scholarly journals Cytosporone B, an Inhibitor of the Type III Secretion System of Salmonella enterica Serovar Typhimurium

2013 ◽  
Vol 57 (5) ◽  
pp. 2191-2198 ◽  
Author(s):  
Jianfang Li ◽  
Chao Lv ◽  
Weiyang Sun ◽  
Zhenyu Li ◽  
Xiaowei Han ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Bacterial Resistance ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Content Type ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACTBacterial virulence factors have been increasingly regarded as attractive targets for development of novel antibacterial agents. Virulence inhibitors are less likely to generate bacterial resistance, which makes them superior to traditional antibiotics that target bacterial viability.Salmonella entericaserovar Typhimurium, an important food-borne human pathogen, has type III secretion system (T3SS) as its major virulence factor. T3SS secretes effector proteins to facilitate invasion into host cells. In this study, we identified several analogs of cytosporone B (Csn-B) that strongly block the secretion ofSalmonellapathogenicity island 1 (SPI-1)-associated effector proteins, without affecting the secretion of flagellar protein FliCin vitro. Csn-B and two other derivatives exhibited a strong inhibitory effect on SPI-1-mediated invasion to HeLa cells, while no significant toxicity to bacteria was observed. Nucleoid proteins Hha and H-NS bind to the promoters of SPI-1 regulator geneshilD,hilC, andrtsAto repress their expression and consequently regulate the expression of SPI-1 apparatus and effector genes. We found that Csn-B upregulated the transcription ofhhaandhns, implying that Csn-B probably affected the secretion of effectors through the Hha–H-NS regulatory pathway. In summary, this study presented an effective SPI-1 inhibitor, Csn-B, which may have potential in drug development against antibiotic-resistantSalmonella.

scholarly journals Identification of Salmonella Pathogenicity Island-2 Type III Secretion System Effectors Involved in Intramacrophage Replication of S. enterica Serovar Typhimurium: Implications for Rational Vaccine Design

mBio ◽  
2013 ◽  
Vol 4 (2) ◽  
Author(s):  
Rita Figueira ◽  
Kathryn G. Watson ◽  
David W. Holden ◽  
Sophie Helaine
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Content Type ◽  
Type Iii ◽  
Serovar Typhimurium ◽  
Bacterial Replication ◽  
Heterologous Antigens

ABSTRACT Salmonella enterica serovars cause severe diseases in humans, such as gastroenteritis and typhoid fever. The development of systemic disease is dependent on a type III secretion system (T3SS) encoded by Salmonella pathogenicity island-2 (SPI-2). Translocation of effector proteins across the Salmonella-containing vacuole, via the SPI-2 T3SS, enables bacterial replication within host cells, including macrophages. Here, we investigated the contribution of these effectors to intramacrophage replication of Salmonella enterica serovar Typhimurium using Fluorescence Dilution, a dual-fluorescence tool which allows direct measurement of bacterial replication. Of 32 strains, each carrying single mutations in genes encoding effectors, 10 (lacking sifA, sseJ, sopD2, sseG, sseF, srfH, sseL, spvD, cigR, or steD) were attenuated in replication in mouse bone marrow-derived macrophages. The replication profiles of strains combining deletions in effector genes were also investigated: a strain lacking the genes sseG, sopD2, and srfH showed an increased replication defect compared to single-mutation strains and was very similar to SPI-2 T3SS-deficient bacteria with respect to its replication defect. This strain was substantially attenuated in virulence in vivo and yet retained intracellular vacuole integrity and a functional SPI-2 T3SS. Moreover, this strain was capable of SPI-2 T3SS-mediated delivery of a model antigen for major histocompatibility complex (MHC) class I-dependent T-cell activation. This work establishes a basis for the use of a poly-effector mutant strain as an attenuated vaccine carrier for delivery of heterologous antigens directly into the cytoplasm of host cells. IMPORTANCE Live attenuated strains of Salmonella enterica serotype Typhi have generated much interest in the search for improved vaccines against typhoid fever and as vaccine vectors for the delivery of heterologous antigens. A promising vaccine candidate is the ΔaroC ΔssaV S. Typhi strain, which owes its attenuation mainly to lack of a type III secretion system (SPI-2 T3SS). The SPI-2 T3SS is important for bacterial proliferation inside macrophages, but not all of the effectors involved in this process have been identified. Here, we show that 10 effectors of the related strain S. Typhimurium contribute to intracellular replication in macrophages. Moreover, we establish that a poly-effector mutant strain of S. Typhimurium can have a severe replication defect and maintain a functional SPI-2 T3SS, which can be exploited for delivery of heterologous antigens.

scholarly journals RNase E Promotes Expression of Type III Secretion System Genes in Pseudomonas aeruginosa

2019 ◽  
Vol 201 (22) ◽  
Author(s):  
Josh S. Sharp ◽  
Arne Rietsch ◽  
Simon L. Dove
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Rnase E ◽  
Content Type ◽  
Type Iii ◽  
Small Regulatory Rnas

ABSTRACT Pseudomonas aeruginosa is an important opportunistic pathogen that employs a type III secretion system (T3SS) to inject effector proteins into host cells. Using a protein depletion system, we show that the endoribonuclease RNase E positively regulates expression of the T3SS genes. We also present evidence that RNase E antagonizes the expression of genes of the type VI secretion system and limits biofilm production in P. aeruginosa. Thus, RNase E, which is thought to be the principal endoribonuclease involved in the initiation of RNA degradation in P. aeruginosa, plays a key role in controlling the production of factors involved in both acute and chronic stages of infection. Although the posttranscriptional regulator RsmA is also known to positively regulate expression of the T3SS genes, we find that RNase E does not appreciably influence the abundance of RsmA in P. aeruginosa. Moreover, we show that RNase E still exerts its effects on T3SS gene expression in cells lacking all four of the key small regulatory RNAs that function by sequestering RsmA. IMPORTANCE The type III secretion system (T3SS) is a protein complex produced by many Gram-negative pathogens. It is capable of injecting effector proteins into host cells that can manipulate cell metabolism and have toxic effects. Understanding how the T3SS is regulated is important in understanding the pathogenesis of bacteria with such systems. Here, we show that RNase E, which is typically thought of as a global regulator of RNA stability, plays a role in regulating the T3SS in Pseudomonas aeruginosa. Depleting RNase E results in the loss of T3SS gene expression as well as a concomitant increase in biofilm formation. These observations are reminiscent of the phenotypes associated with the loss of activity of the posttranscriptional regulator RsmA. However, RNase E-mediated regulation of these systems does not involve changes in the abundance of RsmA and is independent of the known small regulatory RNAs that modulate RsmA activity.

scholarly journals Control of Type III Secretion System Effector/Chaperone Ratio Fosters Pathogen Adaptation to Host-Adherent Lifestyle

mBio ◽  
2019 ◽  
Vol 10 (5) ◽  
Author(s):  
Netanel Elbaz ◽  
Yaakov Socol ◽  
Naama Katsowich ◽  
Ilan Rosenshine
Keyword(s):  
Gene Expression ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Host Colonization ◽  
Content Type ◽  
Type Iii ◽  
Attached State

ABSTRACT The transition from a planktonic lifestyle to a host-attached state is often critical for bacterial virulence. Upon attachment to host cells, enteropathogenic Escherichia coli (EPEC) employs a type III secretion system (T3SS) to inject into the host cells ∼20 effector proteins, including Tir. CesT, which is encoded from the same operon downstream of tir, is a Tir-bound chaperone that facilitates Tir translocation. Upon Tir translocation, the liberated CesT remains in the bacterial cytoplasm and antagonizes the posttranscriptional regulator CsrA, thus eliciting global regulation in the infecting pathogen. Importantly, tight control of the Tir/CesT ratio is vital, since an uncontrolled surge in free CesT levels may repress CsrA in an untimely manner, thus abrogating colonization. We investigated how fluctuations in Tir translation affect the regulation of this ratio. By creating mutations that cause the premature termination of Tir translation, we revealed that the untranslated tir mRNA becomes highly unstable, resulting in a rapid drop in cesT mRNA levels and, thus, CesT levels. This mechanism couples Tir and CesT levels to ensure a stable Tir/CesT ratio. Our results expose an additional level of regulation that enhances the efficacy of the initial interaction of EPEC with the host cell, providing a better understanding of the bacterial switch from the planktonic to the cell-adherent lifestyle. IMPORTANCE Host colonization by extracellular pathogens often entails the transition from a planktonic lifestyle to a host-attached state. Enteropathogenic E. coli (EPEC), a Gram-negative pathogen, attaches to the intestinal epithelium of the host and employs a type III secretion system (T3SS) to inject effector proteins into the cytoplasm of infected cells. The most abundant effector protein injected is Tir, whose translocation is dependent on the Tir-bound chaperon CesT. Upon Tir injection, the liberated CesT binds to and inhibits the posttranscriptional regulator CsrA, resulting in reprogramming of gene expression in the host-attached bacteria. Thus, adaptation to the host-attached state involves dynamic remodeling of EPEC gene expression, which is mediated by the relative levels of Tir and CesT. Fluctuating from the optimal Tir/CesT ratio results in a decrease in EPEC virulence. Here we elucidate a posttranscriptional circuit that prevents sharp variations from this ratio, thus improving host colonization.

scholarly journals The Salmonella enterica Serotype Typhimurium Effector Proteins SipA, SopA, SopB, SopD, and SopE2 Act in Concert To Induce Diarrhea in Calves

2002 ◽  
Vol 70 (7) ◽  
pp. 3843-3855 ◽  
Author(s):  
Shuping Zhang ◽  
Renato L. Santos ◽  
Renee M. Tsolis ◽  
Silke Stender ◽  
Wolf-Dietrich Hardt ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Loop Model ◽  
Fluid Accumulation ◽  
Ileal Loop ◽  
Type Iii

ABSTRACT Salmonella enterica serotype Typhimurium requires a functional type III secretion system encoded by Salmonella pathogenicity island 1 (SPI1) to cause diarrhea. We investigated the role of genes encoding secreted target proteins of the SPI1-associated type III secretion system for enteropathogenicity in calves. Salmonella serotype Typhimurium strains having mutations in sptP, avrA, sspH1, or slrP induced fluid secretion in the bovine ligated ileal loop model at levels similar to that of the wild type. In contrast, mutations in sipA, sopA, sopB, sopD, or sopE2 significantly reduced fluid accumulation in bovine ligated ileal loops at 8 h postinfection. A strain carrying mutations in sipA, sopA, sopB, sopD, and sopE2 (sipA sopABDE2 mutant) caused the same level of fluid accumulation in bovine ligated ileal loops as a strain carrying a mutation in sipB, a SPI1 gene required for the translocation of effector proteins into host cells. A positive correlation was observed between the severity of histopathological lesions detected in the ileal mucosa and the levels of fluid accumulation induced by the different mutants. After oral infection of calves, the Salmonella serotype Typhimurium sipAsopABDE2 mutant caused only mild diarrhea and was more strongly attenuated than strains having only single mutations. These data demonstrate that SipA, SopA, SopB, SopD, and SopE2 are major virulence factors responsible for diarrhea during Salmonella serotype Typhimurium infection of calves.

scholarly journals Type III Secretion System Translocon Component EseB Forms Filaments on and Mediates Autoaggregation of and Biofilm Formation by Edwardsiella tarda

2015 ◽  
Vol 81 (17) ◽  
pp. 6078-6087 ◽  
Author(s):  
Zhi Peng Gao ◽  
Pin Nie ◽  
Jin Fang Lu ◽  
Lu Yi Liu ◽  
Tiao Yi Xiao ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Biofilm Formation ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Dependent Manner ◽  
Content Type ◽  
Type Iii

ABSTRACTThe type III secretion system (T3SS) ofEdwardsiella tardaplays an important role in infection by translocating effector proteins into host cells. EseB, a component required for effector translocation, is reported to mediate autoaggregation ofE. tarda. In this study, we demonstrate that EseB forms filamentous appendages on the surface ofE. tardaand is required for biofilm formation byE. tardain Dulbecco's modified Eagle's medium (DMEM). Biofilm formation byE. tardain DMEM does not require FlhB, an essential component for assembling flagella. Dynamic analysis of EseB filament formation, autoaggregation, and biofilm formation shows that the formation of EseB filaments occurs prior to autoaggregation and biofilm formation. The addition of an EseB antibody toE. tardacultures before bacterial autoaggregation prevents autoaggregation and biofilm formation in a dose-dependent manner, whereas the addition of the EseB antibody toE. tardacultures in which biofilm is already formed does not destroy the biofilm. Therefore, EseB filament-mediated bacterial cell-cell interaction is a prerequisite for autoaggregation and biofilm formation.

scholarly journals Killing of Candida albicans Filaments by Salmonella enterica Serovar Typhimurium Is Mediated by sopB Effectors, Parts of a Type III Secretion System

2011 ◽  
Vol 10 (6) ◽  
pp. 782-790 ◽  
Author(s):  
Younghoon Kim ◽  
Eleftherios Mylonakis
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Critical Role ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Content Type ◽  
Type Iii ◽  
Serovar Typhimurium ◽  
Fungal Interactions

ABSTRACTAlthough bacterial-fungal interactions shape microbial virulence during polymicrobial infections, only a limited number of studies have evaluated this interaction on a genetic level. We report here that one interaction is mediated bysopB, an effector of a type III secretion system (TTSS) ofSalmonella entericaserovar Typhimurium. In these studies, we screened 10 TTSS effector-related mutants and determined their role in the killing ofC. albicansfilamentsin vitroduring coinfection in planktonic environments. We found that deleting thesopBgene (which encodes inositol phosphatase) was associated with a significant decrease inC. albicanskilling at 25°C after 5 days, similar to that caused by the deletion ofsipB(which encodes TTSS translocation machinery components). ThesopBdeletion dramatically influenced the killing ofC. albicansfilaments. It was associated with repressed filamentation in theCaenorhabditis elegansmodel ofC. albicans-S.Typhimurium coinfection, as well as with biofilm formation byC. albicans. We confirmed that SopB translocated to fungal filaments through SipB during coinfection. Using quantitative real-time PCR assays, we found that theCandidasupernatant upregulated theS.Typhimurium genes associated withC. albicanskilling (sopBandsipB). Interestingly, the sopBeffector negatively regulated the transcription ofCDC42, which is involved in fungal viability. Taken together, these results indicate that specific TTSS effectors, including SopB, play a critical role in bacterial-fungal interactions and are important toS.Typhimurium in order to selectively compete with fungal pathogens. These findings highlight a new role for TTSS ofS.Typhimurium in the intestinal tract and may further explain the evolution and maintenance of these traits.

scholarly journals Optimization of the Delivery of Heterologous Proteins by the Salmonella enterica Serovar Typhimurium Type III Secretion System for Vaccine Development

2006 ◽  
Vol 74 (10) ◽  
pp. 5826-5833 ◽  
Author(s):  
Li-Mei Chen ◽  
Gabriel Briones ◽  
Ruben O. Donis ◽  
Jorge E. Galán
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Vaccine Development ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Antigen Delivery ◽  
Secretion Systems ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT Type III protein secretion systems, which are organelles with the capacity to deliver bacterial proteins into host cells, have been adapted to deliver heterologous antigens for vaccine development. A limitation of these antigen delivery systems is that some proteins are not amenable to secretion through this pathway. We show here that proteins from the simian and human immunodeficiency viruses that are not permissive for secretion through a Salmonella enterica serovar Typhimurium type III secretion system can be modified to travel this secretion pathway by introduction of discrete mutations. Proteins optimized for secretion were presented more efficiently via the major histocompatibility complex class I pathway and were able to induce a better immune response.

scholarly journals InvB Is Required for Type III-Dependent Secretion of SopA in Salmonella enterica Serovar Typhimurium

2004 ◽  
Vol 186 (4) ◽  
pp. 1215-1219 ◽  
Author(s):  
Kristin Ehrbar ◽  
Siegfried Hapfelmeier ◽  
Bärbel Stecher ◽  
Wolf-Dietrich Hardt
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Effector Protein ◽  
Enteric Disease ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT The Salmonella effector protein SopA is translocated into host cells via the SPI-1 type III secretion system (TTSS) and contributes to enteric disease. We found that the chaperone InvB binds to SopA and slightly stabilizes it in the bacterial cytosol and that it is required for its transport via the SPI-1 TTSS.

scholarly journals The Salmonella enterica Serovar Typhimurium-Encoded Type III Secretion Systems Can Translocate Chlamydia trachomatis Proteins into the Cytosol of Host Cells

2005 ◽  
Vol 73 (2) ◽  
pp. 905-911 ◽  
Author(s):  
Theresa D. Ho ◽  
Michael N. Starnbach
Keyword(s):  
T Cell ◽  
Chlamydia Trachomatis ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Cell Activity ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT Chlamydia trachomatis is an obligate, intracellular pathogen that is a major cause of preventable blindness and infertility worldwide. Although the published genome sequence suggests that C. trachomatis encodes a type III secretion system, the lack of genetic tools for studying Chlamydia has hindered the examination of this potentially important class of virulence genes. We have developed a technique to identify Chlamydia proteins that can be translocated into the host cell cytoplasm by a type III secretion system. We have selected several Chlamydia proteins and tagged them with a multiple peptide motif element called F8M4. Epitopes contained in the F8M4 tag allow us to use tools corresponding to different arms of the adaptive immune system to detect the expression and translocation of these proteins by Salmonella enterica serovar Typhimurium. In particular, CD8+-T-cell reactivity can be used to detect the translocation of F8M4-tagged proteins into the cytoplasm of host cells. We have found that CD8+-T-cell activity assays are sensitive enough to detect translocation of even a small amount of F8M4-tagged protein. We have used CD8+-T-cell activity to show that CopN, a Chlamydia protein previously shown to be translocated by Yersinia type III secretion, can be translocated by the Salmonella pathogenicity island 1 (SPI-1) type III secretion system. Additionally, we demonstrate that CopD and Pkn5, two Chlamydia proteins hypothesized to be substrates of a type III secretion system, are translocated via the SPI-2 type III secretion system of serovar Typhimurium. The epitope tag system described here can be used more generally to examine the expression and subcellular compartmentalization of bacterial proteins deployed during the interaction of pathogens with mammalian cells.

scholarly journals Type III Secretion of Salmonella enterica Serovar Typhimurium Translocated Effectors and SseFG

2002 ◽  
Vol 70 (3) ◽  
pp. 1403-1409 ◽  
Author(s):  
Imke Hansen-Wester ◽  
Bärbel Stecher ◽  
Michael Hensel
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Type Iii ◽  
Serovar Typhimurium ◽  
Substrate Proteins

ABSTRACT The type III secretion system (TTSS) encoded by Salmonella enterica serovar Typhimurium pathogenicity island 2 (SPI2) is employed by Salmonella enterica for interaction with host cells during the intracellular phase of pathogenesis. This TTSS secretes a set of SPI2-encoded proteins in vitro and translocates Salmonella serovar Typhimurium translocated effectors (STE) that are encoded by genes outside of SPI2 into host cells. Using an epitope-tagging approach, we analyzed secretion of proteins by the TTSS of SPI2 and identified SseF and SseG as further secreted substrate proteins. Three members of the STE family, SifA, SifB, and SseJ, were secreted under conditions that also induce secretion of SPI2-encoded substrate proteins.

Sign in / Sign up

Export Citation Format

Share Document