Dataset Information

Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.

ABSTRACT: The Toll/IL-1 receptor (TIR) domains are crucial signaling modules during innate immune responses involving the Toll-like receptors (TLRs) and IL-1 receptor (IL-1R). Myeloid differential factor 88 (MyD88) is a central TIR domain-containing adapter molecule responsible for nearly all TLR-mediated signaling and is targeted by a TIR domain-containing protein C (TcpC) from virulent uropathogenic Escherichia coli, a common human pathogen. The mechanism of such molecular antagonism has remained elusive. We present the crystal structure of the MyD88 TIR domain with distinct loop conformations that underscore the functional specialization of the adapter, receptor, and microbial TIR domains. Our structural analyses shed light on the genetic mutations at these loops as well as the Poc site. We demonstrate that TcpC directly associates with MyD88 and TLR4 through its predicted DD and BB loops to impair the TLR-induced cytokine induction. Furthermore, NMR titration experiments identify the unique CD, DE, and EE loops from MyD88 at the TcpC-interacting surface, suggesting that TcpC specifically engages these MyD88 structural elements for immune suppression. These findings thus provide a molecular basis for the subversion of TLR signaling by the uropathogenic E. coli virulence factor TcpC and furnish a framework for the design of novel therapeutic agents that modulate immune activation.

SUBMITTER: Snyder GA

PROVIDER: S-EPMC3637702 | biostudies-literature | 2013 Apr

REPOSITORIES: biostudies-literature

ACCESS DATA

Publications

Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.

Snyder Greg A GA Cirl Christine C Jiang Jiansheng J Chen Kang K Waldhuber Anna A Smith Patrick P Römmler Franziska F Snyder Nathaniel N Fresquez Theresa T Dürr Susanne S Tjandra Nico N Miethke Thomas T Xiao Tsan Sam TS

Proceedings of the National Academy of Sciences of the United States of America 20130408 17

The Toll/IL-1 receptor (TIR) domains are crucial signaling modules during innate immune responses involving the Toll-like receptors (TLRs) and IL-1 receptor (IL-1R). Myeloid differential factor 88 (MyD88) is a central TIR domain-containing adapter molecule responsible for nearly all TLR-mediated signaling and is targeted by a TIR domain-containing protein C (TcpC) from virulent uropathogenic Escherichia coli, a common human pathogen. The mechanism of such molecular antagonism has remained elusiv ...[more]

PMID: 23569230

Similar Datasets

Project description:UnlabelledThe vacuolating autotransporter toxin (Vat) contributes to uropathogenic Escherichia coli (UPEC) fitness during systemic infection. Here, we characterized Vat and investigated its regulation in UPEC. We assessed the prevalence of vat in a collection of 45 UPEC urosepsis strains and showed that it was present in 31 (68%) of the isolates. The isolates containing the vat gene corresponded to three major E. coli sequence types (ST12, ST73, and ST95), and these strains secreted the Vat protein. Further analysis of the vat genomic locus identified a conserved gene located directly downstream of vat that encodes a putative MarR-like transcriptional regulator; we termed this gene vatX The vat-vatX genes were present in the UPEC reference strain CFT073, and reverse transcriptase PCR (RT-PCR) revealed that the two genes are cotranscribed. Overexpression of vatX in CFT073 led to a 3-fold increase in vat gene transcription. The vat promoter region contained three putative nucleation sites for the global transcriptional regulator histone-like nucleoid structuring protein (H-NS); thus, the hns gene was mutated in CFT073 (to generate CFT073 hns). Western blot analysis using a Vat-specific antibody revealed a significant increase in Vat expression in CFT073 hns compared to that in wild-type CFT073. Direct H-NS binding to the vat promoter region was demonstrated using purified H-NS in combination with electrophoresis mobility shift assays. Finally, Vat-specific antibodies were detected in plasma samples from urosepsis patients infected by vat-containing UPEC strains, demonstrating that Vat is expressed during infection. Overall, this study has demonstrated that Vat is a highly prevalent and tightly regulated immunogenic serine protease autotransporter protein of Enterobacteriaceae (SPATE) secreted by UPEC during infection.ImportanceUropathogenic Escherichia coli (UPEC) is the major cause of hospital- and community-acquired urinary tract infections. The vacuolating autotransporter toxin (Vat) is a cytotoxin known to contribute to UPEC fitness during murine sepsis infection. In this study, Vat was found to be highly conserved and prevalent among a collection of urosepsis clinical isolates and was expressed at human core body temperature. Regulation of vat was demonstrated to be directly repressed by the global transcriptional regulator H-NS and upregulated by the downstream gene vatX (encoding a new MarR-type transcriptional regulator). Additionally, increased Vat-specific IgG titers were detected in plasma from corresponding urosepsis patients infected with vat-positive isolates. Hence, Vat is a highly conserved and tightly regulated urosepsis-associated virulence factor.

Project description:Escherichia coli (E. coli) urinary tract infections (UTIs) are becoming a serious problem both for pets and humans (zoonosis) due to the close contact and to the increasing resistance to antibiotics. Great progress has been made in the discovery of novel antibiotics to counteract E. coli pathogens. However, this huge progress has been undercut by the evolution of bacteria in the way of drug resistance. Enrofloxacin is one of the most efficient antibiotics against E. coli pathogens and there is considerable evidence that documents how this microorganism is becoming more resistant to this antibiotic and is developing multidrug resistance. This study has been performed in order to unravel the mechanism of induced enrofloxacin resistance in canine E. coli isolates that represent a good tool to study this pathology. For a comprehensive investigation about antibiotic resistance mechanisms, an E. coli isolate from urinary tract infection (UTI) was induced to grow under a concentration of 10 µg/ml of enrofloxacin. Proteins represent the main contributors to the mechanisms involved in antibiotic resistance in bacteria. Their abundance profile provides reliable information about the mechanisms involved in this process. Three biological replicates of control and resistant isolate have been analyzed both through 2D DIGE and shotgun proteomics. In our case, prior to perform the proteomics analysis, the screening with MS profiling of control and resistant isolates was performed highlighting the differences among strains and successfully clustering experimental strains according to PC analysis (PCA). The results clearly demonstrate differential profiles in peptide expression among clusters and between isolate and reference strain. According to these preliminary results, the protein profile of the resistant group was compared with the one of its sensitive counterpart by a proteomic analysis based on 2D-DIGE to separate proteins combined to MALDI MS analysis and database search to identify differentially expressed proteins. This analysis showed the modulation of 19 proteins between the two conditions. At the same time, another comparative proteomics investigation was also carried out by free-label nLC-MSE. This method has allowed the qualitative and quantitative analysis of total protein extracts of the two groups for the simultaneous screening of a larger number of proteins. A total of 57 differentially expressed proteins were identified and a comprehensive study on the proteins associated with enrofloxacin resistance was carried out. We classified these modulated proteins by their molecular functions and pathways where they are principally involved. This approach allowed to highlight some pathways that can be involved in an increased antibiotic resistance. Two major mechanisms were discovered. The first one was related to the stabilization of DNA structure through the up-regulation of Dsp protein. The second one was the downregulation of outer membrane protein W in order to reduce the membrane permeability to enrofloxacin. Discovered differentilally expressed proteins are principally involved in antibiotic resistance and linked to the oxidative stress response, to DNA protection and in membrane permeability. Moreover, since enrofloxacin is an inhibitor of DNA gyrase, the overexpression of DNA starvation/stationary phase protection protein (Dsp) could be a central point to discover the mechanism of this clone to counteract the effects of enrofloxacin. In parallel, the dramatic decrease of the synthesis of the outer membrane protein W, which represents one of the main gates for enrofloxacin entrance, could explain additional mechanism of E. coli defense against this antibiotic. The proteins differentially expressed could represent putative targets for the development of new strategies to counteract drug and multidrug resistance.

Dataset Information

Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.

Publications

Molecular mechanisms for the subversion of MyD88 signaling by TcpC from virulent uropathogenic Escherichia coli.

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure

Tweets