Biomedical subjects

Konrad Trülzsch

Publications and source records attributed to Konrad Trülzsch.

10 recordsLinked to original sources

PubMed2006

The proteasome pathway destabilizes Yersinia outer protein E and represses its antihost cell activities.

Pathogenic Yersinia spp. neutralize host defense mechanisms by engaging a type III protein secretion system that translocates several Yersinia outer proteins (Yops) into the host cell. Although the modulation of the cellular responses by individual Yops has been intensively studied, little is known about the fate of the translocated Yops inside the cell. In this study, we investigated involvement of the proteasome, the major nonlysosomal proteolytic system in eukaryotic cells, in Yop destabilization and repression. Our data show that inhibition of the proteasome in Yersinia enterocolitica-infected cells selectively stabilized the level of YopE, but not of YopH or YopP. In addition, YopE was found to be modified by ubiquitination. This suggests that the cytotoxin YopE is physiologically subjected to degradation via the ubiquitin-proteasome pathway inside the host cell. Importantly, the increased levels of YopE upon proteasome inhibition were associated with decreased activity of its cellular target Rac. Thus, the GTPase-down-regulating function of YopE is enhanced when the proteasome is inhibited. The stabilization of YopE by proteasome inhibitor treatment furthermore led to aggravation of the cytotoxic YopE effects on the actin cytoskeleton and on host cell morphology. Together, these data show that the host cell proteasome functions to destabilize and inactivate the Yersinia effector protein YopE. This implies the proteasome as integral part of the cellular host immune response against the immunomodulatory activities of a translocated bacterial virulence protein.

Bacterial Outer Membrane Proteins↗

PubMed2006

Yersinia's stratagem: targeting innate and adaptive immune defense.

In contrast to Salmonella and Shigella, enteropathogenic Yersinia species are extracellular multiplying Gram-negative bacteria. This life style requires a sophisticated anti-host strategy, which is implemented by the Yersinia virulence plasmid. This plasmid encodes the type 3 secretion system (injectisome), at least six microinjected anti-host effector proteins, a trimeric coiled coil outer membrane protein (Yersinia adhesin) with cell adhesin and protective functions against complement and defensins, and the released V antigen, which has Toll-like receptor 2 agonist activity.

Adhesins, Bacterial↗

PubMed2005

Nosocomial urosepsis caused by Enterobacter kobei with aberrant phenotype.

Enterobacter kobei is the species of the Enterobacter cloacae complex, which is phenotypically most closely related to the species E. cloacae. This is the first report of infection caused by a new biotype of E. kobei. A patient with a history of urinary bladder operation developed a urosepsis with an Enterobacter isolate displaying the E. cloacae phenotype. The isolate was classified to the species E. kobei by sequence analysis of the 16S-rDNA, 4 protein-coding genes and enterobacterial repetitive intergenic consensus (ERIC)-cluster analysis. E. kobei was originally described to be Voges-Proskauer (VP) negative. However, the isolates of the present case were VP-positive. After analyzing 120 biochemical tests included in the API20E and the Biotype 100 systems, 4 biochemical tests were identified potentially differentiating this new biotype from E. cloacae.

Cross Infection↗

PubMed2005

Yersinia outer protein P inhibits CD8 T cell priming in the mouse infection model.

Pathogenic yersiniae translocate a mixture of effector proteins called Yersinia outer proteins (Yops) into the cytosol of eukaryotic cells by their type III secretion system. YopP is one of the best characterized of these effector proteins and known to inhibit the proinflammatory response of the host by interfering with NF-kappaB signal transduction and inducing apoptosis of macrophages. The effects of YopP on the immune response were studied by a Yersinia Ag-independent approach using bacteria that translocate the well-characterized model Ag listeriolysin O of Listeria monocytogenes via their type III secretion system. In this study we demonstrate a novel function for YopP in vivo. It is shown for the first time that YopP not only counteracts the innate immune defense but also inhibits the adaptive immune system by suppressing the development of an effective CD8 T cell response in a mouse model. A possible mechanism for this could be the inhibition of Ag presentation by dendritic cells (DC). In vitro this is shown to be due to the rapid induction of programmed DC death and to inhibition of DC maturation. Using this approach we could further show that the listeriolysin O-specific CD8 T cells generated in vivo by the yopP mutant are functional and are able to protect mice against a lethal challenge with wild type Listeria.

Animals↗

PubMed2004

Transcriptional responses of murine macrophages to infection with Yersinia enterocolitica.

Transcriptional responses of J774 murine macrophage-like cells to infection with Yersinia enterocolitica were evaluated with oligonucleotide microarrays interrogating 12 488 genes and expressed sequence tags. Virulence plasmid (pYV)-cured yersiniae induce a transcriptional programme resembling a general inflammatory response. pYV-carrying yersiniae translocating the Yersinia outer proteins (Yops) impact on this transcriptional programme in two ways: first, by suppressing this inflammatory response and, secondly, by inducing sustained expression of a distinct set of genes with known silencing functions. These tranquilizing patterns of gene expression could be confirmed by real-time reverse transcription polymerase chain reaction, are stable upon reduction in bacterial load and could also be reproduced in BALB/c-derived bone marrow macrophages. Prestimulation of macrophages with interferon (IFN)-gamma, but not with interleukin (IL)-4, induces partial resistance against pYV-mediated transcriptional tranquilization. The first effect, suppression of the inflammatory programme, is mediated by YopP, whereas no YopH- or YopM-regulated genes could be identified under our stringent statistical criteria. The bacterial protein responsible for the second effect, induction of silencing genes, remains elusive. We suggest that Yersinia enterocolitica might use two independent mechanisms to inhibit macrophage inflammatory responses at the transcriptional level.

Adhesins, Bacterial↗

PubMed2004

Yersinia enterocolitica type III secretion depends on the proton motive force but not on the flagellar motor components MotA and MotB.

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.

Animals↗

PubMed2004

Contribution of the major secreted yops of Yersinia enterocolitica O:8 to pathogenicity in the mouse infection model.

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 DeltayopT deletion mutant colonizes mouse tissues to a greater extent than the parental strain. The DeltayopO, DeltayopP, and DeltayopE mutants were only slightly attenuated after oral infection since they were still able to colonize the spleen and liver and cause systemic infection. The DeltayopO mutant was lethal for mice, whereas DeltayopP and DeltayopE mutants were successfully eliminated from the spleen and liver 2 weeks after infection. In contrast the DeltayopH, DeltayopM, and DeltayopQ mutants were highly attenuated and not able to colonize the spleen and liver on any of the days tested. The DeltayopH, DeltayopO, DeltayopP, DeltayopE, DeltayopM, and DeltayopQ mutants had only modest defects in the colonization of the small intestine and Peyer's patches. The DeltayopE mutant was eliminated from the small intestine 3 weeks after infection, whereas the DeltayopH, DeltayopP, DeltayopM, and DeltayopQ mutants continued to colonize the small intestine at this time.

Administration, Oral↗

PubMed2003

Analysis of chaperone-dependent Yop secretion/translocation and effector function using a mini-virulence plasmid of Yersinia enterocolitica.

We have constructed a mini-pYV plasmid (pTTSS) harboring the Yersinia type three secretion system (TTSS) and the adhesin yadA on a low-copy vector. Using this system we could demonstrate for the first time that YopO, YopP, YopM, and YopQ do not require any of the known or orphan chaperones for efficient secretion/translocation. Y. enterocolitica harboring pTTSS, (WA-C(pTTSS)) was able to secrete and translocate single Yop effector proteins in trans. WA-C(pTTSS) proved to be stable and secretion of Yops was Ca2+ and temperature dependent as is the case for the parental strain. This shows that all genes necessary for translocation and expression of the Ca(2+)-dependent phenotype are contained within the cloned region. In contrast to previously published multiple yop mutants which were constructed by sequential deletion of yops, our system which harbors only the TTSS region without yops, chaperones, and unknown ORFs can be sequentially complemented with yops and sycs of choice. WA-C(pTTSS) was able to translocate YopE, YopM and YopT into HeLa cells as demonstrated by Western blotting. Translocation of YopE and YopT was strictly dependent on the presence of their respective chaperones, whereas YopM did not require a chaperone for translocation. WA-C(pTTSS) harboring yopT and sycT was shown to translocate active YopT by demonstrating modification of the small GTP-binding protein RhoA. This shows for the first time that RhoA modification is strictly dependent on YopT and does not require additional effector Yops. WA-C(pTTSS) harboring YopP was shown to induce apoptosis. This system is ideal to study chaperone-dependent Yop secretion/ translocation without the background of other effector Yops (YopE, YopM, YopO, YopP, YopT, YopH), chaperones (SycE, SycH, SycT) and unknown ORFs. In addition this system can secrete heterologous proteins fused to the N-terminal secretion/translocation domain of YopE.

Bacterial Outer Membrane Proteins↗

PubMed2003

Highly resistant metabolically deficient dwarf mutant of Escherichia coli is the cause of a chronic urinary tract infection.

We present the case of a 68-year-old diabetic woman who has been suffering from chronic urinary tract infections, recurring over a period of at least 5 years, caused by a slowly growing metabolically deficient dwarf mutant (MDD) of Escherichia coli. This MDD strain was auxotrophic for histidine, was resistant to multiple antibiotics, and showed atypical growth behavior. Colonies were tiny on routine media but were able to revert to normal growth after extended incubation. This strain was identified as E. coli by 16S ribosomal DNA sequencing, and virulence factor profiles were determined by PCR. Seven MDD isolates collected over the 5-year period were grown from midstream urine to significant colony counts and shown to belong to the same clonal group by pulsed-field gel electrophoresis and enterobacterial repetitive intergenic consensus PCR. These MDDs were repeatedly misidentified by biochemical methods due to their slow growth and atypical colony morphology. This case highlights the importance of recognizing MDDs of Enterobacteriaceae in patients with chronic infections. To our knowledge this is the first report of an MDD of E. coli causing a chronic urinary tract infection.

Aged↗

PubMed2002

"Staphylococcus pettenkoferi," a novel staphylococcal species isolated from clinical specimens.

In this report we describe a novel species of coagulase-negative novobiocin susceptible staphylococci obtained from an epidemiologically unrelated blood culture and a wound infection. These isolates significantly differed from all other validated Staphylococcus species based on phenotypic characteristics and 16S rRNA gene sequencing. Both isolates had identical 16S rRNA sequences and phylogenetic trees constructed from evolutionary distances showed that this species formed a distinct and deep subline that was most closely related to members of the Staphylococcus saprophyticus cluster group (S. kloosii, S. gallinarum, S. arlettae, S. saprophyticus, S. xylosus, S. equorum, S. succinus and S. cohnii) and Staphylococcus auricularis. Furthermore these strains could each be distinguished from all other staphylococci based on at least one phenotypic trait. Therefore we propose the designation of "Staphylococcus pettenkoferi" a novel species of coagulase-negative staphylococci.

Adult↗