scholarly journals Characterization of the role of the Burkholderia pseudomallei type 3 secretion system using in vivo imaging.

2016 ◽  
Author(s):  
Maria Gutierrez
Keyword(s):  
In Vivo Imaging ◽  
Burkholderia Pseudomallei ◽  
Secretion System ◽  
Type 3 Secretion System ◽  
Type 3

scholarly journals Role of the acquisition of a type 3 secretion system in the emergence of novel pathogenic strains of Xanthomonas

2018 ◽  
Vol 20 (1) ◽  
pp. 33-50 ◽  
Author(s):  
Valérian Meline ◽  
Wesley Delage ◽  
Chrystelle Brin ◽  
Camille Li-Marchetti ◽  
Daniel Sochard ◽  
...  
Keyword(s):  
Secretion System ◽  
Type 3 Secretion System ◽  
Type 3

scholarly journals Regulation by ToxR-Like Proteins Converges onvttRBExpression To Control Type 3 Secretion System-Dependent Caco2-BBE Cytotoxicity in Vibrio cholerae

2016 ◽  
Vol 198 (11) ◽  
pp. 1675-1682 ◽  
Author(s):  
Kelly A. Miller ◽  
Madeline K. Sofia ◽  
Jacob W. A. Weaver ◽  
Christopher H. Seward ◽  
Michelle Dziejman
Keyword(s):  
Gene Expression ◽  
Cell Death ◽  
Vibrio Cholerae ◽  
Secretion System ◽  
Content Type ◽  
Transcriptional Regulatory ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACTGenes carried on the type 3 secretion system (T3SS) pathogenicity island ofVibrio choleraenon-O1/non-O139 serogroup strain AM-19226 must be precisely regulated in order for bacteria to cause disease. Previously reported results showed that both T3SS function and the presence of bile are required to cause Caco2-BBE cell cytotoxicity during coculture with strain AM-19226. We therefore investigated additional parameters affectingin vitrocell death, including bacterial load and the role of three transmembrane transcriptional regulatory proteins, VttRA, VttRB, and ToxR. VttRAand VttRBare encoded on the horizontally acquired T3SS genomic island, whereas ToxR is encoded on the ancestral chromosome. While strains carrying deletions in any one of the three transcriptional regulatory genes are unable to cause eukaryotic cell death, the results of complementation studies point to a hierarchy of regulatory control that converges onvttRBexpression. The data suggest both that ToxR and VttRAact upstream of VttRBand that modifying the level of eithervttRAorvttRBexpression can strongly influence T3SS gene expression. We therefore propose a model whereby T3SS activity and, hence,in vitrocytotoxicity are ultimately regulated byvttRBexpression.IMPORTANCEIn contrast to O1 and O139 serogroupV. choleraestrains that cause cholera using two main virulence factors (toxin-coregulated pilus [TCP] and cholera toxin [CT]), O39 serogroup strain AM-19226 uses a type 3 secretion system as its principal virulence mechanism. Although the regulatory network governing TCP and CT expression is well understood, the factors influencing T3SS-associated virulence are not. Using anin vitromammalian cell model to investigate the role of three ToxR-like transmembrane transcriptional activators in causing T3SS-dependent cytotoxicity, we found that expression levels and a hierarchical organization were important for promoting T3SS gene expression. Furthermore, our results suggest that horizontally acquired, ToxR-like proteins act in concert with the ancestral ToxR protein to orchestrate T3SS-mediated pathogenicity.

scholarly journals S-nitrosylation-mediated activation of a histidine kinase represses the type 3 secretion system and promotes virulence of an enteric pathogen

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Dan Gu ◽  
Yibei Zhang ◽  
Qiyao Wang ◽  
Xiaohui Zhou
Keyword(s):  
Histidine Kinase ◽  
Vibrio Parahaemolyticus ◽  
Early Stage ◽  
Rabbit Model ◽  
Secretion System ◽  
Intestinal Colonization ◽  
Type 3 Secretion System ◽  
Proinflammatory Factor ◽  
Type 3

AbstractVibrio parahaemolyticus is the leading cause of seafood-borne diarrheal diseases. Experimental overproduction of a type 3 secretion system (T3SS1) in this pathogen leads to decreased intestinal colonization, which suggests that T3SS1 repression is required for maximal virulence. However, the mechanisms by which T3SS1 is repressed in vivo are unclear. Here, we show that host-derived nitrite modifies the activity of a bacterial histidine kinase and mediates T3SS1 repression. More specifically, nitrite activates histidine kinase sensor VbrK through S-nitrosylation on cysteine 86, which results in downregulation of the entire T3SS1 operon through repression of its positive regulator exsC. Replacement of cysteine 86 with a serine (VbrK C86S mutant) leads to increased expression of inflammatory cytokines in infected Caco-2 cells. In an infant rabbit model of infection, the VbrK C86S mutant induces a stronger inflammatory response at the early stage of infection, and displays reduced intestinal colonization and virulence at the later stage of infection, in comparison with the parent strain. Our results indicate that the pathogen V. parahaemolyticus perceives nitrite as a host-derived signal and responds by downregulating a proinflammatory factor (T3SS1), thus enhancing intestinal colonization and virulence.

scholarly journals Glutamate Limitation, BvgAS Activation, and (p)ppGpp Regulate the Expression of the Bordetella pertussis Type 3 Secretion System

2015 ◽  
Vol 198 (2) ◽  
pp. 343-351 ◽  
Author(s):  
Tomoko Hanawa ◽  
Kazunari Kamachi ◽  
Hideo Yonezawa ◽  
Toshiyuki Fukutomi ◽  
Hayato Kawakami ◽  
...  
Keyword(s):  
Bordetella Pertussis ◽  
Protein Profile ◽  
Secretion System ◽  
Transcriptional Level ◽  
Content Type ◽  
Bacterial Physiology ◽  
Number Of Patients ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACTBordetella pertussisis a bacterium that is considered to be highly adapted to humans, and it has not been isolated from the environment. As this bacterium does not utilize sugars, the abundant supply of glutamate in Stainer Scholte (SS) medium enablesB. pertussisto grow efficiently in liquid culturein vitro, and as such, SS medium is a popular choice for laboratory experiments. However, the concentration of glutamate in thein vivoniche ofB. pertussisis quite low. We investigated the bacterial response to low concentrations of glutamate to elucidate bacterial physiology via the expression of the type 3 secretion system (T3SS), and we discuss its relationship to the Bvg mode in which the two-component regulator of pathogenesis (BvgAS) is activated. Glutamate limitation induced the expression of both the T3SS apparatus and effector genes at the transcriptional level. (p)ppGpp, a modulator of the stringent response, was necessary for maximum expression of the T3SS genes. These observations indicate that the expression of the T3SS is managed by nutrient starvation. In addition, the autoaggregation ability was high in the absence of glutamate and no autoaggregation was observed in glutamate-replete medium. Taken together, glutamate-limited conditions in Bvg+mode elicit the high expression of T3SS genes inB. pertussisand promotes its sessile form.IMPORTANCEBordetella pertussisis a highly contagious pathogen that causes respiratory infectious disease. In spite of the increasing use of vaccination, the number of patients with pertussis is increasing. The proteins producedin vivooften are different from the protein profile under laboratory conditions; therefore, the development of conditions reflecting the host environment is important to understand native bacterial behavior. In the present study, we examined the effect of glutamate limitation, as its concentrationin vivois much lower than that in the culture medium currently used forB. pertussisexperiments. As predicted, the T3SS was induced by glutamate limitation. These results are suggestive of the importance of regulation by nutrient conditions and in the pathogenicity ofB. pertussis.

scholarly journals Human Enteric Defensin 5 Promotes Shigella Infection of Macrophages

2019 ◽  
Vol 88 (1) ◽  
Author(s):  
Dan Xu ◽  
Chongbing Liao ◽  
Jiu Xiao ◽  
Kun Fang ◽  
Wei Zhang ◽  
...  
Keyword(s):  
Intestinal Epithelium ◽  
Protective Factor ◽  
Antimicrobial Activities ◽  
The Status ◽  
Host Defense Peptide ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACT Human α-defensins are 3- to 5-kDa disulfide-bridged peptides with a multitude of antimicrobial activities and immunomodulatory functions. Recent studies show that human enteric α-defensin 5 (HD5), a host defense peptide important for intestinal homeostasis and innate immunity, aids the highly infectious enteropathogen Shigella in breaching the intestinal epithelium in vitro and in vivo. Whether and how HD5 influences Shigella infection of resident macrophages following its invasion of the intestinal epithelium remain poorly understood. Here, we report that HD5 greatly promoted phagocytosis of Shigella by macrophages by targeting the bacteria to enhance bacterium-to-cell contacts in a structure- and sequence-dependent fashion. Subsequent intracellular multiplication of phagocytosed Shigella led to massive necrotic cell death and release of the bacteria. HD5-promoted phagocytosis of Shigella was independent of the status of the type 3 secretion system. Furthermore, HD5 neither inhibited nor enhanced phagosomal escape of Shigella. Collectively, these findings confirm a potential pathogenic role of HD5 in Shigella infection of not only epithelial cells but also macrophages, illuminating how an enteropathogen exploits a host protective factor for virulence and infection.

scholarly journals Invasion of Epithelial Cells Is Correlated with Secretion of Biosurfactant via the Type 3 Secretion System (T3SS) of Shigella flexneri

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
Duchel Jeanedvi Kinouani Kinavouidi ◽  
Christian Aimé Kayath ◽  
Etienne Nguimbi
Keyword(s):  
Organic Solvent ◽  
Type Iii Secretion ◽  
Shigella Flexneri ◽  
Secretion System ◽  
Extracellular Medium ◽  
Membrane Interfaces ◽  
Type 3 Secretion System ◽  
Type 3 ◽  
Hydrophobic Areas

Biosurfactants are amphipathic molecules produced by many microorganisms, usually bacteria, fungi, and yeasts. They possess the property of reducing the tension of the membrane interfaces. No studies have been conducted on Shigella species showing the role of biosurfactant-like molecules (BLM) in pathogenicity. The aim of this study is to assess the ability of Shigella environmental and clinical strains to produce BLM and investigate the involvement of biosurfactants in pathogenicity. Our study has shown that BLM are secreted in the extracellular medium with EI24 ranging from 80% to 100%. The secretion is depending on the type III secretion system (T3SS). Moreover, our results have shown that S. flexneri, S. boydii, and S. sonnei are able to interact with hydrophobic areas with 17.64%, 21.42%, and 22.22% hydrophobicity, respectively. BLM secretion is totally prevented due to inhibition of T3SS by 100 mM benzoic and 1.5 mg/ml salicylic acids. P. aeruginosa harboring T3SS is able to produce 100% of BLM in the presence or in the absence of both T3SS inhibitors. The secreted BLM are extractable with an organic solvent such as chloroform, and this could entirely be considered a lipopeptide or polypeptide compound. Secretion of BLM allows some Shigella strains to induce multicellular phenomena like “swarming.”

scholarly journals The HrpG/HrpX Regulon of Xanthomonads—An Insight to the Complexity of Regulation of Virulence Traits in Phytopathogenic Bacteria

2021 ◽  
Vol 9 (1) ◽  
pp. 187
Author(s):  
Doron Teper ◽  
Sheo Shankar Pandey ◽  
Nian Wang
Keyword(s):  
Regulatory Network ◽  
Regulatory Networks ◽  
Focal Point ◽  
Genetic Regulation ◽  
Transcriptional Regulators ◽  
Secretion System ◽  
In Planta ◽  
Type 3 Secretion System ◽  
Type 3 ◽  
Made In

Bacteria of the genus Xanthomonas cause a wide variety of economically important diseases in most crops. The virulence of the majority of Xanthomonas spp. is dependent on secretion and translocation of effectors by the type 3 secretion system (T3SS) that is controlled by two master transcriptional regulators HrpG and HrpX. Since their discovery in the 1990s, the two regulators were the focal point of many studies aiming to decipher the regulatory network that controls pathogenicity in Xanthomonas bacteria. HrpG controls the expression of HrpX, which subsequently controls the expression of T3SS apparatus genes and effectors. The HrpG/HrpX regulon is activated in planta and subjected to tight metabolic and genetic regulation. In this review, we cover the advances made in understanding the regulatory networks that control and are controlled by the HrpG/HrpX regulon and their conservation between different Xanthomonas spp.

scholarly journals Recruitment and the Role of Nuclear Localization in Polyglutamine-mediated Aggregation

1998 ◽  
Vol 143 (6) ◽  
pp. 1457-1470 ◽  
Author(s):  
Matthew K. Perez ◽  
Henry L. Paulson ◽  
Sagun J. Pendse ◽  
Sarah J. Saionz ◽  
Nancy M. Bonini ◽  
...  
Keyword(s):  
Nuclear Localization ◽  
Green Fluorescence Protein ◽  
Spinocerebellar Ataxia Type ◽  
Spinocerebellar Ataxia Type 3 ◽  
Eyes Absent ◽  
Disease Protein ◽  
Glutamine Repeat ◽  
Type 3

The inherited neurodegenerative diseases caused by an expanded glutamine repeat share the pathologic feature of intranuclear aggregates or inclusions (NI). Here in cell-based studies of the spinocerebellar ataxia type-3 disease protein, ataxin-3, we address two issues central to aggregation: the role of polyglutamine in recruiting proteins into NI and the role of nuclear localization in promoting aggregation. We demonstrate that full-length ataxin-3 is readily recruited from the cytoplasm into NI seeded either by a pathologic ataxin-3 fragment or by a second unrelated glutamine-repeat disease protein, ataxin-1. Experiments with green fluorescence protein/polyglutamine fusion proteins show that a glutamine repeat is sufficient to recruit an otherwise irrelevant protein into NI, and studies of human disease tissue and a Drosophila transgenic model provide evidence that specific glutamine-repeat–containing proteins, including TATA-binding protein and Eyes Absent protein, are recruited into NI in vivo. Finally, we show that nuclear localization promotes aggregation: an ataxin-3 fragment containing a nonpathologic repeat of 27 glutamines forms inclusions only when targeted to the nucleus. Our findings establish the importance of the polyglutamine domain in mediating recruitment and suggest that pathogenesis may be linked in part to the sequestering of glutamine-containing cellular proteins. In addition, we demonstrate that the nuclear environment may be critical for seeding polyglutamine aggregates.

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