proteins and several tailoring enzymes. Antifungal production in D. solani was enhanced in response to experimental conditions found in infected potato tubers and high-density fungal cultures. Solanimycin biosynthesis was cell density dependent in D. solani and was controlled by both the ExpIR acyl-homoserine lactone and Vfm quorum-sensing systems of the bacterial phytopathogen. The expression of the solanimycin cluster was also regulated at the post-transcriptional level, with the regulator RsmA playing a major role. The solanimycin biosynthetic cluster was conserved across phylogenetically distant bacterial genera, and multiple pieces of evidence support that the corresponding gene clusters were acquired by horizontal gene transfer. Given its potent broad-range antifungal properties, this study suggests that solanimycin and related molecules may have potential utility for agricultural and clinical exploitation. IMPORTANCE Fungal infections represent a major clinical, agricultural, and food security threat worldwide, which is accentuated due to the difficult treatment of these infections. Microorganisms represent a prolific source of antibiotics, and current data support that this enormous biosynthetic potential has been scarcely explored. To improve the performance in the discovery of novel antimicrobials, there is a need to diversify the isolation niches for new antibiotic-producing microorganisms as well as to scrutinize novel phylogenetic positions. With the identification of the antifungal antibiotic solanimycin in a broad diversity of phytopathogenic Dickeya spp., we provide further support for the potential of plant-associated bacteria for the biosynthesis of novel antimicrobials. The complex regulatory networks involved in solanimycin production reflect the high metabolic cost of bacterial secondary metabolism. This metabolic regulatory control makes many antibiotics cryptic under standard laboratory conditions, and mimicking environmental conditions, as shown here, is a strategy to activate cryptic antibiotic clusters.
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Affiliation(s)
- Miguel A. Matilla
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
- Department of Environmental Protection, Estación Experimental del Zaidín, Consejo Superior de Investigaciones Científicas, Granada, Spain
| | - Rita E. Monson
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Annabel Murphy
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
| | - Muriel Schicketanz
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Alison Rawlinson
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Caia Duncan
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Juan Mata
- Department of Biochemistry, University of Cambridge, Cambridge, United Kingdom
| | - Finian Leeper
- Yusuf Hamied Department of Chemistry, University of Cambridge, Cambridge, United Kingdom
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4
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Chane A, Barbey C, Robert M, Merieau A, Konto-Ghiorghi Y, Beury-Cirou A, Feuilloley M, Pátek M, Gobert V, Latour X. Biocontrol of Soft Rot: Confocal Microscopy Highlights Virulent Pectobacterial Communication and Its Jamming by Rhodococcal Quorum-Quenching. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2019; 32:802-812. [PMID: 30645157 DOI: 10.1094/mpmi-11-18-0314-r] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
Confocal laser-scanning microscopy was chosen to observe the colonization and damage caused by the soft rot Pectobacterium atrosepticum and the protection mediated by the biocontrol agent Rhodococcus erythropolis. We developed dual-color reporter strains suited for monitoring quorum-sensing and quorum-quenching activities leading to maceration or biocontrol, respectively. A constitutively expressed cyan or red fluorescent protein served as a cell tag for plant colonization, while an inducible expression reporter system based on the green fluorescent protein gene enabled the simultaneous recording of signaling molecule production, detection, or degradation. The dual-colored pathogen and biocontrol strains were used to coinoculate potato tubers. At cellular quorum, images revealed a strong pectobacterial quorum-sensing activity, especially at the plant cell walls, as well as a concomitant rhodococcal quorum-quenching response, at both the single-cell and microcolony levels. The generated biosensors appear to be promising and complementary tools useful for molecular and cellular studies of bacterial communication and interference.
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Affiliation(s)
- Andrea Chane
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
| | - Corinne Barbey
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
- 2 Seeds Innovation Protection Research and Environment, Route de la petite chaussée, 76110 Bretteville du Grand-Caux and Rue des Champs Potez, 62217 Achicourt, France
| | - Magalie Robert
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
| | - Annabelle Merieau
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
| | - Yoan Konto-Ghiorghi
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
| | - Amélie Beury-Cirou
- 2 Seeds Innovation Protection Research and Environment, Route de la petite chaussée, 76110 Bretteville du Grand-Caux and Rue des Champs Potez, 62217 Achicourt, France
- 3 French Federation of seed potato growers (FN3PT/RD3PT), 43-45 rue de Naples, 75008 Paris, France
| | - Marc Feuilloley
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
| | - Miroslav Pátek
- 4 Institute of Microbiology of the CAS, v.v.i. Vídeňská 1083, CZ-14220 Praha 4, Czech Republic
| | - Virginie Gobert
- 2 Seeds Innovation Protection Research and Environment, Route de la petite chaussée, 76110 Bretteville du Grand-Caux and Rue des Champs Potez, 62217 Achicourt, France
- 3 French Federation of seed potato growers (FN3PT/RD3PT), 43-45 rue de Naples, 75008 Paris, France
| | - Xavier Latour
- 1 Laboratoire de Microbiologie Signaux et Microenvironnement (LMSM EA 4312)-Normandie Université-LMSM, 55 rue Saint-Germain, 27000 Evreux, France and Structure Fédérative de Recherche Normandie Végétale 4277
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5
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Monson RE, Apagyi K, Bowden SD, Simpson N, Williamson NR, Cubitt MF, Harris S, Toth IK, Salmond GPC. The rsmS (ybaM) mutation causes bypass suppression of the RsmAB post-transcriptional virulence regulation system in enterobacterial phytopathogens. Sci Rep 2019; 9:4525. [PMID: 30872786 PMCID: PMC6418279 DOI: 10.1038/s41598-019-40970-3] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Accepted: 02/22/2019] [Indexed: 11/09/2022] Open
Abstract
Plant cell wall degrading enzymes (PCWDEs) are the primary virulence determinants of soft rotting bacteria such as the potato pathogen, Pectobacterium atrosepticum. The regulation of secondary metabolite (Rsm) system controls production of PCWDEs in response to changing nutrient conditions. This work identified a new suppressor of an rsmB mutation - ECA1172 or rsmS (rsmB suppressor). Mutants defective in rsmB (encoding a small regulatory RNA), show reduced elaboration of the quorum sensing molecule (N-3-oxohexanoyl-homoserine lactone; OHHL) and PCWDEs. However, OHHL and PCWDE production were partially restored in an rsmB, rsmS double mutant. Single rsmS mutants, overproduced PCWDEs and OHHL relative to wild type P. atrosepticum and exhibited hypervirulence in potato. RsmS overproduction also resulted in increased PCWDEs and OHHL. Homology searches revealed rsmS conservation across pathogens such as Escherichia coli (ybaM), Dickeya solani, Klebsiella pneumoniae and Shigella flexneri. An rsmS mutant of Pectobacterium carotovorum ATCC39048 showed bypass of rsmB-dependent repression of PCWDEs and OHHL production. P. carotovorum ATCC39048 produces the β-lactam antibiotic, 1-carbapen-2-em-3-carboxylic acid (a carbapenem). Production of the antibiotic was repressed in an rsmB mutant but partially restored in an rsmB, rsmS double mutant. This work highlights the importance of RsmS, as a conserved pleiotropic regulator of virulence and antibiotic biosynthesis.
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Affiliation(s)
- Rita E Monson
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Katinka Apagyi
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
- Faculty of Medicine, School of Public Health, Imperial College, London, St Mary's Campus, Norfolk Place, W2 1PG, UK
| | - Steven D Bowden
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
- Department of Food Science and Nutrition, University of Minnesota-Twin Cities, St. Paul, Minnesota, USA
| | - Natalie Simpson
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Neil R Williamson
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Marion F Cubitt
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
| | - Steve Harris
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK
- School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, LE11 3TU, UK
| | - Ian K Toth
- Cell and Molecular Sciences, James Hutton Institute, Invergowrie, Dundee, DD2 5DA, UK
| | - George P C Salmond
- Department of Biochemistry, Hopkins Building, Tennis Court Road, University of Cambridge, Cambridge, CB2 1QW, UK.
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6
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Methylthioadenosine Suppresses Salmonella Virulence. Infect Immun 2018; 86:IAI.00429-18. [PMID: 29866910 PMCID: PMC6105896 DOI: 10.1128/iai.00429-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2018] [Accepted: 05/31/2018] [Indexed: 02/01/2023] Open
Abstract
In order to deploy virulence factors at appropriate times and locations, microbes must rapidly sense and respond to various metabolite signals. Previously, we showed a transient elevation of the methionine-derived metabolite methylthioadenosine (MTA) concentration in serum during systemic Salmonella enterica serovar Typhimurium infection. Here we explored the functional consequences of increased MTA concentrations on S Typhimurium virulence. We found that MTA, but not other related metabolites involved in polyamine synthesis and methionine salvage, reduced motility, host cell pyroptosis, and cellular invasion. Further, we developed a genetic model of increased bacterial endogenous MTA production by knocking out the master repressor of the methionine regulon, metJ Like MTA-treated S Typhimurium, the ΔmetJ mutant displayed reduced motility, host cell pyroptosis, and invasion. These phenotypic effects of MTA correlated with suppression of flagellar and Salmonella pathogenicity island 1 (SPI-1) networks. S Typhimurium ΔmetJ had reduced virulence in oral and intraperitoneal infection of C57BL/6J mice independently of the effects of MTA on SPI-1. Finally, ΔmetJ bacteria induced a less severe inflammatory cytokine response in a mouse sepsis model. Together, these data indicate that exposure of S Typhimurium to MTA or disruption of the bacterial methionine metabolism pathway suppresses S Typhimurium virulence.
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7
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Zhang JL, Wang D, Liang YW, Zhong WY, Ming ZH, Tang DJ, Tang JL. The Gram-negative phytopathogen Xanthomonas campestris pv. campestris employs a 5'UTR as a feedback controller to regulate methionine biosynthesis. MICROBIOLOGY-SGM 2018; 164:1146-1155. [PMID: 30024369 PMCID: PMC6230763 DOI: 10.1099/mic.0.000690] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
The synthesis of methionine is critical for most bacteria. It is known that cellular methionine has a feedback effect on the expression of met genes involved in de novo methionine biosynthesis. Previous studies revealed that Gram-negative bacteria control met gene expression at the transcriptional level by regulator proteins, while most Gram-positive bacteria regulate met genes at post-transcriptional level by RNA regulators (riboregulators) located in the 5′UTR of met genes. However, despite its importance, the methionine biosynthesis pathway in the Gram-negative Xanthomonas genus that includes many important plant pathogens is completely uncharacterized. Here, we address this issue using the crucifer black rot pathogen Xanthomonas campestris pv. campestris (Xcc), a model bacterium in microbe–plant interaction studies. The work identified an operon (met) involved in de novo methionine biosynthesis in Xcc. Disruption of the operon resulted in defective growth in methionine-limited media and in planta. Western blot analysis revealed that the expression of the operon is dependent on methionine levels. Further molecular analyses demonstrated that the 5′UTR, but not the promoter of the operon, is involved in feedback regulation on operon expression in response to methionine availability, providing an example of a Gram-negative bacterium utilizing a 5′UTR region to control the expression of the genes involved in methionine biosynthesis.
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Affiliation(s)
- Jian-Ling Zhang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dan Wang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Yu-Wei Liang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Wan-Ying Zhong
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Zhen-Hua Ming
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
| | - Dong-Jie Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- *Correspondence: Dong-Jie Tang,
| | - Ji-Liang Tang
- State Key Laboratory for Conservation and Utilization of Subtropical Agro-bioresources, College of Life Science and Technology, Guangxi University, 100 Daxue Road, Nanning, Guangxi 530004, PR China
- Ji-Liang Tang,
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8
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Deochand DK, Meariman JK, Grove A. pH-Dependent DNA Distortion and Repression of Gene Expression by Pectobacterium atrosepticum PecS. ACS Chem Biol 2016; 11:2049-56. [PMID: 27213700 DOI: 10.1021/acschembio.6b00168] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
Transcriptional activity is exquisitely sensitive to changes in promoter DNA topology. Transcription factors may therefore control gene activity by modulating the relative positioning of -10 and -35 promoter elements. The plant pathogen Pectobacterium atrosepticum, which causes soft rot in potatoes, must alter gene expression patterns to ensure growth in planta. In the related soft-rot enterobacterium Dickeya dadantii, PecS functions as a master regulator of virulence gene expression. Here, we report that P. atrosepticum PecS controls gene activity by altering promoter DNA topology in response to pH. While PecS binds the pecS promoter with high affinity regardless of pH, it induces significant DNA distortion only at neutral pH, the pH at which the pecS promoter is repressed in vivo. At pH ∼8, DNA distortions are attenuated, and PecS no longer represses the pecS promoter. A specific histidine (H142) located in a crevice between the dimerization- and DNA-binding regions is required for pH-dependent changes in DNA distortion and repression of gene activity, and mutation of this histidine renders the mutant protein incapable of repressing the pecS promoter. We propose that protonated PecS induces a DNA conformation at neutral pH in which -10 and -35 promoter elements are suboptimally positioned for RNA polymerase binding; on deprotonation of PecS, binding is no longer associated with significant changes in DNA conformation, allowing gene expression. We suggest that this mode of gene regulation leads to differential expression of the PecS regulon in response to alkalinization of the plant apoplast.
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Affiliation(s)
- Dinesh K. Deochand
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Jacob K. Meariman
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Anne Grove
- Department
of Biological
Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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9
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Monson R, Smith DS, Matilla MA, Roberts K, Richardson E, Drew A, Williamson N, Ramsay J, Welch M, Salmond GPC. A Plasmid-Transposon Hybrid Mutagenesis System Effective in a Broad Range of Enterobacteria. Front Microbiol 2015; 6:1442. [PMID: 26733980 PMCID: PMC4686594 DOI: 10.3389/fmicb.2015.01442] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2015] [Accepted: 12/03/2015] [Indexed: 11/13/2022] Open
Abstract
Random transposon mutagenesis is a powerful technique used to generate libraries of genetic insertions in many different bacterial strains. Here we develop a system facilitating random transposon mutagenesis in a range of different Gram-negative bacterial strains, including Pectobacterium atrosepticum, Citrobacter rodentium, Serratia sp. ATCC39006, Serratia plymuthica, Dickeya dadantii, and many more. Transposon mutagenesis was optimized in each of these strains and three studies are presented to show the efficacy of this system. Firstly, the important agricultural pathogen D. dadantii was mutagenized. Two mutants that showed reduced protease production and one mutant producing the previously cryptic pigment, indigoidine, were identified and characterized. Secondly, the enterobacterium, Serratia sp. ATCC39006 was mutagenized and mutants incapable of producing gas vesicles, proteinaceous intracellular organelles, were identified. One of these contained a β-galactosidase transcriptional fusion within the gene gvpA1, essential for gas vesicle production. Finally, the system was used to mutate the biosynthetic gene clusters of the antifungal, anti-oomycete and anticancer polyketide, oocydin A, in the plant-associated enterobacterium, Dickeya solani MK10. The mutagenesis system was developed to allow easy identification of transposon insertion sites by sequencing, after facile generation of a replicon encompassing the transposon and adjacent DNA, post-excision. Furthermore, the system can also create transcriptional fusions with either β-galactosidase or β-glucuronidase as reporters, and exploits a variety of drug resistance markers so that multiple selectable fusions can be generated in a single strain. This system of various transposons has wide utility and can be combined in many different ways.
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Affiliation(s)
- Rita Monson
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Debra S Smith
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Miguel A Matilla
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Kevin Roberts
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | | | - Alison Drew
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Neil Williamson
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Josh Ramsay
- Department of Biochemistry, University of Cambridge Cambridge, UK
| | - Martin Welch
- Department of Biochemistry, University of Cambridge Cambridge, UK
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10
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Petrova O, Gorshkov V, Daminova A, Ageeva M, Moleleki LN, Gogolev Y. Stress response in Pectobacterium atrosepticum SCRI1043 under starvation conditions: adaptive reactions at a low population density. Res Microbiol 2014; 165:119-27. [DOI: 10.1016/j.resmic.2013.11.004] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2013] [Accepted: 11/19/2013] [Indexed: 11/27/2022]
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The global response regulator ExpA controls virulence gene expression through RsmA-mediated and RsmA-independent pathways in Pectobacterium wasabiae SCC3193. Appl Environ Microbiol 2014; 80:1972-84. [PMID: 24441162 DOI: 10.1128/aem.03829-13] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
ExpA (GacA) is a global response regulator that controls the expression of major virulence genes, such as those encoding plant cell wall-degrading enzymes (PCWDEs) in the model soft rot phytopathogen Pectobacterium wasabiae SCC3193. Several studies with pectobacteria as well as related phytopathogenic gammaproteobacteria, such as Dickeya and Pseudomonas, suggest that the control of virulence by ExpA and its homologues is executed partly by modulating the activity of RsmA, an RNA-binding posttranscriptional regulator. To elucidate the extent of the overlap between the ExpA and RsmA regulons in P. wasabiae, we characterized both regulons by microarray analysis. To do this, we compared the transcriptomes of the wild-type strain, an expA mutant, an rsmA mutant, and an expA rsmA double mutant. The microarray data for selected virulence-related genes were confirmed through quantitative reverse transcription (qRT-PCR). Subsequently, assays were performed to link the observed transcriptome differences to changes in bacterial phenotypes such as growth, motility, PCWDE production, and virulence in planta. An extensive overlap between the ExpA and RsmA regulons was observed, suggesting that a substantial portion of ExpA regulation appears to be mediated through RsmA. However, a number of genes involved in the electron transport chain and oligogalacturonide metabolism, among other processes, were identified as being regulated by ExpA independently of RsmA. These results suggest that ExpA may only partially impact fitness and virulence via RsmA.
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