We suggest that the presence of GroEL in the OMVs preparation might be due merely to the co-precipitation during the vesicle isolation procedure. Figure 4 Electron microscopy and immunogold labelling of CDT. Immunoelectron microscopic analyses of OMVs from wild type C. jejuni strain. LY411575 in vitro 81-176 (A-C) and the cdtA::km mutant (D-F) using anti-CdtA (A, D), anti-CdtB (B, E), and anti-CdtC antisera (C, F). Arrows show the gold particles associated with OMVs. The square in the upper right corners show enlargements of parts of the micrographs. Bars correspond

to 100 nm. Figure 5 Electron microscopy and immunogold labelling of Hsp and Omp50. Immunoelectron microscopic analyses of OMVs. (A) OMVs of wild type C. jejuni strain 81-176 without antiserum (control). (B), immunolabelling

LDN-193189 ic50 with anti-Hsp antiserum. (C) immunolabelling with anti-Omp50 antiserum. White arrows show the GroEL like particles selleck kinase inhibitor (in A) and the localization of gold particles on the GroEL like particles (in B). Black arrows show the OMVs (in A&B). Bars correspond to 100 nm. Sub-cellular localization of CDT proteins in C. jejuni cells The presence of CDT in OMVs would imply that the proteins should be localized, at least transiently, in the outer membrane and/or periplasmic compartments of the bacterial cells. We also analyzed the localization of the CDT toxin subunits in different sub-cellular (cytosolic, inner membrane, periplasm, outer membrane) fractions of the bacteria. The results from SDS-PAGE with silver staining (here also serving as a control for protein loading) and immunoblot analysis are shown in Figure 6A&6B, respectively. Etofibrate Antisera directed against the cytosolic marker CRP and the periplasmic protein HtrA was used to further verify the fractionation. All CDT subunits could be detected in the whole cell lysate and in the cytoplasmic fraction (Figure 6B). Some amount of CdtA protein was detected in the membrane factions as well whereas very little of the CtdB and CdtC proteins were detected in those

fractions. However, clearly detectable amounts of all CDT proteins were found in the periplasmic fraction (Figure 6B, lane 4). From the relative intensities of the bands detected we could estimate the amount of each Cdt subunit protein in the periplasmic compartment in comparison with that of the cytoplasm. In case of CdtA we estimated that about 50% of the protein appeared in the periplasm whereas only about 5% were detected in the membrane fractions (Figure 6B). The CdtB and CdtC proteins were also present at appreciable levels in the periplasm (about 20% to 30%) in comparison with the levels in the cytoplasm. Figure 6 Analyses of CDT localization in subcellular C. jejuni fractions. Subcellular localization of CDT subunits in C. jejuni strain 81-176. (A), SDS-PAGE gel after silver staining and (B), immunoblot analyses of cell fractions from C. jejuni wild type strain 81-176 (lanes 1-5) and the cdtA::km mutant (lanes 6-10).