151
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Jennings E, Thurston TL, Holden DW. Salmonella SPI-2 Type III Secretion System Effectors: Molecular Mechanisms And Physiological Consequences. Cell Host Microbe 2017; 22:217-231. [DOI: 10.1016/j.chom.2017.07.009] [Citation(s) in RCA: 202] [Impact Index Per Article: 28.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2017] [Revised: 06/14/2017] [Accepted: 07/19/2017] [Indexed: 11/30/2022]
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152
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Abstract
Many bacterial pathogens can cause acute infections that are cleared with the onset of adaptive immunity, but a subset of these pathogens can establish persistent, and sometimes lifelong, infections. While bacteria that cause chronic infections are phylogenetically diverse, they share common features in their interactions with the host that enable a protracted period of colonization. This article will compare the persistence strategies of two chronic pathogens from the Proteobacteria, Brucella abortus and Salmonella enterica serovar Typhi, to consider how these two pathogens, which are very different at the genomic level, can utilize common strategies to evade immune clearance to cause chronic intracellular infections of the mononuclear phagocyte system.
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153
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Kim D, Seo SU, Zeng MY, Kim WU, Kamada N, Inohara N, Núñez G. Mesenchymal Cell-Specific MyD88 Signaling Promotes Systemic Dissemination of Salmonella Typhimurium via Inflammatory Monocytes. THE JOURNAL OF IMMUNOLOGY 2017; 199:1362-1371. [PMID: 28674182 DOI: 10.4049/jimmunol.1601527] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/01/2016] [Accepted: 06/07/2017] [Indexed: 12/24/2022]
Abstract
Enteric pathogens including Salmonella enteric serovar Typhimurium can breach the epithelial barrier of the host and spread to systemic tissues. In response to infection, the host activates innate immune receptors via the signaling molecule MyD88, which induces protective inflammatory and antimicrobial responses. Most of these innate immune responses have been studied in hematopoietic cells, but the role of MyD88 signaling in other cell types remains poorly understood. Surprisingly, we found that Dermo1-Cre;Myd88fl/fl mice with mesenchymal cell-specific deficiency of MyD88 were less susceptible to orogastric and i.p. STyphimurium infection than their Myd88fl/fl littermates. The reduced susceptibility of Dermo1-Cre;Myd88fl/fl mice to infection was associated with lower loads of S. Typhimurium in the liver and spleen. Mutant analyses revealed that S. Typhimurium employs its virulence type III secretion system 2 to promote its growth through MyD88 signaling pathways in mesenchymal cells. Inflammatory monocytes function as a major cell population for systemic dissemination of S. Typhimurium Mechanistically, mesenchymal cell-specific MyD88 signaling promoted CCL2 production in the liver and spleen and recruitment of inflammatory monocytes to systemic organs in response to STyphimurium infection. Consistently, MyD88 signaling in mesenchymal cells enhanced the number of phagocytes including Ly6ChiLy6G- inflammatory monocytes harboring STyphimurium in the liver. These results suggest that S. Typhimurium promotes its systemic growth and dissemination through MyD88 signaling pathways in mesenchymal cells.
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Affiliation(s)
- Donghyun Kim
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109.,Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109.,Center for Integrative Rheumatoid Transcriptomics and Dynamics, Catholic University of Korea, Seoul 06591, Korea
| | - Sang-Uk Seo
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109.,Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109.,Department of Biomedical Sciences, Wide River Institute of Immunology, Seoul National University College of Medicine, Gangwon-do 25159, Korea
| | - Melody Y Zeng
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109.,Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Wan-Uk Kim
- Center for Integrative Rheumatoid Transcriptomics and Dynamics, Catholic University of Korea, Seoul 06591, Korea.,Department of Internal Medicine, College of Medicine, Catholic University of Korea, Seoul 06591, Korea; and
| | - Nobuhiko Kamada
- Division of Gastroenterology, Department of Internal Medicine, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Naohiro Inohara
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109
| | - Gabriel Núñez
- Department of Pathology, University of Michigan Medical School, Ann Arbor, MI 48109; .,Comprehensive Cancer Center, University of Michigan Medical School, Ann Arbor, MI 48109
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154
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Vander Broek CW, Stevens JM. Type III Secretion in the Melioidosis Pathogen Burkholderia pseudomallei. Front Cell Infect Microbiol 2017; 7:255. [PMID: 28664152 PMCID: PMC5471309 DOI: 10.3389/fcimb.2017.00255] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2017] [Accepted: 05/31/2017] [Indexed: 02/03/2023] Open
Abstract
Burkholderia pseudomallei is a Gram-negative intracellular pathogen and the causative agent of melioidosis, a severe disease of both humans and animals. Melioidosis is an emerging disease which is predicted to be vastly under-reported. Type III Secretion Systems (T3SSs) are critical virulence factors in Gram negative pathogens of plants and animals. The genome of B. pseudomallei encodes three T3SSs. T3SS-1 and -2, of which little is known, are homologous to Hrp2 secretion systems of the plant pathogens Ralstonia and Xanthomonas. T3SS-3 is better characterized and is homologous to the Inv/Mxi-Spa secretion systems of Salmonella spp. and Shigella flexneri, respectively. Upon entry into the host cell, B. pseudomallei requires T3SS-3 for efficient escape from the endosome. T3SS-3 is also required for full virulence in both hamster and murine models of infection. The regulatory cascade which controls T3SS-3 expression and the secretome of T3SS-3 have been described, as well as the effect of mutations of some of the structural proteins. Yet only a few effector proteins have been functionally characterized to date and very little work has been carried out to understand the hierarchy of assembly, secretion and temporal regulation of T3SS-3. This review aims to frame current knowledge of B. pseudomallei T3SSs in the context of other well characterized model T3SSs, particularly those of Salmonella and Shigella.
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Affiliation(s)
- Charles W Vander Broek
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of EdinburghMidlothian, United Kingdom
| | - Joanne M Stevens
- The Roslin Institute and Royal (Dick) School of Veterinary Studies, University of EdinburghMidlothian, United Kingdom
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155
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InvS Coordinates Expression of PrgH and FimZ and Is Required for Invasion of Epithelial Cells by Salmonella enterica serovar Typhimurium. J Bacteriol 2017; 199:JB.00824-16. [PMID: 28439039 DOI: 10.1128/jb.00824-16] [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] [Received: 11/28/2016] [Accepted: 04/20/2017] [Indexed: 11/20/2022] Open
Abstract
Deep sequencing has revolutionized our understanding of the bacterial RNA world and has facilitated the identification of 280 small RNAs (sRNAs) in Salmonella Despite the suspicions that sRNAs may play important roles in Salmonella pathogenesis, the functions of most sRNAs remain unknown. To advance our understanding of RNA biology in Salmonella virulence, we searched for sRNAs required for bacterial invasion into nonphagocytic cells. After screening 75 sRNAs, we discovered that the ablation of InvS caused a significant decrease of Salmonella invasion into epithelial cells. A proteomic analysis showed that InvS modulated the levels of several type III secreted Salmonella proteins. The level of PrgH, a type III secretion apparatus protein, was significantly lower in the absence of InvS, consistent with the known roles of PrgH in effector secretion and bacterial invasion. We discovered that InvS modulates fimZ expression and hence flagellar gene expression and motility. We propose that InvS coordinates the increase of PrgH and decrease in FimZ that promote efficient Salmonella invasion into nonphagocytic cells.IMPORTANCE Salmonellosis continues to be the most common foodborne infection reported by the CDC in the United States. Central to Salmonella pathogenesis is the ability to invade nonphagocytic cells and to replicate inside host cells. Invasion genes are known to be regulated by protein transcriptional networks, but little is known about the role played by small RNAs (sRNAs) in this process. We have identified a novel sRNA, InvS, that is involved in Salmonella invasion. Our result will likely provide an opportunity to better understand the fundamental question of how Salmonella regulates invasion gene expression and may inform strategies for therapeutic intervention.
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156
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Chong A, Lee S, Yang YA, Song J. The Role of Typhoid Toxin in Salmonella Typhi Virulence
. THE YALE JOURNAL OF BIOLOGY AND MEDICINE 2017; 90:283-290. [PMID: 28656014 PMCID: PMC5482304] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 10/29/2022]
Abstract
Unlike many of the nontyphoidal Salmonella serovars such as S. Typhimurium that cause restricted gastroenteritis, Salmonella Typhi is unique in that it causes life-threatening typhoid fever in humans. Despite the vast difference in disease outcomes that S. Typhi and S. Typhimurium cause in humans, there are few genomic regions that are unique to S. Typhi. Of these regions, the most notable is the small locus encoding typhoid toxin, an AB toxin that has several distinct characteristics that contribute to S. Typhi's pathogenicity. As a result, typhoid toxin and its role in S. Typhi virulence have been studied in an effort to gain insight into potential treatment and prevention strategies. Given the rise of multidrug-resistant strains, research in this area has become increasingly important. This article discusses the current understanding of typhoid toxin and potential directions for future research endeavors in order to better understand the contribution of typhoid toxin to S. Typhi virulence.
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Affiliation(s)
- Alexander Chong
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY
| | - Sohyoung Lee
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY
| | - Yi-An Yang
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY
| | - Jeongmin Song
- Department of Microbiology and Immunology, Cornell University College of Veterinary Medicine, Ithaca, NY
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157
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Hu Y, Huang H, Cheng X, Shu X, White AP, Stavrinides J, Köster W, Zhu G, Zhao Z, Wang Y. A global survey of bacterial type III secretion systems and their effectors. Environ Microbiol 2017; 19:3879-3895. [DOI: 10.1111/1462-2920.13755] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2016] [Accepted: 04/04/2017] [Indexed: 11/27/2022]
Affiliation(s)
- Yueming Hu
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - He Huang
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
| | - Xi Cheng
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - Xingsheng Shu
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
| | - Aaron P. White
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon SK Canada
| | | | - Wolfgang Köster
- Vaccine and Infectious Disease Organization; University of Saskatchewan; Saskatoon SK Canada
| | - Guoqiang Zhu
- College of Veterinary Medicine; Yangzhou University; Yangzhou China
| | - Zhendong Zhao
- MOH Key Laboratory of Systems Biology of Pathogens, Institute of Pathogen Biology; Chinese Academy of Medical Sciences & Peking Union Medical College; Beijing China
| | - Yejun Wang
- Department of Cell Biology and Genetics, School of Basic Medical Sciences; Shenzhen University Health Science Center; Shenzhen 518060 P.R. China
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158
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Control of type III protein secretion using a minimal genetic system. Nat Commun 2017; 8:14737. [PMID: 28485369 PMCID: PMC5436071 DOI: 10.1038/ncomms14737] [Citation(s) in RCA: 39] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2016] [Accepted: 01/27/2017] [Indexed: 01/12/2023] Open
Abstract
Gram-negative bacteria secrete proteins using a type III secretion system (T3SS), which functions as a needle-like molecular machine. The many proteins involved in T3SS construction are tightly regulated due to its role in pathogenesis and motility. Here, starting with the 35 kb Salmonella pathogenicity island 1 (SPI-1), we eliminated internal regulation and simplified the genetics by removing or recoding genes, scrambling gene order and replacing all non-coding DNA with synthetic genetic parts. This process results in a 16 kb cluster that shares no sequence identity, regulation or organizational principles with SPI-1. Building this simplified system led to the discovery of essential roles for an internal start site (SpaO) and small RNA (InvR). Further, it can be controlled using synthetic regulatory circuits, including under SPI-1 repressing conditions. This work reveals an incredible post-transcriptional robustness in T3SS assembly and aids its control as a tool in biotechnology.
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159
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Finn CE, Chong A, Cooper KG, Starr T, Steele-Mortimer O. A second wave of Salmonella T3SS1 activity prolongs the lifespan of infected epithelial cells. PLoS Pathog 2017; 13:e1006354. [PMID: 28426838 PMCID: PMC5413073 DOI: 10.1371/journal.ppat.1006354] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Revised: 05/02/2017] [Accepted: 04/14/2017] [Indexed: 11/19/2022] Open
Abstract
Type III secretion system 1 (T3SS1) is used by the enteropathogen Salmonella enterica serovar Typhimurium to establish infection in the gut. Effector proteins translocated by this system across the plasma membrane facilitate invasion of intestinal epithelial cells. One such effector, the inositol phosphatase SopB, contributes to invasion and mediates activation of the pro-survival kinase Akt. Following internalization, some bacteria escape from the Salmonella-containing vacuole into the cytosol and there is evidence suggesting that T3SS1 is expressed in this subpopulation. Here, we investigated the post-invasion role of T3SS1, using SopB as a model effector. In cultured epithelial cells, SopB-dependent Akt phosphorylation was observed at two distinct stages of infection: during and immediately after invasion, and later during peak cytosolic replication. Single cell analysis revealed that cytosolic Salmonella deliver SopB via T3SS1. Although intracellular replication was unaffected in a SopB deletion mutant, cells infected with ΔsopB demonstrated a lack of Akt phosphorylation, earlier time to death, and increased lysis. When SopB expression was induced specifically in cytosolic Salmonella, these effects were restored to levels observed in WT infected cells, indicating that the second wave of SopB protects this infected population against cell death via Akt activation. Thus, T3SS1 has two, temporally distinct roles during epithelial cell colonization. Additionally, we found that delivery of SopB by cytosolic bacteria was translocon-independent, in contrast to canonical effector translocation across eukaryotic membranes, which requires formation of a translocon pore. This mechanism was also observed for another T3SS1 effector, SipA. These findings reveal the functional and mechanistic adaptability of a T3SS that can be harnessed in different microenvironments.
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Affiliation(s)
- Ciaran E. Finn
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Audrey Chong
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Kendal G. Cooper
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Tregei Starr
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
| | - Olivia Steele-Mortimer
- Laboratory of Bacteriology, Rocky Mountain Laboratories, National Institutes of Allergy and Infectious Diseases, National Institutes of Health, Hamilton, Montana, United States of America
- * E-mail:
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160
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Rivera-Chávez F, Lopez CA, Bäumler AJ. Oxygen as a driver of gut dysbiosis. Free Radic Biol Med 2017; 105:93-101. [PMID: 27677568 DOI: 10.1016/j.freeradbiomed.2016.09.022] [Citation(s) in RCA: 185] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/09/2016] [Accepted: 09/23/2016] [Indexed: 12/13/2022]
Abstract
Changes in the composition of gut-associated microbial communities may underlie many inflammatory and allergic diseases. However, the processes that help maintain a stable community structure are poorly understood. Here we review topical work elucidating the nutrient-niche occupied by facultative anaerobic bacteria of the family Enterobacteriaceae, whose predominance within the gut-associated microbial community is a common marker of dysbiosis. A paucity of exogenous respiratory electron acceptors limits growth of Enterobacteriaceae within a balanced gut-associated microbial community. However, recent studies suggest that the availability of oxygen in the large bowel is markedly elevated by changes in host physiology that accompany antibiotic treatment or infection with enteric pathogens, such as Salmonella serovars or attaching and effacing (AE) pathogens. The resulting increase in oxygen availability, alone or in conjunction with other electron acceptors, drives an uncontrolled luminal expansion of Enterobacteriaceae. Insights into the underlying mechanisms provide important clues about factors that control the balance between the host and its resident microbial communities.
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Affiliation(s)
- Fabian Rivera-Chávez
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Christopher A Lopez
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, One Shields Ave, Davis, CA 95616, USA
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California Davis, One Shields Ave, Davis, CA 95616, USA.
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161
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Tsou LK, Yount JS, Hang HC. Epigallocatechin-3-gallate inhibits bacterial virulence and invasion of host cells. Bioorg Med Chem 2017; 25:2883-2887. [PMID: 28325635 DOI: 10.1016/j.bmc.2017.03.023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Revised: 03/08/2017] [Accepted: 03/09/2017] [Indexed: 11/28/2022]
Abstract
Increasing antibiotic resistance and beneficial effects of host microbiota has motivated the search for anti-infective agents that attenuate bacterial virulence rather than growth. For example, we discovered that specific flavonoids such as baicalein and quercetin from traditional medicinal plant extracts could attenuate Salmonella enterica serovar Typhimurium type III protein secretion and invasion of host cells. Here, we show epigallocatechin-3-gallate from green tea extracts also inhibits the activity of S. Typhimurium type III protein effectors and significantly reduces bacterial invasion into host cells. These results reveal additional dietary plant metabolites that can attenuate bacterial virulence and infection of host cells.
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Affiliation(s)
- Lun K Tsou
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA; Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes, Zhunan Town, Miaoli County 35053, Taiwan, ROC
| | - Jacob S Yount
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA; Department of Microbial Infection and Immunity, Center for Microbial Interface Biology, The Ohio State University, Columbus, OH 43210, USA
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University, New York, NY 10065, USA.
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162
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Almeida F, Seribelli AA, da Silva P, Medeiros MIC, Dos Prazeres Rodrigues D, Moreira CG, Allard MW, Falcão JP. Multilocus sequence typing of Salmonella Typhimurium reveals the presence of the highly invasive ST313 in Brazil. INFECTION GENETICS AND EVOLUTION 2017; 51:41-44. [PMID: 28288927 DOI: 10.1016/j.meegid.2017.03.009] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/07/2016] [Revised: 03/08/2017] [Accepted: 03/10/2017] [Indexed: 10/20/2022]
Affiliation(s)
- Fernanda Almeida
- Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, São Paulo, Brazil
| | | | - Patrick da Silva
- UNESP, Faculdade de Ciências Farmacêuticas de Araraquara, São Paulo, Brazil
| | | | | | | | - Marc W Allard
- Food and Drug Administration, College Park, MD, United States.
| | - Juliana Pfrimer Falcão
- Universidade de São Paulo, Faculdade de Ciências Farmacêuticas de Ribeirão Preto, São Paulo, Brazil.
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163
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Salmonella Persistence in Tomatoes Requires a Distinct Set of Metabolic Functions Identified by Transposon Insertion Sequencing. Appl Environ Microbiol 2017; 83:AEM.03028-16. [PMID: 28039131 DOI: 10.1128/aem.03028-16] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 12/19/2016] [Indexed: 12/30/2022] Open
Abstract
Human enteric pathogens, such as Salmonella spp. and verotoxigenic Escherichia coli, are increasingly recognized as causes of gastroenteritis outbreaks associated with the consumption of fruits and vegetables. Persistence in plants represents an important part of the life cycle of these pathogens. The identification of the full complement of Salmonella genes involved in the colonization of the model plant (tomato) was carried out using transposon insertion sequencing analysis. With this approach, 230,000 transposon insertions were screened in tomato pericarps to identify loci with reduction in fitness, followed by validation of the screen results using competition assays of the isogenic mutants against the wild type. A comparison with studies in animals revealed a distinct plant-associated set of genes, which only partially overlaps with the genes required to elicit disease in animals. De novo biosynthesis of amino acids was critical to persistence within tomatoes, while amino acid scavenging was prevalent in animal infections. Fitness reduction of the Salmonella amino acid synthesis mutants was generally more severe in the tomato rin mutant, which hyperaccumulates certain amino acids, suggesting that these nutrients remain unavailable to Salmonella spp. within plants. Salmonella lipopolysaccharide (LPS) was required for persistence in both animals and plants, exemplifying some shared pathogenesis-related mechanisms in animal and plant hosts. Similarly to phytopathogens, Salmonella spp. required biosynthesis of amino acids, LPS, and nucleotides to colonize tomatoes. Overall, however, it appears that while Salmonella shares some strategies with phytopathogens and taps into its animal virulence-related functions, colonization of tomatoes represents a distinct strategy, highlighting this pathogen's flexible metabolism.IMPORTANCE Outbreaks of gastroenteritis caused by human pathogens have been increasingly associated with foods of plant origin, with tomatoes being one of the common culprits. Recent studies also suggest that these human pathogens can use plants as alternate hosts as a part of their life cycle. While dual (animal/plant) lifestyles of other members of the Enterobacteriaceae family are well known, the strategies with which Salmonella colonizes plants are only partially understood. Therefore, we undertook a high-throughput characterization of the functions required for Salmonella persistence within tomatoes. The results of this study were compared with what is known about genes required for Salmonella virulence in animals and interactions of plant pathogens with their hosts to determine whether Salmonella repurposes its virulence repertoire inside plants or whether it behaves more as a phytopathogen during plant colonization. Even though Salmonella utilized some of its virulence-related genes in tomatoes, plant colonization required a distinct set of functions.
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164
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Byndloss MX, Rivera-Chávez F, Tsolis RM, Bäumler AJ. How bacterial pathogens use type III and type IV secretion systems to facilitate their transmission. Curr Opin Microbiol 2017; 35:1-7. [DOI: 10.1016/j.mib.2016.08.007] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2016] [Revised: 08/19/2016] [Accepted: 08/24/2016] [Indexed: 10/21/2022]
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165
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Ogunremi D, Nadin-Davis S, Dupras AA, Márquez IG, Omidi K, Pope L, Devenish J, Burke T, Allain R, Leclair D. Evaluation of a Multiplex PCR Assay for the Identification of Salmonella Serovars Enteritidis and Typhimurium Using Retail and Abattoir Samples. J Food Prot 2017; 80:295-301. [PMID: 28221989 DOI: 10.4315/0362-028x.jfp-16-167] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
A multiplex PCR was developed to identify the two most common serovars of Salmonella causing foodborne illness in Canada, namely, serovars Enteritidis and Typhimurium. The PCR was designed to amplify DNA fragments from four Salmonella genes, namely, invA gene (211-bp fragment), iroB gene (309-bp fragment), Typhimurium STM 4497 (523-bp fragment), and Enteritidis SE147228 (612-bp fragment). In addition, a 1,026-bp ribosomal DNA (rDNA) fragment universally present in bacterial species was included in the assay as an internal control fragment. The detection rate of the PCR was 100% among Salmonella Enteritidis (n = 92) and Salmonella Typhimurium (n = 33) isolates. All tested Salmonella isolates (n = 194) were successfully identified based on the amplification of at least one Salmonella -specific DNA fragment. None of the four Salmonella DNA amplicons were detected in any of the non- Salmonella isolates (n = 126), indicating an exclusivity rate of 100%. When applied to crude extracts of 2,001 field isolates of Salmonella obtained during the course of a national microbiological baseline study in broiler chickens and chicken products sampled from abattoir and retail outlets, 163 isolates, or 8.1%, tested positive for Salmonella Enteritidis and another 80 isolates, or 4.0%, tested as Salmonella Typhimurium. All isolates identified by serological testing as Salmonella Enteritidis in the microbiological study were also identified by using the multiplex PCR. The new test can be used to identify or confirm pure isolates of the two serovars and is also amenable for integration into existing culture procedures for accurate detection of Salmonella colonies.
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Affiliation(s)
- Dele Ogunremi
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Susan Nadin-Davis
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Andrée Ann Dupras
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Imelda Gálvan Márquez
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Katayoun Omidi
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Louise Pope
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - John Devenish
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Teresa Burke
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Ray Allain
- Ottawa Laboratory Fallowfield, Canadian Food Inspection Agency, 3851 Fallowfield Road, Ottawa, Ontario, Canada K2H 8P9
| | - Daniel Leclair
- Food Safety Science Division, Floor 5, 1400 Merivale Road, Tower 2, Ottawa, Ontario, Canada K1A 0Y9
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166
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Klein JA, Dave BM, Raphenya AR, McArthur AG, Knodler LA. Functional relatedness in the Inv/Mxi-Spa type III secretion system family. Mol Microbiol 2017; 103:973-991. [PMID: 27997726 DOI: 10.1111/mmi.13602] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 12/06/2016] [Indexed: 01/06/2023]
Abstract
Type III Secretion Systems (T3SSs) are structurally conserved nanomachines that span the inner and outer bacterial membranes, and via a protruding needle complex contact host cell membranes and deliver type III effector proteins. T3SS are phylogenetically divided into several families based on structural basal body components. Here we have studied the evolutionary and functional conservation of four T3SS proteins from the Inv/Mxi-Spa family: a cytosolic chaperone, two hydrophobic translocators that form a plasma membrane-integral pore, and the hydrophilic 'tip complex' translocator that connects the T3SS needle to the translocon pore. Salmonella enterica serovar Typhimurium (S. Typhimurium), a common cause of food-borne gastroenteritis, possesses two T3SSs, one belonging to the Inv/Mxi-Spa family. We used invasion-deficient S. Typhimurium mutants as surrogates for expression of translocator orthologs identified from an extensive phylogenetic analysis, and type III effector translocation and host cell invasion as a readout for complementation efficiency, and identified several Inv/Mxi-Spa orthologs that can functionally substitute for the S. Typhimurium chaperone and translocator proteins. Functional complementation correlates with amino acid sequence identity between orthologs, but varies considerably between the four proteins. This is the first in-depth survey of the functional interchangeability of Inv/Mxi-Spa T3SS proteins acting directly at the host-pathogen interface.
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Affiliation(s)
- Jessica A Klein
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
| | - Biren M Dave
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Amogelang R Raphenya
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Andrew G McArthur
- M.G. DeGroote Institute for Infectious Disease Research, Department of Biochemistry and Biomedical Sciences, DeGroote School of Medicine, McMaster University, Hamilton, ON, L8S 4K1, Canada
| | - Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, Pullman, WA, 99164, USA
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167
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Faber F, Thiennimitr P, Spiga L, Byndloss MX, Litvak Y, Lawhon S, Andrews-Polymenis HL, Winter SE, Bäumler AJ. Respiration of Microbiota-Derived 1,2-propanediol Drives Salmonella Expansion during Colitis. PLoS Pathog 2017; 13:e1006129. [PMID: 28056091 PMCID: PMC5215881 DOI: 10.1371/journal.ppat.1006129] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2016] [Accepted: 12/14/2016] [Indexed: 12/16/2022] Open
Abstract
Intestinal inflammation caused by Salmonella enterica serovar Typhimurium increases the availability of electron acceptors that fuel a respiratory growth of the pathogen in the intestinal lumen. Here we show that one of the carbon sources driving this respiratory expansion in the mouse model is 1,2-propanediol, a microbial fermentation product. 1,2-propanediol utilization required intestinal inflammation induced by virulence factors of the pathogen. S. Typhimurium used both aerobic and anaerobic respiration to consume 1,2-propanediol and expand in the murine large intestine. 1,2-propanediol-utilization did not confer a benefit in germ-free mice, but the pdu genes conferred a fitness advantage upon S. Typhimurium in mice mono-associated with Bacteroides fragilis or Bacteroides thetaiotaomicron. Collectively, our data suggest that intestinal inflammation enables S. Typhimurium to sidestep nutritional competition by respiring a microbiota-derived fermentation product. Salmonella enterica serovar Typhimurium induces intestinal inflammation to induce the generation of host-derived respiratory electron acceptors, thereby driving a respiratory pathogen expansion, which aids infectious transmission by the fecal oral route. However, the identity of nutrients serving as electron donors to enable S. Typhimurium to edge out competing microbes in the competitive environment of the gut are just beginning to be worked out. Here we demonstrate that aerobic and anaerobic respiratory pathways cooperate to promote growth of Salmonella on the microbial fermentation product 1,2-propanediol. We propose that pathogen-induced intestinal inflammation enables Salmonella to sidestep nutritional competition with the largely anaerobic microbiota by respiring a microbe-derived metabolite that cannot be consumed by fermentation.
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Affiliation(s)
- Franziska Faber
- Department of Medial Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, United States of America
| | - Parameth Thiennimitr
- Department of Microbiology, Faculty of Medicine, Chiang Mai University, Chiang Mai, Thailand
| | - Luisella Spiga
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Mariana X. Byndloss
- Department of Medial Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, United States of America
| | - Yael Litvak
- Department of Medial Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, United States of America
| | - Sara Lawhon
- Department of Veterinary Pathobiology, College of Veterinary Medicine, Texas A&M University, College Station, TX, United States of America
| | - Helene L. Andrews-Polymenis
- Department of Microbial Pathogenesis and Immunology, College of Medicine, Texas A&M University Health Science Center, Bryan, TX, United States of America
| | - Sebastian E. Winter
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, TX, United States of America
| | - Andreas J. Bäumler
- Department of Medial Microbiology and Immunology, School of Medicine, University of California Davis, Davis, CA, United States of America
- * E-mail:
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168
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Klein JA, Powers TR, Knodler LA. Measurement of Salmonella enterica Internalization and Vacuole Lysis in Epithelial Cells. Methods Mol Biol 2017; 1519:285-296. [PMID: 27815887 DOI: 10.1007/978-1-4939-6581-6_19] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
Establishment of an intracellular niche within mammalian cells is key to the pathogenesis of the gastrointestinal bacterium, Salmonella enterica serovar Typhimurium (S. Typhimurium). Here we will describe how to study the internalization of S. Typhimurium into human epithelial cells using the gentamicin protection assay. The assay takes advantage of the relatively poor penetration of gentamicin into mammalian cells; internalized bacteria are effectively protected from its antibacterial actions. A second assay, the chloroquine (CHQ) resistance assay, can be used to determine the proportion of internalized bacteria that have lysed or damaged their Salmonella-containing vacuole and are therefore residing within the cytosol. Its application to the quantification of cytosolic S. Typhimurium in epithelial cells will also be presented. Together, these protocols provide an inexpensive, rapid and sensitive quantitative measure of bacterial internalization and vacuole lysis by S. Typhimurium.
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Affiliation(s)
- Jessica A Klein
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA
| | - TuShun R Powers
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA
| | - Leigh A Knodler
- Paul G. Allen School for Global Animal Health, College of Veterinary Medicine, Washington State University, 647090, Pullman, WA, 99164-7090, USA.
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169
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Abstract
Type III secretion systems (T3SSs) afford Gram-negative bacteria an intimate means of altering the biology of their eukaryotic hosts--the direct delivery of effector proteins from the bacterial cytoplasm to that of the eukaryote. This incredible biophysical feat is accomplished by nanosyringe "injectisomes," which form a conduit across the three plasma membranes, peptidoglycan layer, and extracellular space that form a barrier to the direct delivery of proteins from bacterium to host. The focus of this chapter is T3SS function at the structural level; we will summarize the core findings that have shaped our understanding of the structure and function of these systems and highlight recent developments in the field. In turn, we describe the T3SS secretory apparatus, consider its engagement with secretion substrates, and discuss the posttranslational regulation of secretory function. Lastly, we close with a discussion of the future prospects for the interrogation of structure-function relationships in the T3SS.
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170
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Lactococcus lactis subsp. cremoris strain JFR1 attenuates Salmonella adhesion to human intestinal cells in vitro. Food Res Int 2016; 90:147-153. [DOI: 10.1016/j.foodres.2016.10.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 10/06/2016] [Accepted: 10/10/2016] [Indexed: 11/21/2022]
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171
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Postreplication Roles of the Brucella VirB Type IV Secretion System Uncovered via Conditional Expression of the VirB11 ATPase. mBio 2016; 7:mBio.01730-16. [PMID: 27899503 PMCID: PMC5137499 DOI: 10.1128/mbio.01730-16] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Brucella abortus, the bacterial agent of the worldwide zoonosis brucellosis, primarily infects host phagocytes, where it undergoes an intracellular cycle within a dedicated membrane-bound vacuole, the Brucella-containing vacuole (BCV). Initially of endosomal origin (eBCV), BCVs are remodeled into replication-permissive organelles (rBCV) derived from the host endoplasmic reticulum, a process that requires modulation of host secretory functions via delivery of effector proteins by the Brucella VirB type IV secretion system (T4SS). Following replication, rBCVs are converted into autophagic vacuoles (aBCVs) that facilitate bacterial egress and subsequent infections, arguing that the bacterium sequentially manipulates multiple cellular pathways to complete its cycle. The VirB T4SS is essential for rBCV biogenesis, as VirB-deficient mutants are stalled in eBCVs and cannot mediate rBCV biogenesis. This has precluded analysis of whether the VirB apparatus also drives subsequent stages of the Brucella intracellular cycle. To address this issue, we have generated a B. abortus strain in which VirB T4SS function is conditionally controlled via anhydrotetracycline (ATc)-dependent complementation of a deletion of the virB11 gene encoding the VirB11 ATPase. We show in murine bone marrow-derived macrophages (BMMs) that early VirB production is essential for optimal rBCV biogenesis and bacterial replication. Transient expression of virB11 prior to infection was sufficient to mediate normal rBCV biogenesis and bacterial replication but led to T4SS inactivation and decreased aBCV formation and bacterial release, indicating that these postreplication stages are also T4SS dependent. Hence, our findings support the hypothesis of additional, postreplication roles of type IV secretion in the Brucella intracellular cycle. Many intracellular bacterial pathogens encode specialized secretion systems that deliver effector proteins into host cells to mediate the multiple stages of their intracellular cycles. Because these intracellular events occur sequentially, classical genetic approaches cannot address the late roles that these apparatuses play, as secretion-deficient mutants cannot proceed past their initial defect. Here we have designed a functionally controllable VirB type IV secretion system (T4SS) in the bacterial pathogen Brucella abortus to decipher its temporal requirements during the bacterium’s intracellular cycle in macrophages. By controlling production of the VirB11 ATPase, which energizes the T4SS, we show not only that this apparatus is required early to generate the Brucella replicative organelle but also that it contributes to completion of the bacterium’s cycle and bacterial egress. Our findings expand upon the pathogenic functions of the Brucella VirB T4SS and illustrate targeting of secretion ATPases as a useful strategy to manipulate the activity of bacterial secretion systems.
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172
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Huang KY, Wang YH, Chien KY, Janapatla RP, Chiu CH. Hyperinvasiveness of Salmonella enterica serovar Choleraesuis linked to hyperexpression of type III secretion systems in vitro. Sci Rep 2016; 6:37642. [PMID: 27886215 PMCID: PMC5122882 DOI: 10.1038/srep37642] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2016] [Accepted: 11/01/2016] [Indexed: 12/22/2022] Open
Abstract
Salmonella enterica serovars Choleraesuis and Typhimurium are among the non-typhoid Salmonella serovars that are important zoonotic pathogens. In clinical observation, S. Typhimurium typically causes diarrheal diseases; however, S. Choleraesuis shows high predilection to cause bacteremia. The mechanism why S. Choleraesuis is more invasive to humans remains unknown. In this study, we compared the S. Typhimurium LT2 and S. Choleraesuis SC-B67 proteomes through stable isotope labeling of amino acid in cell culture (SILAC). In SILAC, the expression of many virulence proteins in two type III secretion systems (T3SSs) were significantly higher in S. Choleraesuis than in S. Typhimurium. Similar differences were also found at the transcriptional level. Compared to S. Typhimurium, S. Choleraesuis showed a higher penetration level to Caco-2 (>100-fold) and MDCK (>10-fold) monolayers. In mice after oral challenge, the invasion of spleen and liver was also higher in S. Choleraesuis than in S. Typhimurium. The transcription of hilD in S. Choleraesuis was increased in physiological (1 mM) or high (10 mM) concentrations of Mg2+, but not in low (8 μM) concentration. We conclude that S. Choleraesuis showed hyperinvasiveness in cellular as well as mouse models due to hyperexpression of T3SS genes.
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Affiliation(s)
- Kuan-Yeh Huang
- Graduate Institute of Biomedical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Yi-Hsin Wang
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Kun-Yi Chien
- Graduate Institute of Biomedical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Rajendra Prasad Janapatla
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
| | - Cheng-Hsun Chiu
- Graduate Institute of Biomedical Sciences, Chang Gung University College of Medicine, Taoyuan, Taiwan
- Molecular Infectious Disease Research Center, Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taoyuan, Taiwan
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173
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Genetic Determinants of Salmonella enterica Serovar Typhimurium Proliferation in the Cytosol of Epithelial Cells. Infect Immun 2016; 84:3517-3526. [PMID: 27698022 DOI: 10.1128/iai.00734-16] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 09/26/2016] [Indexed: 11/20/2022] Open
Abstract
Intestinal epithelial cells provide an important colonization niche for Salmonella enterica serovar Typhimurium during gastrointestinal infections. In infected epithelial cells, a subpopulation of S Typhimurium bacteria damage their internalization vacuole, leading to escape from the Salmonella-containing vacuole (SCV) and extensive proliferation in the cytosol. Little is known about the bacterial determinants of nascent SCV lysis and subsequent survival and replication of Salmonella in the cytosol. To pinpoint S Typhimurium virulence factors responsible for these steps in the intracellular infectious cycle, we screened a S Typhimurium multigene deletion library in Caco-2 C2Bbe1 and HeLa epithelial cells for mutants that had an altered proportion of cytosolic bacteria compared to the wild type. We used a gentamicin protection assay in combination with a chloroquine resistance assay to quantify total and cytosolic bacteria, respectively, for each strain. Mutants of three S Typhimurium genes, STM1461 (ydgT), STM2829 (recA), and STM3952 (corA), had reduced cytosolic proliferation compared to wild-type bacteria, and one gene, STM2120 (asmA), displayed increased cytosolic replication. None of the mutants were affected for lysis of the nascent SCV or vacuolar replication in epithelial cells, indicating that these genes are specifically required for survival and proliferation of S Typhimurium in the epithelial cell cytosol. These are the first genes identified to contribute to this step of the S Typhimurium infectious cycle.
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174
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Vergnes A, Viala JPM, Ouadah-Tsabet R, Pocachard B, Loiseau L, Méresse S, Barras F, Aussel L. The iron-sulfur cluster sensor IscR is a negative regulator of Spi1 type III secretion system in Salmonella enterica. Cell Microbiol 2016; 19. [PMID: 27704705 DOI: 10.1111/cmi.12680] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Revised: 09/30/2016] [Accepted: 09/30/2016] [Indexed: 11/28/2022]
Abstract
Iron-sulfur (Fe-S)-containing proteins contribute to various biological processes, including redox reactions or regulation of gene expression. Living organisms have evolved by developing distinct biosynthetic pathways to assemble these clusters, including iron sulfur cluster (ISC) and sulfur mobilization (SUF). Salmonella enterica serovar Typhimurium is an intracellular pathogen responsible for a wide range of infections, from gastroenteritis to severe systemic diseases. Salmonella possesses all known prokaryotic systems to assemble Fe-S clusters, including ISC and SUF. Because iron starvation and oxidative stress are detrimental for Fe-S enzyme biogenesis and because such environments are often met by Salmonella during its intracellular life, we investigated the role of the ISC and SUF machineries during the course of the infection. The iscU mutant, which is predicted to have no ISC system functioning, was found to be defective for epithelial cell invasion and for mice infection, whereas the sufBC mutant, which is predicted to have no SUF system functioning, did not present any defect. Moreover, the iscU mutant was highly impaired in the expression of Salmonella pathogenicity island 1 (Spi1) type III secretion system that is essential for the first stage of Salmonella infection. The Fe-S cluster sensor IscR, a transcriptional regulator matured by the ISC machinery, was shown to bind the promoter of hilD, which encodes the master regulator of Spi1. IscR was also demonstrated to repress hilD and subsequently Spi1 gene expression, consistent with the observation that an IscR mutant is hyper-invasive in epithelial cells. Collectively, our findings indicate that the ISC machinery plays a central role in Salmonella virulence through the ability of IscR to down-regulate Spi1 gene expression. At a broader level, this model illustrates an adaptive mechanism used by bacterial pathogens to modulate their infectivity according to iron and oxygen availability.
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Affiliation(s)
- Alexandra Vergnes
- Aix Marseille Université, CNRS, LCB UMR, 7283, IMM, Marseille, France
| | - Julie P M Viala
- Aix Marseille Université, CNRS, LCB UMR, 7283, IMM, Marseille, France
| | | | | | - Laurent Loiseau
- Aix Marseille Université, CNRS, LCB UMR, 7283, IMM, Marseille, France
| | | | - Frédéric Barras
- Aix Marseille Université, CNRS, LCB UMR, 7283, IMM, Marseille, France
| | - Laurent Aussel
- Aix Marseille Université, CNRS, LCB UMR, 7283, IMM, Marseille, France
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175
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Park D, Arabyan N, Williams CC, Song T, Mitra A, Weimer BC, Maverakis E, Lebrilla CB. Salmonella Typhimurium Enzymatically Landscapes the Host Intestinal Epithelial Cell (IEC) Surface Glycome to Increase Invasion. Mol Cell Proteomics 2016; 15:3653-3664. [PMID: 27754876 DOI: 10.1074/mcp.m116.063206] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2016] [Revised: 09/28/2016] [Indexed: 01/01/2023] Open
Abstract
Although gut host-pathogen interactions are glycan-mediated processes, few details are known about the participating structures. Here we employ high-resolution mass spectrometric profiling to comprehensively identify and quantitatively measure the exact modifications of native intestinal epithelial cell surface N-glycans induced by S. typhimurium infection. Sixty minutes postinfection, select sialylated structures showed decreases in terms of total number and abundances. To assess the effect of cell surface mannosylation, we selectively rerouted glycan expression on the host using the alpha-mannosidase inhibitor, kifunensine, toward overexpression of high mannose. Under these conditions, internalization of S. typhimurium significantly increased, demonstrating that bacteria show preference for particular structures. Finally, we developed a novel assay to measure membrane glycoprotein turnover rates, which revealed that glycan modifications occur by bacterial enzyme activity rather than by host-derived restructuring strategies. This study is the first to provide precise structural information on how host N-glycans are altered to support S. typhimurium invasion.
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Affiliation(s)
- Dayoung Park
- From the ‡Department of Chemistry, University of California, Davis, CA, 95616
| | - Narine Arabyan
- §Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616
| | - Cynthia C Williams
- From the ‡Department of Chemistry, University of California, Davis, CA, 95616
| | - Ting Song
- From the ‡Department of Chemistry, University of California, Davis, CA, 95616
| | - Anupam Mitra
- ¶Department of Dermatology, University of California, Davis School of Medicine, Sacramento, CA, 95817
| | - Bart C Weimer
- §Department of Population Health and Reproduction, School of Veterinary Medicine, University of California, Davis, CA, 95616
| | - Emanual Maverakis
- ¶Department of Dermatology, University of California, Davis School of Medicine, Sacramento, CA, 95817
| | - Carlito B Lebrilla
- From the ‡Department of Chemistry, University of California, Davis, CA, 95616;
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176
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Flood P, Alvarez L, Reynaud EG. Free-floating epithelial micro-tissue arrays: a low cost and versatile technique. Biofabrication 2016; 8:045006. [DOI: 10.1088/1758-5090/8/4/045006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
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177
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Oueslati W, Rjeibi MR, Mhadhbi M, Jbeli M, Zrelli S, Ettriqui A. Prevalence, virulence and antibiotic susceptibility of Salmonella spp. strains, isolated from beef in Greater Tunis (Tunisia). Meat Sci 2016; 119:154-9. [DOI: 10.1016/j.meatsci.2016.04.037] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2015] [Revised: 03/29/2016] [Accepted: 04/29/2016] [Indexed: 11/28/2022]
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178
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Zhao Y, Gorvel JP, Méresse S. Effector proteins support the asymmetric apportioning of Salmonella during cytokinesis. Virulence 2016; 7:669-78. [PMID: 27046257 PMCID: PMC4991364 DOI: 10.1080/21505594.2016.1173298] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Salmonella-infected cells are characterized by the presence of intra-cellular membranous tubules that emerge from bacterial vacuoles and extend along microtubules. The formation of Salmonella-induced tubules depends on the Salmonella pathogenicity island 2-encoded type III secretion system (T3SS-2) that translocates bacterial effector proteins inside host cells. Effector proteins have enzymatic activities or allow for hijacking of cellular functions. The role of Salmonella-induced tubules in virulence remains unclear but their absence is correlated with virulence defects. This study describes the presence of inter-cellular tubules that arise between daughter cells during cytokinesis. Inter-cellular tubules connect bacterial vacuoles originally present in the parent cell and that have been apportioned between daughters. Their formation requires a functional T3SS-2 and effector proteins. Our data establish a correlation between the formation of inter-cellular tubules and the asymmetric distribution of bacterial vacuoles in daughters. Thus, by manipulating the distribution of bacteria in cytokinetic cells, Salmonella T3SS-2 effector proteins may increase bacterial spreading and the systemic character of the infection.
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Affiliation(s)
- Yaya Zhao
- a Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
| | - Jean-Pierre Gorvel
- a Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
| | - Stéphane Méresse
- a Centre d'Immunologie de Marseille-Luminy, Aix Marseille Université UM2 , Inserm, U1104, CNRS UMR7280, Marseille , France
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179
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Hung CC, Eade CR, Altier C. The protein acyltransferase Pat post-transcriptionally controls HilD to repress Salmonella invasion. Mol Microbiol 2016; 102:121-36. [PMID: 27341691 DOI: 10.1111/mmi.13451] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 06/22/2016] [Indexed: 01/12/2023]
Abstract
N-Lysine acylation is a post-translational modification important for both prokaryotic and eukaryotic cells to control a wide array of cellular functions. Here we demonstrate that the protein acyltransferase Pat regulates genes on Salmonella Pathogenicity Island 1 (SPI1) that are required for the invasion of the intestinal epithelium. Mutation of pat slightly increased spleen colonization by Salmonella in streptomycin-treated mice, with more of the pat mutant reaching the spleen than the wild type strain. Growth of Salmonella under specific conditions selectively induced expression of Pat, and deletion of pat increased SPI1 gene expression under the same growth conditions. In addition, over-expression of Pat repressed SPI1 expression and bacterial entry into epithelial cells. These results demonstrate that Salmonella invasion is negatively controlled by Pat. Regulation of the SPI1 central regulator HilD was essential for Pat to exert its effects. The control of HilD by Pat was through post-transcriptional mechanisms, moderately repressing hilD translation while significantly reducing HilD stability. Additionally, growth of Salmonella in the presence of histone deacetylases inhibitors reduced expression of SPI1 by affecting HilD stability, supporting the concept that altering the stability of this regulator is required for Pat to control Salmonella invasion.
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Affiliation(s)
- Chien-Che Hung
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA.
| | - Colleen R Eade
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
| | - Craig Altier
- Department of Population Medicine and Diagnostic Sciences, College of Veterinary Medicine, Cornell University, Ithaca, NY, 14853, USA
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180
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Sen R, Nayak L, De RK. A review on host-pathogen interactions: classification and prediction. Eur J Clin Microbiol Infect Dis 2016; 35:1581-99. [PMID: 27470504 DOI: 10.1007/s10096-016-2716-7] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 06/22/2016] [Indexed: 01/01/2023]
Abstract
The research on host-pathogen interactions is an ever-emerging and evolving field. Every other day a new pathogen gets discovered, along with comes the challenge of its prevention and cure. As the intelligent human always vies for prevention, which is better than cure, understanding the mechanisms of host-pathogen interactions gets prior importance. There are many mechanisms involved from the pathogen as well as the host sides while an interaction happens. It is a vis-a-vis fight of the counter genes and proteins from both sides. Who wins depends on whether a host gets an infection or not. Moreover, a higher level of complexity arises when the pathogens evolve and become resistant to a host's defense mechanisms. Such pathogens pose serious challenges for treatment. The entire human population is in danger of such long-lasting persistent infections. Some of these infections even increase the rate of mortality. Hence there is an immediate emergency to understand how the pathogens interact with their host for successful invasion. It may lead to discovery of appropriate preventive measures, and the development of rational therapeutic measures and medication against such infections and diseases. This review, a state-of-the-art updated scenario of host-pathogen interaction research, has been done by keeping in mind this urgency. It covers the biological and computational aspects of host-pathogen interactions, classification of the methods by which the pathogens interact with their hosts, different machine learning techniques for prediction of host-pathogen interactions, and future scopes of this research field.
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Affiliation(s)
- R Sen
- Machine Intelligence Unit, Indian Statistical Institute, 203, Barrackpore Trunk Road, Kolkata, 700108, India
| | - L Nayak
- Machine Intelligence Unit, Indian Statistical Institute, 203, Barrackpore Trunk Road, Kolkata, 700108, India
| | - R K De
- Machine Intelligence Unit, Indian Statistical Institute, 203, Barrackpore Trunk Road, Kolkata, 700108, India.
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181
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Molina-Quiroz RC, Silva CA, Molina CF, Leiva LE, Reyes-Cerpa S, Contreras I, Santiviago CA. Exposure to sub-inhibitory concentrations of cefotaxime enhances the systemic colonization of Salmonella Typhimurium in BALB/c mice. Open Biol 2016; 5:rsob.150070. [PMID: 26468132 PMCID: PMC4632510 DOI: 10.1098/rsob.150070] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
It has been proposed that sub-inhibitory concentrations of antibiotics play a role in virulence modulation. In this study, we evaluated the ability of Salmonella enterica serovar Typhimurium (hereafter S. Typhimurium) to colonize systemically BALB/c mice after exposure to a sub-inhibitory concentration of cefotaxime (CTX). In vivo competition assays showed a fivefold increase in systemic colonization of CTX-exposed bacteria when compared to untreated bacteria. To identify the molecular mechanisms involved in this phenomenon, we carried out a high-throughput genetic screen. A transposon library of S. Typhimurium mutants was subjected to negative selection in the presence of a sub-inhibitory concentration of CTX and genes related to anaerobic metabolism, biosynthesis of purines, pyrimidines, amino acids and other metabolites were identified as needed to survive in this condition. In addition, an impaired ability for oxygen consumption was observed when bacteria were cultured in the presence of a sub-inhibitory concentration of CTX. Altogether, our data indicate that exposure to sub-lethal concentrations of CTX increases the systemic colonization of S. Typhimurium in BALB/c mice in part by the establishment of a fitness alteration conducive to anaerobic metabolism.
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Affiliation(s)
- Roberto C Molina-Quiroz
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile Center for Adaptation Genetics and Drugs Resistance, Molecular Biology and Microbiology Faculty, Tufts University, Boston, MA, USA
| | - Cecilia A Silva
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | | | - Lorenzo E Leiva
- Centro de InmunoBioTecnología, Programa Disciplinario de Inmunología, Instituto de Ciencias Biomédicas, Universidad de Chile, Santiago, Chile
| | - Sebastián Reyes-Cerpa
- Laboratorio de Virología, Centro de Biotecnología Acuícola (CBA), Facultad de Química y Biología, Universidad de Santiago de Chile, Santiago, Chile
| | - Inés Contreras
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
| | - Carlos A Santiviago
- Laboratorio de Microbiología, Departamento de Bioquímica y Biología Molecular, Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile, Santiago, Chile
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182
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Energy Taxis toward Host-Derived Nitrate Supports a Salmonella Pathogenicity Island 1-Independent Mechanism of Invasion. mBio 2016; 7:mBio.00960-16. [PMID: 27435462 PMCID: PMC4958259 DOI: 10.1128/mbio.00960-16] [Citation(s) in RCA: 39] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023] Open
Abstract
Salmonella enterica serovar Typhimurium can cross the epithelial barrier using either the invasion-associated type III secretion system (T3SS-1) or a T3SS-1-independent mechanism that remains poorly characterized. Here we show that flagellum-mediated motility supported a T3SS-1-independent pathway for entering ileal Peyer’s patches in the mouse model. Flagellum-dependent invasion of Peyer’s patches required energy taxis toward nitrate, which was mediated by the methyl-accepting chemotaxis protein (MCP) Tsr. Generation of nitrate in the intestinal lumen required inducible nitric oxide synthase (iNOS), which was synthesized constitutively in the mucosa of the terminal ileum but not in the jejunum, duodenum, or cecum. Tsr-mediated invasion of ileal Peyer’s patches was abrogated in mice deficient for Nos2, the gene encoding iNOS. We conclude that Tsr-mediated energy taxis enables S. Typhimurium to migrate toward the intestinal epithelium by sensing host-derived nitrate, thereby contributing to invasion of Peyer’s patches. Nontyphoidal Salmonella serovars, such as S. enterica serovar Typhimurium, are a common cause of gastroenteritis in immunocompetent individuals but can also cause bacteremia in immunocompromised individuals. While the invasion-associated type III secretion system (T3SS-1) is important for entry, S. Typhimurium strains lacking a functional T3SS-1 can still cross the intestinal epithelium and cause a disseminated lethal infection in mice. Here we observed that flagellum-mediated motility and chemotaxis contributed to a T3SS-1-independent pathway for invasion and systemic dissemination to the spleen. This pathway required the methyl-accepting chemotaxis protein (MCP) Tsr and energy taxis toward host-derived nitrate, which we found to be generated by inducible nitric oxide synthase (iNOS) in the ileal mucosa prior to infection. Collectively, our data suggest that S. Typhimurium enhances invasion by actively migrating toward the intestinal epithelium along a gradient of host-derived nitrate emanating from the mucosal surface of the ileum.
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183
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Bäumler AJ, Sperandio V. Interactions between the microbiota and pathogenic bacteria in the gut. Nature 2016; 535:85-93. [PMID: 27383983 PMCID: PMC5114849 DOI: 10.1038/nature18849] [Citation(s) in RCA: 809] [Impact Index Per Article: 101.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 04/22/2016] [Indexed: 02/07/2023]
Abstract
The microbiome has an important role in human health. Changes in the microbiota can confer resistance to or promote infection by pathogenic bacteria. Antibiotics have a profound impact on the microbiota that alters the nutritional landscape of the gut and can lead to the expansion of pathogenic populations. Pathogenic bacteria exploit microbiota-derived sources of carbon and nitrogen as nutrients and regulatory signals to promote their own growth and virulence. By eliciting inflammation, these bacteria alter the intestinal environment and use unique systems for respiration and metal acquisition to drive their expansion. Unravelling the interactions between the microbiota, the host and pathogenic bacteria will produce strategies for manipulating the microbiota against infectious diseases.
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Affiliation(s)
- Andreas J Bäumler
- Department of Medical Microbiology and Immunology, University of California, Davis, School of Medicine, Davis, California 95616, USA
| | - Vanessa Sperandio
- Department of Microbiology, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9048, USA
- Department of Biochemistry, University of Texas Southwestern Medical Center, Dallas, Texas 75390-9038, USA
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184
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Neutrophils mediate Salmonella Typhimurium clearance through the GBP4 inflammasome-dependent production of prostaglandins. Nat Commun 2016; 7:12077. [PMID: 27363812 PMCID: PMC4932187 DOI: 10.1038/ncomms12077] [Citation(s) in RCA: 81] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Accepted: 05/26/2016] [Indexed: 01/05/2023] Open
Abstract
Inflammasomes are cytosolic molecular platforms that alert the immune system about the presence of infection. Here we report that zebrafish guanylate-binding protein 4 (Gbp4), an IFNγ-inducible GTPase protein harbouring a C-terminal CARD domain, is required for the inflammasome-dependent clearance of Salmonella Typhimurium (ST) by neutrophils in vivo. Despite the presence of the CARD domain, Gbp4 requires the universal inflammasome adaptor Asc for mediating its antibacterial function. In addition, the GTPase activity of Gbp4 is indispensable for inflammasome activation and ST clearance. Mechanistically, neutrophils are recruited to the infection site through the inflammasome-independent production of the chemokine (CXC motif) ligand 8 and leukotriene B4, and then mediate bacterial clearance through the Gbp4 inflammasome-dependent biosynthesis of prostaglandin D2. Our results point to GBPs as key inflammasome adaptors required for prostaglandin biosynthesis and bacterial clearance by neutrophils and suggest that transient activation of the inflammasome may be used to treat bacterial infections. The role of guanylate-binding proteins (GBPs) in innate immunity is increasingly recognized. Here the authors show that GBP4 activates inflammasome in zebrafish neutrophils, and that this process is critical for the clearance of Salmonella infection via prostaglandin D2.
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185
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Clustered Intracellular Salmonella enterica Serovar Typhimurium Blocks Host Cell Cytokinesis. Infect Immun 2016; 84:2149-2158. [PMID: 27185791 PMCID: PMC4936369 DOI: 10.1128/iai.00062-16] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2016] [Accepted: 05/06/2016] [Indexed: 12/27/2022] Open
Abstract
Several bacterial pathogens and viruses interfere with the cell cycle of their host cells to enhance virulence. This is especially apparent in bacteria that colonize the gut epithelium, where inhibition of the cell cycle of infected cells enhances the intestinal colonization. We found that intracellular Salmonella enterica serovar Typhimurium induced the binucleation of a large proportion of epithelial cells by 14 h postinvasion and that the effect was dependent on an intact Salmonella pathogenicity island 2 (SPI-2) type 3 secretion system. The SPI-2 effectors SseF and SseG were required to induce binucleation. SseF and SseG are known to maintain microcolonies of Salmonella-containing vacuoles close to the microtubule organizing center of infected epithelial cells. During host cell division, these clustered microcolonies prevented the correct localization of members of the chromosomal passenger complex and mitotic kinesin-like protein 1 and consequently prevented cytokinesis. Tetraploidy, arising from a cytokinesis defect, is known to have a deleterious effect on subsequent cell divisions, resulting in either chromosomal instabilities or cell cycle arrest. In infected mice, proliferation of small intestinal epithelial cells was compromised in an SseF/SseG-dependent manner, suggesting that cytokinesis failure caused by S. Typhimurium delays epithelial cell turnover in the intestine.
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186
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Brannon JR, Hadjifrangiskou M. The arsenal of pathogens and antivirulence therapeutic strategies for disarming them. Drug Des Devel Ther 2016; 10:1795-806. [PMID: 27313446 PMCID: PMC4890686 DOI: 10.2147/dddt.s98939] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Pathogens deploy an arsenal of virulence factors (VFs) to establish themselves within their infectious niche. The discovery of antimicrobial compounds and their development into therapeutics has made a monumental impact on human and microbial populations. Although humans have used antimicrobials for medicinal and agricultural purposes, microorganism populations have developed and shared resistance mechanisms to persevere in the face of classical antimicrobials. However, a positive substitute is antivirulence therapy; antivirulence therapeutics prevent or interrupt an infection by counteracting a pathogen's VFs. Their application can reduce the use of broad-spectrum antimicrobials and dampen the frequency with which resistant strains emerge. Here, we summarize the contribution of VFs to various acute and chronic infections. In correspondence with this, we provide an overview of the research and development of antivirulence strategies.
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Affiliation(s)
- John R Brannon
- Division of Molecular Pathogenesis, Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
| | - Maria Hadjifrangiskou
- Division of Molecular Pathogenesis, Department of Pathology, Microbiology and Immunology, Vanderbilt University School of Medicine, Nashville, TN, USA
- Department of Urologic Surgery, Vanderbilt University School of Medicine, Nashville, TN, USA
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187
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Song Q, Shen X, Yang Y, Zhang D, Gao H. Genetically Similar Isolates of Salmonella enterica Serotype Enteritidis Persistent in China for a Long-Term Period. J Food Sci 2016; 81:M1778-81. [PMID: 27228342 DOI: 10.1111/1750-3841.13339] [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] [Received: 02/21/2016] [Accepted: 04/12/2016] [Indexed: 12/01/2022]
Abstract
Salmonella enterica serotype Enteritidis (S. Enteritidis) is an important causative agent of nontyphoidal salmonellosis in human populations. In this study, we collected 72 S. Enteritidis strains from 2004 to 2014 in Ningbo, mid-east China. Of the 72 strains, we identified a dominant clone of 58 strains recovered from patient's feces (n = 48), blood (n = 1), pleural effusion (n = 1), chickens (n = 3), and dessert cakes (n = 5) by pulsed-field gel electrophoresis (PFGE) and variable-number of tandem repeat analysis (MLVA). The profile arrangements of MLVA were SE1-SE2-SE3-SE5-SE6-SE8-SE9: 4-4-3-11-10-1-3. These dominant strains were susceptible to ampicillin, chloramphenicol, tetracycline, ciprofloxacin, gentamicin, cefotaxime and trimethoprim-sulfamethoxazole, and resistant to nalidixic acid. Additionally, all isolates harboured virulence genes invA, sipA, sopE, and spvB when tested by PCR. Our results reveal that genetically similar S. Enteritidis strains which accounted for several outbreaks as well as blood infection and pleural cavity infection are prevalent in China for a long-term period. This situation calls for further attention in the prevention and control of foodborne disease caused by Salmonella species.
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Affiliation(s)
- Qifa Song
- Dept. of Microbiology, Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang, People's Republic of China
| | - Xuanyi Shen
- Dept. of Microbiology, Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang, People's Republic of China
| | - Yuanbin Yang
- Dept. of Microbiology, Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang, People's Republic of China
| | - Danyang Zhang
- Dept. of Microbiology, Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang, People's Republic of China
| | - Hong Gao
- Dept. of Microbiology, Ningbo Municipal Centre for Disease Control and Prevention, Ningbo, Zhejiang, People's Republic of China
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188
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Deekshit VK, Kumar BK, Rai P, Karunasagar I, Karunasagar I. Differential expression of virulence genes and role of gyrA mutations in quinolone resistant and susceptible strains of Salmonella Weltevreden and Newport isolated from seafood. J Appl Microbiol 2016; 119:970-80. [PMID: 26249136 DOI: 10.1111/jam.12924] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2015] [Revised: 06/13/2015] [Accepted: 06/27/2015] [Indexed: 11/30/2022]
Abstract
AIMS To investigate the differential expression of virulence genes and role of gyrA mutations in quinolone resistant and susceptible strains of Salmonella isolated from seafood. METHODS AND RESULTS Forty Salmonella isolates from seafood were tested for antibiotic sensitivity. Minimal inhibitory concentration (MIC) was determined and two nalidixic acid-resistant isolates, viz Salmonella Weltevreden (SW9) and Salmonella Newport (SN36) were selected for identifying the mechanism of resistance. SW9 showed mutation in the gyrA gene at codon 83 (Ser to Tyr) while SN36 presented at codon 87 (Asp to Asn). Experimental induction of resistance to a sensitive Salm. Newport (SN71) showed point mutation at codon 87 (Asp to Gly) in the gyrA gene, and was designated SN71R. All the isolates resistant to nalidixic acid had a single mutation at different positions in the gyrA gene. However, induction of resistance to a sensitive Salm. Weltevreden (SW30) was exceptional in that it did not show any mutation in the gyrA region. Use of Phe-Arg-β-naphthylamide (PAβN) also could not reduce MIC below the Clinical and Laboratory Standards Institute guidelines revealing the absence of efflux mediated resistance. Thus, the resistance mechanism in SW30R is unknown. The growth rate of quinolone resistant isolates was slower than the susceptible ones. The resistant isolates showed decreased epithelial cell invasion and intracellular replication. The mRNA expression levels of some of the genes were significantly (P < 0·005) reduced in SN71R compared to the sensitive strain (SN71). CONCLUSIONS Nalidixic acid-resistant Salmonella strains are associated with lower virulence and pathogenicity than the sensitive strains. SIGNIFICANCE AND IMPACT OF THE STUDY This study provided valuable information on the difference in the growth, cytotoxicity, infectivity and expression of virulence genes in resistant and susceptible strains. Furthermore, the gyrA mutation was shown to be the main mechanism of quinolone resistance in Salmonella other than the overexpression of efflux pumps or the presence of plasmid mediated quinolone resistance genes.
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Affiliation(s)
- V K Deekshit
- Department of Biomedical Sciences, Nitte University Center for Science Education and Research, UNESCO MIRCEN for Marine Biotechnology, University Enclave, Mangalore-575018, India
| | - B K Kumar
- Department of Biomedical Sciences, Nitte University Center for Science Education and Research, UNESCO MIRCEN for Marine Biotechnology, University Enclave, Mangalore-575018, India
| | - P Rai
- Department of Biomedical Sciences, Nitte University Center for Science Education and Research, UNESCO MIRCEN for Marine Biotechnology, University Enclave, Mangalore-575018, India
| | - I Karunasagar
- Department of Biomedical Sciences, Nitte University Center for Science Education and Research, UNESCO MIRCEN for Marine Biotechnology, University Enclave, Mangalore-575018, India
| | - I Karunasagar
- Department of Biomedical Sciences, Nitte University Center for Science Education and Research, UNESCO MIRCEN for Marine Biotechnology, University Enclave, Mangalore-575018, India
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189
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Stewart MK, Cookson BT. Evasion and interference: intracellular pathogens modulate caspase-dependent inflammatory responses. Nat Rev Microbiol 2016; 14:346-59. [PMID: 27174147 DOI: 10.1038/nrmicro.2016.50] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Pathogens have evolved to complete the virulence cycle of colonization, replication and dissemination in intimate association with a complex network of extracellular and intracellular surveillance systems that guard tissue spaces. In this Review, we discuss the strategies used by bacteria and viruses to evade or inhibit intracellular detection that is coupled to pro-inflammatory caspase-dependent protective responses. Such strategies include alterations of lipopolysaccharide (LPS) structures, the regulated expression of components of type III secretion systems, and the utilization of proteins that inhibit inflammasome formation, the enzymatic activity of caspases and cytokine signalling. Inflammation is crucial in response to exposure to pathogens, but is potentially damaging and thus tightly regulated. The threshold for the activation of pro-inflammatory caspases is determined by the immediate stimulus in the context of previous signals. Pathogen, genetic and situational factors modulate this threshold, which determines the ability of the host to resist infection while minimizing harm.
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Affiliation(s)
- Mary K Stewart
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA
| | - Brad T Cookson
- Department of Microbiology, University of Washington, Seattle, Washington 98195, USA.,Department of Laboratory Medicine, University of Washington, Seattle, Washington 98195, USA
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190
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Rivera-Chávez F, Zhang LF, Faber F, Lopez CA, Byndloss MX, Olsan EE, Xu G, Velazquez EM, Lebrilla CB, Winter SE, Bäumler AJ. Depletion of Butyrate-Producing Clostridia from the Gut Microbiota Drives an Aerobic Luminal Expansion of Salmonella. Cell Host Microbe 2016; 19:443-54. [PMID: 27078066 PMCID: PMC4832419 DOI: 10.1016/j.chom.2016.03.004] [Citation(s) in RCA: 537] [Impact Index Per Article: 67.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2015] [Revised: 02/17/2016] [Accepted: 03/17/2016] [Indexed: 12/18/2022]
Abstract
The mammalian intestine is host to a microbial community that prevents pathogen expansion through unknown mechanisms, while antibiotic treatment can increase susceptibility to enteric pathogens. Here we show that streptomycin treatment depleted commensal, butyrate-producing Clostridia from the mouse intestinal lumen, leading to decreased butyrate levels, increased epithelial oxygenation, and aerobic expansion of Salmonella enterica serovar Typhimurium. Epithelial hypoxia and Salmonella restriction could be restored by tributyrin treatment. Clostridia depletion and aerobic Salmonella expansion were also observed in the absence of streptomycin treatment in genetically resistant mice but proceeded with slower kinetics and required the presence of functional Salmonella type III secretion systems. The Salmonella cytochrome bd-II oxidase synergized with nitrate reductases to drive luminal expansion, and both were required for fecal-oral transmission. We conclude that Salmonella virulence factors and antibiotic treatment promote pathogen expansion through the same mechanism: depletion of butyrate-producing Clostridia to elevate epithelial oxygenation, allowing aerobic Salmonella growth.
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Affiliation(s)
- Fabian Rivera-Chávez
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Lillian F Zhang
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Franziska Faber
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Christopher A Lopez
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Mariana X Byndloss
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Erin E Olsan
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Gege Xu
- Department of Chemistry, College of Letters and Sciences, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Eric M Velazquez
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Carlito B Lebrilla
- Department of Chemistry, College of Letters and Sciences, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA
| | - Sebastian E Winter
- Department of Microbiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Boulevard, Dallas, TX 75390, USA
| | - Andreas J Bäumler
- Department of Medical Microbiology and Immunology, School of Medicine, University of California at Davis, One Shields Avenue, Davis, CA 95616, USA.
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191
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Domingues L, Ismail A, Charro N, Rodríguez-Escudero I, Holden DW, Molina M, Cid VJ, Mota LJ. The Salmonella effector SteA binds phosphatidylinositol 4-phosphate for subcellular targeting within host cells. Cell Microbiol 2016; 18:949-69. [PMID: 26676327 DOI: 10.1111/cmi.12558] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2015] [Revised: 11/23/2015] [Accepted: 12/09/2015] [Indexed: 12/21/2022]
Abstract
Many bacterial pathogens use specialized secretion systems to deliver virulence effector proteins into eukaryotic host cells. The function of these effectors depends on their localization within infected cells, but the mechanisms determining subcellular targeting of each effector are mostly elusive. Here, we show that the Salmonella type III secretion effector SteA binds specifically to phosphatidylinositol 4-phosphate [PI(4)P]. Ectopically expressed SteA localized at the plasma membrane (PM) of eukaryotic cells. However, SteA was displaced from the PM of Saccharomyces cerevisiae in mutants unable to synthesize the local pool of PI(4)P and from the PM of HeLa cells after localized depletion of PI(4)P. Moreover, in infected cells, bacterially translocated or ectopically expressed SteA localized at the membrane of the Salmonella-containing vacuole (SCV) and to Salmonella-induced tubules; using the PI(4)P-binding domain of the Legionella type IV secretion effector SidC as probe, we found PI(4)P at the SCV membrane and associated tubules throughout Salmonella infection of HeLa cells. Both binding of SteA to PI(4)P and the subcellular localization of ectopically expressed or bacterially translocated SteA were dependent on a lysine residue near the N-terminus of the protein. Overall, this indicates that binding of SteA to PI(4)P is necessary for its localization within host cells.
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Affiliation(s)
- Lia Domingues
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (FCT NOVA), Caparica, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
| | - Ahmad Ismail
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigación Sanitaria (IRyCIS), Madrid, Spain
| | - Nuno Charro
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (FCT NOVA), Caparica, Portugal
| | - Isabel Rodríguez-Escudero
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigación Sanitaria (IRyCIS), Madrid, Spain
| | - David W Holden
- MRC Centre for Molecular Bacteriology and Infection, Imperial College London, London, UK
| | - María Molina
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigación Sanitaria (IRyCIS), Madrid, Spain
| | - Víctor J Cid
- Departamento de Microbiología II, Facultad de Farmacia, Universidad Complutense de Madrid and Instituto Ramón y Cajal de Investigación Sanitaria (IRyCIS), Madrid, Spain
| | - Luís Jaime Mota
- UCIBIO-REQUIMTE, Departamento de Ciências da Vida, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (FCT NOVA), Caparica, Portugal.,Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa (ITQB NOVA), Oeiras, Portugal
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192
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Cordero-Alba M, García-Gómez JJ, Aguilera-Herce J, Ramos-Morales F. Proteomic insight into the effects of the Salmonella ubiquitin ligase SlrP on host cells. Biochem Biophys Res Commun 2016; 472:539-44. [PMID: 26966069 DOI: 10.1016/j.bbrc.2016.03.014] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 03/06/2016] [Indexed: 11/15/2022]
Abstract
The virulence of the human and animal pathogen Salmonella enterica serovar Typhimurium is dependent on two type III secretion systems. These systems translocate proteins called effectors into eukaryotic host cells. SlrP is a Salmonella type III secretion effector with ubiquitin ligase activity. Here, we used two complementary proteomic approaches, two-dimensional gel electrophoresis and iTRAQ (isobaric tags for relative and absolute quantification) to study the consequences of the presence of SlrP in human epithelial cells. We identified 37 proteins that were differentially expressed in HeLa cells expressing slrP compared to control cells. Microarray analysis revealed that more than a half of differentially expressed proteins did not show changes in the transcriptome, suggesting post-transcriptional regulation. A gene ontology overrepresentation test carried out on the differentially expressed proteins revealed enrichment of ontology terms related to several types of junctions mediating adhesion in epithelial cells. Consistently, slrP-transfected cells showed defects in migration and adhesion. Our results suggest that the modification of cell-cell interaction ability of the host could be one of the final consequences of the action of SlrP during an infection.
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Affiliation(s)
- Mar Cordero-Alba
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
| | - Juan José García-Gómez
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
| | - Julia Aguilera-Herce
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
| | - Francisco Ramos-Morales
- Departamento de Genética, Facultad de Biología, Universidad de Sevilla, Apartado 1095, 41080 Sevilla, Spain.
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193
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Tsou LK, Lara-Tejero M, RoseFigura J, Zhang ZJ, Wang YC, Yount JS, Lefebre M, Dossa PD, Kato J, Guan F, Lam W, Cheng YC, Galán JE, Hang HC. Antibacterial Flavonoids from Medicinal Plants Covalently Inactivate Type III Protein Secretion Substrates. J Am Chem Soc 2016; 138:2209-18. [PMID: 26847396 DOI: 10.1021/jacs.5b11575] [Citation(s) in RCA: 70] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Traditional Chinese Medicines (TCMs) have been historically used to treat bacterial infections. However, the molecules responsible for these anti-infective properties and their potential mechanisms of action have remained elusive. Using a high-throughput assay for type III protein secretion in Salmonella enterica serovar Typhimurium, we discovered that several TCMs can attenuate this key virulence pathway without affecting bacterial growth. Among the active TCMs, we discovered that baicalein, a specific flavonoid from Scutellaria baicalensis, targets S. Typhimurium pathogenicity island-1 (SPI-1) type III secretion system (T3SS) effectors and translocases to inhibit bacterial invasion of epithelial cells. Structurally related flavonoids present in other TCMs, such as quercetin, also inactivated the SPI-1 T3SS and attenuated S. Typhimurium invasion. Our results demonstrate that specific plant metabolites from TCMs can directly interfere with key bacterial virulence pathways and reveal a previously unappreciated mechanism of action for anti-infective medicinal plants.
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Affiliation(s)
- Lun K Tsou
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States.,Institute of Biotechnology and Pharmaceutical Research, National Health Research Institutes , Zhunan Town, Miaoli County 35053, Taiwan, R.O.C
| | - María Lara-Tejero
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Jordan RoseFigura
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Zhenrun J Zhang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Yen-Chih Wang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Jacob S Yount
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Matthew Lefebre
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Paul D Dossa
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
| | - Junya Kato
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Fulan Guan
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Wing Lam
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Yung-Chi Cheng
- Department of Pharmacology, Yale University School of Medicine , New Haven, Connecticut 06520, United States
| | - Jorge E Galán
- Department of Microbial Pathogenesis, Yale University School of Medicine , New Haven, Connecticut 06536, United States
| | - Howard C Hang
- Laboratory of Chemical Biology and Microbial Pathogenesis, The Rockefeller University , New York, New York 10065, United States
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194
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Kapetanovic R, Bokil NJ, Achard MES, Ong CLY, Peters KM, Stocks CJ, Phan MD, Monteleone M, Schroder K, Irvine KM, Saunders BM, Walker MJ, Stacey KJ, McEwan AG, Schembri MA, Sweet MJ. Salmonella employs multiple mechanisms to subvert the TLR-inducible zinc-mediated antimicrobial response of human macrophages. FASEB J 2016; 30:1901-12. [PMID: 26839376 DOI: 10.1096/fj.201500061] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/26/2015] [Accepted: 01/19/2016] [Indexed: 12/27/2022]
Abstract
We aimed to characterize antimicrobial zinc trafficking within macrophages and to determine whether the professional intramacrophage pathogen Salmonella enterica serovar Typhimurium (S Typhimurium) subverts this pathway. Using both Escherichia coli and S Typhimurium, we show that TLR signaling promotes the accumulation of vesicular zinc within primary human macrophages. Vesicular zinc is delivered to E. coli to promote microbial clearance, whereas S. Typhimurium evades this response via Salmonella pathogenicity island (SPI)-1. Even in the absence of SPI-1 and the zinc exporter ZntA, S Typhimurium resists the innate immune zinc stress response, implying the existence of additional host subversion mechanisms. We also demonstrate the combinatorial antimicrobial effects of zinc and copper, a pathway that S. Typhimurium again evades. Our use of complementary tools and approaches, including confocal microscopy, direct assessment of intramacrophage bacterial zinc stress responses, specific E. coli and S Typhimurium mutants, and inductively coupled plasma mass spectroscopy, has enabled carefully controlled characterization of this novel innate immune antimicrobial pathway. In summary, our study provides new insights at the cellular level into the well-documented effects of zinc in promoting host defense against infectious disease, as well as the complex host subversion strategies employed by S Typhimurium to combat this pathway.-Kapetanovic, R., Bokil, N. J., Achard, M. E. S., Ong, C.-L. Y., Peters, K. M., Stocks, C. J., Phan, M.-D., Monteleone, M., Schroder, K., Irvine, K. M., Saunders, B. M., Walker, M. J., Stacey, K. J., McEwan, A. G., Schembri, M. A., Sweet, M. J. Salmonella employs multiple mechanisms to subvert the TLR-inducible zinc-mediated antimicrobial response of human macrophages.
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Affiliation(s)
- Ronan Kapetanovic
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Nilesh J Bokil
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Maud E S Achard
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Cheryl-Lynn Y Ong
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Kate M Peters
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Claudia J Stocks
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Minh-Duy Phan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Mercedes Monteleone
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Kate Schroder
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Katharine M Irvine
- IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; School of Medicine, The University of Queensland, Woolloongabba, Australia; and
| | | | - Mark J Walker
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Katryn J Stacey
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Alastair G McEwan
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Mark A Schembri
- School of Chemistry and Molecular Biosciences, The University of Queensland, St. Lucia, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia
| | - Matthew J Sweet
- Institute for Molecular Bioscience (IMB), The University of Queensland, Brisbane, Australia; IMB Centre for Inflammation and Disease Research, The University of Queensland, Brisbane, Australia; Australian Infectious Diseases Research Centre, The University of Queensland, Brisbane, Australia;
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195
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Achouri S, Wright JA, Evans L, Macleod C, Fraser G, Cicuta P, Bryant CE. The frequency and duration of Salmonella-macrophage adhesion events determines infection efficiency. Philos Trans R Soc Lond B Biol Sci 2015; 370:20140033. [PMID: 25533091 PMCID: PMC4275903 DOI: 10.1098/rstb.2014.0033] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Salmonella enterica causes a range of important diseases in humans and a in a variety of animal species. The ability of bacteria to adhere to, invade and survive within host cells plays an important role in the pathogenesis of Salmonella infections. In systemic salmonellosis, macrophages constitute a niche for the proliferation of bacteria within the host organism. Salmonella enterica serovar Typhimurium is flagellated and the frequency with which this bacterium collides with a cell is important for infection efficiency. We investigated how bacterial motility affects infection efficiency, using a combination of population-level macrophage infection experiments and direct imaging of single-cell infection events, comparing wild-type and motility mutants. Non-motile and aflagellate bacterial strains, in contrast to wild-type bacteria, collide less frequently with macrophages, are in contact with the cell for less time and infect less frequently. Run-biased Salmonella also collide less frequently with macrophages but maintain contact with macrophages for a longer period of time than wild-type strains and infect the cells more readily. Our results suggest that uptake of S. Typhimurium by macrophages is dependent upon the duration of contact time of the bacterium with the cell, in addition to the frequency with which the bacteria collide with the cell.
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Affiliation(s)
- Sarra Achouri
- Department of Physics, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
| | - John A Wright
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Lewis Evans
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Charlotte Macleod
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
| | - Gillian Fraser
- Department of Pathology, University of Cambridge, Tennis Court Road, Cambridge CB2 1QP, UK
| | - Pietro Cicuta
- Department of Physics, Cavendish Laboratory, University of Cambridge, J J Thomson Avenue, Cambridge CB3 0HE, UK
| | - Clare E Bryant
- Department of Veterinary Medicine, University of Cambridge, Madingley Road, Cambridge CB3 0ES, UK
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196
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Piscatelli HL, Li M, Zhou D. Dual 4- and 5-phosphatase activities regulate SopB-dependent phosphoinositide dynamics to promote bacterial entry. Cell Microbiol 2015; 18:705-19. [PMID: 26537021 DOI: 10.1111/cmi.12542] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2015] [Revised: 10/21/2015] [Accepted: 10/24/2015] [Indexed: 12/16/2022]
Abstract
Salmonella are able to invade non-phagocytic cells such as intestinal epithelial cells by modulating the host actin cytoskeleton to produce membrane ruffles. Two type III effector proteins SopB and SopE play key roles to this modulation. SopE is a known guanine nucleotide exchange factor (GEF) capable of activating Rac1 and CDC42. SopB is a phosphatidylinositol 4-phosphatase and 5-phosphatase promoting membrane ruffles and invasion of Salmonella through undefined mechanisms. Previous studies have demonstrated that the 4-phosphatase activity of SopB is required for PtdIns-3-phosphate (PtdIns(3)P) accumulation and SopB-mediated invasion. We show here that both the 4-phosphatase as well as the 5-phosphatase activities of SopB are essential in ruffle formation and subsequent invasion. We found that the 5-phosphatase activity of SopB is likely responsible for generating PtdIns-3,4-bisphosphate (PtdIns(3,4)P(2)) and subsequent recruitment of sorting nexin 9 (SNX9), an actin modulating protein. Intriguingly, the 4-phosphatase activity is responsible for the dephosphorylation of PtdIns(3,4)P(2) into PtdIns(3)P. Alone, neither activity is sufficient for ruffling but when acting in conjunction with one another, the 4-phosphatase and 5-phosphatase activities led to SNX9-mediated ruffling and Salmonella invasion. This work reveals the unique ability of bacterial effector protein SopB to utilize both its 4- and 5-phosphatase activities to regulate phosphoinositide dynamics to promote bacterial entry.
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Affiliation(s)
- Heather L Piscatelli
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Menghan Li
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
| | - Daoguo Zhou
- Department of Biological Sciences, Purdue University, West Lafayette, IN, 47907, USA
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197
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Cultured enterocytes internalise bacteria across their basolateral surface for, pathogen-inhibitable, trafficking to the apical compartment. Sci Rep 2015; 5:17359. [PMID: 26612456 PMCID: PMC4661573 DOI: 10.1038/srep17359] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 10/23/2015] [Indexed: 01/13/2023] Open
Abstract
In vitro- and in vivo-polarised absorptive epithelia (enterocytes) are considered to be non-phagocytic towards bacteria with invasive pathogenic strains relying on virulence factors to 'force' entry. Here, we report a serendipitous discovery that questions these beliefs. Thus, we uncover in well-established models of human small (Caco-2; TC-7) and large (T84) intestinal enterocytes a polarization-dependent mechanism that can transfer millions of bacteria from the basal to apical compartment. Antibiotic-protection assays, confocal imaging and drug inhibitor data are consistent with a transcellular route in which internalized, basolateral-membrane enclosed bacteria are trafficked to and across the apical surface. Basal-to-apical transport of non-pathogenic bacteria (and inert beads) challenged the idea of pathogens relying on virulence factors to force entry. Indeed, studies with Salmonella demonstrated that it's entry-forcing virulence factor (SPI-I) was not required to enter via the basolateral surface but to promote another virulence-associated event (intra-enterocyte accumulation).
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198
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Srikumar S, Kröger C, Hébrard M, Colgan A, Owen SV, Sivasankaran SK, Cameron ADS, Hokamp K, Hinton JCD. RNA-seq Brings New Insights to the Intra-Macrophage Transcriptome of Salmonella Typhimurium. PLoS Pathog 2015; 11:e1005262. [PMID: 26561851 PMCID: PMC4643027 DOI: 10.1371/journal.ppat.1005262] [Citation(s) in RCA: 167] [Impact Index Per Article: 18.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2015] [Accepted: 10/17/2015] [Indexed: 11/18/2022] Open
Abstract
Salmonella enterica serovar Typhimurium is arguably the world’s best-understood bacterial pathogen. However, crucial details about the genetic programs used by the bacterium to survive and replicate in macrophages have remained obscure because of the challenge of studying gene expression of intracellular pathogens during infection. Here, we report the use of deep sequencing (RNA-seq) to reveal the transcriptional architecture and gene activity of Salmonella during infection of murine macrophages, providing new insights into the strategies used by the pathogen to survive in a bactericidal immune cell. We characterized 3583 transcriptional start sites that are active within macrophages, and highlight 11 of these as candidates for the delivery of heterologous antigens from Salmonella vaccine strains. A majority (88%) of the 280 S. Typhimurium sRNAs were expressed inside macrophages, and SPI13 and SPI2 were the most highly expressed pathogenicity islands. We identified 31 S. Typhimurium genes that were strongly up-regulated inside macrophages but expressed at very low levels during in vitro growth. The SalComMac online resource allows the visualisation of every transcript expressed during bacterial replication within mammalian cells. This primary transcriptome of intra-macrophage S.-Typhimurium describes the transcriptional start sites and the transcripts responsible for virulence traits, and catalogues the sRNAs that may play a role in the regulation of gene expression during infection. The burden of Salmonellosis remains unacceptably high throughout the world and control measures have had limited success. Because Salmonella bacteria can be transmitted from the wider environment to animals and humans, the bacteria encounter diverse environments that include food, water, plant surfaces and the extracellular and intracellular phases of infection of eukaryotic hosts. An intricate transcriptional network has evolved to respond to a variety of environmental signals and control the “right time/ right place” expression of virulence genes. To understand how transcription is rewired during intracellular infection, we determined the primary transcriptome of Salmonella enterica serovar Typhimurium within murine macrophages. We report the coding genes, sRNAs and transcriptional start sites that are expressed within macrophages at 8 hours after infection, and use these to infer gene function. We identified gene promoters that are specifically expressed within macrophages and could drive the intracellular delivery of antigens by S. Typhimurium vaccine strains. These data contribute to our understanding of the mechanisms used by Salmonella to regulate virulence gene expression whilst replicating inside mammalian cells.
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Affiliation(s)
- Shabarinath Srikumar
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Carsten Kröger
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Magali Hébrard
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Aoife Colgan
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | - Siân V. Owen
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
| | - Sathesh K. Sivasankaran
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
| | | | - Karsten Hokamp
- Department of Genetics, School of Genetics and Microbiology, Smurfit Institute of Genetics, Trinity College, Dublin, Ireland
| | - Jay C. D. Hinton
- Department of Microbiology, School of Genetics and Microbiology, Moyne Institute of Preventive Medicine, Trinity College, Dublin, Ireland
- Institute of Integrative Biology, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
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199
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Anderson CJ, Clark DE, Adli M, Kendall MM. Ethanolamine Signaling Promotes Salmonella Niche Recognition and Adaptation during Infection. PLoS Pathog 2015; 11:e1005278. [PMID: 26565973 PMCID: PMC4643982 DOI: 10.1371/journal.ppat.1005278] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2015] [Accepted: 10/22/2015] [Indexed: 12/21/2022] Open
Abstract
Chemical and nutrient signaling are fundamental for all cellular processes, including interactions between the mammalian host and the microbiota, which have a significant impact on health and disease. Ethanolamine is an essential component of cell membranes and has profound signaling activity within mammalian cells by modulating inflammatory responses and intestinal physiology. Here, we describe a virulence-regulating pathway in which the foodborne pathogen Salmonella enterica serovar Typhimurium (S. Typhimurium) exploits ethanolamine signaling to recognize and adapt to distinct niches within the host. The bacterial transcription factor EutR promotes ethanolamine metabolism in the intestine, which enables S. Typhimurium to establish infection. Subsequently, EutR directly activates expression of the Salmonella pathogenicity island 2 in the intramacrophage environment, and thus augments intramacrophage survival. Moreover, EutR is critical for robust dissemination during mammalian infection. Our findings reveal that S. Typhimurium co-opts ethanolamine as a signal to coordinate metabolism and then virulence. Because the ability to sense ethanolamine is a conserved trait among pathogenic and commensal bacteria, our work indicates that ethanolamine signaling may be a key step in the localized adaptation of bacteria within their mammalian hosts.
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Affiliation(s)
- Christopher J. Anderson
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - David E. Clark
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Mazhar Adli
- Department of Biochemistry and Molecular Genetics, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
| | - Melissa M. Kendall
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America
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200
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Abstract
This review reviews the properties and regulation of the Salmonella enterica serovar Typhimurium and Escherichia coli transporters that mediate Mg2+ influx: CorA and the Mgt P-type ATPases. In addition, potential Mg2+ regulation of transcription and translation, largely via the PhoPQ two component system, is discussed. CorA proteins are a unique class of transporters and are widespread in the Bacteria and Archaea, with rather distant but functional homologs in eukaryotes. The Mgt transporters are highly homologous to other P-type ATPases but are more closely related to the eukaryotic H+ and Ca2+ ATPases than to most prokaryotic ATPases. Hundreds of homologs of CorA are currently known from genomic sequencing. In contrast, only when extracellular and possibly intracellular Mg2+ levels fall significantly is the expression of mgtA and mgtB induced. Topology studies using blaM and lacZ fusions initially indicated that the Salmonella serovar Typhimurium CorA contained three transmembrane (TM) segments; however, subsequent data obtained using a variety of approaches showed that the CorA superfamily of proteins have only two TMs at the extreme C terminus. PhoP-PhoQ is a two-component system consisting of PhoQ, the sensor/receptor histidine kinase, and PhoP, the response regulator/transcriptional activator. The expression of both mgtA and mgtCB in either E. coli or Salmonella serovar Typhimurium is markedly induced in a PhoPQ-dependent manner by low concentrations of Mg2+ in the medium. phoP and phoQ form an operon with two promoters in both E. coli and Salmonella serovar Typhimurium.
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