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Gavriil A, Giannenas I, Skandamis PN. A current insight into Salmonella's inducible acid resistance. Crit Rev Food Sci Nutr 2024:1-21. [PMID: 39014992 DOI: 10.1080/10408398.2024.2373387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/18/2024]
Abstract
Salmonella is a diverse and ubiquitous group of bacteria and a major zoonotic pathogen implicated in several foodborne disease outbreaks worldwide. With more than 2500 distinct serotypes, this pathogen has evolved to survive in a wide spectrum of environments and across multiple hosts. The primary and most common source of transmission is through contaminated food or water. Although the main sources have been primarily linked to animal-related food products, outbreaks due to the consumption of contaminated plant-related food products have increased in the last few years. The perceived ability of Salmonella to trigger defensive mechanisms following pre-exposure to sublethal acid conditions, namely acid adaptation, has renewed a decade-long attention. The impact of acid adaptation on the subsequent resistance against lethal factors of the same or multiple stresses has been underscored by multiple studies. Α plethora of studies have been published, aiming to outline the factors that- alone or in combination- can impact this phenomenon and to unravel the complex networking mechanisms underlying its induction. This review aims to provide a current and updated insight into the factors and mechanisms that rule this phenomenon.
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Affiliation(s)
- Alkmini Gavriil
- Department of Natural Resources Management and Agricultural Engineering, Agricultural University of Athens, Athens, Greece
- Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
| | - Ilias Giannenas
- School of Veterinary Medicine, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Panagiotis N Skandamis
- Department of Food Science and Human Nutrition, Agricultural University of Athens, Athens, Greece
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Jia X, Zhao K, Liu F, Lin J, Lin C, Chen J. Transcriptional factor OmpR positively regulates prodigiosin biosynthesis in Serratia marcescens FZSF02 by binding with the promoter of the prodigiosin cluster. Front Microbiol 2022; 13:1041146. [PMID: 36466667 PMCID: PMC9712742 DOI: 10.3389/fmicb.2022.1041146] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2022] [Accepted: 11/01/2022] [Indexed: 10/27/2023] Open
Abstract
Prodigiosin is a promising secondary metabolite mainly produced by Serratia marcescens. The production of prodigiosin by S. marcescens is regulated by different kinds of regulatory systems, including the EnvZ/OmpR system. In this study, we demonstrated that the regulatory factor OmpR positively regulated prodigiosin production in S. marcescens FZSF02 by directly binding to the promoter region of the prodigiosin biosynthesis cluster with a lacZ reporter assay and electrophoretic mobility shift assay (EMSA). The binding sequence with the pig promoter was identified by a DNase I footprinting assay. We further demonstrate that OmpR regulates its own expression by directly binding to the promoter region of envZ/ompR. For the first time, the regulatory mechanism of prodigiosin production by the transcriptional factor OmpR was revealed.
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Affiliation(s)
- Xianbo Jia
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
| | - Ke Zhao
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Fangchen Liu
- College of Resources and Environment, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Junjie Lin
- College of Life Sciences, Fujian Agriculture and Forestry University, Fuzhou, China
| | - Chenqiang Lin
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
| | - Jichen Chen
- Institute of Soil and Fertilizer, Fujian Academy of Agricultural Sciences, Fujian Key Laboratory of Plant Nutrition and Fertilizer, Fuzhou, China
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Guo J, Deng X, Zhang Y, Song S, Zhao T, Zhu D, Cao S, Baryshnikov PI, Cao G, Blair HT, Chen C, Gu X, Liu L, Zhang H. The Flagellar Transcriptional Regulator FtcR Controls Brucella melitensis 16M Biofilm Formation via a betI-Mediated Pathway in Response to Hyperosmotic Stress. Int J Mol Sci 2022; 23:ijms23179905. [PMID: 36077302 PMCID: PMC9456535 DOI: 10.3390/ijms23179905] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2022] [Revised: 08/26/2022] [Accepted: 08/27/2022] [Indexed: 11/16/2022] Open
Abstract
The expression of flagellar proteins in Brucella species likely evolved through genetic transference from other microorganisms, and contributed to virulence, adaptability, and biofilm formation. Despite significant progress in defining the molecular mechanisms behind flagellar gene expression, the genetic program controlling biofilm formation remains unclear. The flagellar transcriptional factor (FtcR) is a master regulator of the flagellar system’s expression, and is critical for B. melitensis 16M’s flagellar biogenesis and virulence. Here, we demonstrate that FtcR mediates biofilm formation under hyperosmotic stress. Chromatin immunoprecipitation with next-generation sequencing for FtcR and RNA sequencing of ftcR-mutant and wild-type strains revealed a core set of FtcR target genes. We identified a novel FtcR-binding site in the promoter region of the osmotic-stress-response regulator gene betI, which is important for the survival of B. melitensis 16M under hyperosmotic stress. Strikingly, this site autoregulates its expression to benefit biofilm bacteria’s survival under hyperosmotic stress. Moreover, biofilm reduction in ftcR mutants is independent of the flagellar target gene fliF. Collectively, our study provides new insights into the extent and functionality of flagellar-related transcriptional networks in biofilm formation, and presents phenotypic and evolutionary adaptations that alter the regulation of B. melitensis 16M to confer increased tolerance to hyperosmotic stress.
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Affiliation(s)
- Jia Guo
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Xingmei Deng
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Yu Zhang
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Shengnan Song
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Tianyi Zhao
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Dexin Zhu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Shuzhu Cao
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Peter Ivanovic Baryshnikov
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- College of Veterinary, Altai State Agricultural University, 656000 Barnaul, Russia
| | - Gang Cao
- State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430000, China
| | - Hugh T. Blair
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- International Sheep Research Center, School of Agriculture and Environment, Massey University, Palmerston North 4442, New Zealand
| | - Chuangfu Chen
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Xinli Gu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
| | - Liangbo Liu
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- Correspondence: (L.L.); (H.Z.); Tel.: +86-0993-2057971 (L.L. & H.Z.)
| | - Hui Zhang
- State International Joint Research Center for Animal Health Breeding, College of Animal Science and Technology, Shihezi University, Shihezi 832003, China
- Correspondence: (L.L.); (H.Z.); Tel.: +86-0993-2057971 (L.L. & H.Z.)
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Ko D, Choi SH. Mechanistic understanding of antibiotic resistance mediated by EnvZ/OmpR two-component system in Salmonella enterica serovar Enteritidis. J Antimicrob Chemother 2022; 77:2419-2428. [PMID: 35781339 DOI: 10.1093/jac/dkac223] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2022] [Accepted: 06/02/2022] [Indexed: 11/13/2022] Open
Abstract
BACKGROUND Outer membrane porins (OMPs) are a major route for the entry of small hydrophilic antibiotics. Thus, compositional modulation of OMPs is often accompanied by multidrug resistance in a human pathogen Salmonella enterica serovar Enteritidis. OBJECTIVES The role of EnvZ/OmpR two-component system in antibiotic resistance has not been established except that it regulates the expression of two OMPs, OmpC and OmpF. Here, we have gained mechanistic insight into EnvZ/OmpR-mediated antibiotic resistance in S. Enteritidis. METHODS The envZP248L and envZH243A strains, mimicking the S. Enteritidis strains with active and inactive states of EnvZ/OmpR, were used in this study. Antibiotic resistance was determined by the broth microdilution method and the spot plating assay. Transcriptomes of the S. Enteritidis strains were analysed by RNA-seq. Western blot, quantitative reverse transcription-PCR, electrophoretic mobility shift assays and β-galactosidase activity assays were performed. RESULTS The active state of EnvZ/OmpR induced a differential expression of multiple OMP genes including SEN1522, SEN2875, ompD and ompW, enhancing resistance to β-lactams in S. Enteritidis. OmpR directly activated SEN1522 and SEN2875 but repressed ompD and ompW. Interestingly, an increased cellular level of OmpR determined the expression of the four OMP genes, and phosphorylation of OmpR was even not necessary for the repression of ompD and ompW. EnvZ/OmpR increased its own expression in response to β-lactams, decreasing outer membrane permeability and providing S. Enteritidis with benefits for survival upon exposure to the antibiotics. CONCLUSIONS EnvZ/OmpR remodels OMP composition in response to β-lactams and thereby enhances antibiotic resistance in S. Enteritidis.
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Affiliation(s)
- Duhyun Ko
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Center for Food and Bioconvergence, Seoul National University, Seoul, Republic of Korea
| | - Sang Ho Choi
- National Research Laboratory of Molecular Microbiology and Toxicology, Department of Agricultural Biotechnology, Seoul National University, Seoul, Republic of Korea.,Center for Food and Bioconvergence, Seoul National University, Seoul, Republic of Korea.,Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul, Republic of Korea
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Liu Y, Zhang Y, Zhu L, Niu L, Luo X, Dong P. The acid tolerance responses of the Salmonella strains isolated from beef processing plants. Food Microbiol 2022; 104:103977. [DOI: 10.1016/j.fm.2022.103977] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2021] [Revised: 12/27/2021] [Accepted: 01/03/2022] [Indexed: 11/16/2022]
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The Regulatory Circuit Underlying Downregulation of a Type III Secretion System in Yersinia enterocolitica by Transcription Factor OmpR. Int J Mol Sci 2022; 23:ijms23094758. [PMID: 35563149 PMCID: PMC9100119 DOI: 10.3390/ijms23094758] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 04/22/2022] [Accepted: 04/24/2022] [Indexed: 11/17/2022] Open
Abstract
In a previous study, differential proteomic analysis was used to identify membrane proteins of the human enteropathogen Yersinia enterocolitica, whose levels are influenced by OmpR, the transcriptional regulator in the two-component EnvZ/OmpR system. Interestingly, this analysis demonstrated that at 37 °C, OmpR negatively affects the level of over a dozen Ysc-Yop proteins, which constitute a type III secretion system (T3SS) that is essential for the pathogenicity of Y. enterocolitica. Here, we focused our analysis on the role of OmpR in the expression and secretion of Yops (translocators and effectors). Western blotting with anti-Yops antiserum and specific anti-YopD, -YopE and -YopH antibodies, confirmed that the production of Yops is down-regulated by OmpR with the greatest negative effect on YopD. The RT-qPCR analysis demonstrated that, while OmpR had a negligible effect on the activity of regulatory genes virF and yscM1, it highly repressed the expression of yopD. OmpR was found to bind to the promoter of the lcrGVsycD-yopBD operon, suggesting a direct regulatory effect. In addition, we demonstrated that the negative regulatory influence of OmpR on the Ysc-Yop T3SS correlated with its positive role in the expression of flhDC, the master regulator of the flagellar-associated T3SS.
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Clemente-Carazo M, Leal JJ, Huertas JP, Garre A, Palop A, Periago PM. The Different Response to an Acid Shock of Two Salmonella Strains Marks Their Resistance to Thermal Treatments. Front Microbiol 2021; 12:691248. [PMID: 34616373 PMCID: PMC8488367 DOI: 10.3389/fmicb.2021.691248] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2021] [Accepted: 08/18/2021] [Indexed: 11/13/2022] Open
Abstract
Microbial cells respond to sub-lethal stresses with several physiological changes to increase their chance of survival. These changes are of high relevance when combined treatments (hurdle technology) are applied during food production, as the cells surviving the first hurdle may have greater resistance to subsequent treatments than untreated cells. In this study, we analyzed if Salmonella develops increased resistance to thermal treatments after the application of an acid shock. We compared the heat resistance of acid-shocked (pH 4.5 achieved with citric acid) Salmonella cells with that of cells maintained at pH 7 (control cells). Thermal treatments were performed between 57.5 and 65°C. We observed a differential response between the two strains studied. Acid-shocked cells of Salmonella Senftenberg exhibited reduced heat resistance, e.g., for a treatment at 60.0°C and pH 7.0 the time required to reduce the population by 3 log cycles was lowered from 10.75 to 1.98min with respect to control cells. Salmonella Enteritidis showed a different response, with acid-shocked cells having similar resistance than untreated cells (the time required to reduce 3 log cycles at 60.0°C and pH 7.0 was 0.30min for control and 0.31min for acid-shock cells). Based on results by differential plating (with or without adding the maximum non-inhibitory concentration of NaCl to the recovery medium), we hypothesize that the differential response between strains can be associated to sub-lethal damage to the cell membrane of S. Senftenberg caused by the acid shock. These results provide evidence that different strains of the same species can respond differently to an acid shock and highlight the relevance of cross-resistances for microbial risk assessment.
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Affiliation(s)
- Marta Clemente-Carazo
- Departamento Ingeniería Agronómica, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Instituto de Biotecnología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
| | - José-Juan Leal
- Departamento Ingeniería Agronómica, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Instituto de Biotecnología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
| | - Juan-Pablo Huertas
- Departamento Ingeniería Agronómica, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Instituto de Biotecnología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
| | - Alberto Garre
- Food Microbiology, Wageningen University & Research, Wageningen, Netherlands
| | - Alfredo Palop
- Departamento Ingeniería Agronómica, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Instituto de Biotecnología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
| | - Paula M Periago
- Departamento Ingeniería Agronómica, Campus de Excelencia Internacional Regional "Campus Mare Nostrum", Instituto de Biotecnología Vegetal, Escuela Técnica Superior de Ingeniería Agronómica, Universidad Politécnica de Cartagena, Cartagena, Spain
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Medina-Aparicio L, Rodriguez-Gutierrez S, Rebollar-Flores JE, Martínez-Batallar ÁG, Mendoza-Mejía BD, Aguirre-Partida ED, Vázquez A, Encarnación S, Calva E, Hernández-Lucas I. The CRISPR-Cas System Is Involved in OmpR Genetic Regulation for Outer Membrane Protein Synthesis in Salmonella Typhi. Front Microbiol 2021; 12:657404. [PMID: 33854491 PMCID: PMC8039139 DOI: 10.3389/fmicb.2021.657404] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2021] [Accepted: 03/10/2021] [Indexed: 12/11/2022] Open
Abstract
The CRISPR-Cas cluster is found in many prokaryotic genomes including those of the Enterobacteriaceae family. Salmonella enterica serovar Typhi (S. Typhi) harbors a Type I-E CRISPR-Cas locus composed of cas3, cse1, cse2, cas7, cas5, cas6e, cas1, cas2, and a CRISPR1 array. In this work, it was determined that, in the absence of cas5 or cas2, the amount of the OmpC porin decreased substantially, whereas in individual cse2, cas6e, cas1, or cas3 null mutants, the OmpF porin was not observed in an electrophoretic profile of outer membrane proteins. Furthermore, the LysR-type transcriptional regulator LeuO was unable to positively regulate the expression of the quiescent OmpS2 porin, in individual S. Typhi cse2, cas5, cas6e, cas1, cas2, and cas3 mutants. Remarkably, the expression of the master porin regulator OmpR was dependent on the Cse2, Cas5, Cas6e, Cas1, Cas2, and Cas3 proteins. Therefore, the data suggest that the CRISPR-Cas system acts hierarchically on OmpR to control the synthesis of outer membrane proteins in S. Typhi.
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Affiliation(s)
- Liliana Medina-Aparicio
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Sarahí Rodriguez-Gutierrez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Javier E Rebollar-Flores
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | | | - Blanca D Mendoza-Mejía
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Eira D Aguirre-Partida
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Alejandra Vázquez
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Sergio Encarnación
- Centro de Ciencias Genómicas, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Edmundo Calva
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Ismael Hernández-Lucas
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
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Impact of the Resistance Responses to Stress Conditions Encountered in Food and Food Processing Environments on the Virulence and Growth Fitness of Non-Typhoidal Salmonellae. Foods 2021; 10:foods10030617. [PMID: 33799446 PMCID: PMC8001757 DOI: 10.3390/foods10030617] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2021] [Revised: 02/24/2021] [Accepted: 03/10/2021] [Indexed: 01/22/2023] Open
Abstract
The success of Salmonella as a foodborne pathogen can probably be attributed to two major features: its remarkable genetic diversity and its extraordinary ability to adapt. Salmonella cells can survive in harsh environments, successfully compete for nutrients, and cause disease once inside the host. Furthermore, they are capable of rapidly reprogramming their metabolism, evolving in a short time from a stress-resistance mode to a growth or virulent mode, or even to express stress resistance and virulence factors at the same time if needed, thanks to a complex and fine-tuned regulatory network. It is nevertheless generally acknowledged that the development of stress resistance usually has a fitness cost for bacterial cells and that induction of stress resistance responses to certain agents can trigger changes in Salmonella virulence. In this review, we summarize and discuss current knowledge concerning the effects that the development of resistance responses to stress conditions encountered in food and food processing environments (including acid, osmotic and oxidative stress, starvation, modified atmospheres, detergents and disinfectants, chilling, heat, and non-thermal technologies) exerts on different aspects of the physiology of non-typhoidal Salmonellae, with special emphasis on virulence and growth fitness.
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Jaworska K, Ludwiczak M, Murawska E, Raczkowska A, Brzostek K. The Regulator OmpR in Yersinia enterocolitica Participates in Iron Homeostasis by Modulating Fur Level and Affecting the Expression of Genes Involved in Iron Uptake. Int J Mol Sci 2021; 22:ijms22031475. [PMID: 33540627 PMCID: PMC7867234 DOI: 10.3390/ijms22031475] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2021] [Revised: 01/29/2021] [Accepted: 01/29/2021] [Indexed: 12/02/2022] Open
Abstract
In this study, we found that the loss of OmpR, the response regulator of the two-component EnvZ/OmpR system, increases the cellular level of Fur, the master regulator of iron homeostasis in Y. enterocolitica. Furthermore, we demonstrated that transcription of the fur gene from the YePfur promoter is subject to negative OmpR-dependent regulation. Four putative OmpR-binding sites (OBSs) were indicated by in silico analysis of the fur promoter region, and their removal affected OmpR-dependent fur expression. Moreover, OmpR binds specifically to the predicted OBSs which exhibit a distinct hierarchy of binding affinity. Finally, the data demonstrate that OmpR, by direct binding to the promoters of the fecA, fepA and feoA genes, involved in the iron transport and being under Fur repressor activity, modulates their expression. It seems that the negative effect of OmpR on fecA and fepA transcription is sufficient to counteract the indirect, positive effect of OmpR resulting from decreasing the Fur repressor level. The expression of feoA was positively regulated by OmpR and this mode of action seems to be direct and indirect. Together, the expression of fecA, fepA and feoA in Y. enterocolitica has been proposed to be under a complex mode of regulation involving OmpR and Fur regulators.
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Vibrio cholerae OmpR Contributes to Virulence Repression and Fitness at Alkaline pH. Infect Immun 2020; 88:IAI.00141-20. [PMID: 32284367 DOI: 10.1128/iai.00141-20] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2020] [Accepted: 04/05/2020] [Indexed: 12/13/2022] Open
Abstract
Vibrio cholerae is a Gram-negative human pathogen and the causative agent of the life-threatening disease cholera. V. cholerae is a natural inhabitant of marine environments and enters humans through the consumption of contaminated food or water. The ability to transition between aquatic ecosystems and the human host is paramount to the pathogenic success of V. cholerae The transition between these two disparate environments requires the expression of adaptive responses, and such responses are most often regulated by two-component regulatory systems such as the EnvZ/OmpR system, which responds to osmolarity and acidic pH in many Gram-negative bacteria. Previous work in our laboratory indicated that V. cholerae OmpR functioned as a virulence regulator through repression of the LysR-family transcriptional regulator aphB; however, the role of OmpR in V. cholerae biology outside virulence regulation remained unknown. In this work, we sought to further investigate the function of OmpR in V. cholerae biology by defining the OmpR regulon through RNA sequencing. This led to the discovery that V. cholerae ompR was induced at alkaline pH to repress genes involved in acid tolerance and virulence factor production. In addition, OmpR was required for V. cholerae fitness during growth under alkaline conditions. These findings indicate that V. cholerae OmpR has evolved the ability to respond to novel signals during pathogenesis, which may play a role in the regulation of adaptive responses to aid in the transition between the human gastrointestinal tract and the marine ecosystem.
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Schwan WR, Flohr NL, Multerer AR, Starkey JC. GadE regulates fliC gene transcription and motility in Escherichia coli. World J Clin Infect Dis 2020; 10:14-23. [PMID: 32728533 PMCID: PMC7388676 DOI: 10.5495/wjcid.v10.i1.14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Revised: 03/25/2020] [Accepted: 05/05/2020] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Escherichia coli (E. coli) express flagella to ascend human urinary tracts. To survive in the acidic pH of human urine, E. coli uses the glutamate decarboxylase acid response system, which is regulated by the GadE protein.
AIM To determine if growth in an acidic pH environment affected fliC transcription and whether GadE regulated that transcription.
METHODS A fliC-lacZ reporter fusion was created on a single copy number plasmid to assess the effects of acidic pH on fliC transcription. Further, a ΔgadE mutant strain of a uropathogenic E. coli was created and tested for motility compared to the wild-type strain.
RESULTS Escherichia coli cells carrying the fliC-lacZ fusion displayed significantly less fliC transcription when grown in an acidic pH medium compared to when grown in a neutral pH medium. Transcription of fliC fell further when the E. coli was grown in an acidic pH/high osmolarity environment. Since GadE is a critical regulator of one acid response system, fliC transcription was tested in a gadE mutant strain grown under acidic conditions. Expression of fliC was derepressed in the E. coli gadE mutant strain grown under acidic conditions compared to that in wild-type bacteria under the same conditions. Furthermore, a gadE mutation in a uropathogenic E. coli background exhibited significantly greater motility than the wild-type strain following growth in an acidic medium.
CONCLUSION Together, our results suggest that GadE may down-regulate fliC transcription and motility in E. coli grown under acidic conditions.
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Affiliation(s)
- William R Schwan
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, United States
| | - Nicole L Flohr
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, United States
| | - Abigail R Multerer
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, United States
| | - Jordan C Starkey
- Department of Microbiology, University of Wisconsin-La Crosse, La Crosse, WI 54601, United States
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Zhang M, Kang J, Wu B, Qin Y, Huang L, Zhao L, Mao L, Wang S, Yan Q. Comparative transcriptome and phenotype analysis revealed the role and mechanism of ompR in the virulence of fish pathogenic Aeromonas hydrophila. Microbiologyopen 2020; 9:e1041. [PMID: 32282134 PMCID: PMC7349151 DOI: 10.1002/mbo3.1041] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2019] [Revised: 03/18/2020] [Accepted: 03/18/2020] [Indexed: 12/16/2022] Open
Abstract
Aeromonas hydrophila B11 strain was isolated from diseased Anguilla japonica, which had caused severe gill ulcers in farmed eel, causing huge economic losses. EnvZ‐OmpR is a model two‐component system in the bacteria and is widely used in the research of signal transduction and gene transcription regulation. In this study, the ompR of A. hydrophila B11 strain was first silenced by RNAi technology. The role of ompR in the pathogenicity of A. hydrophila B11 was investigated by analyzing both the bacterial comparative transcriptome and phenotype. The qRT‐PCR results showed that the expression of ompR in the ompR‐RNAi strain decreased by 97% compared with the wild‐type strain. The virulence test showed that after inhibition of the ompR expression, the LD50 of A. hydrophila B11 decreased by an order of magnitude, suggesting that ompR is involved in the regulation of bacterial virulence. Comparative transcriptome analysis showed that the expression of ompR can directly regulate the expression of several important virulence‐related genes, such as the bacterial type II secretion system; moreover, ompR expression also regulates the expression of multiple genes related to bacterial chemotaxis, motility, adhesion, and biofilm formation. Further studies on the phenotype of A. hydrophila B11 and ompR‐RNAi also confirmed that the downregulation of ompR expression can decrease bacterial chemotaxis, adhesion, and biofilm formation.
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Affiliation(s)
- Mengmeng Zhang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Jianping Kang
- Fujian Fisheries Technology Extension Center, Fuzhou, China
| | - Bin Wu
- Fujian Fisheries Technology Extension Center, Fuzhou, China
| | - Yingxue Qin
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China.,Fujian Province Key Laboratory of Special Aquatic Formula Feed, Fujian Tianma Science and Technology Group Co., Ltd., Fuqing, China
| | - Lixing Huang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Lingmin Zhao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Leilei Mao
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Suyun Wang
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
| | - Qingpi Yan
- Fisheries College, Key Laboratory of Healthy Mariculture for the East China Sea, Ministry of Agriculture, Jimei University, Xiamen, China
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Kenney LJ, Anand GS. EnvZ/OmpR Two-Component Signaling: An Archetype System That Can Function Noncanonically. EcoSal Plus 2020; 9:10.1128/ecosalplus.ESP-0001-2019. [PMID: 32003321 PMCID: PMC7192543 DOI: 10.1128/ecosalplus.esp-0001-2019] [Citation(s) in RCA: 47] [Impact Index Per Article: 11.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2019] [Indexed: 01/09/2023]
Abstract
Two-component regulatory systems represent the major paradigm for signal transduction in prokaryotes. The simplest systems are composed of a sensor kinase and a response regulator. The sensor is often a membrane protein that senses a change in environmental conditions and is autophosphorylated by ATP on a histidine residue. The phosphoryl group is transferred onto an aspartate of the response regulator, which activates the regulator and alters its output, usually resulting in a change in gene expression. In this review, we present a historical view of the archetype EnvZ/OmpR two-component signaling system, and then we provide a new view of signaling based on our recent experiments. EnvZ responds to cytoplasmic signals that arise from changes in the extracellular milieu, and OmpR acts canonically (requiring phosphorylation) to regulate the porin genes and noncanonically (without phosphorylation) to activate the acid stress response. Herein, we describe how insights gleaned from stimulus recognition and response in EnvZ are relevant to nearly all sensor kinases and response regulators.
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Affiliation(s)
- Linda J Kenney
- Department of Biochemistry & Molecular Biology, University of Texas Medical Branch, Galveston, TX 77555
- Mechanobiology Institute, T-Lab, National University of Singapore, Singapore
| | - Ganesh S Anand
- Department of Biological Sciences, National University of Singapore, Singapore
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15
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Dorman CJ, Ní Bhriain N. CRISPR-Cas, DNA Supercoiling, and Nucleoid-Associated Proteins. Trends Microbiol 2019; 28:19-27. [PMID: 31519332 DOI: 10.1016/j.tim.2019.08.004] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2019] [Revised: 08/02/2019] [Accepted: 08/08/2019] [Indexed: 12/11/2022]
Abstract
In this opinion article we highlight links between the H-NS nucleoid-associated protein, variable DNA topology, the regulation of CRISPR-cas locus expression, CRISPR-Cas activity, and the recruitment of novel genetic information by the CRISPR array. We propose that the requirement that the invading mobile genetic element be negatively supercoiled limits effective CRISPR action to a window in the bacterial growth cycle when DNA topology is optimal, and that this same window is used for the efficient integration of new spacer sequences at the CRISPR array. H-NS silences CRISPR promoters, and we propose that antagonists of H-NS, such as the LeuO transcription factor, provide a basis for a stochastic genetic switch that acts at random in each cell in the bacterial population. In addition, we wish to propose a mechanism by which mobile genetic elements can suppress CRISPR-cas transcription using H-NS homologues. Although the individual components of this network are known, we propose a new model in which they are integrated and linked to the physiological state of the bacterium. The model provides a basis for cell-to-cell variation in the expression and performance of CRISPR systems in bacterial populations.
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Affiliation(s)
- Charles J Dorman
- Department of Microbiology, Trinity College Dublin, Dublin 2, Ireland.
| | - Niamh Ní Bhriain
- Department of Microbiology, Trinity College Dublin, Dublin 2, Ireland
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16
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Dorman CJ. DNA supercoiling and transcription in bacteria: a two-way street. BMC Mol Cell Biol 2019; 20:26. [PMID: 31319794 PMCID: PMC6639932 DOI: 10.1186/s12860-019-0211-6] [Citation(s) in RCA: 58] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2019] [Accepted: 07/09/2019] [Indexed: 11/23/2022] Open
Abstract
BACKGROUND The processes of DNA supercoiling and transcription are interdependent because the movement of a transcription elongation complex simultaneously induces under- and overwinding of the DNA duplex and because the initiation, elongation and termination steps of transcription are all sensitive to the topological state of the DNA. RESULTS Policing of the local and global supercoiling of DNA by topoisomerases helps to sustain the major DNA-based transactions by eliminating barriers to the movement of transcription complexes and replisomes. Recent data from whole-genome and single-molecule studies have provided new insights into how interactions between transcription and the supercoiling of DNA influence the architecture of the chromosome and how they create cell-to-cell diversity at the level of gene expression through transcription bursting. CONCLUSIONS These insights into fundamental molecular processes reveal mechanisms by which bacteria can prevail in unpredictable and often hostile environments by becoming unpredictable themselves.
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Affiliation(s)
- Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
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18
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Cross-talk between the RcsCDB and RstAB systems to control STM1485 gene expression in Salmonella Typhimurium during acid-resistance response. Biochimie 2019; 160:46-54. [PMID: 30763640 DOI: 10.1016/j.biochi.2019.02.005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2018] [Accepted: 02/08/2019] [Indexed: 01/13/2023]
Abstract
Bacterial survive and respond to adverse changes in the environment by regulating gene transcription through two-component regulatory systems. In Salmonella Typhimurium the STM1485 gene expression is induced under low pH (4.5) during replication inside the epithelial host cell, but it is not involved in sensing or resisting to this condition. Since the RcsCDB system is activated under acidic conditions, we investigated whether this system is able to modulate STM1485 expression. We demonstrated that acid-induced activation of the RcsB represses STM1485 transcription by directly binding to the promoter. Under the same condition, the RstA regulator activates the expression of this gene. Physiologically, we observed that RcsB-dependent repression is required for the survival of bacteria when they are exposed to pancreatic fluids. We hypothesized that STM1485 plays an important role in Salmonella adaptation to pH changes, during transition in the gastrointestinal tract. We suggest that bacteria surviving the gastrointestinal environment invade the epithelial cells, where they can remain in vacuoles. In this new environment, acidity and magnesium starvation activate the expression of the RstA regulator in a PhoPQ-dependent manner, which in turn induces STM1485 expression. These levels of STM1485 allow increased bacterial replication within vacuoles to continue the course of infection.
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The Role of the Host in Driving Phenotypic Heterogeneity in Salmonella. Trends Microbiol 2019; 27:508-523. [PMID: 30755344 DOI: 10.1016/j.tim.2019.01.004] [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: 09/10/2018] [Revised: 12/21/2018] [Accepted: 01/18/2019] [Indexed: 02/07/2023]
Abstract
The complex infection environment within hosts exerts unique stresses across tissues and cell types, selecting for phenotypic heterogeneity in bacterial populations. Pathogens maintain variability during infection as a strategy to cope with fluctuating host immune conditions, leading to diversification of virulence phenotypes. Recent improvements in single-cell analyses have revealed that distinct bacterial subpopulations contribute unique colonization and growth strategies across infection sites. We discuss several examples of host-driven phenotypic heterogeneity in Salmonella populations throughout the course of infection, highlighting how variation in gene expression, growth rate, immune evasion, and metabolic activity contribute to overall bacterial success at the population level. We additionally focus our discussion on the implications of diversity within bacterial communities for antimicrobial efficacy.
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Ye B, He S, Zhou X, Cui Y, Zhou M, Shi X. Response to Acid Adaptation in Salmonella enterica Serovar Enteritidis. J Food Sci 2019; 84:599-605. [PMID: 30730584 DOI: 10.1111/1750-3841.14465] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2018] [Revised: 01/01/2019] [Accepted: 01/15/2019] [Indexed: 11/26/2022]
Abstract
Acid adaptation in Salmonella Enteritidis was characterized by phenotypic and gene-expression analyses. S. Enteritidis cells at log-phase and stationary-phase were kept at pH 4.5 to 6.0 for 1 to 4 hours. All treatments induced various levels of acid tolerance response that were dependent on pH, exposure time and growth phase. This acid adaptation resulted in tolerance to 50 °C and 8% NaCl regardless of the growth phase. However, the tolerance of log-phase and stationary-phase cells to low temperatures (4 and -20 °C) was increased and decreased, respectively. RT-qPCR analysis revealed that genes involved in tolerance to acid (SEN1564A and cfa), heat (rpoH, uspB, and htrA), salt (proP, proV, and osmW), and cold (cspA, cspC, and csdA) stress were generally upregulated after acid adaptation. These results provide an initial insight into mechanisms of acid adaptation and induced cross protection in S. Enteritidis. PRACTICAL APPLICATION: Stress tolerance acquisition resulting from acid adaptation in foodborne pathogens poses a great threat to food safety. The current work showed that acid adaptation induced direct tolerance and cross-tolerance to high temperature, low temperature, and salt in Salmonella Enteritidis, possibly due to the upregulation of stress tolerance-related genes. These results provide key insights into acid adaptation mechanisms and efficient control of S. Enteritidis.
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Affiliation(s)
- Beining Ye
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong Univ., Shanghai, 200240, China
| | - Shoukui He
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong Univ., Shanghai, 200240, China
| | - Xiujuan Zhou
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong Univ., Shanghai, 200240, China
| | - Yan Cui
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong Univ., Shanghai, 200240, China
| | - Min Zhou
- School of Food Science and Engineering, Wuhan Polytechnic Univ., Wuhan, 430023, Hubei, China
| | - Xianming Shi
- MOST-USDA Joint Research Center for Food Safety, School of Agriculture and Biology, State Key Lab of Microbial Metabolism, Shanghai Jiao Tong Univ., Shanghai, 200240, China
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21
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Quantitative assessment of tolerance response to stress after exposure to oregano and rosemary essential oils, carvacrol and 1,8-cineole in Salmonella Enteritidis 86 and its isogenic deletion mutants ∆dps, ∆rpoS and ∆ompR. Food Res Int 2019; 122:679-687. [PMID: 31229127 DOI: 10.1016/j.foodres.2019.01.046] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2018] [Revised: 01/17/2019] [Accepted: 01/20/2019] [Indexed: 01/08/2023]
Abstract
This study assessed the influence of rpoS, dps and ompR genes on the tolerance response of Salmonella Enteritidis 86 (SE86) to homologous and heterologous stressing agents after exposure to essential oils (EOs) from Origanum vulgare L. (oregano; OVEO) and Rosmarinus officinalis L. (rosemary; ROEO) and their major constituents (ICs), carvacrol (CAR) and 1,8-cineole (CIN), respectively, by modelling the log reduction over time. Minimum inhibitory concentration values of OVEO (1.25 μL/mL), CAR (0.62 μL/mL), ROEO (20 μL/mL) and CIN (10 μL/mL) against SE86 were always one-fold higher than those against ∆dps, ∆rpoS and ∆ompR mutants. Exposure to the same concentration of OVEO, CAR, ROEO or CIN caused higher reductions (up to 2.5 log CFU/mL) in ∆dps, ∆rpoS and ∆ompR mutants than in SE86 in chicken broth. In assays with homologous stressing agents, ompR, dps and rpoS influenced the tolerance to OEs or ICs. After adaptation to OVEO, CAR, ROEO and CIN, osmotolerance and acid tolerance of SE86 were influenced by rpoS gene, while thermotolerance of SE86 was influenced by ompR. Tolerance of SE86 to sodium hypochlorite after adaptation to OEs or ICs was influenced by rpoS and dps. These findings quantitatively describe for the first time the influence of rpoS, dps and ompR genes on the tolerance of Salmonella Enteritidis to OVEO, CAR, ROEO and CIN.
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22
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Mutz YDS, Rosario DKA, Paschoalin VMF, Conte-Junior CA. Salmonella enterica: A hidden risk for dry-cured meat consumption? Crit Rev Food Sci Nutr 2019; 60:976-990. [DOI: 10.1080/10408398.2018.1555132] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Affiliation(s)
- Yhan da Silva Mutz
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
| | - Denes Kaic Alves Rosario
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
| | | | - Carlos Adam Conte-Junior
- Chemistry Institute, Federal University of Rio de Janeiro, Cidade Universitária, Rio de Janeiro, RJ, Brazil
- Department of Food Technology, Federal Fluminense University, Vital Brazil Filho, Niterói, RJ, Brazil
- National Institute of Health Quality Control, Oswaldo Cruz Foundation, Rio de Janeiro, RJ, Brazil
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23
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Jaworska K, Nieckarz M, Ludwiczak M, Raczkowska A, Brzostek K. OmpR-Mediated Transcriptional Regulation and Function of Two Heme Receptor Proteins of Yersinia enterocolitica Bio-Serotype 2/O:9. Front Cell Infect Microbiol 2018; 8:333. [PMID: 30294593 PMCID: PMC6158557 DOI: 10.3389/fcimb.2018.00333] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2018] [Accepted: 08/29/2018] [Indexed: 12/26/2022] Open
Abstract
We show that Yersinia enterocolitica strain Ye9 (bio-serotype 2/O:9) utilizes heme-containing molecules as an iron source. The Ye9 genome contains two multigenic clusters, hemPRSTUV-1 and hemPRST-2, encoding putative heme receptors HemR1 and HemR2, that share 62% amino acid identity. Expression of these proteins in an Escherichia coli mutant defective in heme biosynthesis allowed this strain to use hemin and hemoglobin as a source of porphyrin. The hemPRSTUV-1 and hemPRST-2 clusters are organized as operons, expressed from the phem−1 and weaker phem−2 promoters, respectively. Expression of both operons is negatively regulated by iron and the iron-responsive transcriptional repressor Fur. In addition, OmpR, the response regulator of two component system (TCSs) EnvZ/OmpR, represses transcription of both operons through interaction with binding sequences overlapping the −35 region of their promoters. Western blot analysis of the level of HemR1 in ompR, fur, and ompRfur mutants, showed an additive effect of these mutations, indicating that OmpR may regulate HemR expression independently of Fur. However, the effect of OmpR on the activity of the phem−1 promoter and on HemR1 production was observed in both iron-depleted and iron-replete conditions, i.e., when Fur represses the iron-regulated promoter. In addition, a hairpin RNA thermometer, composed of four uracil residues (FourU) that pair with the ribosome-binding site in the 5′-untranslated region (5′-UTR) of hemR1 was predicted by in silico analysis. However, thermoregulated expression of HemR1 could not be demonstrated. Taken together, these data suggest that Fur and OmpR control iron/heme acquisition via a complex mechanism based on negative regulation of hemR1 and hemR2 at the transcriptional level. This interplay could fine-tune the level of heme receptor proteins to allow Y. enterocolitica to fulfill its iron/heme requirements without over-accumulation, which might be important for pathogenic growth within human hosts.
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Affiliation(s)
- Karolina Jaworska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Marta Nieckarz
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Marta Ludwiczak
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Adrianna Raczkowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
| | - Katarzyna Brzostek
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Warsaw, Poland
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24
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The OmpR Regulator of Burkholderia multivorans Controls Mucoid-to-Nonmucoid Transition and Other Cell Envelope Properties Associated with Persistence in the Cystic Fibrosis Lung. J Bacteriol 2018; 200:JB.00216-18. [PMID: 29914989 DOI: 10.1128/jb.00216-18] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2018] [Accepted: 06/14/2018] [Indexed: 12/15/2022] Open
Abstract
Bacteria from the Burkholderia cepacia complex grow in different natural and man-made environments and are feared opportunistic pathogens that cause chronic respiratory infections in cystic fibrosis patients. Previous studies showed that Burkholderia mucoid clinical isolates grown under stress conditions give rise to nonmucoid variants devoid of the exopolysaccharide cepacian. Here, we determined that a major cause of the nonmucoid morphotype involves nonsynonymous mutations and small indels in the ompR gene encoding a response regulator of a two-component regulatory system. In trans complementation of nonmucoid variants (NMVs) with the native gene restored exopolysaccharide production. The loss of functional Burkholderia multivorans OmpR had positive effects on growth, adhesion to lung epithelial cells, and biofilm formation in high-osmolarity medium, as well as an increase in swimming and swarming motilities. In contrast, phenotypes such as antibiotic resistance, biofilm formation at low osmolarity, and virulence in Galleria mellonella were compromised by the absence of functional OmpR. Transcriptomic studies indicated that loss of the ompR gene affects the expression of 701 genes, many associated with outer membrane composition, motility, stress response, iron acquisition, and the uptake of nutrients, consistent with starvation tolerance. Since the stresses here imposed on B. multivorans may strongly resemble the ones found in the cystic fibrosis (CF) airways and mutations in the ompR gene from longitudinally collected CF isolates have been found, this regulator might be important for the production of NMVs in the CF environment.IMPORTANCE Within the cystic fibrosis (CF) lung, bacteria experience high-osmolarity conditions due to an ion unbalance resulting from defects in CF transmembrane conductance regulator (CFTR) protein activity in epithelial cells. Understanding how bacterial CF pathogens thrive in this environment might help the development of new therapeutic interventions to prevent chronic respiratory infections. Here, we show that the OmpR response regulator of one of the species found in CF respiratory infections, Burkholderia multivorans, is involved in the emergence of nonmucoid colony variants and is important for osmoadaptation by regulating several cell envelope components. Specifically, genetic, phenotypic, genomic, and transcriptomic approaches uncover OmpR as a regulator of cell wall remodeling under stress conditions, with implications in several phenotypes such as exopolysaccharide production, motility, antibiotic resistance, adhesion, and virulence.
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25
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Hu S, Yu Y, Zhou D, Li R, Xiao X, Wu H. Global transcriptomic Acid Tolerance Response in Salmonella Enteritidis. Lebensm Wiss Technol 2018. [DOI: 10.1016/j.lwt.2018.02.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
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26
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Reciprocal Regulation of OmpR and Hfq and Their Regulatory Actions on the Vi Polysaccharide Capsular Antigen in Salmonella enterica Serovar Typhi. Curr Microbiol 2018; 75:773-778. [DOI: 10.1007/s00284-018-1447-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2017] [Accepted: 01/31/2018] [Indexed: 11/30/2022]
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27
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Colgan AM, Quinn HJ, Kary SC, Mitchenall LA, Maxwell A, Cameron ADS, Dorman CJ. Negative supercoiling of DNA by gyrase is inhibited in Salmonella enterica serovar Typhimurium during adaptation to acid stress. Mol Microbiol 2018; 107:734-746. [PMID: 29352745 DOI: 10.1111/mmi.13911] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2017] [Revised: 01/15/2018] [Accepted: 01/16/2018] [Indexed: 12/26/2022]
Abstract
DNA in intracellular Salmonella enterica serovar Typhimurium relaxes during growth in the acidified (pH 4-5) macrophage vacuole and DNA relaxation correlates with the upregulation of Salmonella genes involved in adaptation to the macrophage environment. Bacterial ATP levels did not increase during adaptation to acid pH unless the bacterium was deficient in MgtC, a cytoplasmic-membrane-located inhibitor of proton-driven F1 F0 ATP synthase activity. Inhibiting ATP binding by DNA gyrase and topo IV with novobiocin enhanced the effect of low pH on DNA relaxation. Bacteria expressing novobiocin-resistant (NovR ) derivatives of gyrase or topo IV also exhibited DNA relaxation at acid pH, although further relaxation with novobiocin was not seen in the strain with NovR gyrase. Thus, inhibition of the negative supercoiling activity of gyrase was the primary cause of enhanced DNA relaxation in drug-treated bacteria. The Salmonella cytosol reaches pH 5-6 in response to an external pH of 4-5: the ATP-dependent DNA supercoiling activity of purified gyrase was progressively inhibited by lowering the pH in this range, as was the ATP-dependent DNA relaxation activity of topo IV. We propose that DNA relaxation in Salmonella within macrophage is due to acid-mediated impairment of the negative supercoiling activity of gyrase.
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Affiliation(s)
- Aoife M Colgan
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Heather J Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
| | - Stefani C Kary
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.,Department of Biology, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Lesley A Mitchenall
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Anthony Maxwell
- Department of Biological Chemistry, John Innes Centre, Norwich Research Park, Norwich, NR4 7UH, UK
| | - Andrew D S Cameron
- Department of Biology, Institute for Microbial Systems and Society, University of Regina, Regina, SK, S4S 0A2, Canada
| | - Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland
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28
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Clark-Curtiss JE, Curtiss R. Salmonella Vaccines: Conduits for Protective Antigens. THE JOURNAL OF IMMUNOLOGY 2018; 200:39-48. [PMID: 29255088 DOI: 10.4049/jimmunol.1600608] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2016] [Accepted: 11/06/2017] [Indexed: 11/19/2022]
Abstract
Vaccines afford a better and more cost-effective approach to combatting infectious diseases than continued reliance on antibiotics or antiviral or antiparasite drugs in the current era of increasing incidences of diseases caused by drug-resistant pathogens. Recombinant attenuated Salmonella vaccines (RASVs) have been significantly improved to exhibit the same or better attributes than wild-type parental strains to colonize internal lymphoid tissues and persist there to serve as factories to continuously synthesize and deliver rAgs. Encoded by codon-optimized pathogen genes, Ags are selected to induce protective immunity to infection by that pathogen. After immunization through a mucosal surface, the RASV attributes maximize their abilities to elicit mucosal and systemic Ab responses and cell-mediated immune responses. This article summarizes many of the numerous innovative technologies and discoveries that have resulted in RASV platforms that will enable development of safe efficacious RASVs to protect animals and humans against a diversity of infectious disease agents.
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Affiliation(s)
- Josephine E Clark-Curtiss
- Division of Infectious Diseases and Global Medicine, Department of Medicine, College of Medicine, University of Florida, Gainesville, FL 32610.,Emerging Pathogens Institute, University of Florida, Gainesville, FL 32611
| | - Roy Curtiss
- Department of Infectious Diseases and Immunology, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611; and .,Department of Comparative, Diagnostic and Population Medicine, College of Veterinary Medicine, University of Florida, Gainesville, FL 32611
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29
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Lee YH, Kim JH. Direct interaction between the transcription factors CadC and OmpR involved in the acid stress response of Salmonella enterica. J Microbiol 2017; 55:966-972. [DOI: 10.1007/s12275-017-7410-7] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2017] [Revised: 10/18/2017] [Accepted: 10/23/2017] [Indexed: 01/12/2023]
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30
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Dorman CJ, Dorman MJ. Control of virulence gene transcription by indirect readout in Vibrio cholerae and Salmonella enterica serovar Typhimurium. Environ Microbiol 2017. [PMID: 28631437 PMCID: PMC5655915 DOI: 10.1111/1462-2920.13838] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Indirect readout mechanisms of transcription control rely on the recognition of DNA shape by transcription factors (TFs). TFs may also employ a direct readout mechanism that involves the reading of the base sequence in the DNA major groove at the binding site. TFs with winged helix-turn-helix (wHTH) motifs use an alpha helix to read the base sequence in the major groove while inserting a beta sheet 'wing' into the adjacent minor groove. Such wHTH proteins are important regulators of virulence gene transcription in many pathogens; they also control housekeeping genes. This article considers the cases of the non-invasive Gram-negative pathogen Vibrio cholerae and the invasive pathogen Salmonella enterica serovar Typhimurium. Both possess clusters of A + T-rich horizontally acquired virulence genes that are silenced by the nucleoid-associated protein H-NS and regulated positively or negatively by wHTH TFs: for example, ToxR and LeuO in V. cholerae; HilA, LeuO, SlyA and OmpR in S. Typhimurium. Because of their relatively relaxed base sequence requirements for target recognition, indirect readout mechanisms have the potential to engage regulatory proteins with many more targets than might be the case using direct readout, making indirect readout an important, yet often ignored, contributor to the expression of pathogenic phenotypes.
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Affiliation(s)
- Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Matthew J Dorman
- Wellcome Trust Sanger Institute, Wellcome Genome Campus, Hinxton, Cambridgeshire, CB10 1SA, UK
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31
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Abstract
Two-component systems are a dominant form of bacterial signal transduction. The prototypical two-component system consists of a sensor that responds to a specific input(s) by modifying the output of a cognate regulator. Because the output of a two-component system is the amount of phosphorylated regulator, feedback mechanisms may alter the amount of regulator, and/or modify the ability of a sensor or other proteins to alter the phosphorylation state of the regulator. Two-component systems may display intrinsic feedback whereby the amount of phosphorylated regulator changes under constant inducing conditions and without the participation of additional proteins. Feedback control allows a two-component system to achieve particular steady-state levels, to reach a given steady state with distinct dynamics, to express coregulated genes in a given order, and to activate a regulator to different extents, depending on the signal acting on the sensor.
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Affiliation(s)
- Eduardo A Groisman
- Department of Microbial Pathogenesis, Yale School of Medicine, New Haven, Connecticut 06536; .,Yale Microbial Sciences Institute, West Haven, Connecticut 06516
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32
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Variability in the adaptive acid tolerance response phenotype of Salmonella enterica strains. Food Microbiol 2017; 62:99-105. [DOI: 10.1016/j.fm.2016.10.011] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 09/18/2016] [Accepted: 10/03/2016] [Indexed: 12/18/2022]
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33
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Dorman CJ, Dorman MJ. DNA supercoiling is a fundamental regulatory principle in the control of bacterial gene expression. Biophys Rev 2016; 8:89-100. [PMID: 28510216 DOI: 10.1007/s12551-016-0238-2] [Citation(s) in RCA: 48] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Accepted: 06/01/2016] [Indexed: 11/28/2022] Open
Abstract
Although it has become routine to consider DNA in terms of its role as a carrier of genetic information, it is also an important contributor to the control of gene expression. This regulatory principle arises from its structural properties. DNA is maintained in an underwound state in most bacterial cells and this has important implications both for DNA storage in the nucleoid and for the expression of genetic information. Underwinding of the DNA through reduction in its linking number potentially imparts energy to the duplex that is available to drive DNA transactions, such as transcription, replication and recombination. The topological state of DNA also influences its affinity for some DNA binding proteins, especially in DNA sequences that have a high A + T base content. The underwinding of DNA by the ATP-dependent topoisomerase DNA gyrase creates a continuum between metabolic flux, DNA topology and gene expression that underpins the global response of the genome to changes in the intracellular and external environments. These connections describe a fundamental and generalised mechanism affecting global gene expression that underlies the specific control of transcription operating through conventional transcription factors. This mechanism also provides a basal level of control for genes acquired by horizontal DNA transfer, assisting microbial evolution, including the evolution of pathogenic bacteria.
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Affiliation(s)
- Charles J Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin 2, Ireland.
| | - Matthew J Dorman
- Department of Genetics, Smurfit Institute of Genetics, Trinity College Dublin, Dublin 2, Ireland.,Wellcome Trust Sanger Institute, Hinxton, Cambridge, CB10 1SA, UK
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34
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DNA supercoiling is a fundamental regulatory principle in the control of bacterial gene expression. Biophys Rev 2016; 8:209-220. [PMID: 28510224 DOI: 10.1007/s12551-016-0205-y] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 06/01/2016] [Indexed: 12/27/2022] Open
Abstract
Although it has become routine to consider DNA in terms of its role as a carrier of genetic information, it is also an important contributor to the control of gene expression. This regulatory principle arises from its structural properties. DNA is maintained in an underwound state in most bacterial cells and this has important implications both for DNA storage in the nucleoid and for the expression of genetic information. Underwinding of the DNA through reduction in its linking number potentially imparts energy to the duplex that is available to drive DNA transactions, such as transcription, replication and recombination. The topological state of DNA also influences its affinity for some DNA binding proteins, especially in DNA sequences that have a high A + T base content. The underwinding of DNA by the ATP-dependent topoisomerase DNA gyrase creates a continuum between metabolic flux, DNA topology and gene expression that underpins the global response of the genome to changes in the intracellular and external environments. These connections describe a fundamental and generalised mechanism affecting global gene expression that underlies the specific control of transcription operating through conventional transcription factors. This mechanism also provides a basal level of control for genes acquired by horizontal DNA transfer, assisting microbial evolution, including the evolution of pathogenic bacteria.
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35
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Nieckarz M, Raczkowska A, Dębski J, Kistowski M, Dadlez M, Heesemann J, Rossier O, Brzostek K. Impact of OmpR on the membrane proteome of Yersinia enterocolitica in different environments: repression of major adhesin YadA and heme receptor HemR. Environ Microbiol 2016; 18:997-1021. [PMID: 26627632 DOI: 10.1111/1462-2920.13165] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2015] [Revised: 11/26/2015] [Accepted: 11/29/2015] [Indexed: 01/22/2023]
Abstract
Enteropathogenic Yersinia enterocolitica is able to grow within or outside the mammalian host. Previous transcriptomic studies have indicated that the regulator OmpR plays a role in the expression of hundreds of genes in enterobacteria. Here, we have examined the impact of OmpR on the production of Y. enterocolitica membrane proteins upon changes in temperature, osmolarity and pH. Proteomic analysis indicated that the loss of OmpR affects the production of 120 proteins, a third of which are involved in uptake/transport, including several that participate in iron or heme acquisition. A set of proteins associated with virulence was also affected. The influence of OmpR on the abundance of adhesin YadA and heme receptor HemR was examined in more detail. OmpR was found to repress YadA production and bind to the yadA promoter, suggesting a direct regulatory effect. In contrast, the repression of hemR expression by OmpR appears to be indirect. These findings provide new insights into the role of OmpR in remodelling the cell surface and the adaptation of Y. enterocolitica to different environmental niches, including the host.
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Affiliation(s)
- Marta Nieckarz
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Ilji Miecznikowa 1, Warsaw, 02-096, Poland
| | - Adrianna Raczkowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Ilji Miecznikowa 1, Warsaw, 02-096, Poland
| | - Janusz Dębski
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, Warsaw, 02-106, Poland
| | - Michał Kistowski
- Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, Warsaw, 02-106, Poland
| | - Michał Dadlez
- Institute of Genetics and Biotechnology, Faculty of Biology, University of Warsaw, Pawińskiego 5a, Warsaw, 02-106, Poland.,Mass Spectrometry Laboratory, Institute of Biochemistry and Biophysics, Polish Academy of Sciences, Pawińskiego 5a, Warsaw, 02-106, Poland
| | - Jürgen Heesemann
- Max von Pettenkofer Institute for Hygiene and Medical Microbiology, Ludwig Maximilians University, Pettenkoferstrasse 9a, Munich, 80336, Germany
| | - Ombeline Rossier
- Max von Pettenkofer Institute for Hygiene and Medical Microbiology, Ludwig Maximilians University, Pettenkoferstrasse 9a, Munich, 80336, Germany
| | - Katarzyna Brzostek
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw, Ilji Miecznikowa 1, Warsaw, 02-096, Poland
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36
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Shimada T, Takada H, Yamamoto K, Ishihama A. Expanded roles of two-component response regulator OmpR in Escherichia coli: genomic SELEX search for novel regulation targets. Genes Cells 2015; 20:915-31. [PMID: 26332955 DOI: 10.1111/gtc.12282] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 07/26/2015] [Indexed: 12/22/2022]
Abstract
The two-component system (TCS) is a sophisticated bacterial signal transduction system for regulation of genome transcription in response to environmental conditions. The EnvZ-OmpR system is one of the well-characterized TCS of Escherichia coli, responding to changes in environmental osmolality. Regulation has largely focused on the differential expression of two porins, OmpF and OmpC, which transport small molecules across the outer membrane. Recently, it has become apparent that OmpR serves a more global regulatory role and regulates additional targets. To identify the entire set of regulatory targets of OmpR, we performed the genomic SELEX screening of OmpR-binding sites along the E. coli genome. As a result, more than 30 novel genes have been identified to be under the direct control of OmpR. One abundant group includes the genes encoding a variety of membrane-associated transporters that mediate uptake or efflux of small molecules, while another group encodes a set of transcription regulators, raising a concept that OmpR is poised to control a diverse set of responses by altering downstream transcriptional regulators.
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Affiliation(s)
- Tomohiro Shimada
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Chemical Resources Laboratory, Tokyo Institute of Technology, Nagatsuda, Yokohama, 226-8503, Japan
| | - Hiraku Takada
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan
| | - Kaneyoshi Yamamoto
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Department of Frontier Bioscience, Hosei University, Koganai, Tokyo, 184-8584, Japan
| | - Akira Ishihama
- Micro-Nano Technology Research Center, Hosei University, Koganai, Tokyo, 184-8584, Japan.,Department of Frontier Bioscience, Hosei University, Koganai, Tokyo, 184-8584, Japan
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37
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Expression of the AcrAB Components of the AcrAB-TolC Multidrug Efflux Pump of Yersinia enterocolitica Is Subject to Dual Regulation by OmpR. PLoS One 2015; 10:e0124248. [PMID: 25893523 PMCID: PMC4403819 DOI: 10.1371/journal.pone.0124248] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2015] [Accepted: 02/28/2015] [Indexed: 11/19/2022] Open
Abstract
OmpR is a transcriptional regulator implicated in the control of various cellular processes and functions in Enterobacteriaceae. This study was undertaken to identify genes comprising the OmpR regulon in the human gastrointestinal pathogen Yersinia enterocolitica. Derivatives of an ompR-negative strain with random transposon insertions creating transcriptional fusions with the reporter gene lacZ were isolated. These were supplied with the wild-type ompR allele in trans and then screened for OmpR-dependent changes in β-galactosidase activity. Using this strategy, five insertions in genes/operons positively regulated by OmpR and two insertions in genes negatively regulated by this protein were identified. Genetic analysis of one of these fusion strains revealed that the gene acrR, encoding transcriptional repressor AcrR is negatively regulated by OmpR. Differential analysis of membrane proteins by SDS-PAGE followed by mass spectrometry identified the protein AcrB, a component of the AcrAB-TolC multidrug efflux pump, as being positively regulated by OmpR. Analysis of the activity of the acrR and acrAB promoters using gfp fusions confirmed their OmpR-dependent repression and activation, respectively. The identification of putative OmpR-binding sites and electrophoretic mobility shift assays confirmed that this regulator binds specifically to both promoter regions with different affinity. Examination of the activity of the acrR and acrAB promoters after the exposure of cells to different chemicals showed that bile salts can act as an OmpR-independent inducer. Taken together, our findings suggest that OmpR positively controls the expression of the AcrAB-TolC efflux pump involved in the adaptive response of Y. enterocolitica O:9 to different chemical stressors, thus conferring an advantage in particular ecological niches.
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38
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O'Leary D, McCabe EM, McCusker MP, Martins M, Fanning S, Duffy G. Acid environments affect biofilm formation and gene expression in isolates of Salmonella enterica Typhimurium DT104. Int J Food Microbiol 2015; 206:7-16. [PMID: 25912312 DOI: 10.1016/j.ijfoodmicro.2015.03.030] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2014] [Revised: 03/24/2015] [Accepted: 03/27/2015] [Indexed: 12/30/2022]
Abstract
The aim of this study was to examine the survival and potential virulence of biofilm-forming Salmonella Typhimurium DT104 under mild acid conditions. Salmonella Typhimurium DT104 employs an acid tolerance response (ATR) allowing it to adapt to acidic environments. The threat that these acid adapted cells pose to food safety could be enhanced if they also produce biofilms in acidic conditions. The cells were acid-adapted by culturing them in 1% glucose and their ability to form biofilms on stainless steel and on the surface of Luria Bertani (LB) broth at pH7 and pH5 was examined. Plate counts were performed to examine cell survival. RNA was isolated from cells to examine changes in the expression of genes associated with virulence, invasion, biofilm formation and global gene regulation in response to acid stress. Of the 4 isolates that were examined only one (1481) that produced a rigid biofilm in LB broth at pH7 also formed this same structure at pH5. This indicated that the lactic acid severely impeded the biofilm producing capabilities of the other isolates examined under these conditions. Isolate 1481 also had higher expression of genes associated with virulence (hilA) and invasion (invA) with a 24.34-fold and 13.68-fold increase in relative gene expression respectively at pH5 compared to pH7. Although genes associated with biofilm formation had increased expression in response to acid stress for all the isolates this only resulted in the formation of a biofilm by isolate 1481. This suggests that in addition to the range of genes associated with biofilm production at neutral pH, there are genes whose protein products specifically aid in biofilm production in acidic environments. Furthermore, it highlights the potential for the use of lactic acid for the inhibition of Salmonella biofilms.
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Affiliation(s)
- Denis O'Leary
- Food Safety Department, Teagasc Food Research Centre, Ashtown Dublin 15, Ireland; UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, University College Dublin, Belfield Dublin 4, Ireland
| | - Evonne M McCabe
- Food Safety Department, Teagasc Food Research Centre, Ashtown Dublin 15, Ireland; UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, University College Dublin, Belfield Dublin 4, Ireland.
| | - Matthew P McCusker
- UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, University College Dublin, Belfield Dublin 4, Ireland
| | - Marta Martins
- UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, University College Dublin, Belfield Dublin 4, Ireland
| | - Séamus Fanning
- UCD School of Public Health, Physiotherapy and Population Science, UCD Centre for Food Safety, University College Dublin, Belfield Dublin 4, Ireland
| | - Geraldine Duffy
- Food Safety Department, Teagasc Food Research Centre, Ashtown Dublin 15, Ireland
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39
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Mulder DT, McPhee JB, Reid-Yu SA, Stogios PJ, Savchenko A, Coombes BK. Multiple histidines in the periplasmic domain of the Salmonella enterica sensor kinase SsrA enhance signaling in response to extracellular acidification. Mol Microbiol 2015; 95:678-91. [PMID: 25442048 DOI: 10.1111/mmi.12895] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/30/2014] [Indexed: 11/28/2022]
Abstract
The two-component regulatory system SsrA-SsrB in Salmonella enterica controls expression of a virulence gene program required for intracellular survival in host cells. SsrA signaling is induced within the acidic host vacuole in which the bacteria reside; however, the mechanism by which SsrA senses this intracellular environment is unknown. Here, we show that the periplasmic sensor domain of SsrA is enriched in histidine residues that increase SsrA signaling below external pH of 6. While no single histidine accounted for the full acid-responsiveness of SsrA, we localized the acid-responsiveness principally to five histidines in the C-terminal end of the periplasmic sensor domain, with input from additional histidines in the N-terminal end of the senor. A sensor mutant lacking critical pH-responsive histidines was defective for acid-promoted activity, yet retained basal activity similar to wild type at neutral pH, indicating that the role of these histidines is to enhance signaling in response to acidification. In support of this, a pH-blind mutant was insensitive to the vacuole acidification blocking activity of bafilomycin, and was attenuated for competitive fitness during infection of mice. Our data demonstrate that SsrA contains a histidine-rich periplasmic sensor that enhances signaling in response to the innate host defense of vacuolar acidification.
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Affiliation(s)
- David T Mulder
- Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, ON, L8N 3Z5, Canada
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40
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Ahirwar SK, Pratap CB, Patel SK, Shukla VK, Singh IG, Mishra OP, Kumar K, Singh TB, Nath G. Acid exposure induces multiplication of Salmonella enterica serovar Typhi. J Clin Microbiol 2014; 52:4330-3. [PMID: 25320227 PMCID: PMC4313307 DOI: 10.1128/jcm.02275-14] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/08/2014] [Accepted: 10/09/2014] [Indexed: 11/20/2022] Open
Abstract
Salmonella enterica serovar Typhi faces several environmental stresses while going through the stomach (acidic pH) to the small intestine (basic pH) and intracellularly in macrophages (acidic pH) in humans. The acidic pH followed by alkaline pH in the small intestine might be responsible for expression of certain stress-induced genes, resulting in not only better survival but also induction of multiplication and invasion of the bacterium in the small intestine. Based on this hypothesis, we developed a process wherein we exposed the blood, urine, and stool specimens from 90 acute typhoid fever patients and 36 chronic typhoid carriers to acidic pH to see the effect on isolation rate of S. Typhi. About 5 g of freshly passed unpreserved stool, a centrifuged deposit of 15 ml of urine, and 5 ml of blood clot were subjected to 5 ml of Luria-Bertani (LB) broth (pH 3.5) for 20 min, followed by enrichment in bile broth-selenite F broth. When the combined isolation from all 3 specimens, i.e., blood, urine, and stool, after acid exposure was considered, a total of 77.7% of the acute typhoid patients were observed to be positive for the isolation of the S. Typhi serotype, compared to 8.8% by the conventional method. Similarly, 42% (15/36) of chronic carriers yielded positive for S. Typhi growth after acid exposure, compared to 5.5% (2/36) by the conventional method. It therefore can be concluded that acid shock triggers the multiplication of the bacteria, resulting in better isolation rates from blood clot, stool, and urine specimens.
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Affiliation(s)
- Suneel Kumar Ahirwar
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Chandra Bhan Pratap
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Saurabh Kumar Patel
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Vijay K Shukla
- Department of General Surgery, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Indarjeet Gambhir Singh
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Om Prakash Mishra
- Department of Pediatrics, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Kailash Kumar
- Department of Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Tej Bali Singh
- Department of Community Medicine, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
| | - Gopal Nath
- Department of Microbiology, Institute of Medical Sciences, Banaras Hindu University, Varanasi, India
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41
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Acid stress management by Cronobacter sakazakii. Int J Food Microbiol 2014; 178:21-8. [DOI: 10.1016/j.ijfoodmicro.2014.03.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2013] [Revised: 02/09/2014] [Accepted: 03/02/2014] [Indexed: 11/24/2022]
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42
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Villarreal JM, Becerra-Lobato N, Rebollar-Flores JE, Medina-Aparicio L, Carbajal-Gómez E, Zavala-García ML, Vázquez A, Gutiérrez-Ríos RM, Olvera L, Encarnación S, Martínez-Batallar AG, Calva E, Hernández-Lucas I. The Salmonella enterica serovar Typhi ltrR-ompR-ompC-ompF genes are involved in resistance to the bile salt sodium deoxycholate and in bacterial transformation. Mol Microbiol 2014; 92:1005-24. [PMID: 24720747 DOI: 10.1111/mmi.12610] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/05/2014] [Indexed: 01/25/2023]
Abstract
A characterization of the LtrR regulator, an S. Typhi protein belonging to the LysR family is presented. Proteomics, outer membrane protein profiles and transcriptional analyses demonstrated that LtrR is required for the synthesis of OmpR, OmpC and OmpF. DNA-protein interaction analysis showed that LtrR binds to the regulatory region of ompR and then OmpR interacts with the ompC and ompF promoters inducing porin synthesis. LtrR-dependent and independent ompR promoters were identified, and both promoters are involved in the synthesis of OmpR for OmpC and OmpF production. To define the functional role of the ltrR-ompR-ompC-ompF genetic network, mutants in each gene were obtained. We found that ltrR, ompR, ompC and ompF were involved in the control of bacterial transformation, while the two regulators and ompC are necessary for the optimal growth of S. Typhi in the presence of one of the major bile salts found in the gut, sodium deoxycholate. The data presented establish the pivotal role of LtrR in the regulatory network of porin synthesis and reveal new genetic strategies of survival and cellular adaptation to the environment used by Salmonella.
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Affiliation(s)
- J M Villarreal
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Av. Universidad 2001, Cuernavaca, Morelos, 62210, México
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43
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Quinn HJ, Cameron ADS, Dorman CJ. Bacterial regulon evolution: distinct responses and roles for the identical OmpR proteins of Salmonella Typhimurium and Escherichia coli in the acid stress response. PLoS Genet 2014; 10:e1004215. [PMID: 24603618 PMCID: PMC3945435 DOI: 10.1371/journal.pgen.1004215] [Citation(s) in RCA: 72] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2013] [Accepted: 01/16/2014] [Indexed: 12/26/2022] Open
Abstract
The evolution of new gene networks is a primary source of genetic innovation that allows bacteria to explore and exploit new niches, including pathogenic interactions with host organisms. For example, the archetypal DNA binding protein, OmpR, is identical between Salmonella Typhimurium serovar Typhimurium and Escherichia coli, but regulatory specialization has resulted in different environmental triggers of OmpR expression and largely divergent OmpR regulons. Specifically, ompR mRNA and OmpR protein levels are elevated by acid pH in S. Typhimurium but not in E. coli. This differential expression pattern is due to differences in the promoter regions of the ompR genes and the E. coli ompR orthologue can be made acid-inducible by introduction of the appropriate sequences from S. Typhimurium. The OmpR regulon in S. Typhimurium overlaps that of E. coli at only 15 genes and includes many horizontally acquired genes (including virulence genes) that E. coli does not have. We found that OmpR binds to its genomic targets in higher abundance when the DNA is relaxed, something that occurs in S. Typhimurium as a result of acid stress and which is a requirement for optimal expression of its virulence genes. The genomic targets of OmpR do not share a strong nucleotide sequence consensus: we propose that the ability of OmpR to recruit additional genes to its regulon arises from its modest requirements for specificity in its DNA targets with its preference for relaxed DNA allowing it to cooperate with DNA-topology-based allostery to modulate transcription in response to acid stress.
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Affiliation(s)
- Heather J. Quinn
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
| | - Andrew D. S. Cameron
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- Department of Biology, University of Regina, Regina, Saskatchewan, Canada
| | - Charles J. Dorman
- Department of Microbiology, Moyne Institute of Preventive Medicine, Trinity College Dublin, Dublin, Ireland
- * E-mail:
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Expression of a Yersinia pseudotuberculosis Type VI Secretion System Is Responsive to Envelope Stresses through the OmpR Transcriptional Activator. PLoS One 2013; 8:e66615. [PMID: 23840509 PMCID: PMC3686713 DOI: 10.1371/journal.pone.0066615] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2012] [Accepted: 05/07/2013] [Indexed: 01/06/2023] Open
Abstract
The Type VI secretion system (T6SS) is a macromolecular complex widespread in Gram-negative bacteria. Although several T6SS are required for virulence towards host models, most are necessary to eliminate competitor bacteria. Other functions, such as resistance to amoeba predation, biofilm formation or adaptation to environmental conditions have also been reported. This multitude of functions is reflected by the large repertoire of regulatory mechanisms shown to control T6SS expression, production or activation. Here, we demonstrate that one T6SS gene cluster encoded within the Yersinia pseudotuberculosis genome, T6SS-4, is regulated by OmpR, the response regulator of the two-component system EnvZ-OmpR. We first identified OmpR in a transposon mutagenesis screen. OmpR does not control the expression of the four other Y. pseudotuberculosis T6SS gene clusters and of an isolated vgrG gene, and responds to osmotic stresses to bind to and activate the T6SS-4 promoter. Finally, we show that T6SS-4 promotes Y. pseudotuberculosis survival in high osmolarity conditions and resistance to deoxycholate.
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Brzóstkowska M, Raczkowska A, Brzostek K. OmpR, a response regulator of the two-component signal transduction pathway, influences inv gene expression in Yersinia enterocolitica O9. Front Cell Infect Microbiol 2012; 2:153. [PMID: 23264953 PMCID: PMC3524506 DOI: 10.3389/fcimb.2012.00153] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2012] [Accepted: 11/19/2012] [Indexed: 11/13/2022] Open
Abstract
The environmental control of invasin (inv) expression in Yersinia enterocolitica is mediated by a regulatory network composed of negative and positive regulators of inv gene transcription. Previously, we demonstrated that OmpR, a response regulator of the two-component signal transduction pathway EnvZ/OmpR, negatively regulates inv gene expression in Y. enterocolitica O9 by direct interaction with the inv promoter region. This study was undertaken to clarify the role of OmpR in the inv regulatory circuit in which RovA protein has been shown to positively regulate inv transcription. Using ompR, rovA, and ompR rovA Y. enterocolitica mutant backgrounds we showed that the inhibitory effect of OmpR on inv transcription may be observed only when RovA is present/active in Y. enterocolitica cells. To extend our research on inv regulation we examined the effect of OmpR on rovA gene expression. Analysis of rovA-lacZ transcriptional fusion in Y. enterocolitica wild-type and ompR background indicated that OmpR does not influence rovA expression. Thus, our results indicate that OmpR influences inv expression directly via binding to the inv promoter, but not through modulation of rovA expression.
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Affiliation(s)
- Marta Brzóstkowska
- Department of Applied Microbiology, Institute of Microbiology, Faculty of Biology, University of Warsaw Warsaw, Poland
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Zhang W, Wang Y, Song Y, Wang T, Xu S, Peng Z, Lin X, Zhang L, Shen X. A type VI secretion system regulated by OmpR in Yersinia pseudotuberculosis functions to maintain intracellular pH homeostasis. Environ Microbiol 2012; 15:557-69. [PMID: 23094603 DOI: 10.1111/1462-2920.12005] [Citation(s) in RCA: 87] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2012] [Accepted: 09/23/2012] [Indexed: 12/22/2022]
Abstract
Type VI secretion systems (T6SSs) which widely distributed in Gram-negative bacteria have been primarily studied in the context of cell interactions with eukaryotic hosts or other bacteria. We have recently identified a thermoregulated T6SS4 in the enteric pathogen Yersinia pseudotuberculosis. Here we report that OmpR directly binds to the promoter of T6SS4 operon and regulates its expression. Further, we observed that the OmpR-regulated T6SS4 is essential for bacterial survival under acidic conditions and that its expression is induced by low pH. Moreover, we showed that T6SS4 plays a role in pumping H(+) out of the cell to maintain intracellular pH homeostasis. The acid tolerance phenotype of T6SS4 is dependent on the ATPase activity of ClpV4, one of the components of T6SS4. These results not only uncover a novel strategy utilized by Y. pseudotuberculosis for acid resistance, but also reveal that T6SS, a bacteria secretion system known to be functional in protein transportation has an unexpected function in H(+) extrusion under acid conditions.
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Affiliation(s)
- Weipeng Zhang
- State Key Laboratory of Crop Stress Biology for Arid Areas and College of Life Sciences, Northwest A&F University, Yangling, Shaanxi 712100, China
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Lv Y, Xiao J, Liu Q, Wu H, Zhang Y, Wang Q. Systematic mutation analysis of two-component signal transduction systems reveals EsrA-EsrB and PhoP-PhoQ as the major virulence regulators in Edwardsiella tarda. Vet Microbiol 2012; 157:190-9. [DOI: 10.1016/j.vetmic.2011.12.018] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Revised: 12/13/2011] [Accepted: 12/15/2011] [Indexed: 12/24/2022]
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A fundamental regulatory mechanism operating through OmpR and DNA topology controls expression of Salmonella pathogenicity islands SPI-1 and SPI-2. PLoS Genet 2012; 8:e1002615. [PMID: 22457642 PMCID: PMC3310775 DOI: 10.1371/journal.pgen.1002615] [Citation(s) in RCA: 105] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2011] [Accepted: 02/07/2012] [Indexed: 01/28/2023] Open
Abstract
DNA topology has fundamental control over the ability of transcription factors to access their target DNA sites at gene promoters. However, the influence of DNA topology on protein–DNA and protein–protein interactions is poorly understood. For example, relaxation of DNA supercoiling strongly induces the well-studied pathogenicity gene ssrA (also called spiR) in Salmonella enterica, but neither the mechanism nor the proteins involved are known. We have found that relaxation of DNA supercoiling induces expression of the Salmonella pathogenicity island (SPI)-2 regulator ssrA as well as the SPI-1 regulator hilC through a mechanism that requires the two-component regulator OmpR-EnvZ. Additionally, the ompR promoter is autoregulated in the same fashion. Conversely, the SPI-1 regulator hilD is induced by DNA relaxation but is repressed by OmpR. Relaxation of DNA supercoiling caused an increase in OmpR binding to DNA and a concomitant decrease in binding by the nucleoid-associated protein FIS. The reciprocal occupancy of DNA by OmpR and FIS was not due to antagonism between these transcription factors, but was instead a more intrinsic response to altered DNA topology. Surprisingly, DNA relaxation had no detectable effect on the binding of the global repressor H-NS. These results reveal the underlying molecular mechanism that primes SPI genes for rapid induction at the onset of host invasion. Additionally, our results reveal novel features of the archetypal two-component regulator OmpR. OmpR binding to relaxed DNA appears to generate a locally supercoiled state, which may assist promoter activation by relocating supercoiling stress-induced destabilization of DNA strands. Much has been made of the mechanisms that have evolved to regulate horizontally-acquired genes such as SPIs, but parallels among the ssrA, hilC, and ompR promoters illustrate that a fundamental form of regulation based on DNA topology coordinates the expression of these genes regardless of their origins. DNA is often considered to be a passive carrier of genetic information, but in fact DNA is an active participant in coordinating the expression of the genes it carries. This is because DNA is a dynamic molecule that can assume a wide range of topologies, and this has a direct impact on the formation of the protein–DNA complexes that drive gene expression. In a bacterium, the chromosome is supercoiled to variable levels according to environmental conditions, and supercoiling in turn governs the topology of gene promoters. Thus DNA supercoiling is able to transduce environmental signals to regulate promoter output. A previous study found that the intestinal pathogen Salmonella enterica may use changes in DNA supercoiling to detect when it has entered host immune cells, allowing the bacterium to induce the pathogenicity genes it requires to evade killing by macrophage. In dissecting the underlying molecular mechanisms, we have found that changes in DNA supercoiling also upregulate other key pathogenicity genes, and we have identified the proteins involved in this gene regulatory process. These findings indicate that a fundamental level of gene control arising from the interplay between protein transcription factors and DNA topology regulates Salmonella pathogenicity.
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Álvarez-Ordóñez A, Prieto M, Bernardo A, Hill C, López M. The Acid Tolerance Response of Salmonella spp.: An adaptive strategy to survive in stressful environments prevailing in foods and the host. Food Res Int 2012. [DOI: 10.1016/j.foodres.2011.04.002] [Citation(s) in RCA: 82] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
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