Helicobacter pylori infection can cause gastritis, peptic ulcer and can lead to gastric cancer. Lengthy antibiotic therapy does not protect the host against reinfection. H. pylori evolved to evade the recognition of the immune response by modifying several of its components whose orthologous proteins from other bacteria activate the innate immune response. Flagella are essential for the H. pylori effective colonization of human duodenum and stomach. TLR5, a member of the Toll-like receptor family, recognizes flagellin of most bacteria, such as Escherichia coli, but does not recognize the flagellin FlaA of H. pylori. We restored the ability of FlaA for the recognition by TLR5 by engineering a chimeric flagellin, in which both terminal segments of H. pylori flagellin were replaced by the corresponding segments from TLR5-activating E. coli flagellin. Recombinant chimeric flagellin folded correctly and was able to activate TLR5. Significantly increased serum IgG and IgA antibody responses were determined in mice vaccinated with chimeric flagellin in comparison to mice vaccinated with a control protein (FlaA) or negative control. Antibody titers remained high eve n8 months after the last immunization. Antibodies were able to bind native flagellin from H. pylori lysate. Vaccination with chimeric flagellin provided mice with significant protection against H. pylori. The approach of chimeric flagellin can therefore generate effective immunogens that enable activation of innate and adaptive immune response and can be used to construct efficient vaccines against H. pylori or other flagellated bacteria that evade TLR5 recognition.
COBISS.SI-ID: 5023770
TIR (Toll/IL-1 receptor) domains mediate interactions between TLR (Toll-like) or IL-1 family receptors and signaling adapters. While homotypic TIR domain interactions mediate receptor activation they are also usurped by microbial TIR-domain containing proteins for immunosuppression. Here we show the role of a dimerized TIR domain platform for the suppression as well as for the activation of MyD88 signaling pathway. Coiled-coil dimerization domain, present in many bacterial TCPs, potently augments suppression of TLR/IL-1R signaling. The addition of a strong coiled-coil dimerization domain conferred the superior inhibition against the wide spectrum of TLRs and prevented the constitutive activation by a dimeric TIR platform. We propose a molecular model of MyD88-mediated signaling based on the dimerization of TIR domains as the limiting step.
COBISS.SI-ID: 5026586
The progress of synthetic biology allows one to design artificial repressors that inhibit selected genes. Combination of repressors enables construction of NOR logical gates that could form the foundation for information processing within cells. The theoretical potentials and limitations of constructing NOR gates were analyzed. They could be experimentally realized in bacterial cells. The number of required artificial repressors was analysed and temporal simulations of an example function were performed.
COBISS.SI-ID: 8956756