scholarly journals Vibrio parahaemolyticus Inhibition of Rho Family GTPase Activation Requires a Functional Chromosome I Type III Secretion System

2008 ◽  
Vol 76 (5) ◽  
pp. 2202-2211 ◽  
Author(s):  
Timothy Casselli ◽  
Tarah Lynch ◽  
Carolyn M. Southward ◽  
Bryan W. Jones ◽  
Rebekah DeVinney
Keyword(s):  
Virulence Factors ◽  
Hela Cells ◽  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Secretion System ◽  
Type Iii ◽  
Rho Family Gtpases ◽  
Rho Family ◽  
Gtpase Activation ◽  
Chromosome I

ABSTRACT Vibrio parahaemolyticus is a leading cause of seafood-borne gastroenteritis; however, its virulence mechanisms are not well understood. The identification of type III secreted proteins has provided candidate virulence factors whose functions are still being elucidated. Genotypic strain variability contributes a level of complexity to understanding the role of different virulence factors. The ability of V. parahaemolyticus to inhibit Rho family GTPases and cause cytoskeletal disruption was examined with HeLa cells. After HeLa cells were infected, intracellular Rho activation was inhibited in response to external stimuli. In vitro activation of Rho, Rac, and Cdc42 isolated from infected HeLa cell lysates was also inhibited, indicating that the bacteria were specifically targeting GTPase activation. The inhibition of Rho family GTPase activation was retained for clinical and environmental isolates of V. parahaemolyticus and was dependent on a functional chromosome I type III secretion system (CI-T3SS). GTPase inhibition was independent of hemolytic toxin genotype and the chromasome II (CII)-T3SS. Rho inhibition was accompanied by a shift in the total actin pool to its monomeric form. These phenotypes were abrogated in a mutant strain lacking the CI-T3S effector Vp1686, suggesting that the inhibiting actin polymerization may be a downstream effect of Vp1686-dependent GTPase inhibition. Although Vp1686 has been previously characterized as a potential virulence factor in macrophages, our findings reveal an effect on cultured HeLa cells. The ability to inhibit Rho family GTPases independently of the CII-T3SS and the hemolytic toxins may provide insight into the mechanisms of virulence used by strains lacking these virulence factors.

scholarly journals Identification of Proteins Secreted via Vibrio parahaemolyticus Type III Secretion System 1

2006 ◽  
Vol 74 (2) ◽  
pp. 1032-1042 ◽  
Author(s):  
Takahiro Ono ◽  
Kwon-Sam Park ◽  
Mayumi Ueta ◽  
Tetsuya Iida ◽  
Takeshi Honda
Keyword(s):  
Hela Cells ◽  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Type Iii Secretion System ◽  
Gene Clusters ◽  
Secretion System ◽  
Secreted Proteins ◽  
Large Chromosome ◽  
Two Dimensional Gel Electrophoresis ◽  
Type Iii

ABSTRACT Vibrio parahaemolyticus, a gram-negative marine bacterium, is an important pathogen causing food-borne gastroenteritis or septicemia. Recent genome sequencing of the RIMD2210633 strain (a Kanagawa phenomenon-positive clinical isolate of serotype O3:K6) revealed that the strain has two sets of gene clusters that encode the type III secretion system (TTSS) apparatus. The first cluster, TTSS1, is located on the large chromosome, and the second, TTSS2, is on the small chromosome. Previously, we reported that TTSS1 is involved in the cytotoxicity of the RIMD2210633 strain against HeLa cells. Here, we analyzed proteins secreted via the TTSS apparatus encoded by TTSS1 by using two-dimensional gel electrophoresis and identified the proteins encoded by genes VP1680, VP1686, and VPA450. To investigate the roles of those secreted proteins, we constructed and analyzed a series of deletion mutants. Flow cytometry analysis using fluorescence-activated cell sorting with fluorescein isothiocyanate-labeled annexin V demonstrated that the TTSS1-dependent cell death was by apoptosis. The cytotoxicity to HeLa cells was related to one of the newly identified secreted proteins encoded by VP1680. Adenylate cyclase fusion protein studies proved that the newly identified secreted proteins were translocated into HeLa cells. Thus, these appear to be the TTSS effector proteins in V. parahaemolyticus.

scholarly journals Derivatives of Plant Phenolic Compound Affect the Type III Secretion System of Pseudomonas aeruginosa via a GacS-GacA Two-Component Signal Transduction System

2011 ◽  
Vol 56 (1) ◽  
pp. 36-43 ◽  
Author(s):  
Akihiro Yamazaki ◽  
Jin Li ◽  
Quan Zeng ◽  
Devanshi Khokhani ◽  
William C. Hutchins ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Phenolic Compounds ◽  
Virulence Factors ◽  
Type Iii Secretion ◽  
Small Rnas ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Human Pathogen ◽  
Content Type ◽  
Type Iii

ABSTRACTAntibiotic therapy is the most commonly used strategy to control pathogenic infections; however, it has contributed to the generation of antibiotic-resistant bacteria. To circumvent this emerging problem, we are searching for compounds that target bacterial virulence factors rather than their viability.Pseudomonas aeruginosa, an opportunistic human pathogen, possesses a type III secretion system (T3SS) as one of the major virulence factors by which it secretes and translocates T3 effector proteins into human host cells. The fact that this human pathogen also is able to infect several plant species led us to screen a library of phenolic compounds involved in plant defense signaling and their derivatives for novel T3 inhibitors. Promoter activity screening ofexoS, which encodes a T3-secreted toxin, identified two T3 inhibitors and two T3 inducers ofP. aeruginosaPAO1. These compounds alterexoStranscription by affecting the expression levels of the regulatory small RNAs RsmY and RsmZ. These two small RNAs are known to control the activity of carbon storage regulator RsmA, which is responsible for the regulation of the key T3SS regulator ExsA. As RsmY and RsmZ are the only targets directly regulated by GacA, our results suggest that these phenolic compounds affect the expression ofexoSthrough the GacSA-RsmYZ-RsmA-ExsA regulatory pathway.

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 SepZ/EspZ Is Secreted and Translocated into HeLa Cells by the Enteropathogenic Escherichia coli Type III Secretion System

2005 ◽  
Vol 73 (7) ◽  
pp. 4327-4337 ◽  
Author(s):  
Kristen J. Kanack ◽  
J. Adam Crawford ◽  
Ichiro Tatsuno ◽  
Mohamed A. Karmali ◽  
James B. Kaper
Keyword(s):  
Escherichia Coli ◽  
Hela Cells ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Bacterial Attachment ◽  
Host Cells ◽  
Dependent Manner ◽  
Cell Infection ◽  
Type Iii

ABSTRACT Enteropathogenic Escherichia coli (EPEC) is a major bacterial cause of infantile diarrhea in developing countries and is the prototype for a group of gastrointestinal pathogens causing characteristic attaching and effacing (A/E) histopathology on intestinal epithelia. A/E pathogens utilize a type III secretion system (TTSS), encoded by the locus of enterocyte effacement (LEE) pathogenicity island, to deliver effector proteins into host cells. Here, we investigate sequence divergence of the LEE-encoded SepZ protein and identify it as a TTSS-secreted and -translocated molecule. SepZ is hypervariable among A/E pathogens, with sequences sharing between 60 to 81% amino acid identity with SepZ of EPEC. A SepZ-CyaA fusion was secreted and translocated into HeLa cells in a TTSS-dependent manner. Additionally, we determined that the first 20 amino acids of SepZ were sufficient to direct its translocation. In contrast to previous studies suggesting a role in invasion and the structure and/or regulation of the TTSS, we found that SepZ does not mediate uptake of EPEC into host cells or affect translocation and tyrosine phosphorylation of the translocated intimin receptor. Immunohistochemistry reveals that, after an extended HeLa cell infection, accumulated SepZ can be detected beneath the site of bacterial attachment in a subset of pedestal regions. To indicate its newly identified status as a translocated effector protein, we propose to rename SepZ as EspZ.

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 High incidence of type III secretion system associated virulence factors (exoenzymes) in Pseudomonas aeruginosa isolated from Iranian burn patients

2019 ◽  
Vol 12 (1) ◽  
Author(s):  
Ramin Khodayary ◽  
Iraj Nikokar ◽  
Mohammad Reza Mobayen ◽  
Farhad Afrasiabi ◽  
Afshin Araghian ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Virulence Factors ◽  
Type Iii Secretion ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Burn Patients ◽  
Type Iii ◽  
High Incidence
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