Dendritic cells (DCs) infected by Francisella tularensis are poorly activated and do not undergo classical maturation process. Although reasons of such unresponsiveness are not fully understood, their impact on the priming of immunity is well appreciated. Previous attempts to explain the behavior of Francisella-infected DCs were hypothesis-driven and focused on events at later stages of infection. Here, we took an alternative unbiased approach by applying methods of global phosphoproteomics to analyze the dynamics of cell signaling in primary DCs during the first hour of infection by Francisella tularensis Presented results show that the early response of DCs to Francisella occurs in phases and that ERK and p38 signaling modules induced at the later stage are differentially regulated by virulent and attenuated ΔdsbA strain. These findings imply that the temporal orchestration of host proinflammatory pathways represents the integral part of Francisella life-cycle inside hijacked DCs.

• MeSH
• buněčné linie MeSH
• dendritické buňky metabolismus   mikrobiologie   MeSH
• extracelulárním signálem regulované MAP kinasy metabolismus   MeSH
• fosforylace MeSH
• Francisella tularensis * MeSH
• mitogenem aktivované proteinkinasy p38 metabolismus   MeSH
• myši inbrední C57BL MeSH
• tularemie metabolismus   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• extracelulárním signálem regulované MAP kinasy MeSH
• mitogenem aktivované proteinkinasy p38 MeSH

The DsbA homolog of Francisella tularensis was previously demonstrated to be required for intracellular replication and animal death. Disruption of the dsbA gene leads to a pleiotropic phenotype that could indirectly affect a number of different cellular pathways. To reveal the broad effects of DsbA, we compared fractions enriched in membrane proteins of the wild-type FSC200 strain with the dsbA deletion strain using a SILAC-based quantitative proteomic analysis. This analysis enabled identification of 63 proteins with significantly altered amounts in the dsbA mutant strain compared to the wild-type strain. These proteins comprise a quite heterogeneous group including hypothetical proteins, proteins associated with membrane structures, and potential secreted proteins. Many of them are known to be associated with F. tularensis virulence. Several proteins were selected for further studies focused on their potential role in tularemia's pathogenesis. Of them, only the gene encoding glyceraldehyde-3-phosphate dehydrogenase, an enzyme of glycolytic pathway, was found to be important for full virulence manifestations both in vivo and in vitro. We next created a viable mutant strain with deleted gapA gene and analyzed its phenotype. The gapA mutant is characterized by reduced virulence in mice, defective replication inside macrophages, and its ability to induce a protective immune response against systemic challenge with parental wild-type strain. We also demonstrate the multiple localization sites of this protein: In addition to within the cytosol, it was found on the cell surface, outside the cells, and in the culture medium. Recombinant GapA was successfully obtained, and it was shown that it binds host extracellular serum proteins like plasminogen, fibrinogen, and fibronectin.

• Klíčová slova
• DsbA, Francisella tularensis, SILAC, glyceraldehyde-3-phosphate dehydrogenase, moonlighting,
• MeSH
• delece genu * MeSH
• faktory virulence analýza   MeSH
• Francisella tularensis enzymologie   imunologie   patogenita   MeSH
• glyceraldehyd-3-fosfátdehydrogenasy nedostatek   metabolismus   MeSH
• krevní proteiny metabolismus   MeSH
• mikrobiální viabilita MeSH
• modely nemocí na zvířatech MeSH
• myši MeSH
• proteindisulfidisomerasy nedostatek   MeSH
• proteom analýza   MeSH
• salmonelová infekce u zvířat mikrobiologie   patologie   MeSH
• vazba proteinů MeSH
• virulence MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• faktory virulence MeSH
• glyceraldehyd-3-fosfátdehydrogenasy MeSH
• krevní proteiny MeSH
• proteindisulfidisomerasy MeSH
• proteom MeSH

Francisella tularensis subspecies tularensis is a highly virulent intracellular bacterial pathogen, causing the disease tularemia. However, a safe and effective vaccine for routine application against F. tularensis has not yet been developed. We have recently constructed the deletion mutants for the DsbA homolog protein (ΔdsbA/FSC200) and a hypothetical protein IglH (ΔiglH/FSC200) in the type B F. tularensis subsp. holarctica FSC200 strain, which exerted different protection capacity against parental virulent strain. In this study, we further investigated the immunological correlates for these different levels of protection provided by ΔdsbA/FSC200 and ΔiglH/FSC200 mutants. Our results show that ΔdsbA/FSC200 mutant, but not ΔiglH/FSC200 mutant, induces an early innate inflammatory response leading to strong Th1-like antibody response. Furthermore, vaccination with ΔdsbA/FSC200 mutant, but not with ΔiglH/FSC200, elicited protection against the subsequent challenge with type A SCHU S4 strain in mice. An immunoproteomic approach was used to map a spectrum of antigens targeted by Th1-like specific antibodies, and more than 80 bacterial antigens, including novel ones, were identified. Comparison of tularemic antigens recognized by the ΔdsbA/FSC200 post-vaccination and the SCHU S4 post-challenge sera then revealed the existence of 22 novel SCHU S4 specific antibody clones.

• Klíčová slova
• antibody response, cytokines, immunoproteomics, protection, tularemia,
• MeSH
• atenuované vakcíny aplikace a dávkování   genetika   imunologie   MeSH
• bakteriální vakcíny aplikace a dávkování   genetika   imunologie   MeSH
• cytokiny metabolismus   MeSH
• faktory virulence nedostatek   MeSH
• Francisella tularensis klasifikace   enzymologie   imunologie   MeSH
• modely nemocí na zvířatech MeSH
• myši inbrední BALB C MeSH
• proteindisulfidisomerasy nedostatek   MeSH
• Th1 buňky imunologie   MeSH
• tularemie imunologie   prevence a kontrola   MeSH
• tvorba protilátek * MeSH
• zkřížená ochrana * MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• atenuované vakcíny MeSH
• bakteriální vakcíny MeSH
• cytokiny MeSH
• faktory virulence MeSH
• proteindisulfidisomerasy MeSH

Francisella tularensis, the etiological agent of tularemia, is an intracellular pathogen that dominantly infects and proliferates inside phagocytic cells but can be seen also in non-phagocytic cells, including B cells. Although protective immunity is known to be almost exclusively associated with the type 1 pathway of cellular immunity, a significant role of B cells in immune responses already has been demonstrated. Whether their role is associated with antibody-dependent or antibody-independent B cell functions is not yet fully understood. The character of early events during B cell-pathogen interaction may determine the type of B cell response regulating the induction of adaptive immunity. We used fluorescence microscopy and flow cytometry to identify the basic requirements for the entry of F. tularensis into B cells within in vivo and in vitro infection models. Here, we present data showing that Francisella tularensis subsp. holarctica strain LVS significantly infects individual subsets of murine peritoneal B cells early after infection. Depending on a given B cell subset, uptake of Francisella into B cells is mediated by B cell receptors (BCRs) with or without complement receptor CR1/2. However, F. tularensis strain FSC200 ΔiglC and ΔftdsbA deletion mutants are defective in the ability to enter B cells. Once internalized into B cells, F. tularensis LVS intracellular trafficking occurs along the endosomal pathway, albeit without significant multiplication. The results strongly suggest that BCRs alone within the B-1a subset can ensure the internalization process while the BCRs on B-1b and B-2 cells need co-signaling from the co receptor containing CR1/2 to initiate F. tularensis engulfment. In this case, fluidity of the surface cell membrane is a prerequisite for the bacteria's internalization. The results substantially underline the functional heterogeneity of B cell subsets in relation to F. tularensis.

• MeSH
• B-lymfocyty metabolismus   mikrobiologie   MeSH
• bakteriální geny MeSH
• biologický transport MeSH
• buněčné linie MeSH
• Francisella tularensis fyziologie   MeSH
• interakce hostitele a patogenu MeSH
• membránové mikrodomény metabolismus   MeSH
• mikrobiální viabilita MeSH
• myši inbrední BALB C MeSH
• receptory antigenů B-buněk metabolismus   MeSH
• receptory IgG metabolismus   MeSH
• receptory komplementu metabolismus   MeSH
• sekvenční delece MeSH
• tularemie mikrobiologie   MeSH
• zvířata MeSH
• Check Tag
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• receptory antigenů B-buněk MeSH
• receptory IgG MeSH
• receptory komplementu MeSH

FTH_0069 is a previously uncharacterized strongly immunoreactive protein that has been proposed to be a novel virulence factor in Francisella tularensis. Here, the glycan structure modifying two C-terminal peptides of FTH_0069 was identified utilizing high resolution, high mass accuracy mass spectrometry, combined with in-source CID tandem MS experiments. The glycan observed at m/z 1156 was determined to be a hexasaccharide, consisting of two hexoses, three N-acetylhexosamines, and an unknown monosaccharide containing a phosphate group. The monosaccharide sequence of the glycan is tentatively proposed as X-P-HexNAc-HexNAc-Hex-Hex-HexNAc, where X denotes the unknown monosaccharide. The glycan is identical to that of DsbA glycoprotein, as well as to one of the multiple glycan structures modifying the type IV pilin PilA, suggesting a common biosynthetic pathway for the protein modification. Here, we demonstrate that the glycosylation of FTH_0069, DsbA, and PilA was affected in an isogenic mutant with a disrupted wbtDEF gene cluster encoding O-antigen synthesis and in a mutant with a deleted pglA gene encoding pilin oligosaccharyltransferase PglA. Based on our findings, we propose that PglA is involved in both pilin and general F. tularensis protein glycosylation, and we further suggest an inter-relationship between the O-antigen and the glycan synthesis in the early steps in their biosynthetic pathways.

• MeSH
• faktory virulence chemie   genetika   metabolismus   MeSH
• Francisella tularensis genetika   metabolismus   patogenita   MeSH
• glykosylace MeSH
• molekulární sekvence - údaje MeSH
• multigenová rodina MeSH
• mutace MeSH
• O-antigeny chemie   genetika   metabolismus   MeSH
• proteiny fimbrií chemie   genetika   metabolismus   MeSH
• sacharidové sekvence MeSH
• sekvence aminokyselin MeSH
• tandemová hmotnostní spektrometrie MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Extramural MeSH
• Názvy látek
• faktory virulence MeSH
• O-antigeny MeSH
• PilA protein, Francisella tularensis MeSH Prohlížeč
• proteiny fimbrií MeSH

It appears that most glycoproteins found in pathogenic bacteria are associated with virulence. Despite the recent identification of novel virulence factors, the mechanisms of virulence in Francisella tularensis are poorly understood. In spite of its importance, questions about glycosylation of proteins in this bacterium and its potential connection with bacterial virulence have not been answered yet. In the present study, several putative Francisella tularensis glycoproteins were characterized through the combination of carbohydrate-specific detection and lectin affinity with highly sensitive mass spectrometry utilizing the bottom-up proteomic approach. The protein PilA that was recently found as being possibly glycosylated, as well as other proteins with designation as novel factors of virulence, were among the proteins identified in this study. The reported data compile the list of potential glycoproteins that may serve as a takeoff platform for a further definition of proteins modified by glycans, faciliting a better understanding of the function of protein glycosylation in pathogenicity of Francisella tularensis.

• MeSH
• 2D gelová elektroforéza MeSH
• bakteriální proteiny chemie   metabolismus   MeSH
• chromatografie afinitní MeSH
• fluorescenční barviva MeSH
• Francisella tularensis chemie   metabolismus   MeSH
• glykoproteiny chemie   metabolismus   MeSH
• glykosylace MeSH
• lektiny MeSH
• molekulární sekvence - údaje MeSH
• polysacharidy metabolismus   MeSH
• proteom chemie   metabolismus   MeSH
• proteomika metody   MeSH
• sekvence aminokyselin MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• bakteriální proteiny MeSH
• fluorescenční barviva MeSH
• glykoproteiny MeSH
• lektiny MeSH
• polysacharidy MeSH
• proteom MeSH