Role of type III secretion in Edwardsiella tarda virulence

Microbiology ◽  
2005 ◽  
Vol 151 (7) ◽  
pp. 2301-2313 ◽  
Author(s):  
Y. P. Tan ◽  
J. Zheng ◽  
S. L. Tung ◽  
I. Rosenshine ◽  
K. Y. Leung
Keyword(s):  
Type Iii Secretion ◽  
Bacterial Pathogen ◽  
Regulatory System ◽  
Host Cells ◽  
Edwardsiella Tarda ◽  
Wild Type ◽  
Type Iii ◽  
Cell Functions ◽  
Survival And Growth

Edwardsiella tarda is a Gram-negative enteric bacterium affecting both animals and humans. Recently, a type III secretion system (TTSS) was found in Ed. tarda. Such systems are generally used by bacterial pathogens to deliver virulence factors into host cells to subvert normal cell functions. Genome-walking was performed from the eseB and esrB genes (homologues of Salmonella sseB and ssrB, respectively) identified in previous studies, to determine the sequences of the TTSS. Thirty-five ORFs were identified which encode the TTSS apparatus, chaperones, effectors and regulators. Mutants affected in genes representing each category were generated and found to have decreased survival and growth in fish phagocytes. LD50 values of the mutants were increased by at least 10-fold in comparison to those of the wild-type strain. The adherence and invasion rates of the esrA and esrB mutants were enhanced while those of the other mutants remained similar to the wild-type. The eseC and eseD mutants showed slight autoaggregation in Dulbecco's Modified Eagle Medium, whereas the rest of the mutants failed to autoaggregate. Regulation of the TTSS was found to involve the two-component regulatory system esrA–esrB. This study showed that the TTSS is important for Ed. tarda pathogenesis. An understanding of this system will provide greater insight into the virulence mechanisms of this bacterial pathogen.

scholarly journals Type III Secretion Decreases Bacterial and Host Survival following Phagocytosis of Yersinia pseudotuberculosis by Macrophages

2008 ◽  
Vol 76 (9) ◽  
pp. 4299-4310 ◽  
Author(s):  
Yue Zhang ◽  
James Murtha ◽  
Margaret A. Roberts ◽  
Richard M. Siegel ◽  
James B. Bliska
Keyword(s):  
Cell Death ◽  
Type Iii Secretion ◽  
Yersinia Pseudotuberculosis ◽  
De Novo ◽  
Host Cells ◽  
Host Responses ◽  
Intracellular Bacteria ◽  
Wild Type ◽  
Macrophage Response ◽  
Type Iii

ABSTRACT Yersinia pseudotuberculosis uses a plasmid (pYV)-encoded type III secretion system (T3SS) to translocate a set of effectors called Yops into infected host cells. YopJ functions to induce apoptosis, and YopT, YopE, and YopH act to antagonize phagocytosis in macrophages. Because Yops do not completely block phagocytosis and Y. pseudotuberculosis can replicate in macrophages, it is important to determine if the T3SS modulates host responses to intracellular bacteria. Isogenic pYV-cured, pYV+ wild-type, and yop mutant Y. pseudotuberculosis strains were allowed to infect bone marrow-derived murine macrophages at a low multiplicity of infection under conditions in which the survival of extracellular bacteria was prevented. Phagocytosis, the intracellular survival of the bacteria, and the apoptosis of the infected macrophages were analyzed. Forty percent of cell-associated wild-type bacteria were intracellular after a 20-min infection, allowing the study of the macrophage response to internalized pYV+ Y. pseudotuberculosis. Interestingly, macrophages restricted survival of pYV+ but not pYV-cured or ΔyopB Y. pseudotuberculosis within phagosomes: only a small fraction of the pYV+ bacteria internalized replicated by 24 h. In addition, ∼20% of macrophages infected with wild-type pYV+ Y. pseudotuberculosis died of apoptosis after 20 h. Analysis of yop mutants expressing catalytically inactive effectors revealed that YopJ was important for apoptosis, while a role for YopE, YopH, and YopT in modulating macrophage responses to intracellular bacteria could not be identified. Apoptosis was reduced in Toll-like receptor 4-deficient macrophages, indicating that cell death required signaling through this receptor. Treatment of macrophages harboring intracellular pYV+ Y. pseudotuberculosis with chloramphenicol reduced apoptosis, indicating that the de novo bacterial protein synthesis was necessary for cell death. Our finding that the presence of a functional T3SS impacts the survival of both bacterium and host following phagocytosis of Y. pseudotuberculosis suggests new roles for the T3SS in Yersinia pathogenesis.

scholarly journals Salmonella enterica subspecies enterica serovar Enteritidis Salmonella pathogenicity island 2 type III secretion system: role in intestinal colonization of chickens and systemic spread

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2770-2781 ◽  
Author(s):  
Amanda L. S. Wisner ◽  
Taseen S. Desin ◽  
Birgit Koch ◽  
Po-King S. Lam ◽  
Emil M. Berberov ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Type Strain ◽  
Wild Type Strain ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Host Cells ◽  
Wild Type ◽  
Type Iii ◽  
Systemic Spread

Salmonella enterica subspecies enterica serovar Enteritidis (S. Enteritidis) has been identified as a significant cause of salmonellosis in humans. Salmonella pathogenicity islands 1 and 2 (SPI-1 and SPI-2) each encode a specialized type III secretion system (T3SS) that enables Salmonella to manipulate host cells at various stages of the invasion/infection process. For the purposes of our studies we used a chicken isolate of S. Enteritidis (Sal18). In one study, we orally co-challenged 35-day-old specific pathogen-free (SPF) chickens with two bacterial strains per group. The control group received two versions of the wild-type strain Sal18: Sal18 attTn7 : : tet and Sal18 attTn7 : : cat, while the other two groups received the wild-type strain (Sal18 attTn7 : : tet) and one of two mutant strains. From this study, we concluded that S. Enteritidis strains deficient in the SPI-1 and SPI-2 systems were outcompeted by the wild-type strain. In a second study, groups of SPF chickens were challenged at 1 week of age with four different strains: the wild-type strain, and three other strains lacking either one or both of the SPI-1 and SPI-2 regions. On days 1 and 2 post-challenge, we observed a reduced systemic spread of the SPI-2 mutants, but by day 3, the systemic distribution levels of the mutants matched that of the wild-type strain. Based on these two studies, we conclude that the S. Enteritidis SPI-2 T3SS facilitates invasion and systemic spread in chickens, although alternative mechanisms for these processes appear to exist.

scholarly journals Role of Adhesin Release for Mucosal Colonization by a Bacterial Pathogen

2003 ◽  
Vol 197 (6) ◽  
pp. 735-742 ◽  
Author(s):  
Loïc Coutte ◽  
Sylvie Alonso ◽  
Nathalie Reveneau ◽  
Eve Willery ◽  
Brigitte Quatannens ◽  
...  
Keyword(s):  
Respiratory Tract ◽  
Bacterial Pathogen ◽  
Host Cells ◽  
Wild Type ◽  
Early Step ◽  
Bacterial Surface ◽  
Extracellular Milieu ◽  
Wild Type Parent

Pathogen attachment is a crucial early step in mucosal infections. This step is mediated by important virulence factors called adhesins. To exert these functions, adhesins are typically surface-exposed, although, surprisingly, some are also released into the extracellular milieu, the relevance of which has previously not been studied. To address the role of adhesin release in pathogenesis, we used Bordetella pertussis as a model, since its major adhesin, filamentous hemagglutinin (FHA), partitions between the bacterial surface and the extracellular milieu. FHA release depends on its maturation by the specific B. pertussis protease SphB1. We constructed SphB1-deficient mutants and found that they were strongly affected in their ability to colonize the mouse respiratory tract, although they adhered even better to host cells in vitro than their wild-type parent strain. The defect in colonization could be overcome by prior nasal instillation of purified FHA or by coinfection with FHA-releasing B. pertussis strains, but not with SphB1-producing FHA-deficient strains, ruling out a nonspecific effect of SphB1. These results indicate that the release of FHA is important for colonization, as it may facilitate the dispersal of bacteria from microcolonies and the binding to new sites in the respiratory tract.

scholarly journals Yersinia enterocolitica Type III Secretion Depends on the Proton Motive Force but Not on the Flagellar Motor Components MotA and MotB

2004 ◽  
Vol 72 (7) ◽  
pp. 4004-4009 ◽  
Author(s):  
Gottfried Wilharm ◽  
Verena Lehmann ◽  
Kristina Krauss ◽  
Beatrix Lehnert ◽  
Susanna Richter ◽  
...  
Keyword(s):  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Proton Motive Force ◽  
Motive Force ◽  
Host Cells ◽  
Infection Model ◽  
Flagellar Motor ◽  
Wild Type ◽  
Secretion Systems ◽  
Type Iii

ABSTRACT The flagellum is believed to be the common ancestor of all type III secretion systems (TTSSs). In Yersinia enterocolitica, expression of the flagellar TTSS and the Ysc (Yop secretion) TTSS are inversely regulated. We therefore hypothesized that the Ysc TTSS may adopt flagellar motor components in order to use the pathogenicity-related translocon in a drill-like manner. As a prerequisite for this hypothesis, we first tested a requirement for the proton motive force by both systems using the protonophore carbonyl cyanide m-chlorophenylhydrazone (CCCP). Motility as well as type III-dependent secretion of Yop proteins was inhibited by CCCP. We deleted motAB, which resulted in an immotile phenotype. This mutant, however, secreted amounts of Yops to the supernatant comparable to those of the wild type. Translocation of Yops into host cells was also not affected by the motAB deletion. Virulence of the mutant was comparable to that of the wild type in the mouse oral infection model. Thus, the hypothesis that the Ysc TTSS might adopt flagellar motor components was not confirmed. The finding that, in addition to consumption of ATP, Ysc TTSS requires the proton motive force is discussed.

scholarly journals SseL Is a Salmonella-Specific Translocated Effector Integrated into the SsrB-Controlled Salmonella Pathogenicity Island 2 Type III Secretion System

2006 ◽  
Vol 75 (2) ◽  
pp. 574-580 ◽  
Author(s):  
Brian K. Coombes ◽  
Michael J. Lowden ◽  
Jennifer L. Bishop ◽  
Mark E. Wickham ◽  
Nat F. Brown ◽  
...  
Keyword(s):  
Virulence Factors ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Regulatory System ◽  
Pathogenicity Island ◽  
Secretion System ◽  
Host Cells ◽  
Dependent Manner ◽  
Host Colonization ◽  
Type Iii

ABSTRACT Bacterial pathogens use horizontal gene transfer to acquire virulence factors that influence host colonization, alter virulence traits, and ultimately shape the outcome of disease following infection. One hallmark of the host-pathogen interaction is the prokaryotic type III secretion system that translocates virulence factors into host cells during infection. Salmonella enterica possesses two type III secretion systems that are utilized during host colonization and intracellular replication. Salmonella pathogenicity island 2 (SPI2) is a genomic island containing approximately 30 contiguous genes required to assemble a functional secretion system including the two-component regulatory system called SsrA-SsrB that positively regulates transcription of the secretion apparatus. We used transcriptional profiling with DNA microarrays to search for genes that coregulate with the SPI2 type III secretion machinery in an SsrB-dependent manner. Here we report the identification of a Salmonella-specific translocated effector called SseL that is required for full virulence during murine typhoid-like disease. Analysis of infected macrophages using fluorescence-activated cell sorting revealed that sseL is induced inside cells and requires SsrB for expression. SseL is retained predominantly in the cytoplasm of infected cells following translocation by the type III system encoded in SPI2. Animal infection experiments with sseL mutant bacteria indicate that integration of SseL into the SsrB response regulatory system contributes to systemic virulence of this pathogen.

scholarly journals Shigella Spa32 Is an Essential Secretory Protein for Functional Type III Secretion Machinery and Uniformity of Its Needle Length

2002 ◽  
Vol 184 (5) ◽  
pp. 1244-1252 ◽  
Author(s):  
Koichi Tamano ◽  
Eisaku Katayama ◽  
Takahito Toyotome ◽  
Chihiro Sasakawa
Keyword(s):  
Hela Cells ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretory Protein ◽  
Secretion System ◽  
Host Cells ◽  
Functional Type ◽  
Wild Type ◽  
Needle Length ◽  
Type Iii

ABSTRACT The Shigella type III secretion machinery is responsible for delivering to host cells the set of effectors required for invasion. The type III secretion complex comprises a needle composed of MxiH and MxiI and a basal body made up of MxiD, MxiG, and MxiJ. In S. flexneri, the needle length has a narrow range, with a mean of approximately 45 nm, suggesting that it is strictly regulated. Here we show that Spa32, encoded by one of the spa genes, is an essential protein translocated via the type III secretion system and is involved in the control of needle length as well as type III secretion activity. When the spa32 gene was mutated, the type III secretion complexes possessed needles of various lengths, ranging from 40 to 1,150 nm. Upon introduction of a cloned spa32 into the spa32 mutant, the bacteria produced needles of wild-type length. The spa32 mutant overexpressing MxiH produced extremely long (>5 μm) needles. Spa32 was secreted into the medium via the type III secretion system, but secretion did not depend on activation of the system. The spa32 mutant and the mutant overexpressing MxiH did not secrete effectors such as Ipa proteins into the medium or invade HeLa cells. Upon introduction of Salmonella invJ, encoding InvJ, which has 15.4% amino acid identity with Spa32, into the spa32 mutant, the bacteria produced type III needles of wild-type length and efficiently entered HeLa cells. These findings suggest that Spa32 is an essential secreted protein for a functional type III secretion system in Shigella spp. and is involved in the control of needle length. Furthermore, its function is interchangeable with that of Salmonella InvJ.

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 Role of the Salmonella Pathogenicity Island 1 (SPI-1) Protein InvB in Type III Secretion of SopE and SopE2, Two Salmonella Effector Proteins Encoded Outside of SPI-1

2003 ◽  
Vol 185 (23) ◽  
pp. 6950-6967 ◽  
Author(s):  
Kristin Ehrbar ◽  
Andrea Friebel ◽  
Samuel I. Miller ◽  
Wolf-Dietrich Hardt
Keyword(s):  
Type Iii Secretion ◽  
Inflammatory Responses ◽  
Pathogenicity Island ◽  
Effector Proteins ◽  
Host Cells ◽  
Effector Protein ◽  
Dependent Manner ◽  
Type Iii ◽  
Serovar Typhimurium

ABSTRACT Salmonella enterica subspecies 1 serovar Typhimurium encodes a type III secretion system (TTSS) within Salmonella pathogenicity island 1 (SPI-1). This TTSS injects effector proteins into host cells to trigger invasion and inflammatory responses. Effector proteins are recognized by the TTSS via signals encoded in their N termini. Specific chaperones can be involved in this process. The chaperones InvB, SicA, and SicP are encoded in SPI-1 and are required for transport of SPI-1-encoded effectors. Several key effector proteins, like SopE and SopE2, are located outside of SPI-1 but are secreted in an SPI-1-dependent manner. It has not been clear how these effector proteins are recognized by the SPI-1 TTSS. Using pull-down and coimmunoprecipitation assays, we found that SopE is copurified with InvB, the known chaperone for the SPI-1-encoded effector protein Sip/SspA. We also found that InvB is required for secretion and translocation of SopE and SopE2 and for stabilization of SopE2 in the bacterial cytosol. Our data demonstrate that effector proteins encoded within and outside of SPI-1 use the same chaperone for secretion via the SPI-1 TTSS.

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 Regulation of the Ysa Type III Secretion System of Yersinia enterocolitica by YsaE/SycB and YsrS/YsrR

2004 ◽  
Vol 186 (13) ◽  
pp. 4056-4066 ◽  
Author(s):  
Kimberly A. Walker ◽  
Virginia L. Miller
Keyword(s):  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Shigella Flexneri ◽  
Wild Type ◽  
Secretion Systems ◽  
Type Iii ◽  
Regulatory Cascade ◽  
Two Component

ABSTRACT Yersinia enterocolitica biovar 1B contains two type III secretion systems (TTSSs), the plasmid-encoded Ysc-Yop system and the chromosomally encoded Ysa-Ysp system. Proteins secreted from the Ysa TTSS (Ysps) have only been detected in vitro when cells are cultured at 26°C in a high-NaCl medium. However, the exact role of the Ysa TTSS is unclear. Thus, investigations into the regulation of this system may help elucidate the role of the Ysps during the life cycle of Y. enterocolitica. Here we present evidence that the AraC-like regulator YsaE acts together with the chaperone SycB to regulate transcription of the sycByspBCDA operon, a phenomenon similar to that seen in the closely related Salmonella SPI-1 and Shigella flexneri Mxi-Spa-Ipa TTSSs. Deletion of either sycB or ysaE results in a twofold reduction in the activity of a sycB-lacZ fusion compared to the wild type. In a reconstituted Escherichia coli system, transcription of sycB was activated sixfold only when both YsaE and SycB were present, demonstrating that they are necessary for activation. ysrR and ysrS are located near the ysa genes and encode a putative two-component regulatory system. Mutations in either gene indicated that both YsrR and YsrS were required for secretion of Ysps. In addition, transcription from sycB-lacZ and ysaE-lacZ fusions was decreased 6.5- and 25-fold, respectively, in the ysrS mutant compared to the wild type. Furthermore, in the absence of NaCl, the activity of ysaE-lacZ was reduced 25-fold in the wild-type and ΔysrS strains, indicating that YsrS is probably required for the salt-dependent expression of the ysa locus. These results suggest that the putative two-component system YsrRS may be a key element in the regulatory cascade for the Ysa TTSS.

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