Project description:Identification of human proteins targeted by Citrobacter secreted effectors by affinity purification followed by mass spectrometry.
Project description:Strains of Salmonella utilise two distinct type three secretion systems to deliver effector proteins directly into host cells. The Salmonella effectors SseK1 and SseK3 are arginine glycosyltransferases that modify mammalian death domain containing proteins with N-acetyl glucosamine (GlcNAc) when overexpressed ectopically or as recombinant protein fusions. Here, we combined Arg-GlcNAc glycopeptide immunoprecipitation and mass spectrometry to identify host proteins GlcNAcylated by endogenous levels of SseK1 and SseK3 during Salmonella infection. We observed that SseK1 modified the mammalian signaling protein TRADD, but not FADD as previously reported. Overexpression of SseK1 greatly broadened substrate specificity, while ectopic co-expression of SseK1 and TRADD increased the range of modified arginine residues within the death domain of TRADD. In contrast, endogenous levels of SseK3 resulted in modification of the death domains of receptors of the mammalian TNF superfamily, TNFR1 and TRAILR, at residues Arg376 and Arg293 respectively. Structural studies on SseK3 showed that the enzyme displays a classic GT-A glycosyltransferase fold and binds UDP-GlcNAc in a narrow and deep cleft with the GlcNAc facing the surface. Together our data suggests that Salmonellae carrying sseK1 and sseK3 employ the glycosyltransferase effectors to antagonise different components of death receptor signaling.
Project description:Comparison of Campylobacter proteome in MH media with and without deoxycholic acid, in presence of FBS or after being exposed to INT 407 and Caco2 intestinal epithelial cells.
Project description:Strains of Salmonella utilise two distinct type three secretion systems to deliver effector proteins directly into host cells. The Salmonella effector SseK3 is a arginine glycosyltransferase that modify mammalian proteins with N-acetyl glucosamine (GlcNAc). Here, we used Arg-GlcNAc glycopeptide immunoprecipitation and mass spectrometry appraoch to identify host proteins GlcNAcylated by endogenous levels of SseK3 during Salmonella infection. Focusing on the insoluble proteome we demostrate multiple typically insoluble proteins are targetted by SseK3 during infections. Surpisingly unlike SseK1 and the EPEC homologue NleB1 which target death domain contain proteins SseK3 appears to modify a number of proteins lacking death domains. These results demostrate that under endogenous infection non-death domain containing proteins can be modified by Salmonella.
Project description:Utilized sensitive, high throughput multiplexed ion mobility-mass spectrometry (IM-MS) to characterize the serum proteome of tuberculosis patients prior to and at 8 weeks of antibiotic treatment. Goal is to identify a serum protein signature indicative of treatment effect.
Project description:Many pathogenic bacteria of the family Enterobacteriaceae use type III secretion systems to inject virulence proteins, termed "effectors," into the host cell cytosol. Although host-cellular activities of several effectors have been demonstrated, the function and host-targeted pathways of most of the effectors identified to date are largely undetermined. To gain insight into host proteins targeted by bacterial effectors, we performed coaffinity purification of host proteins from cell lysates using recombinant effectors from the Enterobacteriaceae intracellular pathogens Salmonella enterica serovar Typhimurium and Citrobacter rodentium. We identified 54 high-confidence host interactors for the Salmonella effectors GogA, GtgA, GtgE, SpvC, SrfH, SseL, SspH1, and SssB collectively and 21 interactors for the Citrobacter effectors EspT, NleA, NleG1, and NleK. We biochemically validated the interaction between the SrfH Salmonella protein and the extracellular signal-regulated kinase 2 (ERK2) host protein kinase, which revealed a role for this effector in regulating phosphorylation levels of this enzyme, which plays a central role in signal transduction. IMPORTANCE During infection, pathogenic bacteria face an adverse environment of factors driven by both cellular and humoral defense mechanisms. To help evade the immune response and ultimately proliferate inside the host, many bacteria evolved specialized secretion systems to deliver effector proteins directly into host cells. Translocated effector proteins function to subvert host defense mechanisms. Numerous pathogenic bacteria use a specialized secretion system called type III secretion to deliver effectors into the host cell cytosol. Here, we identified 75 new host targets of Salmonella and Citrobacter effectors, which will help elucidate their mechanisms of action.
Project description:In the context of host-pathogen interactions, gram-negative bacterial virulence factors, such as effectors, may be transferred from bacterial to eukaryotic host cytoplasm by multicomponent Type III protein secretion systems (T3SSs). Central to Salmonella enterica serovar Typhimurium (S. Typhimurium) pathogenesis is the secretion of over 40 effectors by two T3SSs encoded within pathogenicity islands SPI-1 and SPI-2. These effectors manipulate miscellaneous host cellular processes, such as cytoskeleton organization and immune signaling pathways, thereby permitting host colonization and bacterial dissemination. Recent research on effector biology provided mechanistic insights for some effectors. However, for many effectors, clearly defined roles and host target repertoires—further clarifying effector interconnectivity and virulence networks—are yet to be uncovered. Here we demonstrate the utility of the recently described viral-like particle trapping technology Virotrap as an effective approach to catalogue S. Typhimurium effector-host protein complexes (EH-PCs). Mass spectrometry-based Virotrap analysis of the novel E3 ubiquitin ligase SspH2 previously shown to be implicated in modulating actin dynamics and immune signaling, exposed known host interactors PFN1 and -2 and several putative novel, interconnected host targets. Network analysis revealed an actin(-binding) cluster among the significantly enriched hits for SspH2, consistent with the known localization of the S-palmitoylated effector with actin cytoskeleton components in the host. We show that Virotrap complements the current state-of-the-art toolkit to study protein complexes and represents a valuable means to screen for effector host targets in a high-throughput manner, thereby bridging the knowledge gap between effector-host interplay and pathogenesis.
Project description:Quantitative proteome analysis of progressive phycobilisome mutant variants CB, CK, and PAL to understand systematic alterations in protein expression profiles.
Project description:We have developed a quantitative chemical probe approach for live cell labeling of proteins that are sensitive to redox modifications. We utilize this in vivo strategy coupled to mass spectrometry-based proteomics to identify 176 proteins undergoing ~5-10 fold dynamic redox change in response to nutrient limitation and subsequent replenishment in the photoautotrophic cyanobacterium, Synechococcus sp. PCC 7002. This method enables the identification of redox changes in as little as 30 seconds after nutrient perturbation, and oscillations in reduction and oxidation for 60 minutes following the perturbation. The redox changes were validated by demonstrating that protein abundances did not change per global proteomic analyses. Peptides identified by MS for global and probe-labeled samples were required to be at least six amino acids in length having a mass spectra generating function score of <=1E-10, which corresponds to an FDR of <1%. Additionally, only peptides unique in identifying a single protein were utilized to estimate protein abundances, and proteins represented by <2 unique peptides were removed. This resulted in the identification of 176 redox probe labeled protein identifications, and 808 protein identifications in the global data.
Project description:Data includes proteomics analysis of P450-ABP (2EN, ATW8, ATW12), FP-2, and ATP-ABP labeled mouse lung lysate S9. Lungs from the following developmental stages were used in the study: gestational day 17, post natal days 0, 21, and 42. Also included are global analyses of the same mice lungs.