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The bacterium Helicobacter pylori is the causative agent for peptic ulcer disease. Bacterial adherence to the human gastric epithelial lining, a prerequisite for the pathological action of H. pylori, is caused by its outer membrane proteins. One of their most prominent members is the Lewis B binding adhesin, BabA which interacts with the bloodgroup antigen carbohydrate epitopes. To elucidate the structural basis of Lewis-b antigen recognition by BabA, STD (Saturation Transfer Difference) NMR experiments enabled the specific detection of Helicobacter-glycan interactions by using living Helicobacter cell suspensions and Lewis B blood group O determinant. In the NMR spectra, one can identify several carbohydrate segments which bind to BabA. This unique setup is ideal for continuing functional analyses of fully functional BabA adhesion protein in its native environment, the bacterial outer membrane.Further work is using combined liquid/solid state 31P NMR studies to elucidate the variation in membrane lipid compounds arising from outer membrane vesicles (OMV) which the bacterium produce to deliver bacterial virulence factors. Using tailored-made solution NMR (1H, 31P NMR, 1H-13C and 1H-31P correlation NMR spectroscopy) we could identify and quantify various lipids as a function of strain, clinical isolates, mutants and the different membranes. We observed marked differences in the phospholipid composition between inner (IM) and outer membrane (OM) as well as vesicles (OMV). |
