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Abstract
The two-component system PhoP/PhoQ is essential for Salmonella enterica serovar Typhimurium virulence. Here, we report that PhoP is methylated extensively. Two consecutive glutamate (E) and aspartate (D)/E residues, i.e., E8/D9 and E107/E108, and arginine (R) 112 can be methylated. Individual mutation of these above-mentioned residues caused impaired phosphorylation and dimerization or DNA-binding ability of PhoP to a different extent and led to attenuated bacterial virulence. With the help of specific antibodies recognizing methylated E8 and monomethylated R112, we found that the methylation levels of E8 or R112 decreased dramatically when bacteria encountered low magnesium, acidic pH, or phagocytosis by macrophages, under which PhoP can be activated. Furthermore, CheR, a bacterial chemotaxis methyltransferase, was identified to methylate R112. Overexpression of cheR decreased PhoP activity but increased PhoP stability. Together, the current study reveals that methylation plays an important role in regulating PhoP activities in response to environmental cues and, consequently, modulates Salmonella virulence.
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Schroll C, Huang K, Ahmed S, Kristensen BM, Pors SE, Jelsbak L, Lemire S, Thomsen LE, Christensen JP, Jensen PR, Olsen JE. The SPI-19 encoded type-six secretion-systems (T6SS) of Salmonella enterica serovars Gallinarum and Dublin play different roles during infection. Vet Microbiol 2019; 230:23-31. [PMID: 30827393 DOI: 10.1016/j.vetmic.2019.01.006] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2018] [Revised: 01/05/2019] [Accepted: 01/06/2019] [Indexed: 12/19/2022]
Abstract
Salmonella Pathogenicity Islands 19 (SPI19) encodes a type VI secretion system (T6SS). SPI19 is only present in few serovars of S. enterica, including the host-adapted serovar S. Dublin and the host-specific serovar S. Gallinarum. The role of the SPI19 encoded T6SS in virulence in these serovar is not fully understood. Here we show that during infection of mice, a SPI19/T6SS deleted strain of S. Dublin 2229 was less virulent than the wild type strain after oral challenge, but not after IP challenge. The mutant strain also competed significantly poorer than the wild type strain when co-cultured with strains of E. coli, suggesting that this T6SS plays a role in pathogenicity by killing competing bacteria in the intestine. No significant difference was found between wild type S. Gallinarum G9 and its ΔSPI19/T6SS mutant in infection, whether chicken were challenged orally or by the IP route, and the S. Gallinarum G9 ΔSPI19/T6SS strain competed equally well as the wild type strain against strains of E. coli. However, contrary to what was observed with S. Dublin, the wild type G9 strains was significantly more cytotoxic to monocyte derived primary macrophages from hens than the mutant, suggesting that SPI19/T6SS in S. Gallinarum mediates killing of eukaryotic cells. The lack of significant importance of SPI19/T6SS after oral and systemic challenge of chicken was confirmed by knocking out SPI19 in a second strain, J91. Together the results suggest that the T6SS encoded from SPI19 have different roles in the two serovars and that it is a virulence-factor after oral challenge of mice in S. Dublin, while we cannot confirm previous results that SPI19/T6SS influence virulence significantly in S. Gallinarum.
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Affiliation(s)
- Casper Schroll
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Kaisong Huang
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Shahana Ahmed
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Bodil M Kristensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Susanne Elisabeth Pors
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Lotte Jelsbak
- Department of Science and Environment, Roskilde University, Denmark
| | | | - Line E Thomsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Jens Peter Christensen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark
| | - Peter R Jensen
- Department of Food, Technical University of Denmark, Denmark
| | - John E Olsen
- Department of Veterinary and Animal Sciences, Faculty of Health and Medical Sciences, University of Copenhagen, Denmark.
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Pardo-Esté C, Hidalgo AA, Aguirre C, Briones AC, Cabezas CE, Castro-Severyn J, Fuentes JA, Opazo CM, Riedel CA, Otero C, Pacheco R, Valvano MA, Saavedra CP. The ArcAB two-component regulatory system promotes resistance to reactive oxygen species and systemic infection by Salmonella Typhimurium. PLoS One 2018; 13:e0203497. [PMID: 30180204 PMCID: PMC6122832 DOI: 10.1371/journal.pone.0203497] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/25/2018] [Accepted: 08/21/2018] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica Serovar Typhimurium (S. Typhimurium) is an intracellular bacterium that overcomes host immune system barriers for successful infection. The bacterium colonizes the proximal small intestine, penetrates the epithelial layer, and is engulfed by macrophages and neutrophils. Intracellularly, S. Typhimurium encounters highly toxic reactive oxygen species including hydrogen peroxide and hypochlorous acid. The molecular mechanisms of Salmonella resistance to intracellular oxidative stress is not completely understood. The ArcAB two-component system is a global regulatory system that responds to oxygen. In this work, we show that the ArcA response regulator participates in Salmonella adaptation to changing oxygen levels and is also involved in promoting intracellular survival in macrophages and neutrophils, enabling S. Typhimurium to successfully establish a systemic infection.
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Affiliation(s)
- Coral Pardo-Esté
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alejandro A. Hidalgo
- Laboratorio de Patogenesis Bacteriana, Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Camila Aguirre
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Alan C. Briones
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Carolina E. Cabezas
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan Castro-Severyn
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Juan A. Fuentes
- Laboratorio de Genética y Patogénesis Bacteriana, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Cecilia M. Opazo
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Claudia A. Riedel
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Carolina Otero
- Center for Integrative Medicine and Innovative Science (CIMIS), Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
| | - Rodrigo Pacheco
- Laboratorio de Neuroinmunología, Fundación Ciencia & Vida, Santiago, Chile
- Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
| | - Miguel A. Valvano
- The Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast, United Kingdom
| | - Claudia P. Saavedra
- Laboratorio de Microbiología Molecular, Departamento de Ciencias Biológicas, Facultad de Ciencias de la Vida, Universidad Andres Bello, Santiago, Chile
- Millennium Institute on Immunology and Immunotherapy, Departamento de Ciencias Biológicas, Facultad de la Vida y Facultad de Medicina, Universidad Andres Bello, Santiago, Chile
- * E-mail:
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Ye Y, Zhang X, Zhang M, Ling N, Zeng H, Gao J, Jiao R, Wu Q, Zhang J. Potential factors involved in virulence of Cronobacter sakazakii isolates by comparative transcriptome analysis. J Dairy Sci 2017; 100:8826-8837. [PMID: 28888603 DOI: 10.3168/jds.2017-12801] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2017] [Accepted: 07/11/2017] [Indexed: 01/15/2023]
Abstract
Cronobacter species are important foodborne pathogens causing severe infections in neonates through consumption of contaminated powdered infant formula. However, the virulence-associated factors in Cronobacter are largely unknown. In this study, the transcriptome analysis between highly virulent Cronobacter sakazakii G362 and attenuated L3101 strains was used to reveal the potential factors involved in virulence. The total transcripts were grouped into 20 clusters of orthologous group categories and summarized in 3 gene ontology categories (biological process, cellular component, and molecular function). In addition, the differentially expressed genes (DEG) between these isolates were analyzed using Volcano plots and gene ontology enrichment. The predominant DEG were flagella-associated genes such as flhD, motA, flgM, flgB, and fliC. Furthermore, the expression abundance of outer membrane protein or lipoprotein genes (ompW, slyB, blc, tolC, and lolA), potential virulence-related factors (hlyIII and hha), and regulation factors (sdiA, cheY, Bss, fliZ) was also significantly different between G362 and L3101. Interestingly, 3 hypothetical protein genes (ESA_01022, ESA_01609, and ESA_00609) were found to be expressed only in G362. Our findings provide valuable transcriptomic information about potential virulence factor genes, which will be needed in future molecular biology studies designed to understand the pathogenic mechanism of Cronobacter.
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Affiliation(s)
- Yingwang Ye
- School of Food Science and Technology, Hefei University of Technology, Hefei, 230009, China; State Key Laboratory of Applied Microbiology, South China (the Ministry-Province Joint Development), Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, 510070, China.
| | - Xiyan Zhang
- School of Food Science and Technology, Hefei University of Technology, Hefei, 230009, China
| | - Maofeng Zhang
- School of Food Science and Technology, Hefei University of Technology, Hefei, 230009, China
| | - Na Ling
- State Key Laboratory of Applied Microbiology, South China (the Ministry-Province Joint Development), Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, 510070, China
| | - Haiyan Zeng
- State Key Laboratory of Applied Microbiology, South China (the Ministry-Province Joint Development), Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, 510070, China
| | - Jina Gao
- School of Food Science and Technology, Hefei University of Technology, Hefei, 230009, China
| | - Rui Jiao
- School of Food Science and Technology, Hefei University of Technology, Hefei, 230009, China
| | - Qingping Wu
- State Key Laboratory of Applied Microbiology, South China (the Ministry-Province Joint Development), Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, 510070, China
| | - Jumei Zhang
- State Key Laboratory of Applied Microbiology, South China (the Ministry-Province Joint Development), Provincial Key Laboratory of Microbiology Culture Collection and Application, Guangdong Institute of Microbiology, Guangzhou, 510070, China
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Leclerc JM, Dozois CM, Daigle F. Salmonella enterica serovar Typhi siderophore production is elevated and Fur inactivation causes cell filamentation and attenuation in macrophages. FEMS Microbiol Lett 2017; 364:3958796. [PMID: 28859315 DOI: 10.1093/femsle/fnx147] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2017] [Accepted: 07/10/2017] [Indexed: 11/13/2022] Open
Abstract
Salmonella enterica serovars Typhi and Typhimurium are two closely related bacteria causing different types of infection in humans. Iron acquisition is considered essential for virulence. Siderophores are important iron chelators and production of enterobactin and salmochelins by these serovars was quantified. Overall, Salmonella Typhi produced higher levels of siderophores than Salmonella Typhimurium. The role of the global regulator Fur, involved in iron homeostasis, present and conserved in both these serovars, was then investigated. Deletion of the fur gene led to distinct phenotypes in these serovars. Defective growth in iron-rich and iron-limiting conditions and formation of filamentous cells was only observed in the S. Typhi fur mutant. Furthermore, Fur was required for optimal motility in both serovars, but motility was more reduced for the fur mutant of S. Typhi compared to S. Typhimurium. During interaction with human-cultured macrophages, Fur was more important for S. Typhi, as the fur mutant had severe defects in uptake and survival. Globally, these results demonstrate that Fur differentially affects the physiology and the virulence phenotypes of the two strains and is more critical for S. Typhi growth, morphology, motility and interaction with host cells than it is for S. Typhimurium.
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Affiliation(s)
- Jean-Mathieu Leclerc
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montreal, Quebec H3C 3J7, Canada
| | - Charles M Dozois
- INRS-Institut Armand-Frappier, 531 boul. des Prairies, Laval, Québec H7V 1B7, Canada
| | - France Daigle
- Department of Microbiology, Infectiology and Immunology, Université de Montréal, C.P. 6128 Succursale Centre-Ville, Montreal, Quebec H3C 3J7, Canada
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Arnold ME, Gosling RJ, La Ragione RM, Davies RH, Martelli F. Estimation of the impact of vaccination on faecal shedding and organ and egg contamination forSalmonellaEnteritidis,SalmonellaTyphiumurium and monophasicSalmonellaTyphimurium. Avian Pathol 2014; 43:155-63. [DOI: 10.1080/03079457.2014.896990] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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Polyamines are essential for virulence in Salmonella enterica serovar Gallinarum despite evolutionary decay of polyamine biosynthesis genes. Vet Microbiol 2014; 170:144-50. [PMID: 24602405 DOI: 10.1016/j.vetmic.2014.01.034] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2013] [Revised: 01/27/2014] [Accepted: 01/28/2014] [Indexed: 11/23/2022]
Abstract
Serovars of Salmonella enterica exhibit different host-specificities where some have broad host-ranges and others, like S. Gallinarum and S. Typhi, are host-specific for poultry and humans, respectively. With the recent availability of whole genome sequences it has been reported that host-specificity coincides with accumulation of pseudogenes, indicating adaptation of host-restricted serovars to their narrow niches. Polyamines are small cationic amines and in Salmonella they can be synthesized through two alternative pathways directly from l-ornithine to putrescine and from l-arginine via agmatine to putrescine. The first pathway is not active in S. Gallinarum and S. Typhi, and this prompted us to investigate the importance of polyamines for virulence in S. Gallinarum. Bioinformatic analysis of all sequenced genomes of Salmonella revealed that pseudogene formation of the speC gene was exclusive for S. Typhi and S. Gallinarum and happened through independent events. The remaining polyamine biosynthesis pathway was found to be essential for oral infection with S. Gallinarum since single and double mutants in speB and speE, encoding the pathways from agmatine to putrescine and from putrescine to spermidine, were attenuated. In contrast, speB was dispensable after intraperitoneal challenge, suggesting that putrescine was less important for the systemic phase of the disease. In support of this hypothesis, a ΔspeE;ΔpotCD mutant, unable to synthesize and import spermidine, but with retained ability to import and synthesize putrescine, was attenuated after intraperitoneal infection. We therefore conclude that polyamines are essential for virulence of S. Gallinarum. Furthermore, our results point to distinct roles for putrescine and spermidine during systemic infection.
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