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Xu T, Fang D, Li F, Wang Z, Liu Y. A Dietary Source of High Level of Fluoroquinolone Tolerance in mcr-Carrying Gram-Negative Bacteria. RESEARCH (WASHINGTON, D.C.) 2023; 6:0245. [PMID: 37808177 PMCID: PMC10557118 DOI: 10.34133/research.0245] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Accepted: 09/14/2023] [Indexed: 10/10/2023]
Abstract
The emergence of antibiotic tolerance, characterized by the prolonged survival of bacteria following antibiotic exposure, in natural bacterial populations, especially in pathogens carrying antibiotic resistance genes, has been an increasing threat to public health. However, the major causes contributing to the formation of antibiotic tolerance and underlying molecular mechanisms are yet poorly understood. Herein, we show that potassium sorbate (PS), a widely used food additive, triggers a high level of fluoroquinolone tolerance in bacteria carrying mobile colistin resistance gene mcr. Mechanistic studies demonstrate that PS treatment results in the accumulation of intracellular fumarate, which activates bacterial two-component system and decreases the expression level of outer membrane protein OmpF, thereby reducing the uptake of ciprofloxacin. In addition, the supplementation of PS inhibits aerobic respiration, reduces reactive oxygen species production and alleviates DNA damage caused by bactericidal antibiotics. Furthermore, we demonstrate that succinate, an intermediate product of the tricarboxylic acid cycle, overcomes PS-mediated ciprofloxacin tolerance. In multiple animal models, ciprofloxacin treatment displays failure outcomes in PS preadministrated animals, including comparable survival and bacterial loads with the vehicle group. Taken together, our works offer novel mechanistic insights into the development of antibiotic tolerance and uncover potential risks associated with PS use.
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Affiliation(s)
- Tianqi Xu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine,
Yangzhou University, Yangzhou 225009, China
| | - Dan Fang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine,
Yangzhou University, Yangzhou 225009, China
| | - Fulei Li
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine,
Yangzhou University, Yangzhou 225009, China
| | - Zhiqiang Wang
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine,
Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China,
Yangzhou University, Yangzhou 225009, China
| | - Yuan Liu
- Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, College of Veterinary Medicine,
Yangzhou University, Yangzhou 225009, China
- Joint International Research Laboratory of Agriculture and Agri-Product Safety, the Ministry of Education of China,
Yangzhou University, Yangzhou 225009, China
- Institute of Comparative Medicine,
Yangzhou University, Yangzhou 225009, China
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Hewawaduge C, Senevirathne A, Sivasankar C, Lee JH. The impact of lipid A modification on biofilm and related pathophysiological phenotypes, endotoxicity, immunogenicity, and protection of Salmonella Typhimurium. Vet Microbiol 2023; 282:109759. [PMID: 37104940 DOI: 10.1016/j.vetmic.2023.109759] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/02/2023] [Accepted: 04/22/2023] [Indexed: 04/29/2023]
Abstract
This study presents the engineering of a less endotoxic Salmonella Typhimurium strain by manipulating the lipid-A structure of the lipopolysaccharide (LPS) component. Salmonella lipid A was dephosphorylated by using lpxE from Francisella tularensis. The 1-phosphate group from lipid-A was removed selectively, resulting in a close analog of monophosphoryl lipid A. We observed a significant impact of ∆pagL on major virulence factors such as biofilm formation, motility, persistency, and immune evasion. In correlation with biofilm and motility retardation, adhesion and invasion were elevated but with reduced intracellular survival, a favorable phenotype prospect of a vaccine strain. Western blotting and silver staining confirmed the absence of the O-antigen and truncated lipid-A core in the detoxified Salmonella mutant. In vitro and in vivo studies demonstrated that the dephosphorylated Salmonella mutant mediated lower pro-inflammatory cytokine secretion than the wild-type strain. The vaccine strains were present in the spleen and liver for five days and were cleared from the organs by day seven. However, the wild-type strain persisted in the spleen, liver, and brain, leading to sepsis-induced death. Histological evaluations of tissue samples further confirmed the reduced endotoxic activity of the detoxified Salmonella mutant. The detoxification strategy did not compromise the level of protective immunity, as the vaccine strain could enhance humoral and cellular immune responses and protect against the wild-type challenge in immunized mice.
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Affiliation(s)
- Chamith Hewawaduge
- College of Veterinary Medicine, Jeonbuk National University, Iksan Campus, 54596 Iksan, Republic of Korea
| | - Amal Senevirathne
- College of Veterinary Medicine, Jeonbuk National University, Iksan Campus, 54596 Iksan, Republic of Korea
| | - Chandran Sivasankar
- College of Veterinary Medicine, Jeonbuk National University, Iksan Campus, 54596 Iksan, Republic of Korea
| | - John Hwa Lee
- College of Veterinary Medicine, Jeonbuk National University, Iksan Campus, 54596 Iksan, Republic of Korea.
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Hirakawa H, Takita A, Sato Y, Hiramoto S, Hashimoto Y, Ohshima N, Minamishima YA, Murakami M, Tomita H. Inactivation of ackA and pta Genes Reduces GlpT Expression and Susceptibility to Fosfomycin in Escherichia coli. Microbiol Spectr 2023; 11:e0506922. [PMID: 37199605 PMCID: PMC10269713 DOI: 10.1128/spectrum.05069-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2022] [Accepted: 04/29/2023] [Indexed: 05/19/2023] Open
Abstract
Fosfomycin is used to treat a variety of bacterial infections, including urinary tract infections caused by Escherichia coli. In recent years, quinolone-resistant and extended-spectrum β-lactamase (ESBL)-producing bacteria have been increasing. Because fosfomycin is effective against many of these drug-resistant bacteria, the clinical importance of fosfomycin is increasing. Against this background, information on the mechanisms of resistance and the antimicrobial activity of this drug is desired to enhance the usefulness of fosfomycin therapy. In this study, we aimed to explore novel factors affecting the antimicrobial activity of fosfomycin. Here, we found that ackA and pta contribute to fosfomycin activity against E. coli. ackA and pta mutant E. coli had reduced fosfomycin uptake capacity and became less sensitive to this drug. In addition, ackA and pta mutants had decreased expression of glpT that encodes one of the fosfomycin transporters. Expression of glpT is enhanced by a nucleoid-associated protein, Fis. We found that mutations in ackA and pta also caused a decrease in fis expression. Thus, we interpret the decrease in glpT expression in ackA and pta defective strains to be due to a decrease in Fis levels in these mutants. Furthermore, ackA and pta are conserved in multidrug-resistant E. coli isolated from patients with pyelonephritis and enterohemorrhagic E. coli, and deletion of ackA and pta from these strains resulted in decreased susceptibility to fosfomycin. These results suggest that ackA and pta in E. coli contribute to fosfomycin activity and that mutation of these genes may pose a risk of reducing the effect of fosfomycin. IMPORTANCE The spread of drug-resistant bacteria is a major threat in the field of medicine. Although fosfomycin is an old type of antimicrobial agent, it has recently come back into the limelight because of its effectiveness against many drug-resistant bacteria, including quinolone-resistant and ESBL-producing bacteria. Since fosfomycin is taken up into the bacteria by GlpT and UhpT transporters, its antimicrobial activity fluctuates with changes in GlpT and UhpT function and expression. In this study, we found that inactivation of the ackA and pta genes responsible for the acetic acid metabolism system reduced GlpT expression and fosfomycin activity. In other words, this study shows a new genetic mutation that leads to fosfomycin resistance in bacteria. The results of this study will lead to further understanding of the mechanism of fosfomycin resistance and the creation of new ideas to enhance fosfomycin therapy.
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Affiliation(s)
- Hidetada Hirakawa
- Department of Bacteriology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Ayako Takita
- Department of Bacteriology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yumika Sato
- Department of Bacteriology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Suguru Hiramoto
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yusuke Hashimoto
- Department of Bacteriology, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Noriyasu Ohshima
- Department of Biochemistry, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Yoji A. Minamishima
- Department of Biochemistry, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Masami Murakami
- Department of Clinical Laboratory Medicine, Gunma University Graduate School of Medicine, Gunma, Japan
| | - Haruyoshi Tomita
- Department of Bacteriology, Gunma University Graduate School of Medicine, Gunma, Japan
- Laboratory of Bacterial Drug Resistance, Gunma University Graduate School of Medicine, Gunma, Japan
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Cho THS, Wang J, Raivio TL. NlpE Is an OmpA-Associated Outer Membrane Sensor of the Cpx Envelope Stress Response. J Bacteriol 2023; 205:e0040722. [PMID: 37022159 PMCID: PMC10127795 DOI: 10.1128/jb.00407-22] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2022] [Accepted: 03/10/2023] [Indexed: 04/07/2023] Open
Abstract
Gram-negative bacteria utilize several envelope stress responses (ESRs) to sense and respond to diverse signals within a multilayered cell envelope. The CpxRA ESR responds to multiple stresses that perturb envelope protein homeostasis. Signaling in the Cpx response is regulated by auxiliary factors, such as the outer membrane (OM) lipoprotein NlpE, an activator of the response. NlpE communicates surface adhesion to the Cpx response; however, the mechanism by which NlpE accomplishes this remains unknown. In this study, we report a novel interaction between NlpE and the major OM protein OmpA. Both NlpE and OmpA are required to activate the Cpx response in surface-adhered cells. Furthermore, NlpE senses OmpA overexpression and the NlpE C-terminal domain transduces this signal to the Cpx response, revealing a novel signaling function for this domain. Mutation of OmpA peptidoglycan-binding residues abrogates signaling during OmpA overexpression, suggesting that NlpE signaling from the OM through the cell wall is coordinated via OmpA. Overall, these findings reveal NlpE to be a versatile envelope sensor that takes advantage of its structure, localization, and cooperation with other envelope proteins to initiate adaptation to diverse signals. IMPORTANCE The envelope is not only a barrier that protects bacteria from the environment but also a crucial site for the transduction of signals critical for colonization and pathogenesis. The discovery of novel complexes between NlpE and OmpA contributes to an emerging understanding of the key contribution of OM β-barrel protein and lipoprotein complexes to envelope stress signaling. Overall, our findings provide mechanistic insight into how the Cpx response senses signals relevant to surface adhesion and biofilm growth to facilitate bacterial adaptation.
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Affiliation(s)
- Timothy H. S. Cho
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Junshu Wang
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
| | - Tracy L. Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada
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5
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Moreau PL. Regulation of phosphate starvation-specific responses in Escherichia coli. MICROBIOLOGY (READING, ENGLAND) 2023; 169. [PMID: 36972330 DOI: 10.1099/mic.0.001312] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/29/2023]
Abstract
Toxic agents added into the medium of rapidly growing Escherichia coli induce specific stress responses through the activation of specialized transcription factors. Each transcription factor and downstream regulon (e.g. SoxR) are linked to a unique stress (e.g. superoxide stress). Cells starved of phosphate induce several specific stress regulons during the transition to stationary phase when the growth rate is steadily declining. Whereas the regulatory cascades leading to the expression of specific stress regulons are well known in rapidly growing cells stressed by toxic products, they are poorly understood in cells starved of phosphate. The intent of this review is to both describe the unique mechanisms of activation of specialized transcription factors and discuss signalling cascades leading to the induction of specific stress regulons in phosphate-starved cells. Finally, I discuss unique defence mechanisms that could be induced in cells starved of ammonium and glucose.
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Affiliation(s)
- Patrice L Moreau
- Laboratoire Chimie Bactérienne, LCB-UMR 7283, Institut Microbiologie Méditerranée, CNRS/Université Aix-Marseille, Marseille, France
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6
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Kuo CH, Lin WF, Liu CJ, Wang ZC, Liu TY, Peng HL. Role of the stress-responsive two-component system CpxAR in regulating fimbriae expression in Klebsiella pneumoniae CG43. JOURNAL OF MICROBIOLOGY, IMMUNOLOGY, AND INFECTION = WEI MIAN YU GAN RAN ZA ZHI 2023:S1684-1182(23)00040-3. [PMID: 36898943 DOI: 10.1016/j.jmii.2023.02.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Revised: 02/06/2023] [Accepted: 02/18/2023] [Indexed: 02/27/2023]
Abstract
BACKGROUND CpxAR is a two-component system that allows bacteria to reorganize envelope structures in response to extracellular stimuli. CpxAR negatively affects type 1 fimbriae expression in Klebsiella pneumoniae CG43, a hypervirulent strain. The involvement of CpxAR in the regulation of type 3 fimbriae expression was investigated. METHODS cpxAR, cpxA, and cpxR gene-specific deletion mutants were generated. The deletion effects on the expression of type 1 and type 3 fimbriae were analyzed via measuring the promoter activity, mannose sensitive yeast agglutination activity, biofilm formation, and the production of the major pilins FimA and MrkA respectively. RNA sequencing analysis of CG43S3, ΔcpxAR, ΔcpxR and Δfur was employed to study the regulatory mechanism influencing the expression of type 3 fimbriae. RESULTS Deletion of cpxAR increased type 1 and type 3 fimbrial expression. Comparative transcriptomic analysis showed that the expression of oxidative stress-responsive enzymes, type 1 and type 3 fimbriae, and iron acquisition and homeostasis control systems were differentially affected by cpxAR or cpxR deletion. Subsequent analysis revealed that the small RNA RyhB negatively affects the expression of type 3 fimbriae, while CpxAR positively controls ryhB expression. Finally, the site-directed mutation of the predicted interacting sequences of RyhB with the mRNA of MrkA attenuated the RyhB repression of type 3 fimbriae. CONCLUSION CpxAR negatively regulates the expression of type 3 fimbriae by modulating cellular iron levels thereafter activating the expression of RyhB. The activated RyhB represses the expression of type 3 fimbriae by base-pairing binding to the 5'region of mrkA mRNA.
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Affiliation(s)
- Chih-Hao Kuo
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Wei-Feng Lin
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Chia-Jui Liu
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Zhe-Chong Wang
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Ting-Yi Liu
- Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan
| | - Hwei-Ling Peng
- Department of Biological Science and Technology, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan; Institute of Molecular Medicine and Bioengineering, School of Biological Science and Technology, National Yang Ming Chiao Tung University, Hsin Chu, Taiwan.
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7
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Sevak P, Pushkar B, Mazumdar S. Mechanistic evaluation of chromium bioremediation in Acinetobacter junii strain b2w: A proteomic approach. JOURNAL OF ENVIRONMENTAL MANAGEMENT 2023; 328:116978. [PMID: 36521220 DOI: 10.1016/j.jenvman.2022.116978] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/29/2022] [Revised: 12/01/2022] [Accepted: 12/03/2022] [Indexed: 06/17/2023]
Abstract
Growing industrialization and unchecked release of industrial waste, including heavy metals have resulted in disastrous effects on environment. Considering the problem of heavy metal pollution, the present research was designed to study the bioremediation of chromium, a highly toxic and prominent heavy metal pollutant by Acinetobacter junii strain b2w isolated from the Mithi river, Mumbai, India. The bacterial isolate could grow without affecting its growth kinetics up to a concentration of 200 ppm of chromium and showed resistance towards 400 ppm of chromium. It was able to bioremediate 83.06% of total chromium and reduces 98.24% of Cr6+ to C3+ at a concentration of 10 ppm of chromium. The bacterial isolate could grow well at a wide pH range from 5 to 9, salinity of up to 3.5% and could also tolerate heavy metals such as Cd, Zn, As, Hg, Pb and Cu. Thus, indicating its possible on-ground applicability for bioremediation of chromium. Acinetobacter junii bioaccumulate chromium without disrupting the cell integrity and biosorption. However, chromium alters the functional groups on bacterial cell surface and led to decrease in sulfate-containing molecules. Further, the protein expression study has revealed that Cr significantly up-regulates proteins broadly classified under envelope stress responses, oxidative stress responses, energy metabolism and quorum sensing and growth regulator. The possible mechanisms of Cr detoxification in Acinetobacter junii strain b2w could be reduction, bioaccumulation and efflux along with neutralization of oxidative stress generated by Cr. Thus, based on bacterial bioremediation potential and its molecular response, it can be proposed that the isolated Acinetobacter junii has potential applicability for chromium bioremediation.
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Affiliation(s)
- Pooja Sevak
- Department of Biotechnology, University of Mumbai, Santacruz (E), Mumbai, 400098, Maharashtra, India
| | - Bhupendra Pushkar
- Department of Biotechnology, University of Mumbai, Santacruz (E), Mumbai, 400098, Maharashtra, India.
| | - Shyamalava Mazumdar
- Department of Chemical Sciences, Tata Institute of Fundamental Research, Mumbai, 400005, Maharashtra, India
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Guidi C, De Wannemaeker L, De Baets J, Demeester W, Maertens J, De Paepe B, De Mey M. Dynamic feedback regulation for efficient membrane protein production using a small RNA-based genetic circuit in Escherichia coli. Microb Cell Fact 2022; 21:260. [PMID: 36522655 PMCID: PMC9753035 DOI: 10.1186/s12934-022-01983-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/10/2022] [Accepted: 12/05/2022] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Membrane proteins (MPs) are an important class of molecules with a wide array of cellular functions and are part of many metabolic pathways. Despite their great potential-as therapeutic drug targets or in microbial cell factory optimization-many challenges remain for efficient and functional expression in a host such as Escherichia coli. RESULTS A dynamically regulated small RNA-based circuit was developed to counter membrane stress caused by overexpression of different MPs. The best performing small RNAs were able to enhance the maximum specific growth rate with 123%. On culture level, the total MP production was increased two-to three-fold compared to a system without dynamic control. This strategy not only improved cell growth and production of the studied MPs, it also suggested the potential use for countering metabolic burden in general. CONCLUSIONS A dynamically regulated feedback circuit was developed that can sense metabolic stress caused by, in casu, the overexpression of an MP and responds to it by balancing the metabolic state of the cell and more specifically by downregulating the expression of the MP of interest. This negative feedback mechanism was established by implementing and optimizing simple-to-use genetic control elements based on post-transcriptional regulation: small non-coding RNAs. In addition to membrane-related stress when the MP accumulated in the cytoplasm as aggregates, the sRNA-based feedback control system was still effective for improving cell growth but resulted in a decreased total protein production. This result suggests promiscuity of the MP sensor for more than solely membrane stress.
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Affiliation(s)
- Chiara Guidi
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium
| | | | - Jasmine De Baets
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium
| | - Wouter Demeester
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium
| | - Jo Maertens
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium
| | - Brecht De Paepe
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium
| | - Marjan De Mey
- Centre for Synthetic Biology, Ghent University, 9000, Ghent, Belgium.
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León-Montes N, Nava-Galeana J, Rodríguez-Valverde D, Soria-Bustos J, Rosales-Reyes R, Rivera-Gutiérrez S, Hirakawa H, Ares MA, Bustamante VH, De la Cruz MA. The Two-Component System CpxRA Represses Salmonella Pathogenicity Island 2 by Directly Acting on the ssrAB Regulatory Operon. Microbiol Spectr 2022; 10:e0271022. [PMID: 36073960 PMCID: PMC9603713 DOI: 10.1128/spectrum.02710-22] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2022] [Accepted: 08/15/2022] [Indexed: 01/04/2023] Open
Abstract
The acquisition of Salmonella pathogenicity island 2 (SPI-2) conferred on Salmonella the ability to survive and replicate within host cells. The ssrAB bicistronic operon, located in SPI-2, encodes the SsrAB two-component system (TCS), which is the central positive regulator that induces the expression of SPI-2 genes as well as other genes located outside this island. On the other hand, CpxRA is a two-component system that regulates expression of virulence genes in many bacteria in response to different stimuli that perturb the cell envelope. We previously reported that the CpxRA system represses the expression of SPI-1 and SPI-2 genes under SPI-1-inducing conditions by decreasing the stability of the SPI-1 regulator HilD. Here, we show that under SPI-2-inducing conditions, which mimic the intracellular environment, CpxRA represses the expression of SPI-2 genes by the direct action of phosphorylated CpxR (CpxR-P) on the ssrAB regulatory operon. CpxR-P recognized two sites located proximal and distal from the promoter located upstream of ssrA. Consistently, we found that CpxRA reduces the replication of Salmonella enterica serovar Typhimurium inside murine macrophages. Therefore, our results reveal CpxRA as an additional regulator involved in the intracellular lifestyle of Salmonella, which in turn adds a new layer to the intricate regulatory network controlling the expression of Salmonella virulence genes. IMPORTANCE SPI-2 encodes a type III secretion system (T3SS) that is a hallmark for the species Salmonella enterica, which is essential for the survival and replication within macrophages. Expression of SPI-2 genes is positively controlled by the two-component system SsrAB. Here, we determined a regulatory mechanism involved in controlling the overgrowth of Salmonella inside macrophages. In this mechanism, CpxRA, a two-component system that is activated by extracytoplasmic stress, directly represses expression of the ssrAB regulatory operon; as a consequence, expression of SsrAB target genes is decreased. Our findings reveal a novel mechanism involved in the intracellular lifestyle of Salmonella, which is expected to sense perturbations in the bacterial envelope that Salmonella faces inside host cells, as the synthesis of the T3SS-2 itself.
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Affiliation(s)
- Nancy León-Montes
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Jessica Nava-Galeana
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Diana Rodríguez-Valverde
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Jorge Soria-Bustos
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
| | - Roberto Rosales-Reyes
- Unidad de Medicina Experimental, Facultad de Medicina, Universidad Nacional Autónoma de México, Mexico City, Mexico
| | - Sandra Rivera-Gutiérrez
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Hidetada Hirakawa
- Department of Bacteriology, Gunma University Graduate School of Medicine, Maebashi, Japan
| | - Miguel A. Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
- Departamento de Microbiología, Escuela Nacional de Ciencias Biológicas, Instituto Politécnico Nacional, Mexico City, Mexico
| | - Víctor H. Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México, Cuernavaca, Mexico
| | - Miguel A. De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Hospital de Pediatría, Centro Médico Nacional Siglo XXI, Instituto Mexicano del Seguro Social, Mexico City, Mexico
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Abstract
The two-component system CpxRA can sense environmental stresses and regulate transcription of a wide range of genes for the purpose of adaptation. Despite extensive research on this system, the identification of the CpxR regulon is not systematic or comprehensive. Herein, genome-wide screening was performed using a position-specific scoring matrix, resulting in the discovery of more than 10,000 putative CpxR binding sites, which provides an extensive and selective set of targets based on sequence. More than half of the candidate genes ultimately selected (73/97) were experimentally confirmed to be CpxR-regulated genes through experimental analysis. These genes are involved in various physiological functions, indicating that the CpxRA system regulates complex cellular processes. The study also found for the first time that the CpxR-regulated genes ydeE, xylE, alx, and galP contribute to Escherichia coli resistance to acid stress, whereas prlF, alx, casA, yacH, ydeE, sbmA, and ampH contribute to E. coli resistance to cationic antimicrobial peptide stress. Among these CpxR-regulated genes, ydeE and alx responded to both stressors. In a similar way, a cationic antimicrobial peptide is capable of directly activating the periplasmic domain of CpxA kinase in vitro, which is consistent with the CpxA response to acid stress. These results greatly expand our understanding of the CpxRA-dependent stress response network in E. coli. IMPORTANCE CpxRA system is found in many pathogens and plays an essential role in sensing environmental signals and transducing information inside cells for adaptation. It usually regulates expression of specific genes in response to different environmental stresses and is important for bacterial pathogenesis. However, systematically identifying CpxRA-regulated genes and elucidating the regulative role of CpxRA in bacteria responding to environmental stress remains challenging. This study discovered more than 10,000 putative CpxR binding sites based on sequence. This bioinformatics approach, combined with experimental assays, allowed the identification of many previously unknown CpxR-regulated genes. Among the novel 73 CpxRA-regulated genes identified in this study, the role of nine of them in contributing to E. coli resistance to acid or cationic antimicrobial peptide stress was studied. The potential correlation between these two environmental stress responses provides insight into the CpxRA-dependent stress response network. This also improves our understanding of environment-bacterium interaction and Gram-negative pathogenesis.
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Fortney KR, Smith SN, van Rensburg JJ, Brothwell JA, Gardner JJ, Katz BP, Ahsan N, Duerfeldt AS, Mobley HLT, Spinola SM. CpxA Phosphatase Inhibitor Activates CpxRA and Is a Potential Treatment for Uropathogenic Escherichia coli in a Murine Model of Infection. Microbiol Spectr 2022; 10:e0243021. [PMID: 35297652 PMCID: PMC9045377 DOI: 10.1128/spectrum.02430-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2021] [Accepted: 02/19/2022] [Indexed: 11/20/2022] Open
Abstract
CpxRA is an envelope stress response system that is highly conserved in the Enterobacteriaceae. CpxA has kinase activity for CpxR and phosphatase activity for phospho-CpxR (CpxR-P), a transcription factor. In response to membrane stress, CpxR-P is produced and upregulates genes involved in membrane repair and downregulates genes that encode virulence factors that are trafficked across the cell membrane. Mutants that constitutively activate CpxRA in Salmonella enterica serovar Typhimurium and in uropathogenic Escherichia coli (UPEC) are attenuated in murine models. We hypothesized that pharmacologic activation of CpxR could serve as an antimicrobial/antivirulence strategy and recently showed that 2,3,4,9-tetrahydro-1H-carbazol-1-amines activate the CpxRA system by inhibiting CpxA phosphatase activity. Here, we tested the ability of a series of three CpxRA-activating compounds with increasing potency to clear UPEC stain CFT073 in a murine urinary tract infection model. We show that these compounds are well tolerated and achieve sufficient levels to activate CpxR in the kidneys, bladder, and urine. Although the first two compounds were ineffective in promoting clearance of CFT073 in the murine model, the most potent derivative, compound 26, significantly reduced bacterial recovery in the urine and trended toward reducing bacterial recovery in the bladder and kidneys, with efficacy similar to ciprofloxacin. Treatment of CFT073 cultured in human urine with compound 26 fostered accumulation of CpxR-P and decreased the expression of proteins involved in siderophore biosynthesis and binding, heme degradation, and flagellar movement. These studies suggest that chemical activation of CpxRA may present a viable strategy for treating infections due to UPEC. IMPORTANCE The increasing prevalence of urinary tract infections (UTIs) due to antibiotic-resistant uropathogenic Escherichia coli (UPEC) is a major public health concern. Bacteria contain proteins that sense their environment and have no human homologs and, thus, are attractive drug targets. CpxRA is a conserved sensing system whose function is to reduce stress in the bacterial cell membrane; activation of CpxRA reduces the expression of virulence determinants, which must cross the cell membrane to reach the bacterial surface. We previously identified a class of compounds that activate CpxRA. We show in a mouse UTI model that our most potent compound significantly reduced recovery of UPEC in the urine, trended toward reducing bacterial recovery in the bladder and kidneys, did not kill UPEC, and downregulated multiple proteins involved in UPEC virulence. Since these compounds do not act by a killing mechanism, they have potential to treat UTIs caused by antibiotic-resistant bacteria.
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Affiliation(s)
- Kate R. Fortney
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Sara N. Smith
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Julia J. van Rensburg
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Julie A. Brothwell
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Jessi J. Gardner
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
| | - Barry P. Katz
- Department of Biostatistics, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Biostatistics, Richard M. Fairbanks School of Public Health, Indiana University, Indianapolis, Indiana, USA
| | - Nagib Ahsan
- Department of Chemistry and Biochemistry, University of Oklahoma, Norman, Oklahoma, USA
- Mass Spectrometry, Proteomics and Metabolomics Core Facility, Stephenson Life Sciences Research Center, University of Oklahoma, Norman, Oklahoma, USA
| | - Adam S. Duerfeldt
- Department of Medicinal Chemistry, University of Minnesota, Minneapolis, Minnesota, USA
| | - Harry L. T. Mobley
- Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, USA
| | - Stanley M. Spinola
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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12
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Fei K, Chao HJ, Hu Y, Francis MS, Chen S. CpxR regulates the Rcs phosphorelay system in controlling the Ysc-Yop type III secretion system in Yersinia pseudotuberculosis. MICROBIOLOGY-SGM 2021; 167. [PMID: 33295859 DOI: 10.1099/mic.0.000998] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
The CpxRA two-component regulatory system and the Rcs phosphorelay system are both employed by the Enterobacteriaceae family to preserve bacterial envelope integrity and function when growing under stress. Although both systems regulate several overlapping physiological processes, evidence demonstrating a molecular connection between Cpx and Rcs signalling outputs is scarce. Here, we show that CpxR negatively regulates the transcription of the rcsB gene in the Rcs phosphorelay system in Yersinia pseudotuberculosis. Interestingly, transcription of rcsB is under the control of three promoters, which were all repressed by CpxR. Critically, synthetic activation of Cpx signalling through mislocalization of the NlpE lipoprotein to the inner membrane resulted in an active form of CpxR that repressed activity of rcsB promoters. On the other hand, a site-directed mutation of the phosphorylation site at residue 51 in CpxR generated an inactive non-phosphorylated variant that was unable to regulate output from these rcsB promoters. Importantly, CpxR-mediated inhibition of rcsB transcription in turn restricted activation of the Ysc-Yop type III secretion system (T3SS). Moreover, active CpxR blocks zinc-mediated activation of Rcs signalling and the subsequent activation of lcrF transcription. Our results demonstrate a novel regulatory cascade linking CpxR-RcsB-LcrF to control production of the Ysc-Yop T3SS.
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Affiliation(s)
- Keke Fei
- University of Chinese Academy of Sciences, Beijing, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Hong-Jun Chao
- Present address: School of Biological & pharmaceutical Engineering, Wuhan Polytechnic University, Wuhan, PR China.,Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Yangbo Hu
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
| | - Matthew S Francis
- Department of Molecular Biology, Umeå University, Umeå, Sweden; Umeå Centre for Microbial Research, Umeå University, Umeå, Sweden
| | - Shiyun Chen
- Key Laboratory of Special Pathogens and Biosafety, Wuhan Institute of Virology, Center for Biosafety Mega-Science, Chinese Academy of Sciences, Wuhan, PR China
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13
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He X, Zhang J, Wang S, Yang Z, Zhang H, Zhou X. Cloning, expression, purification, and biochemical characterization of CpxR protein from pectobacterium carotovorum. Biotechnol Appl Biochem 2021; 69:898-905. [PMID: 33811674 DOI: 10.1002/bab.2161] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2020] [Accepted: 03/26/2021] [Indexed: 11/09/2022]
Abstract
The cpxR gene, encoding a new cytoplasmic response regulator, which effects virulence, biofilm formation, chemotaxis, resistance to antimicrobials, and controls soft rot, was amplified by the polymerase chain reaction, cloned into the prokaryotic expression vector pET-15b, and expressed through the induction of isopropyl-β-d-thiogalactoside in Escherichia coli BL21 (DE3). Then, highly purified and stable CpxR protein was produced by nickel affinity chromatography and fast protein liquid chromatography, digested by thrombin and identified by Western blotting. Furthermore, the structure of the CpxR protein was estimated by circular dichroism spectroscopy and SWISS-MODEL. The CpxR protein was a functional part in signal transduction and bacterial resistance for Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis. The resear ch of the protein stability indicated the CpxR protein had excellent thermal stability and was suitable for crystallization. Then the small crystals of CpxR protein were found in the crystallizing tank. The latest 34 cpxR sequences from the public database were selected and analyzed by molecular clustering and multisequence alignment. These cpxR sequences were roughly divided into four categories. These results laid an important foundation for the further structural study of the CpxR protein.
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Affiliation(s)
- Xiaoliang He
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
| | - Jing Zhang
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
| | - Shuai Wang
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
| | - Zi Yang
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
| | - Huan Zhang
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
| | - Xiaohui Zhou
- School of Biological Science and Engineering, Hebei University of Science and Technology, Shijiazhang, Hebei, China
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14
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Jing W, Liu J, Wu S, Li X, Liu Y. Role of cpxA Mutations in the Resistance to Aminoglycosides and β-Lactams in Salmonella enterica serovar Typhimurium. Front Microbiol 2021; 12:604079. [PMID: 33613478 PMCID: PMC7889517 DOI: 10.3389/fmicb.2021.604079] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2020] [Accepted: 01/12/2021] [Indexed: 11/13/2022] Open
Abstract
Although it has been reported that deletion of the response regulator, CpxR, in the CpxRA system confers sensitivity to aminoglycosides (AGAs) and β-lactams in Salmonella enterica serovar Typhimurium, the regulatory effects of CpxA on multidrug resistance (MDR) are yet to be fully investigated in this organism. Here, to explore the role of CpxA in MDR, various cpxA mutants including a null mutant (JSΔcpxA), a site-directed mutant (JSΔcpxA 38) and an internal in-frame deletion mutant (JSΔcpxA92 - 104 ) of the S. enterica serovar Typhimurium strain JS, were constructed. It was revealed that cpxA and cpxR deletion mutants have opposing roles in the regulation of resistance to AGAs and β-lactams. Amikacin and cefuroxime can activate the CpxRA system, which results in increased resistance of the wild-type compared with the cpxR deletion mutant. All the cpxA mutations significantly increased resistance to AGAs and β-lactams due to CpxRA system activation via the phosphorylation of CpxR. Moreover, AckA-Pta-dependent activation of CpxR increased the antibiotic resistance of cpxA deletion mutants. Further research revealed that the AcrAB-TolC conferred resistance to some AGAs and β-lactams but does not influence the regulation of resistance by CpxRA against these antibiotics. The detection of candidate MDR-related CpxR regulons revealed that the mRNA expression levels of spy, ycca, ppia, htpX, stm3031, and acrD were upregulated and that of ompW was downregulated in various cpxA mutants. Furthermore, the expression levels of nuoA and sdhC mRNAs were downregulated only in JSΔcpxA92 - 104 . These results suggested that cpxA mutations contribute to AGAs and β-lactams resistance, which is dependent on CpxR.
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Affiliation(s)
- Wenxian Jing
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Juan Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Shanshan Wu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Xuerui Li
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
| | - Yongsheng Liu
- State Key Laboratory of Veterinary Etiological Biology, Lanzhou Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Lanzhou, China
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15
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Jaswal K, Shrivastava M, Roy D, Agrawal S, Chaba R. Metabolism of long-chain fatty acids affects disulfide bond formation in Escherichia coli and activates envelope stress response pathways as a combat strategy. PLoS Genet 2020; 16:e1009081. [PMID: 33079953 PMCID: PMC7598926 DOI: 10.1371/journal.pgen.1009081] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2020] [Revised: 10/30/2020] [Accepted: 08/25/2020] [Indexed: 12/28/2022] Open
Abstract
The envelope of gram-negative bacteria serves as the first line of defense against environmental insults. Therefore, its integrity is continuously monitored and maintained by several envelope stress response (ESR) systems. Due to its oxidizing environment, the envelope represents an important site for disulfide bond formation. In Escherichia coli, the periplasmic oxidoreductase, DsbA introduces disulfide bonds in substrate proteins and transfers electrons to the inner membrane oxidoreductase, DsbB. Under aerobic conditions, the reduced form of DsbB is re-oxidized by ubiquinone, an electron carrier in the electron transport chain (ETC). Given the critical role of ubiquinone in transferring electrons derived from the oxidation of reduced cofactors, we were intrigued whether metabolic conditions that generate a large number of reduced cofactors render ubiquinone unavailable for disulfide bond formation. To test this, here we investigated the influence of metabolism of long-chain fatty acid (LCFA), an energy-rich carbon source, on the redox state of the envelope. We show that LCFA degradation increases electron flow in the ETC. Further, whereas cells metabolizing LCFAs exhibit characteristics of insufficient disulfide bond formation, these hallmarks are averted in cells exogenously provided with ubiquinone. Importantly, the ESR pathways, Cpx and σE, are activated by envelope signals generated during LCFA metabolism. Our results argue that Cpx is the primary ESR that senses and maintains envelope redox homeostasis. Amongst the two ESRs, Cpx is induced to a greater extent by LCFAs and senses redox-dependent signal. Further, ubiquinone accumulation during LCFA metabolism is prevented in cells lacking Cpx response, suggesting that Cpx activation helps maintain redox homeostasis by increasing the oxidizing power for disulfide bond formation. Taken together, our results demonstrate an intricate relationship between cellular metabolism and disulfide bond formation dictated by ETC and ESR, and provide the basis for examining whether similar mechanisms control envelope redox status in other gram-negative bacteria.
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Affiliation(s)
- Kanchan Jaswal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Megha Shrivastava
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Deeptodeep Roy
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Shashank Agrawal
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
| | - Rachna Chaba
- Department of Biological Sciences, Indian Institute of Science Education and Research (IISER) Mohali, SAS Nagar, Punjab, India
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16
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Hews CL, Cho T, Rowley G, Raivio TL. Maintaining Integrity Under Stress: Envelope Stress Response Regulation of Pathogenesis in Gram-Negative Bacteria. Front Cell Infect Microbiol 2019; 9:313. [PMID: 31552196 PMCID: PMC6737893 DOI: 10.3389/fcimb.2019.00313] [Citation(s) in RCA: 77] [Impact Index Per Article: 15.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 08/19/2019] [Indexed: 12/20/2022] Open
Abstract
The Gram-negative bacterial envelope is an essential interface between the intracellular and harsh extracellular environment. Envelope stress responses (ESRs) are crucial to the maintenance of this barrier and function to detect and respond to perturbations in the envelope, caused by environmental stresses. Pathogenic bacteria are exposed to an array of challenging and stressful conditions during their lifecycle and, in particular, during infection of a host. As such, maintenance of envelope homeostasis is essential to their ability to successfully cause infection. This review will discuss our current understanding of the σE- and Cpx-regulated ESRs, with a specific focus on their role in the virulence of a number of model pathogens.
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Affiliation(s)
- Claire L Hews
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Timothy Cho
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
| | - Gary Rowley
- School of Biological Sciences, University of East Anglia, Norwich, United Kingdom
| | - Tracy L Raivio
- Department of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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17
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Lalaouna D, Prévost K, Laliberté G, Houé V, Massé E. Contrasting silencing mechanisms of the same target mRNA by two regulatory RNAs in Escherichia coli. Nucleic Acids Res 2019; 46:2600-2612. [PMID: 29294085 PMCID: PMC5861431 DOI: 10.1093/nar/gkx1287] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Accepted: 12/18/2017] [Indexed: 12/21/2022] Open
Abstract
Small RNAs are key components of complex regulatory networks. These molecules can integrate multiple cellular signals to control specific target mRNAs. The recent development of high-throughput methods tremendously helped to characterize the full targetome of sRNAs. Using MS2-affinity purification coupled with RNA sequencing (MAPS) technology, we reveal the targetomes of two sRNAs, CyaR and RprA. Interestingly, both CyaR and RprA interact with the 5′-UTR of hdeD mRNA, which encodes an acid-resistance membrane protein. We demonstrate that CyaR classically binds to the RBS of hdeD, interfering with translational initiation. We identified an A/U-rich motif on hdeD, which is bound by the RNA chaperone Hfq. Our results indicate that binding of this motif by Hfq is required for CyaR-induced degradation of hdeD mRNA. Additional data suggest that two molecules of RprA must bind the 5′-UTR of hdeD to block translation initiation. Surprisingly, while both CyaR and RprA sRNAs bind to the same motif on hdeD mRNA, RprA solely acts at the translational level, leaving the target RNA intact. By interchanging the seed region of CyaR and RprA sRNAs, we also swap their regulatory behavior. These results suggest that slight changes in the seed region could modulate the regulation of target mRNAs.
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Affiliation(s)
- David Lalaouna
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Karine Prévost
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Guillaume Laliberté
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Vincent Houé
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
| | - Eric Massé
- Department of Biochemistry, RNA Group, Université de Sherbrooke, Sherbrooke, Québec, Canada
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18
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Yi Z, Wang D, Xin S, Zhou D, Li T, Tian M, Qi J, Ding C, Wang S, Yu S. The CpxR regulates type VI secretion system 2 expression and facilitates the interbacterial competition activity and virulence of avian pathogenic Escherichia coli. Vet Res 2019; 50:40. [PMID: 31126325 PMCID: PMC6534853 DOI: 10.1186/s13567-019-0658-7] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2019] [Accepted: 05/08/2019] [Indexed: 11/18/2022] Open
Abstract
Systemic infections caused by avian pathogenic Escherichia coli (APEC) are economically devastating to poultry industries worldwide and are also potentially threatening to human health. Pathogens must be able to precisely modulate gene expression to facilitate their survival and the successful infection. The Cpx two-component signal transduction system (TCS) regulates surface structure assembly and virulence factors implicated in Gram-negative bacterial pathogenesis. However, the roles of the Cpx TCS in bacterial fitness and pathogenesis during APEC infection are not completely understood. Here, we show that the Cpx TCS response regulator CpxR is critical to the survival and virulence of APEC. Inactivation of cpxR leads to significant defects in the interbacterial competition activity, invasion and survival of APEC in vitro and in vivo. Moreover, activation of CpxR positive regulates the expression of the APEC type VI secretion system 2 (T6SS2). Further investigations revealed that phosphorylated CpxR directly bound to the T6SS2 hcp2B promoter region. Taken together, our results demonstrated that CpxR contributes to the pathogensis of APEC at least through directly regulating the expression and function of T6SS2. This study broadens understanding of the regulatory effect of Cpx TCS, thus elucidating the mechanisms through which Cpx TCS involved in bacterial virulence.
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Affiliation(s)
- Zhengfei Yi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Dong Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Suhua Xin
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Dongliang Zhou
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Tao Li
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Mingxing Tian
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Jingjing Qi
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Chan Ding
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China
| | - Shaohui Wang
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China.
| | - Shengqing Yu
- Shanghai Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Shanghai, 200241, China.
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19
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Thanikkal EJ, Gahlot DK, Liu J, Fredriksson Sundbom M, Gurung JM, Ruuth K, Francis MK, Obi IR, Thompson KM, Chen S, Dersch P, Francis MS. The Yersinia pseudotuberculosis Cpx envelope stress system contributes to transcriptional activation of rovM. Virulence 2019; 10:37-57. [PMID: 30518290 PMCID: PMC6298763 DOI: 10.1080/21505594.2018.1556151] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
The Gram-negative enteropathogen Yersinia pseudotuberculosis possesses a number of regulatory systems that detect cell envelope damage caused by noxious extracytoplasmic stresses. The CpxA sensor kinase and CpxR response regulator two-component regulatory system is one such pathway. Active Cpx signalling upregulates various factors designed to repair and restore cell envelope integrity. Concomitantly, this pathway also down-regulates key determinants of virulence. In Yersinia, cpxA deletion accumulates high levels of phosphorylated CpxR (CpxR~P). Accumulated CpxR~P directly repressed rovA expression and this limited expression of virulence-associated processes. A second transcriptional regulator, RovM, also negatively regulates rovA expression in response to nutrient stress. Hence, this study aimed to determine if CpxR~P can influence rovA expression through control of RovM levels. We determined that the active CpxR~P isoform bound to the promoter of rovM and directly induced its expression, which naturally associated with a concurrent reduction in rovA expression. Site-directed mutagenesis of the CpxR~P binding sequence in the rovM promoter region desensitised rovM expression to CpxR~P. These data suggest that accumulated CpxR~P inversely manipulates the levels of two global transcriptional regulators, RovA and RovM, and this would be expected to have considerable influence on Yersinia pathophysiology and metabolism.
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Affiliation(s)
- Edvin J Thanikkal
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Dharmender K Gahlot
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Junfa Liu
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | | | - Jyoti M Gurung
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Kristina Ruuth
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Monika K Francis
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Ikenna R Obi
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
| | - Karl M Thompson
- c Department of Microbiology , College of Medicine, Howard University , Washington , DC , USA.,d Interdisciplinary Research Building , Howard University , Washington , DC , USA
| | - Shiyun Chen
- e Key Laboratory of Special Pathogens and Biosafety , Wuhan Institute of Virology, Chinese Academy of Sciences , Wuhan , China
| | - Petra Dersch
- f Department of Molecular Infection Biology , Helmholtz Centre for Infection Research , Braunschweig , Germany
| | - Matthew S Francis
- a Department of Molecular Biology , Umeå University , Umeå , Sweden.,b Umeå Centre for Microbial Research , Umeå University , Umeå , Sweden
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20
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Contribution of the Cpx envelope stress system to metabolism and virulence regulation in Salmonella enterica serovar Typhimurium. PLoS One 2019; 14:e0211584. [PMID: 30716090 PMCID: PMC6361445 DOI: 10.1371/journal.pone.0211584] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2018] [Accepted: 01/16/2019] [Indexed: 11/19/2022] Open
Abstract
The Cpx-envelope stress system regulates the expression of virulence factors in many Gram-negative pathogens. In Salmonella enterica serovar Typhimurium deletion of the sensor kinase CpxA but not of the response regulator CpxR results in the down regulation of the key regulator for invasion, HilA encoded by the Salmonella pathogenicity island 1 (SPI-1). Here, we provide evidence that cpxA deletion interferes with dephosphorylation of CpxR resulting in increased levels of active CpxR and consequently in misregulation of target genes. 14 potential operons were identified to be under direct control of CpxR. These include the virulence determinants ecotin, the omptin PgtE, and the SPI-2 regulator SsrB. The Tat-system and the PocR regulator that together promote anaerobic respiration of tetrathionate on 1,2-propanediol are also under direct CpxR control. Notably, 1,2-propanediol represses hilA expression. Thus, our work demonstrates for the first time the involvement of the Cpx system in a complex network mediating metabolism and virulence function.
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21
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Guo S, Wang Z, Liu B, Gao J, Fang X, Tang Q, Bilal M, Wang Y, Zhang X. Effects of cpxR on the growth characteristics and antibiotic production of Xenorhabdus nematophila. Microb Biotechnol 2019; 12:447-458. [PMID: 30623566 PMCID: PMC6465229 DOI: 10.1111/1751-7915.13362] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2018] [Revised: 09/23/2018] [Accepted: 12/11/2018] [Indexed: 11/28/2022] Open
Abstract
CpxR is a global response regulator that negatively influences the antimicrobial activities of Xenorhabdus nematophila. Herein, the wildtype and ΔcpxR mutant of X. nematophila were cultured in a 5‐l and 70‐l bioreactor. The kinetic analysis showed that ΔcpxR significantly increased the cell biomass and antibiotic activity. The maximum dry cell weight (DCW) and antibiotic activity of ΔcpxR were 20.77 ± 1.56 g L−1 and 492.0 ± 31.2 U ml−1 and increased by 17.28 and 97.33% compared to the wildtype respectively. Xenocoumacin 1 (Xcn1), a major antimicrobial compound, was increased 3.07‐fold, but nematophin was decreased by 48.7%. In 70‐l bioreactor, DCW was increased by 18.97%, while antibiotic activity and Xcn1 were decreased by 27.71% and 11.0% compared to that in 5‐l bioreactor respectively. Notably, pH had remarkable effects on the cell biomass and antibiotic activity of ΔcpxR, where ΔcpxR was sensitive to alkaline pH conditions. The optimal cell growth and antibiotic activity of ΔcpxR occurred at pH 7.0, while Xcn1 was increased 5.45‐ and 3.87‐fold relative to that at pH 5.5 and 8.5 respectively. These findings confirmed that ΔcpxR considerably increased the biomass of X. nematophila at a late stage of fermentation. In addition, ΔcpxR significantly promoted the biosynthesis of Xcns but decreased the production of nematophin.
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Affiliation(s)
- Shuqi Guo
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,State Key Laboratory of Microbial Metabolism, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, Shanghai, 200240, China
| | - Zeyu Wang
- School of Food and Biological Engineering, Shaanxi University of Science & Technology, Weiyang University Campus, Xi 'an Shaanxi, 710021, China
| | - Beiling Liu
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Jiangtao Gao
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Xiangling Fang
- State Key Laboratory of Grassland Agro-ecosystems, College of Pastoral Agriculture Science and Technology, Lanzhou University, Lanzhou, 730020, China.,School of Agriculture and Environment, Faculty of Science, The University of Western Australia, 35 Stirling Highway, Crawley, WA, 6009, Australia
| | - Qian Tang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Muhammad Bilal
- School of Life Science and Food Engineering, Huaiyin Institute of Technology, Huaian, 223003, China
| | - Yonghong Wang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,Shaanxi Research Center of Biopesticide Engineering and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
| | - Xing Zhang
- Research and Development Center of Biorational Pesticides, Key Laboratory of Plant Protection Resources and Pest Management of Ministry of Education, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China.,Shaanxi Research Center of Biopesticide Engineering and Technology, Northwest A&F University, 22 Xinong Road, Yangling, Shaanxi, 712100, China
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22
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Mechaly AE, Haouz A, Sassoon N, Buschiazzo A, Betton JM, Alzari PM. Conformational plasticity of the response regulator CpxR, a key player in Gammaproteobacteria virulence and drug-resistance. J Struct Biol 2018; 204:165-171. [DOI: 10.1016/j.jsb.2018.08.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2018] [Revised: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 01/27/2023]
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23
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Sato K, Kakuda S, Yukitake H, Kondo Y, Shoji M, Takebe K, Narita Y, Naito M, Nakane D, Abiko Y, Hiratsuka K, Suzuki M, Nakayama K. Immunoglobulin‐like domains of the cargo proteins are essential for protein stability during secretion by the type IX secretion system. Mol Microbiol 2018; 110:64-81. [DOI: 10.1111/mmi.14083] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 07/12/2018] [Indexed: 01/12/2023]
Affiliation(s)
- Keiko Sato
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Shinji Kakuda
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Hideharu Yukitake
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Yoshio Kondo
- Department of Pediatric Dentistry Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Mikio Shoji
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Katsuki Takebe
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Yuka Narita
- Department of Functional Bioscience, Infection Biology Fukuoka Dental College Matsudo, Tamura, Sawara, Fukuoka 814‐0913Japan
| | - Mariko Naito
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
| | - Daisuke Nakane
- Department of Physics, Faculty of Science Gakushuin University Toshima‐ku, Tokyo 171‐8588Japan
| | - Yoshimitsu Abiko
- Department of Biochemistry and Molecular Biology Nihon University School of Dentistry at Matsudo Matsudo Chiba 271‐8587Japan
| | - Koichi Hiratsuka
- Department of Biochemistry and Molecular Biology Nihon University School of Dentistry at Matsudo Matsudo Chiba 271‐8587Japan
| | - Mamoru Suzuki
- Institute for Protein Research Osaka University Yamadaoka, Suita Osaka 565‐0871Japan
| | - Koji Nakayama
- Department of Microbiology and Oral Infection Nagasaki University Graduate School of Biomedical Sciences Nagasaki Nagasaki 852‐8588Japan
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24
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DeAngelis CM, Saul-McBeth J, Matson JS. Vibrio responses to extracytoplasmic stress. ENVIRONMENTAL MICROBIOLOGY REPORTS 2018; 10:511-521. [PMID: 30246498 DOI: 10.1111/1758-2229.12693] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2018] [Revised: 09/11/2018] [Accepted: 09/12/2018] [Indexed: 06/08/2023]
Abstract
A critical factor for bacterial survival in any environment is the ability to sense and respond appropriately to any stresses encountered. This is especially important for bacteria that inhabit environments that are constantly changing, or for those that inhabit more than one biological niche. Vibrio species are unique in that they are aquatic organisms, and must adapt to ever-changing temperatures, salinity levels and nutrient concentrations. In addition, many species of Vibrio colonize other organisms, and must also deal with components of the host immune response. Vibrio infections of humans and other organisms have become more common in recent years, due to increasing water temperatures in many parts of the world. Therefore, understanding how these ubiquitous marine bacteria adapt to their changing environments is of importance. In this review, we discuss some of the ways that Vibrios sense and respond to the variety of stresses that negatively affect the bacterial cell envelope. Specifically, we will focus on what is currently known about the σE response, the Cpx response and the contributions of OmpU to extracytoplasmic stress relief.
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Affiliation(s)
- Cara M DeAngelis
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
| | - Jessica Saul-McBeth
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
| | - Jyl S Matson
- Department of Medical Microbiology and Immunology, University of Toledo Medical School, Toledo, OH, USA
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25
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Platenkamp A, Mellies JL. Environment Controls LEE Regulation in Enteropathogenic Escherichia coli. Front Microbiol 2018; 9:1694. [PMID: 30140259 PMCID: PMC6094958 DOI: 10.3389/fmicb.2018.01694] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2018] [Accepted: 07/09/2018] [Indexed: 12/11/2022] Open
Abstract
Enteropathogenic Escherichia coli (EPEC) is a significant cause of infant morbidity and mortality in developing regions of the world. Horizontally acquired genetic elements encode virulence structures, effectors, and regulators that promote bacterial colonization and disease. One such genetic element, the locus of enterocyte effacement (LEE), encodes the type three secretion system (T3SS) which acts as a bridge between bacterial and host cells to pass effector molecules that exert changes on the host. Due to its importance in EPEC virulence, regulation of the LEE has been of high priority and its investigation has elucidated many virulence regulators, including master regulator of the LEE Ler, H-NS, other nucleoid-associated proteins, GrlA, and PerC. Media type, environmental signals, sRNA signaling, metabolic processes, and stress responses have profound, strain-specific effects on regulators and LEE expression, and thus T3SS formation. Here we review virulence gene regulation in EPEC, which includes approaches for lessening disease by exploiting the elucidated regulatory pathways.
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Affiliation(s)
- Amy Platenkamp
- Department of Biology, Reed College, Portland, OR, United States
| | - Jay L Mellies
- Department of Biology, Reed College, Portland, OR, United States
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26
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Evaluation of CpxRA as a Therapeutic Target for Uropathogenic Escherichia coli Infections. Infect Immun 2018; 86:IAI.00798-17. [PMID: 29311237 DOI: 10.1128/iai.00798-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2017] [Accepted: 12/31/2017] [Indexed: 12/18/2022] Open
Abstract
CpxRA is an envelope stress response system found in all members of the family Enterobacteriaceae; CpxA has kinase activity for CpxR and phosphatase activity for phospho-CpxR, a transcription factor. CpxR also accepts phosphate groups from acetyl phosphate, a glucose metabolite. Activation of CpxR increases the transcription of genes encoding membrane repair and downregulates virulence determinants. We hypothesized that activation of CpxR could serve as an antimicrobial/antivirulence strategy and discovered compounds that activate CpxR in Escherichia coli by inhibiting CpxA phosphatase activity. As a prelude to testing such compounds in vivo, here we constructed cpxA (in the presence of glucose, CpxR is activated because of a lack of CpxA phosphatase) and cpxR (system absent) deletion mutants of uropathogenic E. coli (UPEC) CFT073. By RNA sequencing, few transcriptional differences were noted between the cpxR mutant and its parent, but in the cpxA mutant, several UPEC virulence determinants were downregulated, including the fim and pap operons, and it exhibited reduced mannose-sensitive hemagglutination of guinea pig red blood cells in vitro In competition experiments with mice, both mutants were less fit than the parent in the urine, bladder, and kidney; these fitness defects were complemented in trans Unexpectedly, in single-strain challenges, only the cpxA mutant was attenuated for virulence in the kidney but not in the bladder or urine. For the cpxA mutant, this may be due to the preferential use of amino acids over glucose as a carbon source in the bladder and urine by UPEC. These studies suggest that CpxA phosphatase inhibitors may have some utility for treating complex urinary tract infections.
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27
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Cao Q, Feng F, Wang H, Xu X, Chen H, Cai X, Wang X. Haemophilus parasuis CpxRA two-component system confers bacterial tolerance to environmental stresses and macrolide resistance. Microbiol Res 2017; 206:177-185. [PMID: 29146255 DOI: 10.1016/j.micres.2017.10.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2017] [Revised: 10/17/2017] [Accepted: 10/20/2017] [Indexed: 11/29/2022]
Abstract
Haemophilus parasuis is an opportunistic pathogen localized in the upper respiratory tracts of pigs, its infection begins from bacterial survival under complex conditions, like hyperosmosis, oxidative stress, phagocytosis, and sometimes antibiotics as well. The two-component signal transduction (TCST) system serves as a common stimulus-response mechanism that allows microbes to sense and respond to diverse environmental conditions via a series of phosphorylation reactions. In this study, we investigated the role of TCST system CpxRA in H. parasuis in response to different environmental stimuli by constructing the ΔcpxA and ΔcpxR single deletion mutants as well as the ΔcpxRA double deletion mutant from H. parasuis serotype 4 isolate JS0135. We demonstrated that H. parasuis TCST system CpxRA confers bacterial tolerance to stresses and bactericidal antibiotics. The CpxR was found to play essential roles in mediating oxidative stress, osmotic stresses and alkaline pH stress tolerance, as well as macrolide resistance (i.e. erythromycin), but the CpxA deletion did not decrease bacterial resistance to abovementioned stresses. Moreover, we found via RT-qPCR approach that HAPS_RS00160 and HAPS_RS09425, both encoding multidrug efflux pumps, were significantly decreased in erythromycin challenged ΔcpxR and ΔcpxRA mutants compared with wild-type strain JS0135. These findings characterize the role of the TCST system CpxRA in H. parasuis conferring stress response tolerance and bactericidal resistance, which will deepen our understanding of the pathogenic mechanism in H. parasuis.
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Affiliation(s)
- Qi Cao
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Fenfen Feng
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Huan Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Xiaojuan Xu
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China
| | - Huanchun Chen
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China
| | - Xuwang Cai
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China.
| | - Xiangru Wang
- State Key Laboratory of Agricultural Microbiology, College of Veterinary Medicine, Huazhong Agricultural University, Wuhan 430070, China; The Cooperative Innovation Center for Sustainable Pig Production, Huazhong Agricultural University, Wuhan 430070, China.
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28
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Métris A, Sudhakar P, Fazekas D, Demeter A, Ari E, Olbei M, Branchu P, Kingsley RA, Baranyi J, Korcsmáros T. SalmoNet, an integrated network of ten Salmonella enterica strains reveals common and distinct pathways to host adaptation. NPJ Syst Biol Appl 2017; 3:31. [PMID: 29057095 PMCID: PMC5647365 DOI: 10.1038/s41540-017-0034-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2016] [Revised: 09/19/2017] [Accepted: 09/22/2017] [Indexed: 12/31/2022] Open
Abstract
Salmonella enterica is a prominent bacterial pathogen with implications on human and animal health. Salmonella serovars could be classified as gastro-intestinal or extra-intestinal. Genome-wide comparisons revealed that extra-intestinal strains are closer relatives of gastro-intestinal strains than to each other indicating a parallel evolution of this trait. Given the complexity of the differences, a systems-level comparison could reveal key mechanisms enabling extra-intestinal serovars to cause systemic infections. Accordingly, in this work, we introduce a unique resource, SalmoNet, which combines manual curation, high-throughput data and computational predictions to provide an integrated network for Salmonella at the metabolic, transcriptional regulatory and protein-protein interaction levels. SalmoNet provides the networks separately for five gastro-intestinal and five extra-intestinal strains. As a multi-layered, multi-strain database containing experimental data, SalmoNet is the first dedicated network resource for Salmonella. It comprehensively contains interactions between proteins encoded in Salmonella pathogenicity islands, as well as regulatory mechanisms of metabolic processes with the option to zoom-in and analyze the interactions at specific loci in more detail. Application of SalmoNet is not limited to strain comparisons as it also provides a Salmonella resource for biochemical network modeling, host-pathogen interaction studies, drug discovery, experimental validation of novel interactions, uncovering new pathological mechanisms from emergent properties and epidemiological studies. SalmoNet is available at http://salmonet.org.
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Affiliation(s)
- Aline Métris
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,Present Address: Safety and Environmental Assurance Centre, Unilever, Colworth Science Park, Sharnbrook, Bedfordshire UK
| | - Padhmanand Sudhakar
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ UK
| | - David Fazekas
- Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ UK.,Department of Genetics, Eötvös Loránd University, Pázmány P. s. 1C, H-1117 Budapest, Hungary
| | - Amanda Demeter
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ UK.,Department of Genetics, Eötvös Loránd University, Pázmány P. s. 1C, H-1117 Budapest, Hungary
| | - Eszter Ari
- Department of Genetics, Eötvös Loránd University, Pázmány P. s. 1C, H-1117 Budapest, Hungary.,Synthetic and Systems Biology Unit, Institute of Biochemistry, Biological Research Centre of the Hungarian Academy of Sciences, Szeged, Hungary
| | - Marton Olbei
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ UK
| | - Priscilla Branchu
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,IRSD, Université de Toulouse, INSERM, INRA, ENVT, UPS, Toulouse, France
| | - Rob A Kingsley
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK
| | - Jozsef Baranyi
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK
| | - Tamas Korcsmáros
- Quadram Institute Bioscience, Norwich Research Park, Norwich, NR4 7UA UK.,Earlham Institute, Norwich Research Park, Norwich, NR4 7UZ UK
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29
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A Bacterial Stress Response Regulates Respiratory Protein Complexes To Control Envelope Stress Adaptation. J Bacteriol 2017; 199:JB.00153-17. [PMID: 28760851 DOI: 10.1128/jb.00153-17] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2017] [Accepted: 07/18/2017] [Indexed: 01/02/2023] Open
Abstract
The Cpx envelope stress response mediates adaptation to stresses that affect protein folding within the envelope of Gram-negative bacteria. Recent transcriptome analyses revealed that the Cpx response impacts genes that affect multiple cellular functions predominantly associated with the cytoplasmic membrane. In this study, we examined the connection between the Cpx response and the respiratory complexes NADH dehydrogenase I and cytochrome bo3 in enteropathogenic Escherichia coli We found that the Cpx response directly represses the transcription of the nuo and cyo operons and that Cpx-mediated repression of these complexes confers adaptation to stresses that compromise envelope integrity. Furthermore, we found that the activity of the aerobic electron transport chain is reduced in E. coli lacking a functional Cpx response despite no change in the transcription of either the nuo or the cyo operon. Finally, we show that expression of NADH dehydrogenase I and cytochrome bo3 contributes to basal Cpx pathway activity and that overproduction of individual subunits can influence pathway activation. Our results demonstrate that the Cpx response gauges and adjusts the expression, and possibly the function, of inner membrane protein complexes to enable adaptation to envelope stress.IMPORTANCE Bacterial stress responses allow microbes to survive environmental transitions and conditions, such as those encountered during infection and colonization, that would otherwise kill them. Enteric microbes that inhabit or infect the gut are exposed to a plethora of stresses, including changes in pH, nutrient composition, and the presence of other bacteria and toxic compounds. Bacteria detect and adapt to many of these conditions by using envelope stress responses that measure the presence of stressors in the outermost compartment of the bacterium by monitoring its physiology. The Cpx envelope stress response plays a role in antibiotic resistance and host colonization, and we have shown that it regulates many functions at the bacterial inner membrane. In this report, we describe a novel role for the Cpx response in sensing and controlling the expression of large, multiprotein respiratory complexes at the cytoplasmic membrane of Escherichia coli The significance of our research is that it will increase our understanding of how these stress responses are involved in antibiotic resistance and the mechanisms used by bacteria to colonize the gut.
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30
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Gangaiah D, Raterman EL, Wu H, Fortney KR, Gao H, Liu Y, Jerse AE, Spinola SM. Both MisR (CpxR) and MisS (CpxA) Are Required for Neisseria gonorrhoeae Infection in a Murine Model of Lower Genital Tract Infection. Infect Immun 2017; 85:e00307-17. [PMID: 28652307 PMCID: PMC5563589 DOI: 10.1128/iai.00307-17] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2017] [Accepted: 06/17/2017] [Indexed: 12/29/2022] Open
Abstract
During infection, Neisseria gonorrhoeae senses and responds to stress; such responses may be modulated by MisRS (NGO0177 and NGO0176), a two-component system that is a homolog of CpxRA. In Escherichia coli, CpxRA senses and responds to envelope stress; CpxA is a sensor kinase/phosphatase for CpxR, a response regulator. When a cpxA mutant is grown in medium containing glucose, CpxR is phosphorylated by acetyl phosphate but cannot be dephosphorylated, resulting in constitutive activation. Kandler and coworkers (J. L. Kandler, C. L. Holley, J. L. Reimche, V. Dhulipala, J. T. Balthazar, A. Muszyński, R. W. Carlson, and W. M. Shafer, Antimicrob Agents Chemother 60:4690-4700, 2016, https://doi.org/10.1128/AAC.00823-16) showed that MisR (CpxR) is required for the maintenance of membrane integrity and resistance to antimicrobial peptides, suggesting a role in gonococcal survival in vivo Here, we evaluated the contributions of MisR and MisS (CpxA) to gonococcal infection in a murine model of cervicovaginal colonization and identified MisR-regulated genes using RNA sequencing (RNA-Seq). The deletion of misR or misS severely reduced the capacity of N. gonorrhoeae to colonize mice or maintain infection over a 7-day period and reduced microbial fitness after exposure to heat shock. Compared to the wild type (WT), the inactivation of misR identified 157 differentially regulated genes, most of which encoded putative envelope proteins. The inactivation of misS identified 17 differentially regulated genes compared to the WT and 139 differentially regulated genes compared to the misR mutant, 111 of which overlapped those differentially expressed in the comparison of the WT versus the misR mutant. These data indicate that an intact MisRS system is required for gonococcal infection of mice. Provided the MisR is constitutively phosphorylated in the misS mutant, the data suggest that controlled but not constitutive activation is required for gonococcal infection in mice.
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Affiliation(s)
- Dharanesh Gangaiah
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Erica L Raterman
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Hong Wu
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Kate R Fortney
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Hongyu Gao
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Yunlong Liu
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana, USA
| | - Ann E Jerse
- Department of Microbiology and Immunology, F. Edward Herbert School of Medicine, Uniformed Services University, Bethesda, Maryland, USA
| | - Stanley M Spinola
- Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Pathology and Laboratory Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
- Department of Medicine, Indiana University School of Medicine, Indianapolis, Indiana, USA
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31
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Baron F, Bonnassie S, Alabdeh M, Cochet MF, Nau F, Guérin-Dubiard C, Gautier M, Andrews SC, Jan S. Global Gene-expression Analysis of the Response of Salmonella Enteritidis to Egg White Exposure Reveals Multiple Egg White-imposed Stress Responses. Front Microbiol 2017; 8:829. [PMID: 28553268 PMCID: PMC5428311 DOI: 10.3389/fmicb.2017.00829] [Citation(s) in RCA: 28] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2017] [Accepted: 04/24/2017] [Indexed: 12/20/2022] Open
Abstract
Chicken egg white protects the embryo from bacterial invaders by presenting an assortment of antagonistic activities that combine together to both kill and inhibit growth. The key features of the egg white anti-bacterial system are iron restriction, high pH, antibacterial peptides and proteins, and viscosity. Salmonella enterica serovar Enteritidis is the major pathogen responsible for egg-borne infection in humans, which is partly explained by its exceptional capacity for survival under the harsh conditions encountered within egg white. However, at temperatures up to 42°C, egg white exerts a much stronger bactericidal effect on S. Enteritidis than at lower temperatures, although the mechanism of egg white-induced killing is only partly understood. Here, for the first time, the impact of exposure of S. Enteritidis to egg white under bactericidal conditions (45°C) is explored by global-expression analysis. A large-scale (18.7% of genome) shift in transcription is revealed suggesting major changes in specific aspects of S. Enteritidis physiology: induction of egg white related stress-responses (envelope damage, exposure to heat and alkalinity, and translation shutdown); shift in energy metabolism from respiration to fermentation; and enhanced micronutrient provision (due to iron and biotin restriction). Little evidence of DNA damage or redox stress was obtained. Instead, data are consistent with envelope damage resulting in cell death by lysis. A surprise was the high degree of induction of hexonate/hexuronate utilization genes, despite no evidence indicating the presence of these substrates in egg white.
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Affiliation(s)
- Florence Baron
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Sylvie Bonnassie
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- Science de la Vie et de la Terre, Université de Rennes IRennes, France
| | - Mariah Alabdeh
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Marie-Françoise Cochet
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Françoise Nau
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Catherine Guérin-Dubiard
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | - Michel Gautier
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
| | | | - Sophie Jan
- Agrocampus Ouest, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
- INRA, UMR1253 Science et Technologie du Lait et de l'OeufRennes, France
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Kamble NM, Jawale CV, Lee JH. Interaction of a live attenuated Salmonella Gallinarum vaccine candidate with chicken bone marrow-derived dendritic cells. Avian Pathol 2017; 45:235-43. [PMID: 26813292 DOI: 10.1080/03079457.2016.1144919] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
Salmonella enterica serovar Gallinarum (SG) is a Gram-negative intracellular host-adapted pathogen that causes fowl typhoid. Attenuated strains of SG are proven and widely used vaccine candidates because of advantages like induction of strong humoral and cell-mediated immune responses. In the present study, we investigated the interaction of chicken bone marrow-derived dendritic cells (chBM-DCs) with an attenuated SG (JOL1355) strain that secretes a heat-labile enterotoxin B subunit protein previously shown to successfully vaccinate chickens. ChBM-DCs were isolated and cultured in the presence of recombinant chicken GM-CSF and IL-4 cytokines. The chBM-DCs were infected with JOL1355 at an multiplicity of infection of 10. JOL1355 was able to invade dendritic cells (DCs); however, the survival of JOL1355 in DCs decreased over time. At 24 h post infection, IL-6, IL-10 and IFN-γ transcript levels were significantly increased in JOL1355-infected DCs compared to non-stimulated DCs. Flow cytometry analysis showed an increased proportion of cells producing CD40, CD80, and MHC class II in the JOL1355-infected cultures compared to the non-stimulated control. In addition, JOL1355-stimulated chBM-DCs could induce significant expression of IL-2 in co-culture with autologous CD4+ T cells. Based on these results, we conclude that chBM-DCs are capable of internalizing the live attenuated SG vaccine candidate and the infected chBM-DCs show signs of maturation as evidenced by the upregulated expression of costimulatory molecules and cytokines.
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Affiliation(s)
- Nitin Machindra Kamble
- a Department of Veterinary Public Health, College of Veterinary Medicine , Chonbuk National University , Jeonju , Republic of Korea
| | - Chetan Vilas Jawale
- a Department of Veterinary Public Health, College of Veterinary Medicine , Chonbuk National University , Jeonju , Republic of Korea
| | - John Hwa Lee
- a Department of Veterinary Public Health, College of Veterinary Medicine , Chonbuk National University , Jeonju , Republic of Korea
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Legionella pneumophila OxyR Is a Redundant Transcriptional Regulator That Contributes to Expression Control of the Two-Component CpxRA System. J Bacteriol 2017; 199:JB.00690-16. [PMID: 27994017 DOI: 10.1128/jb.00690-16] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2016] [Accepted: 12/13/2016] [Indexed: 12/27/2022] Open
Abstract
Nominally an environmental organism, Legionella pneumophila is an intracellular parasite of protozoa but is also the causative agent of the pneumonia termed Legionnaires' disease, which results from inhalation of aerosolized bacteria by susceptible humans. Coordination of gene expression by a number of identified regulatory factors, including OxyR, assists L. pneumophila in adapting to the stresses of changing environments. L. pneumophila OxyR (OxyRLp) is an ortholog of Escherichia coli OxyR; however, OxyRLp was shown elsewhere to be functionally divergent, such that it acts as a transcription regulator independently of the oxidative stress response. In this study, the use of improved gene deletion methods has enabled us to generate an unmarked in-frame deletion of oxyR in L. pneumophila Lack of OxyRLp did not affect in vitro growth or intracellular growth in Acanthamoeba castellanii protozoa and U937-derived macrophages. The expression of OxyRLp does not appear to be regulated by CpxR, even though purified recombinant CpxR bound a DNA sequence similar to that reported for CpxR elsewhere. Surprisingly, a lack of OxyRLp resulted in elevated activity of the promoters located upstream of icmR and the lpg1441-cpxA operon, and OxyRLp directly bound to these promoter regions, suggesting that OxyRLp is a direct repressor. Interestingly, a strain overexpressing OxyRLp demonstrated reduced intracellular growth in A. castellanii but not in U937-derived macrophages, suggesting that balanced expression control of the two-component CpxRA system is necessary for survival in protozoa. Taken together, this study suggests that OxyRLp is a functionally redundant transcriptional regulator in L. pneumophila under the conditions evaluated herein.IMPORTANCELegionella pneumophila is an environmental pathogen, with its transmission to the human host dependent upon its ability to replicate in protozoa and survive within its aquatic niche. Understanding the genetic factors that contribute to L. pneumophila survival within each of these unique environments will be key to limiting future point-source outbreaks of Legionnaires' disease. The transcriptional regulator L. pneumophila OxyR (OxyRLp) has been previously identified as a potential regulator of virulence traits warranting further investigation. This study demonstrated that oxyR is nonessential for L. pneumophila survival in vitro and in vivo via mutational analysis. While the mechanisms of how OxyRLp expression is regulated remain elusive, this study shows that OxyRLp negatively regulates the expression of the cpxRA two-component system necessary for intracellular survival in protozoa.
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Lalsiamthara J, Lee JH. Virulence Associated Genes-Deleted Salmonella Montevideo Is Attenuated, Highly Immunogenic and Confers Protection against Virulent Challenge in Chickens. Front Microbiol 2016; 7:1634. [PMID: 27785128 PMCID: PMC5060950 DOI: 10.3389/fmicb.2016.01634] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 09/30/2016] [Indexed: 12/27/2022] Open
Abstract
To construct a novel live vaccine against Salmonella enterica serovar Montevideo (SM) infection in chickens, two important bacterial regulatory genes, lon and cpxR, which are associated with invasion and virulence, were deleted from the wild type SM genome. Attenuated strains, JOL1625 (Δlon), JOL1597 (ΔcpxR), and JOL1599 (ΔlonΔcpxR) were thereby generated. Observations with scanning electron microscopy suggested that JOL1625 and JOL1599 cells showed increased ruffled surface which may be related to abundant extracellular polysaccharide (EPS) production. JOL1597 depicted milder ruffled surface but showed increased surface corrugation. ConA affinity-based fluorometric quantification and fluorescence microscopy revealed significant increases in EPS production in JOL1625 and JOL1599. Four weeks old chickens were used for safety and immunological studies. The mutants were not observed in feces beyond day 3 nor in spleen and cecum beyond day 7, whereas wild type SM was detected for at least 2 weeks in spleen and cecum. JOL1599 was further evaluated as a vaccine candidate. Chickens immunized with JOL1599 showed strong humoral responses, as indicated by systemic IgG and secretory IgA levels, as well as strong cell-mediated immune response, as indicated by increased lymphocyte proliferation. JOL1599-immunized groups also showed significant degree of protection against wild type challenge. Our results indicate that Δlon- and/or ΔcpxR-deleted SM exhibited EPS-enhanced immunogenicity and attenuation via reduced bacterial cell intracellular replication, conferred increased protection, and possess safety qualities favorable for effective vaccine development against virulent SM infections.
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Affiliation(s)
- Jonathan Lalsiamthara
- Department of Bioactive Material Sciences and Department of Veterinary Public Health, College of Veterinary Medicine, Chonbuk National University Iksan, South Korea
| | - John H Lee
- Department of Bioactive Material Sciences and Department of Veterinary Public Health, College of Veterinary Medicine, Chonbuk National University Iksan, South Korea
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Characterization and Evaluation of a Salmonella enterica Serotype Senftenberg Mutant Created by Deletion of Virulence-Related Genes for Use as a Live Attenuated Vaccine. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2016; 23:802-812. [PMID: 27489135 DOI: 10.1128/cvi.00233-16] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/02/2016] [Accepted: 07/25/2016] [Indexed: 01/13/2023]
Abstract
Natural infections of chickens with Salmonella enterica subsp. enterica serovar Senftenberg (S. Senftenberg) are characterized by low-level intestinal invasiveness and insignificant production of antibodies. In this study, we investigated the potential effects of lon and cpxR gene deletions on the invasiveness of S Senftenberg into the intestinal epithelium of chickens and its ability to induce an immune response, conferring protection against S Senftenberg infection. With the allelic exchange method, we developed JOL1596 (Δlon), JOL1571 (ΔcpxR), and JOL1587 (Δlon ΔcpxR) deletion mutants from wild-type S Senftenberg. Deletion of the lon gene from S Senftenberg produced increased frequency of elongated cells, with significantly greater amounts of exopolysaccharide (EPS) than in the cpxR-deleted strain and the wild-type strain. The in vivo intestinal loop invasion assay showed a significant increase in epithelial invasiveness for JOL1596 (Δlon) and JOL1587 (Δlon ΔcpxR), compared to JOL1571 (ΔcpxR) and the wild-type strain. Furthermore, the S Senftenberg wild-type and mutant strains were internalized at high levels inside activated abdominal macrophages from chicken. The in vivo inoculation of JOL1587 (Δlon ΔcpxR) into chickens led to colonization of the liver, spleen, and cecum for a short time. Chickens inoculated with JOL1587 (Δlon ΔcpxR) showed significant increases in humoral, mucosal, and cellular immune responses specific to S Senftenberg antigens. Postchallenge, compared to the control group, the JOL1587 (Δlon ΔcpxR)-inoculated chickens showed not only lower persistence but also faster clearance of wild-type S Senftenberg from the cecum. We conclude that the increased intestinal invasiveness and colonization of internal organs exhibited by JOL1587 (Δlon ΔcpxR) led to the establishment of immunogenicity and conferred protective efficacy against S Senftenberg infections in chickens.
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Huang H, Sun Y, Yuan L, Pan Y, Gao Y, Ma C, Hu G. Regulation of the Two-Component Regulator CpxR on Aminoglycosides and β-lactams Resistance in Salmonella enterica serovar Typhimurium. Front Microbiol 2016; 7:604. [PMID: 27199934 PMCID: PMC4846824 DOI: 10.3389/fmicb.2016.00604] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2015] [Accepted: 04/11/2016] [Indexed: 11/13/2022] Open
Abstract
The two-component signal transduction system CpxAR is especially widespread in Gram-negative bacteria. It has been reported that CpxAR contributes to the multidrug resistance (MDR) in Escherichia coli. CpxR is a response regulator in the two-component CpxAR system. The aim of this study was to explore the role of cpxR in the MDR of S. enterica serovar Typhimurium. The minimal inhibitory concentrations (MICs) of various antibiotics commonly used in veterinary medicine for strains JS (a multidrug-susceptible standard strain of S. enterica serovar Typhimurium), JSΔcpxR, JSΔcpxR/pcpxR, JSΔcpxR/pcpxR (*), JSΔcpxRΔacrB, JSΔcpxRΔacrB/pcpxR, JSΔcpxRΔacrB/pcpxR (*), 9 S. enterica serovar Typhimurium isolates (SH1-9), and SH1-9ΔcpxR were determined by the 2-fold broth microdilution method. The relative mRNA expression levels of ompF, ompC, ompW, ompD, tolC, acrB, acrD, acrF, mdtA, marA, and soxS in strains JS, JSΔcpxR, and JSΔcpxR/pcpxR were detected by real-time PCR. The results showed 2- to 4-fold decreases in the MICs of amikacin (AMK), gentamycin (GEN), apramycin (APR), neomycin (NEO), ceftriaxone (CRO), ceftiofur (CEF), and cefquinome (CEQ) for strain JSΔcpxR, as compared to those for the parental strain JS. Likewise, SH1-9ΔcpxR were found to have 2- to 8-fold reduction in resistance to the above antibiotics, except for NEO, as compared to their parental strains SH1-9. Furthermore, 2- to 4-fold further decreases in the MICs of AMK, GEN, APR, and CEF for strain JSΔcpxRΔacrB were observed, as compared to those for strain JSΔacrB. In addition, CpxR overproduction in strain JSΔcpxR led to significant decreases in the mRNA expression levels of ompF, ompC, ompW, ompD, tolC, acrB, marA, and soxS, and significant increases in those of stm3031 and stm1530. Notably, after all strains were induced simultaneously by GEN to the 15th passage at subinhibitory concentrations, strain JSΔcpxR/pcpxR showed significant increases in mRNA expression levels of the efflux pump acrD and mdtA genes, as compared to strain JSΔcpxR. Our results indicate that the two-component regulator CpxR contributes to resistance of S. enterica serovar Typhimurium to aminoglycosides and β-lactams by influencing the expression level of the MDR-related genes.
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Affiliation(s)
- Hui Huang
- College of Veterinary Medicine, Henan Agricultural University Zhengzhou, China
| | - Yawei Sun
- College of Veterinary Medicine, Henan Agricultural UniversityZhengzhou, China; College of Animal Science and Technology, Henan Institute of Science and TechnologyXinxiang, China
| | - Li Yuan
- College of Veterinary Medicine, Henan Agricultural University Zhengzhou, China
| | - Yushan Pan
- College of Veterinary Medicine, Henan Agricultural University Zhengzhou, China
| | - Yanlin Gao
- Animal Husbandry Bureau of Henan Province Zhengzhou, China
| | - Caihui Ma
- College of Veterinary Medicine, Henan Agricultural University Zhengzhou, China
| | - Gongzheng Hu
- College of Veterinary Medicine, Henan Agricultural University Zhengzhou, China
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Runkel S, Wells HC, Rowley G. Living with Stress: A Lesson from the Enteric Pathogen Salmonella enterica. ADVANCES IN APPLIED MICROBIOLOGY 2016; 83:87-144. [PMID: 23651595 DOI: 10.1016/b978-0-12-407678-5.00003-9] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
Abstract
The ability to sense and respond to the environment is essential for the survival of all living organisms. Bacterial pathogens such as Salmonella enterica are of particular interest due to their ability to sense and adapt to the diverse range of conditions they encounter, both in vivo and in environmental reservoirs. During this cycling from host to non-host environments, Salmonella encounter a variety of environmental insults ranging from temperature fluctuations, nutrient availability and changes in osmolarity, to the presence of antimicrobial peptides and reactive oxygen/nitrogen species. Such fluctuating conditions impact on various areas of bacterial physiology including virulence, growth and antimicrobial resistance. A key component of the success of any bacterial pathogen is the ability to recognize and mount a suitable response to the discrete chemical and physical stresses elicited by the host. Such responses occur through a coordinated and complex programme of gene expression and protein activity, involving a range of transcriptional regulators, sigma factors and two component regulatory systems. This review briefly outlines the various stresses encountered throughout the Salmonella life cycle and the repertoire of regulatory responses with which Salmonella counters. In particular, how these Gram-negative bacteria are able to alleviate disruption in periplasmic envelope homeostasis through a group of stress responses, known collectively as the Envelope Stress Responses, alongside the mechanisms used to overcome nitrosative stress, will be examined in more detail.
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Affiliation(s)
- Sebastian Runkel
- School of Biological Sciences, University of East Anglia, Norwich, UK
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Tanner JR, Li L, Faucher SP, Brassinga AKC. The CpxRA two-component system contributes to Legionella pneumophila virulence. Mol Microbiol 2016; 100:1017-38. [PMID: 26934669 DOI: 10.1111/mmi.13365] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/26/2016] [Indexed: 12/11/2022]
Abstract
The bacterium Legionella pneumophila is capable of intracellular replication within freshwater protozoa as well as human macrophages, the latter of which results in the serious pneumonia Legionnaires' disease. A primary factor involved in these host cell interactions is the Dot/Icm Type IV secretion system responsible for translocating effector proteins needed to establish and maintain the bacterial replicative niche. Several regulatory factors have been identified to control the expression of the Dot/Icm system and effectors, one of which is the CpxRA two-component system, suggesting essentiality for virulence. In this study, we generated cpxR, cpxA and cpxRA in-frame null mutant strains to further delineate the role of the CpxRA system in bacterial survival and virulence. We found that cpxR is essential for intracellular replication within Acanthamoeba castellanii, but not in U937-derived macrophages. Transcriptome analysis revealed that CpxRA regulates a large number of virulence-associated proteins including Dot/Icm effectors as well as Type II secreted substrates. Furthermore, the cpxR and cpxRA mutant strains were more sodium resistant than the parental strain Lp02, and cpxRA expression reaches maximal levels during postexponential phase. Taken together, our findings suggest the CpxRA system is a key contributor to L. pneumophila virulence in protozoa via virulence factor regulation.
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Affiliation(s)
- Jennifer R Tanner
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
| | - Laam Li
- Faculty of Agricultural and Environmental Sciences, Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Sébastien P Faucher
- Faculty of Agricultural and Environmental Sciences, Department of Natural Resource Sciences, McGill University, Ste-Anne-de-Bellevue, QC, H9X 3V9, Canada
| | - Ann Karen C Brassinga
- Department of Microbiology, Faculty of Science, University of Manitoba, Winnipeg, MB, R3T 2N2, Canada
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Courbet A, Endy D, Renard E, Molina F, Bonnet J. Detection of pathological biomarkers in human clinical samples via amplifying genetic switches and logic gates. Sci Transl Med 2016; 7:289ra83. [PMID: 26019219 DOI: 10.1126/scitranslmed.aaa3601] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Whole-cell biosensors have several advantages for the detection of biological substances and have proven to be useful analytical tools. However, several hurdles have limited whole-cell biosensor application in the clinic, primarily their unreliable operation in complex media and low signal-to-noise ratio. We report that bacterial biosensors with genetically encoded digital amplifying genetic switches can detect clinically relevant biomarkers in human urine and serum. These bactosensors perform signal digitization and amplification, multiplexed signal processing with the use of Boolean logic gates, and data storage. In addition, we provide a framework with which to quantify whole-cell biosensor robustness in clinical samples together with a method for easily reprogramming the sensor module for distinct medical detection agendas. Last, we demonstrate that bactosensors can be used to detect pathological glycosuria in urine from diabetic patients. These next-generation whole-cell biosensors with improved computing and amplification capacity could meet clinical requirements and should enable new approaches for medical diagnosis.
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Affiliation(s)
- Alexis Courbet
- Sys2Diag FRE3690-CNRS/ALCEDIAG, Cap Delta, 34090 Montpellier, France
| | - Drew Endy
- Department of Bioengineering, Stanford University, Stanford, CA 94305, USA
| | - Eric Renard
- Sys2Diag FRE3690-CNRS/ALCEDIAG, Cap Delta, 34090 Montpellier, France. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. Department of Endocrinology, Diabetes, Nutrition, Montpellier University Hospital; INSERM 1411 Clinical Investigation Center; Institute of Functional Genomics, CNRS UMR 5203, INSERM U661, University of Montpellier, 34090 Montpellier, France. Centre de Biochimie Structurale, INSERM U1054, CNRS UMR5048, University of Montpellier, 29 Rue de Navacelles, 34090 Montpellier, France
| | - Franck Molina
- Sys2Diag FRE3690-CNRS/ALCEDIAG, Cap Delta, 34090 Montpellier, France.
| | - Jérôme Bonnet
- Sys2Diag FRE3690-CNRS/ALCEDIAG, Cap Delta, 34090 Montpellier, France. Department of Bioengineering, Stanford University, Stanford, CA 94305, USA. Department of Endocrinology, Diabetes, Nutrition, Montpellier University Hospital; INSERM 1411 Clinical Investigation Center; Institute of Functional Genomics, CNRS UMR 5203, INSERM U661, University of Montpellier, 34090 Montpellier, France. Centre de Biochimie Structurale, INSERM U1054, CNRS UMR5048, University of Montpellier, 29 Rue de Navacelles, 34090 Montpellier, France.
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Shafiq MH, Kamble NM, Kim TH, Choi Y, Lee JH. A Live Salmonella Gallinarum Vaccine Candidate Secreting an Adjuvant Protein Confers Enhanced Safety and Protection Against Fowl Typhoid. Avian Dis 2016; 59:537-42. [PMID: 26629629 DOI: 10.1637/11243-072815-reg.1] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Live attenuated vaccines are used for effective protection against fowl typhoid (FT) in domestic poultry. In this study, a lon/cpxR/asd deletion mutant of Salmonella Gallinarum expressing the B subunit of a heat labile toxin (LTB) from Escherichia coli, a known adjuvant, was cloned in a recombinant p15A ori plasmid, JOL1355, and evaluated as a vaccine candidate in chickens. The plasmid was shown to be stable inside the attenuated Salmonella Gallinarum cell after three successive generations. Moreover, from an environmental safety point of view, apart from day 1 the JOL1355 strain was not detected in feces through day 21 postinoculation. For the efficacy of JOL1355, a total of 100 chickens were equally divided into two groups. Group A (control) chickens were intramuscularly inoculated with phosphate-buffered saline at 4 and 8 wk of age. Group B chickens were primed and boosted via the intramuscular route with 200 μL of a bacterial suspension of JOL1355 containing 1 × 10(8) colony forming units. All the chickens in Group A and B were challenged at 3 wk postbooster by oral inoculation with a wild-type Salmonella Gallinarum strain, JOL420. The JOL1355-immunized group showed significant protection and survival against the virulent challenge compared to the nonimmunized group. In addition, Group B exhibited a significantly higher humoral immune response, and the chickens remained healthy without any symptoms of anorexia, diarrhea, or depression. Group B also exhibited a significantly lower mortality rate of 4% compared to the 46% of the control group, which can be attributed to higher immunogenicity and better protection. The Group B chickens had significantly lower lesion scores for affected organs, such as the liver and spleen, compared to those of the control chickens (P < 0.01). These findings suggest that JOL1355 is a promising candidate for a safe and highly immunogenic vaccine against FT.
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Affiliation(s)
- Muhammad Hassan Shafiq
- College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Iksan, 570-752 Korea
| | - Nitin M Kamble
- College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Iksan, 570-752 Korea
| | - Tae Hoon Kim
- College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Iksan, 570-752 Korea
| | - Yoonyoung Choi
- College of Veterinary Medicine and Bio-Safety Research Institute, Chonbuk National University, Iksan, 570-752 Korea
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Hörnschemeyer P, Liss V, Heermann R, Jung K, Hunke S. Interaction Analysis of a Two-Component System Using Nanodiscs. PLoS One 2016; 11:e0149187. [PMID: 26882435 PMCID: PMC4755656 DOI: 10.1371/journal.pone.0149187] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Accepted: 01/28/2016] [Indexed: 11/25/2022] Open
Abstract
Two-component systems are the major means by which bacteria couple adaptation to environmental changes. All utilize a phosphorylation cascade from a histidine kinase to a response regulator, and some also employ an accessory protein. The system-wide signaling fidelity of two-component systems is based on preferential binding between the signaling proteins. However, information on the interaction kinetics between membrane embedded histidine kinase and its partner proteins is lacking. Here, we report the first analysis of the interactions between the full-length membrane-bound histidine kinase CpxA, which was reconstituted in nanodiscs, and its cognate response regulator CpxR and accessory protein CpxP. Using surface plasmon resonance spectroscopy in combination with interaction map analysis, the affinity of membrane-embedded CpxA for CpxR was quantified, and found to increase by tenfold in the presence of ATP, suggesting that a considerable portion of phosphorylated CpxR might be stably associated with CpxA in vivo. Using microscale thermophoresis, the affinity between CpxA in nanodiscs and CpxP was determined to be substantially lower than that between CpxA and CpxR. Taken together, the quantitative interaction data extend our understanding of the signal transduction mechanism used by two-component systems.
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Affiliation(s)
- Patrick Hörnschemeyer
- Fachbereich Biologie/Chemie, Mikrobiologie, Universität Osnabrück, Barbarastrasse 11, D-49076, Osnabrück, Germany
| | - Viktoria Liss
- Fachbereich Biologie/Chemie, Mikrobiologie, Universität Osnabrück, Barbarastrasse 11, D-49076, Osnabrück, Germany
| | - Ralf Heermann
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Microbiology, Ludwig-Maximilians-Universität München, 82152, Martinsried, Germany
| | - Kirsten Jung
- Munich Center for Integrated Protein Science (CiPSM) at the Department of Microbiology, Ludwig-Maximilians-Universität München, 82152, Martinsried, Germany
| | - Sabine Hunke
- Fachbereich Biologie/Chemie, Mikrobiologie, Universität Osnabrück, Barbarastrasse 11, D-49076, Osnabrück, Germany
- * E-mail:
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De la Cruz MA, Morgan JK, Ares MA, Yáñez-Santos JA, Riordan JT, Girón JA. The Two-Component System CpxRA Negatively Regulates the Locus of Enterocyte Effacement of Enterohemorrhagic Escherichia coli Involving σ(32) and Lon protease. Front Cell Infect Microbiol 2016; 6:11. [PMID: 26904510 PMCID: PMC4742615 DOI: 10.3389/fcimb.2016.00011] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 01/18/2016] [Indexed: 12/05/2022] Open
Abstract
Enterohemorrhagic Escherichia coli (EHEC) is a significant cause of serious human gastrointestinal disease worldwide. EHEC strains contain a pathogenicity island called the locus of enterocyte effacement (LEE), which encodes virulence factors responsible for damaging the gut mucosa. The Cpx envelope stress response of E. coli is controlled by a two-component system (TCS) consisting of a sensor histidine kinase (CpxA) and a cytoplasmic response regulator (CpxR). In this study, we investigated the role of CpxRA in the expression of LEE-encoded virulence factors of EHEC. We found that a mutation in cpxA significantly affected adherence of EHEC to human epithelial cells. Analysis of this mutant revealed the presence of high levels of CpxR which repressed transcription of grlA and ler, the main positive virulence regulators of the LEE, and influenced negatively the production of the type 3 secretion system–associated EspABD translocator proteins. It is known that CpxR activates rpoH (Sigma factor 32), which in turns activates transcription of the lon protease gene. We found that transcription levels of ler and grlA were significantly increased in the lon and cpxA lon mutants suggesting that lon is involved in down-regulating LEE genes. In addition, the Galleria mellonella model of infection was used to analyze the effect of the loss of the cpx and lon genes in EHEC's ability to kill the larvae. We found that the cpxA mutant was significantly deficient at killing the larvae however, the cpxA lon mutant which overexpresses LEE genes in vitro, was unable to kill the larvae, suggesting that virulence in the G. mellonella model is T3SS independent and that CpxA modulates virulence through a yet unknown EHEC-specific factor. Our data provides new insights and broadens our scope into the complex regulatory network of the LEE in which the CpxA sensor kinase plays an important role in a cascade involving both global and virulence regulators.
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Affiliation(s)
- Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI-IMSSMexico City, Mexico; Emerging Pathogens Institute, University of FloridaGainesville, FL, USA
| | - Jason K Morgan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida Tampa, FL, USA
| | - Miguel A Ares
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XXI-IMSS Mexico City, Mexico
| | - Jorge A Yáñez-Santos
- Facultad de Estomatología, Benemerita Universidad Autonoma de Puebla Puebla, Mexico
| | - James T Riordan
- Department of Cell Biology, Microbiology, and Molecular Biology, University of South Florida Tampa, FL, USA
| | - Jorge A Girón
- Emerging Pathogens Institute, University of FloridaGainesville, FL, USA; Centro de Deteccion Biomolecular, Benemerita Universidad Autonoma de PueblaPuebla, Mexico
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Feldheim YS, Zusman T, Speiser Y, Segal G. The Legionella pneumophila CpxRA two-component regulatory system: new insights into CpxR's function as a dual regulator and its connection to the effectors regulatory network. Mol Microbiol 2016; 99:1059-79. [PMID: 26713766 DOI: 10.1111/mmi.13290] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/24/2015] [Indexed: 12/22/2022]
Abstract
Legionella pneumophila utilizes the Icm/Dot type-IV secretion system to translocate approximately 300 effector proteins into host cells, and the CpxRA two-component system (TCS) was previously shown to regulate the expression of several of these effectors. In this study, we expanded the pool of L. pneumophila CpxR-regulated genes to 38, including 27 effector-encoding genes. Our study demonstrates for the first time that the CpxR dual regulator has different requirements for activation and repression of target genes. These differences include the positioning of the CpxR regulatory element relative to the promoter element, and the effect of CpxR phosphate donors on the expression of CpxR target genes. In addition, unlike most response regulators, a mutant form of the L. pneumophila CpxR which cannot be phosphorylated was found to self-interact, and to repress gene expression similarly to wild-type CpxR, even though its ability to activate gene expression was reduced. Moreover, the CpxRA TCS was found to activate the expression of LetE which was found to function as a connector protein between the CpxRA TCS and the LetAS-RsmYZ-CsrA regulatory cascade. Our results show that CpxR plays a major role in L. pneumophila pathogenesis gene expression and functions as part of a regulatory network.
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Affiliation(s)
- Yaron S Feldheim
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 69978, Israel
| | - Tal Zusman
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 69978, Israel
| | - Yariv Speiser
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 69978, Israel
| | - Gil Segal
- Department of Molecular Microbiology and Biotechnology, George S. Wise Faculty of Life Sciences, Tel-Aviv University, Tel-Aviv, 69978, Israel
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Lima BP, Lennon CW, Ross W, Gourse RL, Wolfe AJ. In vitro evidence that RNA Polymerase acetylation and acetyl phosphate-dependent CpxR phosphorylation affect cpxP transcription regulation. FEMS Microbiol Lett 2016; 363:fnw011. [PMID: 26790713 DOI: 10.1093/femsle/fnw011] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/14/2016] [Indexed: 12/21/2022] Open
Abstract
The central metabolite acetyl phosphate (acP) has long been proposed to influence transcription regulation by directly transferring its phosphoryl group to a number of response regulators in many bacterial species. Here, we provide in vitro evidence for this proposition and demonstrate, using an in vitro transcription system, that acP-dependent phosphorylation of aspartate 51 of CpxR induces transcription of one of its regulon members in E. coli, cpxP. We also used this in vitro transcription system to extend our previously reported in vivo data that hypothesized that acetylation of RNA polymerase (RNAP) influences acP-dependent cpxP transcription, using glutamine as a genetic mimic for acetylated arginine 291 of the carboxy-terminal domain of RNAP α subunit. The data we present here lend strong support to the hypothesis that acP has a direct effect on transcription regulation in E. coli via phosphorylation of CpxR, and that RNAP acetylation can modulate this response.
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Affiliation(s)
- Bruno P Lima
- Department of Microbiology and Immunology, Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
| | - Christopher W Lennon
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Wilma Ross
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Richard L Gourse
- Department of Bacteriology, University of Wisconsin-Madison, Madison, WI 53706, USA
| | - Alan J Wolfe
- Department of Microbiology and Immunology, Stritch School of Medicine, Health Sciences Division, Loyola University Chicago, Maywood, IL 60153, USA
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Kamble NM, Nandre RM, Lee JH. Inhibition of Salmonella-induced apoptosis as a marker of the protective efficacy of virulence gene-deleted live attenuated vaccine. Vet Immunol Immunopathol 2015; 169:96-101. [PMID: 26651227 DOI: 10.1016/j.vetimm.2015.11.002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2015] [Revised: 08/04/2015] [Accepted: 11/09/2015] [Indexed: 01/26/2023]
Abstract
Vaccination is one of the best protection strategies against Salmonella infection in humans and chickens. Salmonella bacteria must induce apoptosis prior to initiating infection, pathogenesis and evasion of host immune responses. In this study, we evaluated the efficacy of vaccinating chickens against Salmonella Enteritidis (SE) using a vaccine candidate strain (JOL919), constructed by deleting the lon and cpxR genes from a wild-type SE using an allelic exchange method. In present study day old chickens were inoculated with 1×10(7)cfu (colony forming unit) of JOL919 per os. We measured cell-mediated immunity, protective efficacy and extent of apoptosis induction in splenocytes. Seven days post-immunization, the number of CD3+CD4+ and CD3+ CD8+ T cells was significantly higher in the immunized group compared to the control group, indicating a significant augmentation of systemic immune response. The internal organs of chickens immunized with JOL919 had a significantly lower challenge-strain recovery, indicating effective protection and clearance of the challenge strain. Post-challenge, the number of apoptotic cells in the immunized group was significantly lower than in the control group. Additionally, AV/PI (Annexin V/propidium iodide) staining was performed to differentiate between apoptotic cells and necrotic cells, which corroborated TUNEL-assay (terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling) results. The proportions of AV+/PI- and AV+/PI+ cells, which represent the proportions of early apoptotic and late apoptotic/early necrotic cells present, respectively, were significantly lower in the immunized group. Our findings suggest that the apoptotic splenocytes in immunized chickens significantly decreased in number, which occurred concomitantly with a significant rise in systemic immune response and bacterial clearance. This suggests that inhibition of apoptosis may be a marker of protection efficacy in immunized chickens.
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Affiliation(s)
- Nitin M Kamble
- College of Veterinary Medicine, Chonbuk National University, Jeonbuk 570-752, South Korea
| | - Rahul M Nandre
- College of Veterinary Medicine, Chonbuk National University, Jeonbuk 570-752, South Korea
| | - John Hwa Lee
- College of Veterinary Medicine, Chonbuk National University, Jeonbuk 570-752, South Korea.
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Cross Talk Inhibition Nullified by a Receiver Domain Missense Substitution. J Bacteriol 2015; 197:3294-306. [PMID: 26260457 DOI: 10.1128/jb.00436-15] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2015] [Accepted: 08/03/2015] [Indexed: 11/20/2022] Open
Abstract
UNLABELLED In two-component signal transduction, a sensor protein transmitter module controls cognate receiver domain phosphorylation. Most receiver domain sequences contain a small residue (Gly or Ala) at position T + 1 just distal to the essential Thr or Ser residue that forms part of the active site. However, some members of the NarL receiver subfamily have a large hydrophobic residue at position T + 1. Our laboratory previously isolated a NarL mutant in which the T + 1 residue Val-88 was replaced with an orthodox small Ala. This NarL V88A mutant confers a striking phenotype in which high-level target operon expression is both signal (nitrate) and sensor (NarX and NarQ) independent. This suggests that the NarL V88A protein is phosphorylated by cross talk from noncognate sources. Although cross talk was enhanced in ackA null strains that accumulate acetyl phosphate, it persisted in pta ackA double null strains that cannot synthesize this compound and was observed also in narL(+) strains. This indicates that acetate metabolism has complex roles in mediating NarL cross talk. Contrariwise, cross talk was sharply diminished in an arcB barA double null strain, suggesting that the encoded sensors contribute substantially to NarL V88A cross talk. Separately, the V88A substitution altered the in vitro rates of NarL autodephosphorylation and transmitter-stimulated dephosphorylation and decreased affinity for the cognate sensor, NarX. Together, these experiments show that the residue at position T + 1 can strongly influence two distinct aspects of receiver domain function, the autodephosphorylation rate and cross talk inhibition. IMPORTANCE Many bacterial species contain a dozen or more discrete sensor-response regulator two-component systems that convert a specific input into a distinct output pattern. Cross talk, the unwanted transfer of signals between circuits, occurs when a response regulator is phosphorylated inappropriately from a noncognate source. Cross talk is inhibited in part by the high interaction specificity between cognate sensor-response regulator pairs. This study shows that a relatively subtle missense change from Val to Ala nullifies cross talk inhibition, enabling at least two noncognate sensors to enforce an inappropriate output independently of the relevant input.
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De la Cruz MA, Pérez-Morales D, Palacios IJ, Fernández-Mora M, Calva E, Bustamante VH. The two-component system CpxR/A represses the expression of Salmonella virulence genes by affecting the stability of the transcriptional regulator HilD. Front Microbiol 2015; 6:807. [PMID: 26300871 PMCID: PMC4526804 DOI: 10.3389/fmicb.2015.00807] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 07/22/2015] [Indexed: 11/30/2022] Open
Abstract
Salmonella enterica can cause intestinal or systemic infections in humans and animals mainly by the presence of pathogenicity islands SPI-1 and SPI-2, containing 39 and 44 genes, respectively. The AraC-like regulator HilD positively controls the expression of the SPI-1 genes, as well as many other Salmonella virulence genes including those located in SPI-2. A previous report indicates that the two-component system CpxR/A regulates the SPI-1 genes: the absence of the sensor kinase CpxA, but not the absence of its cognate response regulator CpxR, reduces their expression. The presence and absence of cell envelope stress activates kinase and phosphatase activities of CpxA, respectively, which in turn controls the level of phosphorylated CpxR (CpxR-P). In this work, we further define the mechanism for the CpxR/A-mediated regulation of SPI-1 genes. The negative effect exerted by the absence of CpxA on the expression of SPI-1 genes was counteracted by the absence of CpxR or by the absence of the two enzymes, AckA and Pta, which render acetyl-phosphate that phosphorylates CpxR. Furthermore, overexpression of the lipoprotein NlpE, which activates CpxA kinase activity on CpxR, or overexpression of CpxR, repressed the expression of SPI-1 genes. Thus, our results provide several lines of evidence strongly supporting that the absence of CpxA leads to the phosphorylation of CpxR via the AckA/Pta enzymes, which represses both the SPI-1 and SPI-2 genes. Additionally, we show that in the absence of the Lon protease, which degrades HilD, the CpxR-P-mediated repression of the SPI-1 genes is mostly lost; moreover, we demonstrate that CpxR-P negatively affects the stability of HilD and thus decreases the expression of HilD-target genes, such as hilD itself and hilA, located in SPI-1. Our data further expand the insight on the different regulatory pathways for gene expression involving CpxR/A and on the complex regulatory network governing virulence in Salmonella.
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Affiliation(s)
- Miguel A De la Cruz
- Unidad de Investigación Médica en Enfermedades Infecciosas y Parasitarias, Centro Médico Nacional Siglo XX1-IMSS México DF, Mexico
| | - Deyanira Pérez-Morales
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México Cuernavaca, Morelos, Mexico
| | - Irene J Palacios
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México Cuernavaca, Morelos, Mexico
| | - Marcos Fernández-Mora
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México Cuernavaca, Morelos, Mexico
| | - Edmundo Calva
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México Cuernavaca, Morelos, Mexico
| | - Víctor H Bustamante
- Departamento de Microbiología Molecular, Instituto de Biotecnología, Universidad Nacional Autónoma de México Cuernavaca, Morelos, Mexico
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Bontemps-Gallo S, Madec E, Lacroix JM. The two-component system CpxAR is essential for virulence in the phytopathogen bacteria Dickeya dadantii EC3937. Environ Microbiol 2015; 17:4415-28. [PMID: 25856505 DOI: 10.1111/1462-2920.12874] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2015] [Revised: 04/01/2015] [Accepted: 04/05/2015] [Indexed: 12/22/2022]
Abstract
The CpxAR two-component system is present in many Proteobacteria. It controls expression of genes required to maintain envelope integrity in response to environmental injury. Consequently, this two-component system was shown to be required for virulence of several zoo-pathogens, but it has never been investigated in phyto-pathogens. In this paper, we investigate the role of the CpxAR two-component system in vitro and in vivo in Dickeya dadantii, an enterobacterial phytopathogen that causes soft-rot disease in a large variety of plant species. cpxA null mutant displays a constitutively phosphorylated CpxR phenotype as shown by direct analysis of phosphorylation of CpxR by a Phos-Tag retardation gel approach. Virulence in plants is completely abolished in cpxA or cpxR mutants of D. dadantii. In planta, CpxAR is only activated at an early stage of the infection process as shown by Phos-Tag and gene fusion analyses. To our knowledge, this is the first time that the timing of CpxAR phosphorelay activation has been investigated during the infection process by direct monitoring of response regulator phosphorylation.
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Affiliation(s)
- Sébastien Bontemps-Gallo
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Villeneuve d'Ascq, F-59655, France
| | - Edwige Madec
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Villeneuve d'Ascq, F-59655, France
| | - Jean-Marie Lacroix
- Unité de Glycobiologie Structurale et Fonctionnelle, UMR CNRS 8576, Université des Sciences et Technologies de Lille, Université de Lille, Villeneuve d'Ascq, F-59655, France
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Development and validation of a high-throughput cell-based screen to identify activators of a bacterial two-component signal transduction system. Antimicrob Agents Chemother 2015; 59:3789-99. [PMID: 25870061 DOI: 10.1128/aac.00236-15] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2015] [Accepted: 04/05/2015] [Indexed: 01/16/2023] Open
Abstract
CpxRA is a two-component signal transduction system (2CSTS) found in many drug-resistant Gram-negative bacteria. In response to periplasmic stress, CpxA autophosphorylates and donates a phosphoryl group to its cognate response regulator, CpxR. Phosphorylated CpxR (CpxR-P) upregulates genes involved in membrane repair and downregulates multiple genes that encode virulence factors, which are trafficked across the cell membrane. Mutants that constitutively activate CpxRA in Salmonella enterica serovar Typhimurium and Haemophilus ducreyi are avirulent in mice and humans, respectively. Thus, the activation of CpxRA has high potential as a novel antimicrobial/antivirulence strategy. Using a series of Escherichia coli strains containing a CpxR-P-responsive lacZ reporter and deletions in genes encoding CpxRA system components, we developed and validated a novel cell-based high-throughput screen (HTS) for CpxRA activators. A screen of 36,000 compounds yielded one hit compound that increased reporter activity in wild-type cells. This is the first report of a compound that activates, rather than inhibits, a 2CSTS. The activity profile of the compound against CpxRA pathway mutants in the presence of glucose suggested that the compound inhibits CpxA phosphatase activity. We confirmed that the compound induced the accumulation of CpxR-P in treated cells. Although the hit compound contained a nitro group, a derivative lacking this group retained activity in serum and had lower cytotoxicity than that of the initial hit. This HTS is amenable for the screening of larger libraries to find compounds that activate CpxRA by other mechanisms, and it could be adapted to find activators of other two-component systems.
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Si W, Wang X, Liu H, Yu S, Li Z, Chen L, Zhang W, Liu S. Physiology, pathogenicity and immunogenicity of live, attenuated Salmonella enterica serovar Enteritidis mutants in chicks. Microb Pathog 2015; 83-84:6-11. [PMID: 25819881 DOI: 10.1016/j.micpath.2015.03.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2015] [Accepted: 03/23/2015] [Indexed: 12/12/2022]
Abstract
To construct a novel live, attenuated Salmonella vaccine, the lon, cpxR and cpdB genes were deleted from a wild-type Salmonella enterica serovar Enteritidis-6 (SM-6) strain using the phage λ Red homologous recombination system, resulting in SM-△CpxR, SM-△C/Lon and SM-△C/L/CpdB. The growth curves of strain SM-△C/Lon grew more rapidly than the other strains and had OD 600 values higher than the other strains starting at the 4 h time point. The growth curves of strain SM-△C/L/CpdB were relatively flat. The colonization time of SM-△C/L/CpdB is about 8-10 days. Deleting the lon/cpxR/cpdB (SM-6) genes resulted in an approximate 10(3)-fold attenuation in virulence assessed by the analysis of the LD50 of specific pathogen-free (SPF) chicks. This result indicated that the deletion of the lon, cpxR and cpdB genes induced significant virulence attenuation. The protective effects of SM-△C/L/CpdB vaccination in SPF chicks against 5 × 10(9) colony forming units (CFU) of S. Enteritidis were resulted from the induction of an effective immune response. These findings demonstrate the potential of mutant SM-△C/L/CpdB to be used as an effective vaccine.
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Affiliation(s)
- Wei Si
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Xiumei Wang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Huifang Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Shenye Yu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Zhaoli Li
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Liping Chen
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Wanjiang Zhang
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China
| | - Siguo Liu
- State Key Laboratory of Veterinary Biotechnology, Division of Bacterial Disease of Harbin Veterinary Research Institute of Chinese Academy of Agricultural Sciences, 427 Maduan Street, Harbin 150001, China.
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