scholarly journals Tandem tyrosine residues in the EPEC multicargo chaperone CesT support differential type III effector translocation and early host colonization

2018 ◽  
Author(s):  
Cameron Runte ◽  
Umang Jain ◽  
Landon J. Getz ◽  
Sabrina Secord ◽  
Asaomi Kuwae ◽  
...  
Keyword(s):  
Effector Proteins ◽  
Host Cells ◽  
Economic Losses ◽  
Infection Model ◽  
Tyrosine Residues ◽  
Mouse Infection Model ◽  
Differential Type ◽  
Functional Relevance ◽  
Type 3 ◽  
Effector Secretion

AbstractEnteropathogenic Escherichia coli (EPEC) are worldwide human enteric pathogens inflicting significant morbidity and causing large economic losses. A type 3 secretion system (T3SS) is critical for EPEC intestinal colonization, and injection of effectors into host cells contributes to cellular subversion and innate immune evasion. Here, we demonstrate that two strictly conserved C-terminal tyrosine residues, Y152 and Y153, within the multicargo T3SS chaperone CesT serve differential roles in regulating effector secretion in EPEC. Conservative substitution of both tyrosine residues to phenylalanine attenuated EPEC type 3 effector injection into host cells, and significantly limited Tir effector mediated intimate adherence, a key feature of attaching and effacing pathogenesis. Whereas CesT Y153 supported normal levels of Tir translocation, CesT Y152 was strictly required for the effector NleA to be expressed and subsequently translocated into host cells during infection. Other effectors were observed to be dependent on CesT Y152 for maximal translocation efficiency. Unexpectedly, EPEC expressing a CesT Y152, Y153F variant exhibited significantly enhanced effector translocation of many CesT-interacting effectors, further implicating Y152 in CesT functionality. A mouse infection model of EPEC intestinal disease using Citrobacter rodentium revealed that CesT tyrosine substitution variants displayed delayed colonization and were more rapidly cleared from the intestine. These data demonstrate genetically separable functions for strictly conserved tandem tyrosine residues within CesT. Tyrosine 152 of CesT is implicated in NleA expression, providing functional relevance for localized amino acid conservation. Therefore, CesT via its novel C-terminal domain, has relevant roles beyond typical T3SC that interact and stabilize effector proteins.

scholarly journals Contribution of the Major Secreted Yops of Yersinia enterocolitica O:8 to Pathogenicity in the Mouse Infection Model

2004 ◽  
Vol 72 (9) ◽  
pp. 5227-5234 ◽  
Author(s):  
Konrad Trülzsch ◽  
Thorsten Sporleder ◽  
Emeka I. Igwe ◽  
Holger Rüssmann ◽  
Jürgen Heesemann
Keyword(s):  
Small Intestine ◽  
Systemic Infection ◽  
Effector Proteins ◽  
Infection Model ◽  
Virulence Plasmid ◽  
The Novel ◽  
Serotype O ◽  
Mouse Infection Model ◽  
Mouse Tissues ◽  
First Time

ABSTRACT Pathogenic yersiniae (Yersinia pestis, Y. pseudotuberculosis, and Y. enterocolitica) harbor a 70-kb virulence plasmid (pYV) that encodes a type III secretion system and a set of at least six effector proteins (YopH, YopO, YopP, YopE, YopM, and YopT) that are injected into the host cell cytoplasm. Yops (Yersinia outer proteins) disturb the dynamics of the cytoskeleton, inhibit phagocytosis by macrophages, and downregulate the production of proinflammatory cytokines, which makes it possible for yersiniae to multiply extracellularly in lymphoid tissue. Y. enterocolitica serotype O:8 belongs to the highly mouse-pathogenic group of yersiniae in contrast to Y. enterocolitica serotype O:9. However, there has been no systematic study of the contribution of Yops to the pathogenicity of Y. enterocolitica O:8 in mice. We generated a set of yop gene deletion mutants of Y. enterocolitica O:8 by using the novel Red cloning procedure. We subsequently analyzed the contribution of yopH, -O, -P, -E, -M, -T, and -Q deletions to pathogenicity after oral and intravenous infection of mice. Here we showed for the first time that a ΔyopT deletion mutant colonizes mouse tissues to a greater extent than the parental strain. The ΔyopO, ΔyopP, and ΔyopE mutants were only slightly attenuated after oral infection since they were still able to colonize the spleen and liver and cause systemic infection. The ΔyopO mutant was lethal for mice, whereas ΔyopP and ΔyopE mutants were successfully eliminated from the spleen and liver 2 weeks after infection. In contrast the ΔyopH, ΔyopM, and ΔyopQ mutants were highly attenuated and not able to colonize the spleen and liver on any of the days tested. The ΔyopH, ΔyopO, ΔyopP, ΔyopE, ΔyopM, and ΔyopQ mutants had only modest defects in the colonization of the small intestine and Peyer's patches. The ΔyopE mutant was eliminated from the small intestine 3 weeks after infection, whereas the ΔyopH, ΔyopP, ΔyopM, and ΔyopQ mutants continued to colonize the small intestine at this time.

scholarly journals Acellular Pertussis Vaccine Inhibits Bordetella pertussis Clearance from the Nasal Mucosa of Mice

Vaccines ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 695
Author(s):  
Jana Holubová ◽  
Ondřej Staněk ◽  
Ludmila Brázdilová ◽  
Jiří Mašín ◽  
Ladislav Bumba ◽  
...  
Keyword(s):  
Nasal Mucosa ◽  
Bordetella Pertussis ◽  
High Capacity ◽  
Developed Countries ◽  
Infection Model ◽  
Pertussis Infection ◽  
Protective Antigens ◽  
Mouse Infection Model ◽  
Type 3

Bordetella pertussis whole-cell vaccines (wP) caused a spectacular drop of global pertussis incidence, but since the replacement of wP with acellular pertussis vaccines (aP), pertussis has resurged in developed countries within 7 to 12 years of the change from wP to aP. In the mouse infection model, we examined whether addition of further protective antigens into the aP vaccine, such as type 2 and type 3 fimbriae (FIM2/3) with outer membrane lipooligosaccharide (LOS) and/or of the adenylate cyclase toxoid (dACT), which elicits antibodies neutralizing the CyaA toxin, could enhance the capacity of the aP vaccine to prevent colonization of the nasal mucosa by B. pertussis. The addition of the toxoid and of the opsonizing antibody-inducing agglutinogens modestly enhanced the already high capacity of intraperitoneally-administered aP vaccine to elicit sterilizing immunity, protecting mouse lungs from B. pertussis infection. At the same time, irrespective of FIM2/3 with LOS and dACT addition, the aP vaccination ablated the natural capacity of BALB/c mice to clear B. pertussis infection from the nasal cavity. While wP or sham-vaccinated animals cleared the nasal infection with similar kinetics within 7 weeks, administration of the aP vaccine promoted persistent colonization of mouse nasal mucosa by B. pertussis.

scholarly journals Extra! Extracellular Effector Delivery into Host Cells via the Type 3 Secretion System

mBio ◽  
2017 ◽  
Vol 8 (3) ◽  
Author(s):  
Melissa M. Kendall
Keyword(s):  
Host Cell ◽  
Secretion System ◽  
Effector Proteins ◽  
Host Cells ◽  
Alternative Mechanism ◽  
Host Cell Membrane ◽  
Type Three Secretion System ◽  
Host Signaling ◽  
Type 3 Secretion System ◽  
Type 3

ABSTRACT The type three secretion system (T3SS) is critical for the virulence of diverse bacterial pathogens. Pathogens use the T3SS to deliver effector proteins into host cells and manipulate host signaling pathways. The prevailing mechanism is that effectors translocate from inside the T3SS directly into the host cell. Recent studies reveal an alternative mechanism of effector translocation, in which an effector protein located outside the bacterial cell relies on the T3SS for delivery into host cells. Tejeda-Dominguez et al. (F. Tejeda-Dominguez, J. Huerta-Cantillo, L. Chavez-Dueñas, and F. Navarro-Garcia, mBio 8:e00184-17, 2017, https://doi.org/10.1128/mBio.00184-17 !) demonstrate that the EspC effector of enteropathogenic Escherichia coli is translocated by binding to the outside of the T3SS and subsequently gains access to the host cell cytoplasm through the T3SS pore embedded within the host cell membrane. This work reveals a novel mechanism of translocation that is likely relevant for a variety of other pathogens that use the T3SS as part of their virulence arsenal.

scholarly journals Unraveling neutrophil–Yersinia interactions during tissue infection

F1000Research ◽  
2019 ◽  
Vol 8 ◽  
pp. 1046 ◽  
Author(s):  
Joan Mecsas
Keyword(s):  
Yersinia Pseudotuberculosis ◽  
Signal Transduction Pathway ◽  
Effector Proteins ◽  
Tissue Infection ◽  
Host Cells ◽  
Serum Factors ◽  
Bacterial Adhesins ◽  
Animal Pathogens ◽  
Close Proximity ◽  
Type 3

The human and animal pathogens Yersinia pestis, which causes bubonic and pneumonic plague, and Yersinia pseudotuberculosis and Yersinia enterocolitica, which cause gastroenteritis, share a type 3 secretion system which injects effector proteins, Yops, into host cells. This system is critical for virulence of all three pathogens in tissue infection. Neutrophils are rapidly recruited to infected sites and all three pathogens frequently interact with and inject Yops into these cells during tissue infection. Host receptors, serum factors, and bacterial adhesins appear to collaborate to promote neutrophil–Yersinia interactions in tissues. The ability of neutrophils to control infection is mixed depending on the stage of infection and points to the efficiency of Yops and other bacterial factors to mitigate bactericidal effects of neutrophils. Yersinia in close proximity to neutrophils has higher levels of expression from yop promoters, and neutrophils in close proximity to Yersinia express higher levels of pro-survival genes than migrating neutrophils. In infected tissues, YopM increases neutrophil survival and YopH targets a SKAP2/SLP-76 signal transduction pathway. Yet the full impact of these and other Yops and other Yersinia factors on neutrophils in infected tissues has yet to be understood.

scholarly journals The anti-apoptotic Coxiella burnetii effector protein AnkG is a strain specific virulence factor

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Walter Schäfer ◽  
Teresa Schmidt ◽  
Arne Cordsmeier ◽  
Vítor Borges ◽  
Paul A. Beare ◽  
...  
Keyword(s):  
Host Cell ◽  
Coxiella Burnetii ◽  
Cell Apoptosis ◽  
Effector Proteins ◽  
Host Cells ◽  
Infection Model ◽  
Effector Protein ◽  
Host Cell Apoptosis ◽  
Bacterial Replication ◽  
Apoptotic Activity

Abstract The ability to inhibit host cell apoptosis is important for the intracellular replication of the obligate intracellular pathogen Coxiella burnetii, as it allows the completion of the lengthy bacterial replication cycle. Effector proteins injected into the host cell by the C. burnetii type IVB secretion system (T4BSS) are required for the inhibition of host cell apoptosis. AnkG is one of these anti-apoptotic effector proteins. The inhibitory effect of AnkG requires its nuclear localization, which depends on p32-dependent intracellular trafficking and importin-α1-mediated nuclear entry of AnkG. Here, we compared the sequences of ankG from 37 C. burnetii isolates and classified them in three groups based on the predicted protein size. The comparison of the three different groups allowed us to identify the first 28 amino acids as essential and sufficient for the anti-apoptotic activity of AnkG. Importantly, only the full-length protein from the first group is a bona fide effector protein injected into host cells during infection and has anti-apoptotic activity. Finally, using the Galleria mellonella infection model, we observed that AnkG from the first group has the ability to attenuate pathology during in vivo infection, as it allows survival of the larvae despite bacterial replication.

scholarly journals The Potassium Transporter Trk and External Potassium Modulate Salmonella enterica Protein Secretion and Virulence

2008 ◽  
Vol 77 (2) ◽  
pp. 667-675 ◽  
Author(s):  
Jing Su ◽  
Hao Gong ◽  
Jeff Lai ◽  
Andrew Main ◽  
Sangwei Lu
Keyword(s):  
Salmonella Enterica ◽  
Bacterial Pathogen ◽  
Effector Proteins ◽  
Host Cells ◽  
Infection Model ◽  
Human Pathogens ◽  
Food Borne ◽  
External Potassium ◽  
Living Organisms ◽  
External K

ABSTRACT Potassium (K+) is the most abundant intracellular cation and is essential for many physiological functions of all living organisms; however, its role in the pathogenesis of human pathogens is not well understood. In this study, we characterized the functions of the bacterial Trk K+ transport system and external K+ in the pathogenesis of Salmonella enterica, a major food-borne bacterial pathogen. Here we report that Trk is important for Salmonella to invade and grow inside epithelial cells. It is also necessary for the full virulence of Salmonella in an animal infection model. Analysis of proteins of Salmonella indicated that Trk is involved in the expression and secretion of effector proteins of the type III secretion system (TTSS) encoded by Salmonella pathogenicity island 1 (SPI1) that were previously shown to be necessary for Salmonella invasion. In addition to the role of the Trk transporter in the pathogenesis of Salmonella, we discovered that external K+ modulates the pathogenic properties of Salmonella by increasing the expression and secretion of effector proteins of the SPI1-encoded TTSS and by enhancing epithelial cell invasion. Our studies demonstrated that K+ is actively involved in the pathogenesis of Salmonella and indicated that Salmonella may take advantage of the high K+ content inside host cells and in the intestinal fluid during diarrhea to become more virulent.

scholarly journals A pipeline to evaluate inhibitors of the Pseudomonas aeruginosa exotoxin U

2021 ◽  
Vol 478 (3) ◽  
pp. 647-668
Author(s):  
Daniel M. Foulkes ◽  
Keri McLean ◽  
Yalin Zheng ◽  
Joscelyn Sarsby ◽  
Atikah S. Haneef ◽  
...  
Keyword(s):  
Pseudomonas Aeruginosa ◽  
T Cells ◽  
Bacterial Load ◽  
World Health Organisation ◽  
Host Cells ◽  
World Health ◽  
Infection Model ◽  
Compound A ◽  
Type 3

Pseudomonas aeruginosa has recently been highlighted by the World Health Organisation (WHO) as a major threat with high priority for the development of new therapies. In severe P. aeruginosa infections, the phospholipase activity of the type 3 secretion system toxin, ExoU, induces lysis of target host cells and results in the poorest clinical outcomes. We have developed an integrated pipeline to evaluate small molecule inhibitors of ExoU in vitro and in cultured cell models, including a disease-relevant corneal epithelial (HCE-T) scratch and infection model using florescence microscopy and cell viability assays. Compounds Pseudolipasin A, compound A and compound B were effective in vitro inhibitors of ExoU and mitigated P. aeruginosa ExoU-dependent cytotoxicity after infection of HCE-T cells at concentrations as low as 0.5 µM. Addition of the antimicrobial moxifloxacin controlled bacterial load, allowing these assays to be extended from 6 h to 24 h. P. aeruginosa remained cytotoxic to HCE-T cells with moxifloxacin, present at the minimal inhibitory concentration for 24 h, but, when used in combination with either Pseudolipasin A, compound A or compound B, a greater amount of viable cells and scratch healing were observed. Thus, our pipeline provides evidence that ExoU inhibitors could be used in combination with certain antimicrobials as a novel means to treat infections due to ExoU producing P. aeruginosa, as well as the means to identify more potent ExoU inhibitors for future therapeutics.

scholarly journals A Shigella type 3 effector protein co-opts host inositol pyrophosphates for activity

2021 ◽  
Author(s):  
Thomas E. Wood ◽  
Jessica M. Yoon ◽  
Heather D. Eshleman ◽  
Daniel J. Slade ◽  
Cammie F. Lesser ◽  
...  
Keyword(s):  
Mammalian Cells ◽  
Inositol Phosphates ◽  
Bacterial Pathogen ◽  
Cysteine Proteases ◽  
Effector Proteins ◽  
Host Cells ◽  
Expression Library ◽  
Inositol Pyrophosphates ◽  
Type 3

Shigella spp. cause diarrhea by invading human intestinal epithelial cells. Effector proteins delivered into target host cells by the Shigella type 3 secretion system modulate host signaling pathways and processes in a manner that promotes infection. The effector OspB activates mTOR, the central cellular regulator of growth and metabolism, and potentiates the inhibition of mTOR by rapamycin. The net effect of OspB on cell monolayers is cell proliferation at infectious foci. To gain insights into the mechanism by which OspB potentiates rapamycin inhibition of mTOR, we employ in silico analyses to identify putative catalytic residues of OspB and show that a conserved cysteine-histidine dyad is required for this activity of OspB. In a screen of an over-expression library in Saccharomyces cerevisiae, we identify a dependency of OspB activity on inositol pyrophosphates, a class of eukaryotic secondary messengers that are distinct from the inositol phosphates known to act as cofactors for bacterial cysteine proteases. We show that inositol pyrophosphates are required for OspB activity not only in yeast, but also in mammalian cells - the first demonstration of inositol pyrophosphates being required for virulence of a bacterial pathogen in vivo.

scholarly journals Peptidoglycan Deacetylation in Helicobacter pylori Contributes to Bacterial Survival by Mitigating Host Immune Responses

2010 ◽  
Vol 78 (11) ◽  
pp. 4660-4666 ◽  
Author(s):  
Ge Wang ◽  
Susan E. Maier ◽  
Leja F. Lo ◽  
George Maier ◽  
Shruti Dosi ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Helicobacter Pylori ◽  
Immune Responses ◽  
Bacterial Load ◽  
Host Cells ◽  
Infection Model ◽  
Wild Type ◽  
Mouse Infection Model ◽  
Mouse Infection ◽  
H Pylori

ABSTRACT An oxidative stress-induced enzyme, peptidoglycan deacetylase (PgdA), in the human gastric pathogen Helicobacter pylori was previously identified and characterized. In this study, we constructed H. pylori pgdA mutants in two mouse-adapted strains, X47 and B128, to investigate the role of PgdA in vivo (to determine the mutants’ abilities to colonize mice and to induce an immune response). H. pylori pgdA mutant cells showed increased sensitivity to lysozyme compared to the sensitivities of the parent strains. We demonstrated that the expression of PgdA was significantly induced (3.5-fold) when H. pylori cells were in contact with macrophages, similar to the effect observed with oxidative stress as the environmental inducer. Using a mouse infection model, we first examined the mouse colonization ability of an H. pylori pgdA mutant in X47, a strain deficient in the major pathway (cag pathogenicity island [PAI] encoded) for delivery of peptidoglycan into host cells. No animal colonization difference between the wild type and the mutant was observed 3 weeks after inoculation. However, the pgdA mutant showed a significantly attenuated ability to colonize mouse stomachs (9-fold-lower bacterial load) at 9 weeks postinoculation. With the cag PAI-positive strain B128, a significant colonization difference between the wild type and the pgdA mutant was observed at 3 weeks postinoculation (1.32 × 104 versus 1.85 × 103 CFU/gram of stomach). To monitor the immune responses elicited by H. pylori in the mouse infection model, we determined the concentrations of cytokines present in mouse sera. In the mice infected with the pgdA mutant strain, we observed a highly significant increase in the level of MIP-2. In addition, significant increases in interleukin-10 and tumor necrosis factor alpha in the pgdA mutant-infected mice compared to the levels in the wild-type H. pylori-infected mice were also observed. These results indicated that H. pylori peptidoglycan deacetylation is an important mechanism for mitigating host immune detection; this likely contributes to pathogen persistence.

scholarly journals Role ofSalmonellaPathogenicity Island 1 Protein IacP inSalmonella entericaSerovar Typhimurium Pathogenesis

2011 ◽  
Vol 79 (4) ◽  
pp. 1440-1450 ◽  
Author(s):  
Jin Seok Kim ◽  
Jeong Seon Eom ◽  
Jung Im Jang ◽  
Hyeon Guk Kim ◽  
Doo Won Seo ◽  
...  
Keyword(s):  
Effector Proteins ◽  
Infection Model ◽  
Secretion Systems ◽  
Virulence Proteins ◽  
Type Iii ◽  
Mouse Infection Model ◽  
T3ss Effector ◽  
Cytoplasmic Proteins ◽  
Type Iii Secretion Systems ◽  
Serovar Typhimurium

ABSTRACTGram-negative bacteria, includingSalmonella entericaserovar Typhimurium, exploit type III secretion systems (T3SSs) through which virulence proteins are delivered into the host cytosol to reinforce invasive and replicative niches in their host. Although many secreted effector proteins and membrane-bound structural proteins in the T3SS have been characterized, the functions of many cytoplasmic proteins still remain unknown. In this study, we found that IacP, encoded bySalmonellapathogenicity island 1, was important for nonphagocytic cell invasion and bacterial virulence. When theiacPgene was deleted from severalSalmonellaserovar Typhimurium strains, the invasion into INT-407 epithelial cells was significantly decreased compared to that of their parental strains, and retarded rearrangements of actin fibers were observed for theiacPmutant-infected cells. Although IacP had no effect on the secretion of type III translocon proteins, the levels of secretion of the effector proteins SopB, SopA, and SopD into the culture medium were decreased in theiacPmutant. In a mouse infection model, mice infected with theiacPmutant exhibited alleviated pathological signs in the intestine and survived longer than did wild-type-infected mice. Taken together, IacP plays a key role inSalmonellavirulence by regulating the translocation of T3SS effector proteins.

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