Translocation of Toxins by Gram-Negative Pathogens Using the Type III Secretion System

2018 ◽  
pp. 403-420
Author(s):  
Arjan J. Vermeulen ◽  
Yuzhou Tang ◽  
Alejandro P. Heuck
Keyword(s):  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Gram Negative ◽  
Type Iii

scholarly journals Developing Cyclic Peptomers as Broad-Spectrum Gram negative Bacterial Type III Secretion System Inhibitors

2020 ◽  
Author(s):  
Hanh N. Lam ◽  
Tannia Lau ◽  
Adam Lentz ◽  
Jessica Sherry ◽  
Alejandro Cabrera-Cortez ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Chlamydia Trachomatis ◽  
Broad Spectrum ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Gram Negative Bacteria ◽  
Gram Negative ◽  
Type Iii ◽  
Bacterial Type

ABSTRACTAntibiotic resistant bacteria are an emerging global health threat. New antimicrobials are urgently needed. The injectisome type III secretion system (T3SS), required by dozens of Gram-negative bacteria for virulence but largely absent from non-pathogenic bacteria, is an attractive antimicrobial target. We previously identified synthetic cyclic peptomers, inspired by the natural product phepropeptin D, that inhibit protein secretion through the Yersinia Ysc and Pseudomonas aeruginosa Psc T3SSs, but do not inhibit bacterial growth. Here we describe identification of an isomer, 4EpDN, that is two-fold more potent (IC50 4 μM) than its parental compound. Furthermore, 4EpDN inhibited the Yersinia Ysa and the Salmonella SPI-1 T3SSs, suggesting that this cyclic peptomer has broad efficacy against evolutionarily distant injectisome T3SSs. Indeed, 4EpDN strongly inhibited intracellular growth of Chlamydia trachomatis in HeLa cells, which requires the T3SS. 4EpDN did not inhibit the unrelated Twin arginine translocation (Tat) system, nor did it impact T3SS gene transcription. Moreover, although the injectisome and flagellar T3SSs are evolutionarily and structurally related, the 4EpDN cyclic peptomer did not inhibit secretion of substrates through the Salmonella flagellar T3SS, indicating that cyclic peptomers broadly but specifically target the injestisome T3SS. 4EpDN reduced the number of T3SS basal bodies detected on the surface of Y. enterocolitica, as visualized using a fluorescent derivative of YscD, an inner membrane ring with low homology to flagellar protein FliG. Collectively, these data suggest that cyclic peptomers specifically inhibit the injectisome T3SS from a variety of Gram-negative bacteria, possibly by preventing complete T3SS assembly.IMPORTANCETraditional antibiotics target both pathogenic and commensal bacteria, resulting in a disruption of the microbiota, which in turn is tied to a number of acute and chronic diseases. The bacterial type III secretion system (T3SS) is an appendage used by many bacterial pathogens to establish infection, but is largely absent from commensal members of the microbiota. In this study, we identify a new derivative of the cyclic peptomer class of T3SS inhibitors. These compounds inhibit the T3SS of the nosocomial ESKAPE pathogen Pseudomonas aeruginosa and enteropathogenic Yersinia and Salmonella. The impact of cyclic peptomers is specific to the T3SS, as other bacterial secretory systems are unaffected. Importantly, cyclic peptomers completely block replication of Chlamydia trachomatis, the causative agent of genital, eye, and lung infections, in human cells, a process that requires the T3SS. Therefore, cyclic peptomers represent promising virulence blockers that can specifically disarm a broad spectrum of Gram-negative pathogens.

scholarly journals Cell Individuality: The Bistable Gene Expression of the Type III Secretion System in Dickeya dadantii 3937

2012 ◽  
Vol 25 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Quan Zeng ◽  
Michael D. Laiosa ◽  
Douglas A. Steeber ◽  
Eulandria M. Biddle ◽  
Quan Peng ◽  
...  
Keyword(s):  
Gene Expression ◽  
Type Iii Secretion ◽  
Expression Patterns ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Expression Level ◽  
Dickeya Dadantii ◽  
Phytopathogenic Bacterium ◽  
Gram Negative ◽  
Type Iii

Dickeya dadantii 3937 is a gram-negative phytopathogenic bacterium that expresses genes encoding a type III secretion system (T3SS) in a bistable pattern when cultured in a homogeneous minimal media. In this work, we further characterized the bistable gene expression of T3SS at the single-cell level. We demonstrated that bistable expression of the HrpL-regulon genes, such as hrpA and hrpN, is controlled by the same regulatory mechanism. We also showed that the expression level of the T3SS master regulatory gene hrpL plays an important role in the development of the bistable expression of hrpA. A high expression level of hrpL is required but unable to guarantee the high-state expression of hrpA in a cell. In addition, bistable expression patterns of T3SS genes in other gram-negative pathogens of the Enterobacteriaceae and Pseudomonadaceae families were also described in this study. This suggests that the T3SS bistability might be a conserved population behavior in several gram-negative bacterial pathogens.

scholarly journals The Ruler Protein EscP of the Enteropathogenic Escherichia coli Type III Secretion System Is Involved in Calcium Sensing and Secretion Hierarchy Regulation by Interacting with the Gatekeeper Protein SepL

mBio ◽  
2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Lihi Shaulov ◽  
Jenia Gershberg ◽  
Wanyin Deng ◽  
B. Brett Finlay ◽  
Neta Sal-Man
Keyword(s):  
Host Cell ◽  
Type Iii Secretion ◽  
Bacterial Pathogens ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Bacterial Virulence ◽  
Effector Proteins ◽  
Host Cells ◽  
Gram Negative ◽  
Type Iii

ABSTRACT The type III secretion system (T3SS) is a multiprotein complex that plays a central role in the virulence of many Gram-negative bacterial pathogens. To ensure that effector proteins are efficiently translocated into the host cell, bacteria must be able to sense their contact with the host cell. In this study, we found that EscP, which was previously shown to function as the ruler protein of the enteropathogenic Escherichia coli T3SS, is also involved in the switch from the secretion of translocator proteins to the secretion of effector proteins. In addition, we demonstrated that EscP can interact with the gatekeeper protein SepL and that the EscP-SepL complex dissociates upon a calcium concentration drop. We suggest a model in which bacterial contact with the host cell is accompanied by a drop in the calcium concentration that causes SepL-EscP complex dissociation and triggers the secretion of effector proteins. IMPORTANCE The emergence of multidrug-resistant bacterial strains, especially those of pathogenic bacteria, has serious medical and clinical implications. At the same time, the development and approval of new antibiotics have been limited for years. Recently, antivirulence drugs have received considerable attention as a novel antibiotic strategy that specifically targets bacterial virulence rather than growth, an approach that applies milder evolutionary pressure on the bacteria to develop resistance. A highly attractive target for the development of antivirulence compounds is the type III secretion system, a specialized secretory system possessed by many Gram-negative bacterial pathogens for injecting virulence factors (effectors) into host cells. In this study, we shed light on the molecular mechanism that allows bacteria to sense their contact with the host cell and to respond with the timed secretion of effector proteins. Understanding this critical step for bacterial virulence may provide a new therapeutic strategy. IMPORTANCE The emergence of multidrug-resistant bacterial strains, especially those of pathogenic bacteria, has serious medical and clinical implications. At the same time, the development and approval of new antibiotics have been limited for years. Recently, antivirulence drugs have received considerable attention as a novel antibiotic strategy that specifically targets bacterial virulence rather than growth, an approach that applies milder evolutionary pressure on the bacteria to develop resistance. A highly attractive target for the development of antivirulence compounds is the type III secretion system, a specialized secretory system possessed by many Gram-negative bacterial pathogens for injecting virulence factors (effectors) into host cells. In this study, we shed light on the molecular mechanism that allows bacteria to sense their contact with the host cell and to respond with the timed secretion of effector proteins. Understanding this critical step for bacterial virulence may provide a new therapeutic strategy.

scholarly journals Antibodies Inhibiting the Type III Secretion System of Gram-Negative Pathogenic Bacteria

Antibodies ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 35
Author(s):  
Julia A. Hotinger ◽  
Aaron E. May
Keyword(s):  
Type Iii Secretion ◽  
Pathogenic Bacteria ◽  
Type Iii Secretion System ◽  
The United States ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Gram Negative ◽  
Type Iii ◽  
Shigella Spp

Pathogenic bacteria are a global health threat, with over 2 million infections caused by Gram-negative bacteria every year in the United States. This problem is exacerbated by the increase in resistance to common antibiotics that are routinely used to treat these infections, creating an urgent need for innovative ways to treat and prevent virulence caused by these pathogens. Many Gram-negative pathogenic bacteria use a type III secretion system (T3SS) to inject toxins and other effector proteins directly into host cells. The T3SS has become a popular anti-virulence target because it is required for pathogenesis and knockouts have attenuated virulence. It is also not required for survival, which should result in less selective pressure for resistance formation against T3SS inhibitors. In this review, we will highlight selected examples of direct antibody immunizations and the use of antibodies in immunotherapy treatments that target the bacterial T3SS. These examples include antibodies targeting the T3SS of Pseudomonas aeruginosa, Yersinia pestis, Escherichia coli, Salmonella enterica, Shigella spp., and Chlamydia trachomatis.

scholarly journals Edwardsiella tarda-Induced Cytotoxicity Depends on Its Type III Secretion System and Flagellin

2014 ◽  
Vol 82 (8) ◽  
pp. 3436-3445 ◽  
Author(s):  
Hai-Xia Xie ◽  
Jin-Fang Lu ◽  
Nathalie Rolhion ◽  
David W. Holden ◽  
Pin Nie ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Dependent Manner ◽  
Gram Negative ◽  
Content Type ◽  
Murine Bone Marrow ◽  
Type Iii

ABSTRACTMany Gram-negative bacteria utilize a type III secretion system (T3SS) to translocate virulence proteins into host cells to cause diseases. In responding to infection, macrophages detect some of the translocated proteins to activate caspase-1-mediated cell death, called pyroptosis, and secretion of proinflammatory cytokines to control the infection.Edwardsiella tardais a Gram-negative enteric pathogen that causes hemorrhagic septicemia in fish and both gastrointestinal and extraintestinal infections in humans. In this study, we report that the T3SS ofE. tardafacilitates its survival and replication in murine bone marrow-derived macrophages, andE. tardainfection triggers pyroptosis of infected macrophages from mice and fish and increased secretion of the cytokine interleukin 1β in a T3SS-dependent manner. Deletion of the flagellin genefliCofE. tardaresults in decreased cytotoxicity for infected macrophages and does not attenuate its virulence in a fish model of infection, whereas upregulated expression of FliC in thefliCmutant strain reduces its virulence. We propose that the host controlsE. tardainfection partially by detecting FliC translocated by the T3SS, whereas the bacteria downregulate the expression of FliC to evade innate immunity.

scholarly journals Cloning and Transfer of the Salmonella Pathogenicity Island 2 Type III Secretion System for Studies of a Range of Gram-Negative Genera

2007 ◽  
Vol 73 (18) ◽  
pp. 5911-5918 ◽  
Author(s):  
James W. Wilson ◽  
Clint Coleman ◽  
Cheryl A. Nickerson
Keyword(s):  
Type Iii Secretion ◽  
Vaccine Development ◽  
Type Iii Secretion System ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Host Cells ◽  
Secretion Systems ◽  
Gram Negative ◽  
Type Iii ◽  
Type Iii Secretion Systems

ABSTRACT The engineering of bacterial strains with specific phenotypes frequently requires the use of blocks or “cassettes” of genes that act together to perform a desired function. The potential benefits of utilizing type III secretion systems in this regard are becoming increasingly realized since these systems can be used to direct interactions with host cells for beneficial purposes such as vaccine development, anticancer therapies, and targeted protein delivery. However, convenient methods to clone and transfer type III secretion systems for studies of a range of different types of bacteria are lacking. In addition to functional applications, such methods would also reveal important information about the evolution of a given type III secretion system, such as its ability to be expressed and functional outside of the strain of origin. We describe here the cloning of the Salmonella enterica serovar Typhimurium pathogenicity island 2 (SPI-2) type III secretion system onto a vector that can be easily transferred to a range of gram-negative bacterial genera. We found that expression of the cloned SPI-2 system in different Gammaproteobacteria and Alphaproteobacteria (as monitored by SseB protein levels) is dependent on the bacterial strain and growth medium. We also demonstrate that the cloned system is functional for secretion, can direct interactions with macrophages, and can be used as a novel tool to analyze the predicted interaction of SseB with host cells. This work provides a foundation for future applications where the cloned SPI-2 region (or other cloned type III systems) can provide a desired function to an engineered gram-negative strain.

scholarly journals Investigation of EscA as a chaperone for the Edwardsiella tarda type III secretion system putative translocon component EseC

Microbiology ◽  
2009 ◽  
Vol 155 (4) ◽  
pp. 1260-1271 ◽  
Author(s):  
Bo Wang ◽  
Zhao Lan Mo ◽  
Yun Xiang Mao ◽  
Yu Xia Zou ◽  
Peng Xiao ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Cytoplasmic Membrane ◽  
Specific Interaction ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Edwardsiella Tarda ◽  
Cell Fractionation ◽  
Wild Type ◽  
Gram Negative ◽  
Type Iii

Edwardsiella tarda is an important Gram-negative enteric pathogen affecting both animals and humans. It possesses a type III secretion system (T3SS) essential for pathogenesis. EseB, EseC and EseD have been shown to form a translocon complex after secretion, while EscC functions as a T3SS chaperone for EseB and EseD. In this paper we identify EscA, a protein required for accumulation and proper secretion of another translocon component, EseC. The escA gene is located upstream of eseC and the EscA protein has the characteristics of T3SS chaperones. Cell fractionation experiments indicated that EscA is located in the cytoplasm and on the cytoplasmic membrane. Mutation with in-frame deletion of escA greatly decreased the secretion of EseC, while complementation of escA restored the wild-type secretion phenotype. The stabilization and accumulation of EseC in the cytoplasm were also affected in the absence of EscA. Mutation of escA did not affect the transcription of eseC but reduced the accumulation level of EseC as measured by using an EseC-LacZ fusion protein in Ed. tarda. Co-purification and co-immunoprecipitation studies demonstrated a specific interaction between EscA and EseC. Further analysis showed that residues 31–137 of EseC are required for EseC-EscA interaction. Mutation of EseC residues 31–137 reduced the secretion and accumulation of EseC in Ed. tarda. Finally, infection experiments showed that mutations of EscA and residues 31–137 of EseC increased the LD50 by approximately 10-fold in blue gourami fish. These results indicated that EscA functions as a specific chaperone for EseC and contributes to the virulence of Ed. tarda.

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