scholarly journals Type III Secretion Is Essential for the Rapidly Fatal Diarrheal Disease Caused by Non-O1, Non-O139 Vibrio cholerae

mBio ◽  
2011 ◽  
Vol 2 (3) ◽  
Author(s):  
Ok S. Shin ◽  
Vincent C. Tam ◽  
Masato Suzuki ◽  
Jennifer M. Ritchie ◽  
Roderick T. Bronson ◽  
...  
Keyword(s):  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Intestinal Epithelium ◽  
Type Iii Secretion ◽  
Diarrheal Disease ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Severe Diarrhea ◽  
Toxin Coregulated Pilus

ABSTRACTCholera is a severe diarrheal disease typically caused by O1 serogroup strains ofVibrio cholerae. The pathogenicity of all pandemicV. choleraeO1 strains relies on two critical virulence factors: cholera toxin, a potent enterotoxin, and toxin coregulated pilus (TCP), an intestinal colonization factor. However, certain non-O1, non-O139V. choleraestrains, such as AM-19226, do not produce cholera toxin or TCP, yet they still cause severe diarrhea. The molecular basis for the pathogenicity of non-O1, non-O139V. choleraehas not been extensively characterized, but many of these strains encode related type III secretion systems (TTSSs). Here, we used infant rabbits to assess the contribution of the TTSS to non-O1, non-O139V. choleraepathogenicity. We found that all animals infected with wild-type AM-19226 developed severe diarrhea even more rapidly than rabbits infected withV. choleraeO1. UnlikeV. choleraeO1 strains, which do not damage the intestinal epithelium in rabbits or humans, AM-19226 caused marked disruptions of the epithelial surface in the rabbit small intestine. TTSS proved to be essential for AM-19226 virulence in infant rabbits; an AM-19226 derivative deficient for TTSS did not elicit diarrhea, colonize the intestine, or induce pathological changes in the intestine. Deletion of either one of the two previously identified or two newly identified AM-19226 TTSS effectors reduced but did not eliminate AM-19226 pathogenicity, suggesting that at least four effectors contribute to this strain’s virulence. In aggregate, our results suggest that the TTSS-dependent virulence in non-O1, non-O139V. choleraerepresents a new type of diarrheagenic mechanism.IMPORTANCECholera, which is caused byVibrio cholerae, is an important cause of diarrheal disease in many developing countries. The mechanisms of virulence of nonpandemic strains that can cause a diarrheal illness are poorly understood. AM-19226, like several other pathogenic, nonpandemicV. choleraestrains, carries genes that encode a type III secretion system (TTSS), but not cholera toxin (CT) or toxin coregulated pilus (TCP). In this study, we used infant rabbits to study AM-19226 virulence. Infant rabbits orally inoculated with this strain rapidly developed a fatal diarrheal disease, which was accompanied by marked disruptions of the intestinal epithelium. This strain’s TTSS proved essential for its pathogenicity, and there was no diarrhea, intestinal pathology, or colonization in rabbits infected with a TTSS mutant. The effector proteins translocated by the TTSS all appear to contribute to AM-19226 virulence. Thus, our study provides insight intoin vivomechanisms by which a novel TTSS contributes to diarrheal disease caused by nonpandemic strains ofV. cholerae.

scholarly journals Cyclic Di-GMP and VpsR Induce the Expression of Type II Secretion in Vibrio cholerae

2017 ◽  
Vol 199 (19) ◽  
Author(s):  
Rudolph E. Sloup ◽  
Ashley E. Konal ◽  
Geoffrey B. Severin ◽  
Michelle L. Korir ◽  
Mira M. Bagdasarian ◽  
...  
Keyword(s):  
Vibrio Cholerae ◽  
Protein Complexes ◽  
Second Messenger ◽  
Type Ii Secretion ◽  
Type Ii ◽  
Secretion Systems ◽  
Content Type ◽  
Severe Diarrhea ◽  
Wide Range ◽  
Genes Encoding

ABSTRACT Vibrio cholerae is a human pathogen that alternates between growth in environmental reservoirs and infection of human hosts, causing severe diarrhea. The second messenger cyclic di-GMP (c-di-GMP) mediates this transition by controlling a wide range of functions, such as biofilms, virulence, and motility. Here, we report that c-di-GMP induces expression of the extracellular protein secretion (eps) gene cluster, which encodes the type II secretion system (T2SS) in V. cholerae. Analysis of the eps genes confirmed the presence of two promoters located upstream of epsC, the first gene in the operon, one of which is induced by c-di-GMP. This induction is directly mediated by the c-di-GMP-binding transcriptional activator VpsR. Increased expression of the eps operon did not impact secretion of extracellular toxin or biofilm formation but did increase expression of the pseudopilin protein EpsG on the cell surface. IMPORTANCE Type II secretion systems (T2SSs) are the primary molecular machines by which Gram-negative bacteria secrete proteins and protein complexes that are folded and assembled in the periplasm. The substrates of T2SSs include extracellular factors, such as proteases and toxins. Here, we show that the widely conserved second messenger cyclic di-GMP (c-di-GMP) upregulates expression of the eps genes encoding the T2SS in the pathogen V. cholerae via the c-di-GMP-dependent transcription factor VpsR.

scholarly journals Identification of YsaP, the Pilotin of the Yersinia enterocolitica Ysa Type III Secretion System

2015 ◽  
Vol 197 (17) ◽  
pp. 2770-2779 ◽  
Author(s):  
Reina Rau ◽  
Andrew J. Darwin
Keyword(s):  
Outer Membrane ◽  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Outer Membrane Proteins ◽  
State Level ◽  
Secretion Systems ◽  
Membrane Pore ◽  
Content Type ◽  
Type Iii ◽  
Null Strain

ABSTRACTSecretins are multimeric outer membrane pore-forming proteins found in complex export systems in Gram-negative bacteria. All type III secretion systems (T3SSs) have a secretin, and one of these is the YsaC secretin of the chromosomally encoded Ysa T3SS ofYersinia enterocolitica. In some cases, pilotin proteins, which are outer membrane lipoproteins, are required for their cognate secretins to multimerize and/or localize to the outer membrane. However, if secretin multimers mislocalize to the inner membrane, this can trigger the protective phage shock protein (Psp) stress response. During a screen for mutations that suppress YsaC toxicity to apspnull strain, we isolated several independent mutations predicted to increase expression of the YE3559 gene within the Ysa pathogenicity island. YE3559, which we have namedysaP, is predicted to encode a small outer membrane lipoprotein, and this location was confirmed by membrane fractionation. ElevatedysaPexpression increased the steady-state level of YsaC but made it less toxic to apspnull strain, and it also decreased YsaC-dependent induction ofpspgene expression. Subsequent experiments showed that YsaP was not required for YsaC multimerization but was required for the multimers to localize to the outer membrane. Consistent with this, aysaPnull mutation compromised protein export by the Ysa T3SS. All these observations suggest that YsaP is the pilotin for the YsaC secretin. This is only the second pilotin to be characterized forYersiniaand one of only a small number of pilotins described for all bacteria.IMPORTANCESecretins are essential for the virulence of many bacterial pathogens and also play roles in surface attachment, motility, and competence. This has generated considerable interest in understanding how secretins function. However, their fundamental differences from typical outer membrane proteins have raised various questions about secretins, including how they are assembled into outer membrane multimers. Pilotin proteins facilitate the assembly of some secretins, but only a small number of pilotins have been identified, slowing efforts to understand common and distinct features of secretin assembly. This study provides an important advance by identifying a novel member of the pilotin family and also demonstrating a method of pilotin discovery that could be broadly applied.

scholarly journals The Bacterium Pantoea stewartii Uses Two Different Type III Secretion Systems To Colonize Its Plant Host and Insect Vector

2012 ◽  
Vol 78 (17) ◽  
pp. 6327-6336 ◽  
Author(s):  
Valdir R. Correa ◽  
Doris R. Majerczak ◽  
El-Desouky Ammar ◽  
Massimo Merighi ◽  
Richard C. Pratt ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Flea Beetle ◽  
Insect Vector ◽  
Secretion Systems ◽  
Plant Host ◽  
Content Type ◽  
Type Iii ◽  
Pantoea Stewartii ◽  
Type Iii Secretion Systems ◽  
Animal Pathogens

ABSTRACTPlant- and animal-pathogenic bacteria utilize phylogenetically distinct type III secretion systems (T3SS) that produce needle-like injectisomes or pili for the delivery of effector proteins into host cells.Pantoea stewartiisubsp.stewartii(herein referred to asP. stewartii), the causative agent of Stewart's bacterial wilt and leaf blight of maize, carries phylogenetically distinct T3SSs. In addition to an Hrc-Hrp T3SS, known to be essential for maize pathogenesis,P. stewartiihas a second T3SS (Pantoeasecretion island 2 [PSI-2]) that is required for persistence in its flea beetle vector,Chaetocnema pulicaria(Melsh). PSI-2 belongs to the Inv-Mxi-Spa T3SS family, typically found in animal pathogens. Mutagenesis of the PSI-2psaNgene, which encodes an ATPase essential for secretion of T3SS effectors by the injectisome, greatly reduces both the persistence ofP. stewartiiin flea beetle guts and the beetle's ability to transmitP. stewartiito maize. Ectopic expression of thepsaNgene complements these phenotypes. In addition, the PSI-2psaNgene is not required forP. stewartiipathogenesis of maize and is transcriptionally upregulated in insects compared to maize tissues. Thus, the Hrp and PSI-2 T3SSs play different roles in the life cycle ofP. stewartiias it alternates between its insect vector and plant host.

scholarly journals Identification of Potential Type III Secretion Proteins via Heterologous Expression of Vibrio parahaemolyticus DNA

2012 ◽  
Vol 78 (9) ◽  
pp. 3492-3494 ◽  
Author(s):  
Xiaohui Zhou ◽  
Seth D. Nydam ◽  
Jeffrey E. Christensen ◽  
Michael E. Konkel ◽  
Lisa Orfe ◽  
...  
Keyword(s):  
Heterologous Expression ◽  
Yersinia Enterocolitica ◽  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Genomic Islands ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Type Iii Secretion Systems ◽  
Secretion Assay

ABSTRACTWe employed a heterologous secretion assay to identify proteins potentially secreted by type III secretion systems (T3SSs) inVibrio parahaemolyticus. N-terminal sequences from 32 proteins within T3SS genomic islands and seven proteins from elsewhere in the chromosome included proteins that were recognized for export by theYersinia enterocoliticaflagellar T3SS.

scholarly journals Dynamics of the Type III Secretion System Activity of Enteropathogenic Escherichia coli

mBio ◽  
2013 ◽  
Vol 4 (4) ◽  
Author(s):  
Erez Mills ◽  
Kobi Baruch ◽  
Gili Aviv ◽  
Mor Nitzan ◽  
Ilan Rosenshine
Keyword(s):  
Escherichia Coli ◽  
Type Iii Secretion ◽  
Public Health Problem ◽  
Effector Proteins ◽  
Host Cells ◽  
Global Public Health ◽  
Secretion Systems ◽  
Comprehensive Description ◽  
Content Type ◽  
Type Iii

ABSTRACT Type III secretion systems (TTSSs) are employed by pathogens to translocate host cells with effector proteins, which are crucial for virulence. The dynamics of effector translocation, behavior of the translocating bacteria, translocation temporal order, and relative amounts of each of the translocated effectors are all poorly characterized. To address these issues, we developed a microscopy-based assay that tracks effector translocation. We used this assay alongside a previously described real-time population-based translocation assay, focusing mainly on enteropathogenic Escherichia coli (EPEC) and partly comparing it to Salmonella. We found that the two pathogens exhibit different translocation behaviors: in EPEC, a subpopulation that formed microcolonies carried out most of the translocation activity, while Salmonella executed protein translocation as planktonic bacteria. We also noted variability in host cell susceptibility, with some cells highly resistant to translocation. We next extended the study to determine the translocation dynamics of twenty EPEC effectors and found that all exhibited distinct levels of translocation efficiency. Further, we mapped the global effects of key TTSS-related components on TTSS activity. Our results provide a comprehensive description of the dynamics of the TTSS activity of EPEC and new insights into the mechanisms that control the dynamics. IMPORTANCE EPEC and the closely related enterohemorrhagic Escherichia coli (EHEC) represent a global public health problem. New strategies to combat EPEC and EHEC infections are needed, and development of such strategies requires better understanding of their virulence machinery. The TTSS is a critical virulence mechanism employed by these pathogens, and by others, including Salmonella. In this study, we aimed at elucidating new aspects of TTSS function. The results obtained provide a comprehensive description of the dynamics of TTSS activity of EPEC and new insights into the mechanisms that control these changes. This knowledge sets the stage for further analysis of the system and may accelerate the development of new ways to treat EPEC and EHEC infections. Further, the newly described microscopy-based assay can be readily adapted to study the dynamics of TTSS activity in other pathogens.

scholarly journals Persistence of Vibrio parahaemolyticus in the Pacific Oyster, Crassostrea gigas, Is a Multifactorial Process Involving Pili and Flagella but Not Type III Secretion Systems or Phase Variation

2013 ◽  
Vol 79 (10) ◽  
pp. 3303-3305 ◽  
Author(s):  
Alisha M. Aagesen ◽  
Sureerat Phuvasate ◽  
Yi-Cheng Su ◽  
Claudia C. Häse
Keyword(s):  
Type Iii Secretion ◽  
Vibrio Parahaemolyticus ◽  
Phase Variation ◽  
Type I ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Type Iv ◽  
Pacific Oysters ◽  
Type Iii Secretion Systems

ABSTRACTVibrio parahaemolyticuscan resist oyster depuration, suggesting that it possesses specific factors for persistence. We show that type I pili, type IV pili, and both flagellar systems contribute toV. parahaemolyticuspersistence in Pacific oysters whereas type III secretion systems and phase variation do not.

scholarly journals The Type III Secretion System Effector SptP of Salmonella enterica Serovar Typhi

2016 ◽  
Vol 199 (4) ◽  
Author(s):  
Rebecca Johnson ◽  
Alexander Byrne ◽  
Cedric N. Berger ◽  
Elizabeth Klemm ◽  
Valerie F. Crepin ◽  
...  
Keyword(s):  
Amino Acid ◽  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Binding Domain ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Chaperone Binding

ABSTRACT Strains of the various Salmonella enterica serovars cause gastroenteritis or typhoid fever in humans, with virulence depending on the action of two type III secretion systems (Salmonella pathogenicity island 1 [SPI-1] and SPI-2). SptP is a Salmonella SPI-1 effector, involved in mediating recovery of the host cytoskeleton postinfection. SptP requires a chaperone, SicP, for stability and secretion. SptP has 94% identity between S. enterica serovar Typhimurium and S. Typhi; direct comparison of the protein sequences revealed that S. Typhi SptP has numerous amino acid changes within its chaperone-binding domain. Subsequent comparison of ΔsptP S. Typhi and S. Typhimurium strains demonstrated that, unlike SptP in S. Typhimurium, SptP in S. Typhi was not involved in invasion or cytoskeletal recovery postinfection. Investigation of whether the observed amino acid changes within SptP of S. Typhi affected its function revealed that S. Typhi SptP was unable to complement S. Typhimurium ΔsptP due to an absence of secretion. We further demonstrated that while S. Typhimurium SptP is stable intracellularly within S. Typhi, S. Typhi SptP is unstable, although stability could be recovered following replacement of the chaperone-binding domain with that of S. Typhimurium. Direct assessment of the strength of the interaction between SptP and SicP of both serovars via bacterial two-hybrid analysis demonstrated that S. Typhi SptP has a significantly weaker interaction with SicP than the equivalent proteins in S. Typhimurium. Taken together, our results suggest that changes within the chaperone-binding domain of SptP in S. Typhi hinder binding to its chaperone, resulting in instability, preventing translocation, and therefore restricting the intracellular activity of this effector. IMPORTANCE Studies investigating Salmonella pathogenesis typically rely on Salmonella Typhimurium, even though Salmonella Typhi causes the more severe disease in humans. As such, an understanding of S. Typhi pathogenesis is lacking. Differences within the type III secretion system effector SptP between typhoidal and nontyphoidal serovars led us to characterize this effector within S. Typhi. Our results suggest that SptP is not translocated from typhoidal serovars, even though the loss of sptP results in virulence defects in S. Typhimurium. Although SptP is just one effector, our results exemplify that the behavior of these serovars is significantly different and genes identified to be important for S. Typhimurium virulence may not translate to S. Typhi.

scholarly journals Characterization and Protective Efficacy of Type III Secretion Proteins as a Broadly Protective Subunit Vaccine against Salmonella enterica Serotypes

2018 ◽  
Vol 86 (3) ◽  
Author(s):  
Francisco J. Martinez-Becerra ◽  
Prashant Kumar ◽  
Vikalp Vishwakarma ◽  
Jae Hyun Kim ◽  
Olivia Arizmendi ◽  
...  
Keyword(s):  
Type Iii Secretion ◽  
Salmonella Enterica ◽  
Subunit Vaccine ◽  
Protective Efficacy ◽  
Spectroscopic Techniques ◽  
Secretion Systems ◽  
Amino Acid Sequence Level ◽  
Lethal Challenge ◽  
Content Type ◽  
Type Iii

ABSTRACT Nontyphoidal Salmonella enterica serotypes (NTS) are the leading cause of hospitalization and death due to foodborne illnesses. NTS are the costliest of the foodborne pathogens and cause ∼$4 billion annually in health care costs. In Africa, new invasive NTS are the leading cause of bacteremia, especially in HIV-positive children and adults. Current vaccines against S. enterica are not broadly protective and most are directed at the typhoid-causing serotypes, not the NTS. All S. enterica strains require two type III secretion systems (T3SS) for virulence. The T3SS needle tip protein and the first translocator are localized to the T3SS needle tip and are required for pathogenesis of S. enterica . Collectively they are 95 to 98% conserved at the amino acid sequence level among all S. enterica strains. The Salmonella pathogenicity island 1 or 2 tip and first translocator proteins were genetically fused to produce the S1 and S2 fusion proteins, respectively, as potential vaccine candidates. S1 and S2 were then characterized using spectroscopic techniques to understand their structural and biophysical properties. Formulated at the proper pH, S1, S2, or S1 plus S2 (S1S2), admixed with adjuvant, was used to immunize mice followed by a lethal challenge with S. enterica serotype Typhimurium or S. enterica serotype Enteritidis. The S1S2 formulation provided the highest protective efficacy, thus demonstrating that an S1S2 subunit vaccine can provide broad, serotype-independent protection, possibly against all S. enterica serotypes. Such a finding would be transformative in improving human health.

scholarly journals Back to the Future: Studying Cholera Pathogenesis Using Infant Rabbits

mBio ◽  
2010 ◽  
Vol 1 (1) ◽  
Author(s):  
Jennifer M. Ritchie ◽  
Haopeng Rui ◽  
Roderick T. Bronson ◽  
Matthew K. Waldor
Keyword(s):  
Animal Model ◽  
Cholera Toxin ◽  
Vibrio Cholerae ◽  
Diarrheal Disease ◽  
Close Association ◽  
Disease Model ◽  
Rabbit Model ◽  
Secretory Diarrhea ◽  
Watery Diarrhea ◽  
Content Type

ABSTRACTCholera is a severe diarrheal disease, caused byVibrio cholerae, for which there has been no reproducible, nonsurgical animal model. Here, we report that orogastric inoculation ofV. choleraeinto 3-day-old rabbits pretreated with cimetidine led to lethal, watery diarrhea in virtually all rabbits. The appearance and chemical composition of the rabbit diarrheal fluid were comparable to those of the “rice-water stool” produced by cholera patients. As in humans,V. choleraemutants that do not produce cholera toxin (CT) and toxin-coregulated pilus (TCP) did not induce cholera-like disease in rabbits. CT induced extensive exocytosis of mucin from intestinal goblet cells, and wild-typeV. choleraewas predominantly found in close association with mucin. Large aggregates of mucin-embeddedV. choleraewere observed, both attached to the epithelium and floating within the diarrheal fluid. These findings suggest that CT-dependent mucin secretion significantly influencesV. cholerae’s association with the host intestine and its exit from the intestinal tract. Our model should facilitate identification and analyses of factors that may governV. choleraeinfection, survival, and transmission, such as mucin. In addition, our results using nontoxigenicV. choleraesuggest that infant rabbits will be useful for study of the reactogenicity of live attenuated-V. choleraevaccines.IMPORTANCECholera remains a significant threat to populations in developing nations. Currently, there is no reproducible, nonsurgical animal model of cholera, the secretory diarrheal disease caused byVibrio cholerae. We found that oral infection of infant rabbits withV. choleraeled to lethal, watery diarrhea in most rabbits. Using this disease model, we discovered a new role for cholera toxin (CT) during infection. This toxin not only caused secretory diarrhea but also profoundly influenced howV. choleraeassociates with the intestine and how the pathogen exits from the host. Rabbits inoculated withV. choleraethat does not produce CT developed mild diarrhea, suggesting that this model may prove useful for generating improved live attenuated-V. choleraevaccine candidates. Overall, our findings suggest that the infant rabbit model will enable pursuit of several new avenues for research on cholera pathogenesis, as well as serve as a vehicle for testing new therapeutics.

scholarly journals A Type III Secretion System Inhibitor Targets YopD while Revealing Differential Regulation of Secretion in Calcium-Blind Mutants of Yersinia pestis

2013 ◽  
Vol 58 (2) ◽  
pp. 839-850 ◽  
Author(s):  
Danielle L. Jessen ◽  
David S. Bradley ◽  
Matthew L. Nilles
Keyword(s):  
Yersinia Pestis ◽  
Type Iii Secretion ◽  
Yersinia Pseudotuberculosis ◽  
Type Iii Secretion System ◽  
Secretion System ◽  
Secretion Systems ◽  
Content Type ◽  
Type Iii ◽  
Regulatory Processes ◽  
Secretion Inhibition

ABSTRACTNumerous Gram-negative pathogens rely upon type III secretion (T3S) systems to cause disease. Several small-molecule inhibitors of the type III secretion systems have been identified; however, few targets of these inhibitors have been elucidated. Here we report that 2,2′-thiobis-(4-methylphenol) (compound D), inhibits type III secretion inYersinia pestis,Yersinia pseudotuberculosis, andPseudomonas aeruginosa. YopD, a protein involved in the formation of the translocon and regulatory processes of the type III secretion system, appears to play a role in the inhibition of secretion by compound D. The use of compound D in T3S regulatory mutants demonstrated a difference in secretion inhibition in the presence and absence of calcium. Interestingly, compound D was effective only under conditions without calcium, indicating that a secretion-active needle structure may be necessary for compound D to inhibit secretion.

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