1
|
Hodges LM, Cooper A, Koziol A, Carrillo CD. Characterization of MLST-99 Salmonella Typhimurium and the monophasic variant I:4,[5],12:i:- isolated from Canadian Atlantic coast shellfish. MICROBIOLOGY (READING, ENGLAND) 2024; 170:001456. [PMID: 38753417 PMCID: PMC11256474 DOI: 10.1099/mic.0.001456] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/19/2023] [Accepted: 04/15/2024] [Indexed: 05/18/2024]
Abstract
Salmonella enterica subsp. enterica Typhimurium and its monophasic variant I 1;4,[5],12:i:- (MVST) are responsible for thousands of reported cases of salmonellosis each year in Canada, and countries worldwide. We investigated S. Typhimurium and MVST isolates recovered from raw shellfish harvested in Atlantic Canada by the Canadian Food Inspection Agency (CFIA) over the past decade, to assess the potential impact of these isolates on human illness and to explore possible routes of shellfish contamination. Whole-genome sequence analysis was performed on 210 isolates of S. Typhimurium and MVST recovered from various food sources, including shellfish. The objective was to identify genetic markers linked to ST-99, a sequence type specifically associated with shellfish, which could explain their high prevalence in shellfish. We also investigated the genetic similarity amongst CFIA ST-99 isolates recovered in different years and geographical locations. Finally, the study aimed to enhance the molecular serotyping of ST-99 isolates, as they are serologically classified as MVST but are frequently misidentified as S. Typhimurium through sequence analysis. To ensure recovery of ST-99 from shellfish was not due to favourable growth kinetics, we measured the growth rates of these isolates relative to other Salmonella and determined that ST-99 did not have a faster growth rate and/or shorter lag phase than other Salmonella evaluated. The CFIA ST-99 isolates from shellfish were highly clonal, with up to 81 high-quality single nucleotide variants amongst isolates. ST-99 isolates both within the CFIA collection and those isolated globally carried numerous unique deletions, insertions and mutations in genes, including some considered important for virulence, such as gene deletions in the type VI secretion system. Interestingly, several of these genetic characteristics appear to be unique to North America. Most notably was a large genomic region showing a high prevalence in genomes from Canadian isolates compared to those from the USA. Although the functions of the majority of the proteins encoded within this region remain unknown, the genes umuC and umuD, known to be protective against UV light damage, were present. While this study did not specifically examine the effects of mutations and insertions, results indicate that these isolates may be adapted to survive in specific environments, such as ocean water, where wild birds and/or animals serve as the natural hosts. Our hypothesis is reinforced by a global phylogenetic analysis, which indicates that isolates obtained from North American shellfish and wild birds are infrequently connected to isolates from human sources. These findings suggest a distinct ecological niche for ST-99, potentially indicating their specialization and adaptation to non-human hosts and environments, such as oceanic habitats.
Collapse
Affiliation(s)
| | | | - Adam Koziol
- Canadian Food Inspection Agency, Ottawa, Canada
| | | |
Collapse
|
2
|
Ray S, Pandey NK, Kushwaha GS, Das S, Ganguly AK, Vashi N, Kumar D, Suar M, Bhavesh NS. Structural investigation on SPI-6 associated Salmonella Typhimurium VirG-like stress protein that promotes pathogen survival in macrophages. Protein Sci 2022; 31:835-849. [PMID: 34997791 DOI: 10.1002/pro.4272] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Revised: 12/29/2021] [Accepted: 12/30/2021] [Indexed: 11/10/2022]
Abstract
Enteric microbial pathogenesis, remarkably a complex process, is achieved by virulence factors encoded by genes located within regions of the bacterial genome termed pathogenicity islands. Salmonella pathogenicity islands (SPI) encodes proteins, that are essential virulence determinants for pathogen colonization and virulence. In addition to the well-characterized SPI-1 and SPI-2 proteins, which are required for bacterial invasion and intracellular replication, respectively, SPI-6 (formerly known as Salmonella enterica centisome 7 island; SCI) encoding proteins are also known to play pivotal role in Salmonella pathogenesis. However, the underlying molecular mechanism of these proteins remained elusive. To gain molecular insights into SPI-6 associated proteins, in this study, a SPI-6 Salmonella Typhimurium VirG-like protein (STV) is characterized using interdisciplinary experimental approaches including X-ray crystallography, NMR spectroscopy, infection assays, and mice model. The high-resolution crystal structure, determined by the single-wavelength anomalous dispersion (SAD) method, reveals that STV belongs to the LTxxQ motif family. Solution-state NMR spectroscopy studies reveal that STV form a dimer involving interconnected helices. Interestingly, functional studies shows that STV influence pathogen persistence inside macrophages in vitro at later stages of infection. Altogether, our findings suggest that STV, a member of the LTxxQ stress protein family, modulates bacterial survival mechanism in macrophages through SPI-1 and SPI-2 genes, respectively. This article is protected by copyright. All rights reserved.
Collapse
Affiliation(s)
- Shilpa Ray
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Nishant Kumar Pandey
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India.,Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Gajraj Singh Kushwaha
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India.,KIIT-Technology Business Incubator, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Susmita Das
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Akshay Kumar Ganguly
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Nimi Vashi
- Cellular Immunology group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Dhiraj Kumar
- Cellular Immunology group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| | - Mrutyunjay Suar
- School of Biotechnology, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India.,KIIT-Technology Business Incubator, Kalinga Institute of Industrial Technology (KIIT), Deemed to be university, Bhubaneswar, India
| | - Neel Sarovar Bhavesh
- Transcription Regulation group, International Centre of Genetic Engineering and Biotechnology (ICGEB), Aruna Asaf Ali Marg, New Delhi, India
| |
Collapse
|
3
|
Wang P, Dong JF, Li RQ, Li L, Zou QH. Roles of the Hcp family proteins in the pathogenicity of Salmonella typhimurium 14028s. Virulence 2020; 11:1716-1726. [PMID: 33300449 PMCID: PMC7733977 DOI: 10.1080/21505594.2020.1854538] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
The type VI secretion system (T6SS) is a new secretion system that is widely distributed among Gram-negative bacteria. The core component hemolysin-coregulated protein (Hcp) can be used as both its structural protein and secretory protein or chaperone protein. Studies on Hcp are important to elucidate the overall virulence mechanism of T6SS. Salmonella typhimurium is an important foodborne pathogen. There are three copies of hcp genes identified in S. Typhimurium 14028s. This study aimed to characterize the functions of the three Hcp family proteins and to elucidate the interactions among them. The hcp gene deletion mutants were constructed by λ Red-based recombination system. Effects of hcp mutation on the pathogenicity of 14028s were studied by bacterial competition assays, Dictyostelium discoideum assays and mouse model. The three Hcp family proteins were found to play different roles. Hcp1 can affect the transcription of rpoS and type 2 flagellar gene and influence the motility of 14028s. It is also involved in the intracellular survival of 14028s in Dictyostelium discoideum; Hcp2 is involved in the early proliferative capacity of 14028s in mice and can prevent its excessive proliferation; Hcp3 did not show direct functions in these assays. Hcp1 can interact with Hcp2 and Hcp3. Deletion of one hcp gene can result in a transcription level variation in the other two hcp genes. Our findings elucidated the functions of the three Hcp family proteins in S.Typhimurium and illustrated that there are interactions between different Hcp proteins. This study will be helpful to fully understand how T6SS actions in an organism.
Collapse
Affiliation(s)
- Ping Wang
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Jun-Fang Dong
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| | - Ren-Qing Li
- Institute for Infectious Disease and Endemic Disease Control, Beijing Center for Disease Prevention and Control, Beijing Research Center for Preventive Medicine , Beijing, China
| | - Lei Li
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China.,The MOH Key Laboratory of Geriatrics, Beijing Hospital, National Center of Gerontology , Beijing, China
| | - Qing-Hua Zou
- Department of Microbiology& Infectious Disease Center, School of Basic Medical Sciences, Peking University Health Science Center , Beijing, China
| |
Collapse
|
4
|
Xie Z, Zhang Y, Huang X. Evidence and speculation: the response of Salmonella confronted by autophagy in macrophages. Future Microbiol 2020; 15:1277-1286. [PMID: 33026883 DOI: 10.2217/fmb-2020-0125] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Bacteria of the Salmonella genus cause diseases ranging from self-limited gastroenteritis to typhoid fever. Macrophages are immune cells that engulf and restrict Salmonella. These cells will carry Salmonella into the circulatory system and provoke a systemic infection. Therefore, the interaction between macrophages and intracellular Salmonella is vital for its pathogenicity. As one of the immune responses of macrophages, autophagy, along with the fusion of autophagosomes with lysosomes, occupies an important position in eliminating Salmonella. However, Salmonella that can overcome cellular defensive responses and infect neighboring cells must derive strategies to escape autophagy. This review introduces novel findings on Salmonella and macrophage autophagy as a mechanism against infection and explores the strategies used by Salmonella to escape autophagy.
Collapse
Affiliation(s)
- Zhongyi Xie
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China.,International Genome Center, Jiangsu University, Zhenjiang, Jiangsu 212013, China
| | - Ying Zhang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| | - Xinxiang Huang
- Department of Biochemistry & Molecular Biology, Jiangsu University School of Medicine, Zhenjiang, Jiangsu 212013, China
| |
Collapse
|
5
|
Bao H, Wang S, Zhao JH, Liu SL. Salmonella secretion systems: Differential roles in pathogen-host interactions. Microbiol Res 2020; 241:126591. [PMID: 32932132 DOI: 10.1016/j.micres.2020.126591] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 08/24/2020] [Accepted: 08/29/2020] [Indexed: 12/26/2022]
Abstract
The bacterial genus Salmonella includes a large group of food-borne pathogens that cause a variety of gastrointestinal or systemic diseases in hosts. Salmonella use several secretion devices to inject various effectors targeting eukaryotic hosts, or bacteria. In the past few years, considerable progress has been made towards understanding the structural features and molecular mechanisms of the secretion systems of Salmonella, particularly regarding their roles in host-pathogen interactions. In this review, we summarize the current advances about the main characteristics of the Salmonella secretion systems. Clarifying the roles of the secretion systems in the process of infecting various hosts will broaden our understanding of the importance of microbial interactions in maintaining human health and will provide information for developing novel therapeutic approaches.
Collapse
Affiliation(s)
- Hongxia Bao
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China.
| | - Shuang Wang
- Department of Biopharmaceutical Sciences (State-Province Key Laboratories of Biomedicine-Pharmaceutics of China), College of Pharmacy, Harbin Medical University, Harbin, China
| | - Jian-Hua Zhao
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China
| | - Shu-Lin Liu
- Genomics Research Center, College of Pharmacy, Harbin Medical University, Harbin, China; HMU-UCCSM Centre for Infection and Genomics, Harbin Medical University, Harbin, China; Translational Medicine Research and Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, China; Department of Microbiology, Immunology and Infectious Diseases, University of Calgary, Calgary, Canada.
| |
Collapse
|
6
|
The Ferric Uptake Regulator Represses Type VI Secretion System Function by Binding Directly to the clpV Promoter in Salmonella enterica Serovar Typhimurium. Infect Immun 2019; 87:IAI.00562-19. [PMID: 31383745 DOI: 10.1128/iai.00562-19] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/23/2019] [Accepted: 07/25/2019] [Indexed: 12/16/2022] Open
Abstract
Type VI secretion systems (T6SSs) are highly conserved and complex protein secretion systems that deliver effector proteins into eukaryotic hosts or other bacteria. T6SSs are regulated precisely by a variety of regulatory systems, which enables bacteria to adapt to varied environments. A T6SS within Salmonella pathogenicity island 6 (SPI-6) is activated during infection, and it contributes to the pathogenesis, as well as interbacterial competition, of Salmonella enterica serovar Typhimurium (S. Typhimurium). However, the regulation of the SPI-6 T6SS in S. Typhimurium is not well understood. In this study, we found that the SPI-6 T6SS core gene clpV was significantly upregulated in response to the iron-depleted condition and during infection. The global ferric uptake regulator (Fur) was shown to repress the clpV expression in the iron-replete medium. Moreover, electrophoretic mobility shift and DNase I footprinting assays revealed that Fur binds directly to the clpV promoter region at multiple sites spanning the transcriptional start site. We also observed that the relieving of Fur-mediated repression on clpV contributed to the interbacterial competition activity and pathogenicity of S. Typhimurium. These findings provide insights into the direct regulation of Fur in the expression and functional activity of SPI-6 T6SS in S. Typhimurium and thus help to elucidate the mechanisms of bacterial adaptability and virulence.
Collapse
|
7
|
Bao H, Zhao JH, Zhu S, Wang S, Zhang J, Wang XY, Hua B, Liu C, Liu H, Liu SL. Genetic diversity and evolutionary features of type VI secretion systems in Salmonella. Future Microbiol 2019; 14:139-154. [PMID: 30672329 DOI: 10.2217/fmb-2018-0260] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
AIM Type VI secretion systems (T6SS) play key roles in bacterial pathogenesis, but their evolutionary features remain largely unclear. In this study, we conducted systematic comparisons among the documented T6SSs in Salmonella and determined their structural diversity, phylogenetic distribution and lineage-specific properties. MATERIALS & METHODS We screened 295 Salmonella genomes for 13 T6SS core components by hidden Markov models and identified 363 T6SS clusters covering types i1, i2, i3 and i4a. RESULTS Type i3 and i4a T6SSs were restricted to Salmonella enterica subspecies enterica and Salmonella bongori, respectively. whereas type i2 T6SSs were conserved between S. enterica subspecies, arizonae and diarizonae. S. enterica subspecies salamae, indica and houtenae harbored only type i1 T6SSs, which had wide distribution and high sequence diversity. CONCLUSION The diverse Salmonella T6SSs have undergone purifying selection pressures during the bacterial evolution and may be involved in host adaptation.
Collapse
Affiliation(s)
- Hongxia Bao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Jian-Hua Zhao
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Songling Zhu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shuang Wang
- Department of Biopharmaceutical Sciences, College of Pharmacy, Harbin Medical University, Harbin, PR China
| | - Jianjuan Zhang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Xiao-Yu Wang
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Bing Hua
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Chang Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Huidi Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China
| | - Shu-Lin Liu
- Systemomics Center, College of Pharmacy & Genomics Research Center, Harbin Medical University, Harbin, PR China.,HMU-UCCSM Centre for Infection & Genomics, Harbin Medical University, Harbin, PR China.,Translational Medicine Research & Cooperation Center of Northern China, Heilongjiang Academy of Medical Sciences, Harbin, PR China.,Department of Microbiology, Immunology & Infectious Diseases, University of Calgary, Calgary, T2N 1N4, Canada
| |
Collapse
|
8
|
Lamas A, Miranda JM, Regal P, Vázquez B, Franco CM, Cepeda A. A comprehensive review of non-enterica subspecies of Salmonella enterica. Microbiol Res 2018; 206:60-73. [DOI: 10.1016/j.micres.2017.09.010] [Citation(s) in RCA: 109] [Impact Index Per Article: 18.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 09/22/2017] [Accepted: 09/26/2017] [Indexed: 12/11/2022]
|
9
|
Abstract
The type VI secretion system (T6SS) is a multiprotein complex widespread in Proteobacteria and dedicated to the delivery of toxins into both prokaryotic and eukaryotic cells. It thus participates in interbacterial competition as well as pathogenesis. The T6SS is a contractile weapon, related to the injection apparatus of contractile tailed bacteriophages. Basically, it assembles an inner tube wrapped by a sheath-like structure and anchored to the cell envelope via a membrane complex. The energy released by the contraction of the sheath propels the inner tube through the membrane channel and toward the target cell. Although the assembly and the mechanism of action are conserved across species, the repertoire of secreted toxins and the diversity of the regulatory mechanisms and of target cells make the T6SS a highly versatile secretion system. The T6SS is particularly represented in Escherichia coli pathotypes and Salmonella serotypes. In this review we summarize the current knowledge regarding the prevalence, the assembly, the regulation, and the roles of the T6SS in E. coli, Salmonella, and related species.
Collapse
|
10
|
Silva-Valenzuela CA, Molina-Quiroz RC, Desai P, Valenzuela C, Porwollik S, Zhao M, Hoffman RM, Andrews-Polymenis H, Contreras I, Santiviago CA, McClelland M. Analysis of Two Complementary Single-Gene Deletion Mutant Libraries of Salmonella Typhimurium in Intraperitoneal Infection of BALB/c Mice. Front Microbiol 2016; 6:1455. [PMID: 26779130 PMCID: PMC4700939 DOI: 10.3389/fmicb.2015.01455] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 12/04/2015] [Indexed: 01/20/2023] Open
Abstract
Two pools of individual single gene deletion (SGD) mutants of S. Typhimurium 14028s encompassing deletions of 3,923 annotated non-essential ORFs and sRNAs were screened by intraperitoneal (IP) injection in BALB/c mice followed by recovery from spleen and liver 2 days post infection. The relative abundance of each mutant was measured by microarray hybridization. The two mutant libraries differed in the orientation of the antibiotic resistance cassettes (either sense-oriented Kan(R), SGD-K, or antisense-oriented Cam(R), SGD-C). Consistent systemic colonization defects were observed in both libraries and both organs for hundreds of mutants of genes previously reported to be important after IP injection in this animal model, and for about 100 new candidate genes required for systemic colonization. Four mutants with a range of apparent fitness defects were confirmed using competitive infections with the wild-type parental strain: ΔSTM0286, ΔSTM0551, ΔSTM2363, and ΔSTM3356. Two mutants, ΔSTM0286 and ΔSTM2363, were then complemented in trans with a plasmid encoding an intact copy of the corresponding wild-type gene, and regained the ability to fully colonize BALB/c mice systemically. These results suggest the presence of many more undiscovered Salmonella genes with phenotypes in IP infection of BALB/c mice, and validate the libraries for application to other systems.
Collapse
Affiliation(s)
- Cecilia A. Silva-Valenzuela
- Department of Microbiology and Molecular Genetics, University of California, IrvineIrvine, CA, USA
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Roberto C. Molina-Quiroz
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
- Center for Adaptation Genetics and Drug Resistance, Tufts UniversityBoston, MA, USA
| | - Prerak Desai
- Department of Microbiology and Molecular Genetics, University of California, IrvineIrvine, CA, USA
| | - Camila Valenzuela
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Steffen Porwollik
- Department of Microbiology and Molecular Genetics, University of California, IrvineIrvine, CA, USA
| | | | - Robert M. Hoffman
- Anticancer Inc.San Diego, CA, USA
- Department of Surgery, UC San Diego School of Medicine, University of California, San DiegoSan Diego, CA, USA
| | - Helene Andrews-Polymenis
- Department of Microbial Pathogenesis and Immunology, Texas A&M UniversityCollege Station, TX, USA
| | - Inés Contreras
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Carlos A. Santiviago
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de ChileSantiago, Chile
| | - Michael McClelland
- Department of Microbiology and Molecular Genetics, University of California, IrvineIrvine, CA, USA
| |
Collapse
|
11
|
H-NS Silencing of the Salmonella Pathogenicity Island 6-Encoded Type VI Secretion System Limits Salmonella enterica Serovar Typhimurium Interbacterial Killing. Infect Immun 2015; 83:2738-50. [PMID: 25916986 DOI: 10.1128/iai.00198-15] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2015] [Accepted: 04/16/2015] [Indexed: 12/26/2022] Open
Abstract
The secretion of bacterial toxin proteins is achieved by dedicated machineries called secretion systems. The type VI secretion system (T6SS) is a widespread versatile machine used for the delivery of protein toxins to both prokaryotic and eukaryotic cells. In Salmonella enterica serovar Typhimurium, the expression of the T6SS genes is activated during macrophage or mouse infection. Here, we show that the T6SS gene cluster is silenced by the histone-like nucleoid structuring H-NS protein using a combination of reporter fusions, electrophoretic mobility shift assays, DNase footprinting, and fluorescence microscopy. We further demonstrate that derepression of the S. Typhimurium T6SS genes induces T6SS-dependent intoxication of competing bacteria. Our results suggest that relieving T6SS H-NS silencing may be used as a sense-and-kill mechanism that will help S. Typhimurium to homogenize and synchronize the microbial population to gain efficiency during infection.
Collapse
|
12
|
An inducible and secreted eukaryote-like serine/threonine kinase of Salmonella enterica serovar Typhi promotes intracellular survival and pathogenesis. Infect Immun 2014; 83:522-33. [PMID: 25404028 DOI: 10.1128/iai.02521-14] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Eukaryote-like serine/threonine kinases (eSTKs) constitute an important family of bacterial virulence factors. Genome analysis had predicted putative eSTKs in Salmonella enterica serovar Typhi, although their functional characterization and the elucidation of their role in pathogenesis are still awaited. We show here that the primary sequence and secondary structure of the t4519 locus of Salmonella Typhi Ty2 have all the signatures of eukaryotic superfamily kinases. t4519 encodes a ∼39-kDa protein (T4519), which shows serine/threonine kinase activities in vitro. Recombinant T4519 (rT4519) is autophosphorylated and phosphorylates the universal substrate myelin basic protein. Infection of macrophages results in decreased viability of the mutant (Ty2Δt4519) strain, which is reversed by gene complementation. Moreover, reactive oxygen species produced by the macrophages signal to the bacteria to induce T4519, which is translocated to the host cell cytoplasm. That T4519 may target a host substrate(s) is further supported by the activation of host cellular signaling pathways and the induction of cytokines/chemokines. Finally, the role of T4519 in the pathogenesis of Salmonella Typhi is underscored by the significantly decreased mortality of mice infected with the Ty2Δt4519 strain and the fact that the competitive index of this strain for causing systemic infection is 0.25% that of the wild-type strain. This study characterizes the first eSTK of Salmonella Typhi and demonstrates its role in promoting phagosomal survival of the bacteria within macrophages, which is a key determinant of pathogenesis. This, to the best of our knowledge, is the first study to describe the essential role of eSTKs in the in vivo pathogenesis of Salmonella spp.
Collapse
|
13
|
Pezoa D, Yang HJ, Blondel CJ, Santiviago CA, Andrews-Polymenis HL, Contreras I. The type VI secretion system encoded in SPI-6 plays a role in gastrointestinal colonization and systemic spread of Salmonella enterica serovar Typhimurium in the chicken. PLoS One 2013; 8:e63917. [PMID: 23691117 PMCID: PMC3653874 DOI: 10.1371/journal.pone.0063917] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2013] [Accepted: 04/09/2013] [Indexed: 02/06/2023] Open
Abstract
The role of the Salmonella Pathogenicity Islands (SPIs) in pathogenesis of Salmonella enterica Typhimurium infection in the chicken is poorly studied, while many studies have been completed in murine models. The Type VI Secretion System (T6SS) is a recently described protein secretion system in Gram-negative bacteria. The genus Salmonella contains five phylogenetically distinct T6SS encoded in differentially distributed genomic islands. S. Typhimurium harbors a T6SS encoded in SPI-6 (T6SSSPI-6), which contributes to the ability of Salmonella to colonize mice. On the other hand, serotype Gallinarum harbors a T6SS encoded in SPI-19 (T6SSSPI-19) that is required for colonization of chicks. In this work, we investigated the role of T6SSSPI-6 in infection of chicks by S. Typhimurium. Oral infection of White Leghorn chicks showed that a ΔT6SSSPI-6 mutant had reduced colonization of the gut and internal organs, compared with the wild-type strain. Transfer of the intact T6SSSPI-6 gene cluster into the T6SS mutant restored bacterial colonization. In addition, our results showed that transfer of T6SSSPI-19 from S. Gallinarum to the ΔT6SSSPI-6 mutant of S. Typhimurium not only complemented the colonization defect but also resulted in a transient increase in the colonization of the cecum and ileum of chicks at days 1 and 3 post-infection. Our data indicates that T6SSSPI-6 contributes to chicken colonization and suggests that both T6SSSPI-6 and T6SSSPI-19 perform similar functions in vivo despite belonging to different phylogenetic families.
Collapse
Affiliation(s)
- David Pezoa
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Hee-Jeong Yang
- Department of Microbial and Molecular Pathogenesis, Texas A&M University System Health Science Center, College of Medicine, College Station, Texas, United States of America
| | - Carlos J. Blondel
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos A. Santiviago
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Helene L. Andrews-Polymenis
- Department of Microbial and Molecular Pathogenesis, Texas A&M University System Health Science Center, College of Medicine, College Station, Texas, United States of America
| | - Inés Contreras
- Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| |
Collapse
|
14
|
Kapitein N, Mogk A. Deadly syringes: type VI secretion system activities in pathogenicity and interbacterial competition. Curr Opin Microbiol 2013; 16:52-8. [DOI: 10.1016/j.mib.2012.11.009] [Citation(s) in RCA: 71] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2012] [Revised: 11/12/2012] [Accepted: 11/26/2012] [Indexed: 11/26/2022]
|
15
|
The type VI secretion system encoded in Salmonella pathogenicity island 19 is required for Salmonella enterica serotype Gallinarum survival within infected macrophages. Infect Immun 2013; 81:1207-20. [PMID: 23357385 DOI: 10.1128/iai.01165-12] [Citation(s) in RCA: 46] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Salmonella enterica serotype Gallinarum is the causative agent of fowl typhoid, a disease characterized by high morbidity and mortality that causes major economic losses in poultry production. We have reported that S. Gallinarum harbors a type VI secretion system (T6SS) encoded in Salmonella pathogenicity island 19 (SPI-19) that is required for efficient colonization of chicks. In the present study, we aimed to characterize the SPI-19 T6SS functionality and to investigate the mechanisms behind the phenotypes previously observed in vivo. Expression analyses revealed that SPI-19 T6SS core components are expressed and produced under in vitro bacterial growth conditions. However, secretion of the structural/secreted components Hcp1, Hcp2, and VgrG to the culture medium could not be determined, suggesting that additional signals are required for T6SS-dependent secretion of these proteins. In vitro bacterial competition assays failed to demonstrate a role for SPI-19 T6SS in interbacterial killing. In contrast, cell culture experiments with murine and avian macrophages (RAW264.7 and HD11, respectively) revealed production of a green fluorescent protein-tagged version of VgrG soon after Salmonella uptake. Furthermore, infection of RAW264.7 and HD11 macrophages with deletion mutants of SPI-19 or strains with genes encoding specific T6SS core components (clpV and vgrG) revealed that SPI-19 T6SS contributes to S. Gallinarum survival within macrophages at 20 h postuptake. SPI-19 T6SS function was not linked to Salmonella-induced cytotoxicity or cell death of infected macrophages, as has been described for other T6SS. Our data indicate that SPI-19 T6SS corresponds to a novel tool used by Salmonella to survive within host cells.
Collapse
|