The research project entails identification and structural characterization of receptor-active carbohydrate sequences in the target tissues of microbes and microbial toxins, and definition of the molecular interactions that determine the specific recognition of binding-active carbohydrates, to create a basis for structural drug design of anti-adhesive receptor saccharide analogues. A further ambition is to identify conserved microbial carbohydrate-binding adhesins for development of vaccines. The methodology involves solid-phase binding assays for definition of carbohydrate binding properties of microbial proteins, isolation of binding-active compounds by multi-step chromatography, and structural characterization by various mass spectrometry techniques, 1H NMR and gas chromatography-mass spectrometry after degradation, and high-resolution studies of protein-carbohydrate complexes by X-ray crystallography. Through the years we have gained deep experience in identifying glycosphingolipids and created a unique bank of pure species and mixtures for screening purposes.
One focus is on the human gastric pathogen Helicobacter pylori. Several H. pylori carbohydrate binding specificities have been defined by us, and using affinity methods and proteomics-based mass spectrometry techniques the sialic acid binding adhesin SabA has been identified. Recently we have established that the SabA adhesin has a pivotal role of in the nonopsonic H. pylori-induced activation of human neutrophils.
Another focus is definition of the structural basis of the differences in carbohydrate binding between the B-subunits of cholera toxin (CTB) and Escherichia coli heat-labile enterotoxin (LTB). Site-directed mutagenesis of the B-subunits has been used for identification of critical amino acid residues involved in the carbohydrate binding processes. Thereby a hybrid of CTB and LTB which, in addition to the well-known sialic acid-depending binding of the GM1 ganglioside, had an additional binding to A and B blood group determinants was created. By docking and molecular dynamics simulations a second binding site, distinct from the GM1 binding site, was located at the top of B-subunit pentamer interfaces. This gain-of-function mutation represents the first example of the creation of a novel binding site in a carbohydrate-binding protein. The location of the binding site has now been confirmed by crystallizing the hybrid subunits in complex with blood group A pentasaccharide.
In addition, we are currently investigating the carbohydrate binding properties of H. pylori vacuolating cytotoxin VacA, non-gastric Helicobacters (e.g. H. hepaticus), uropathogenic E. coli, and viruses.
Ångström, J., Bäckström, M., Berntsson, A., Karlsson, N., Holmgren, J., Karlsson, K.-A., Teneberg, S. (2000) Novel carbohydrate binding site recognizing blood group A and B determinants in a cholera toxin/heat-labile enterotoxin B-subunit hybrid. J. Biol. Chem. 275, 3231-3238
Teneberg, S., Leonardsson, I., Karlsson, H., Jovall, P.-Å., Ångström, J., Danielsson, D., Näslund, I., Ljungh, Å., Wadström, T., and Karlsson, K.-A. (2002) Lactotetraosylceramide, a novel glycosphingolipid receptor for Helicobacter pylori, present in human gastric epithelium. J. Biol. Chem. 277, 19709-19719
Mahdavi, J., Sondén, B., Hurtig, M., Olfat, F. O., Forsberg, L., Roche, N., Ångström, J., Larsson, T., Teneberg, S., Karlsson, K.-A., Altraja, S., Wadström, T., Kersulyte, D., Berg, D. E., Dubois, A., Peterson, C., Magnusson, K.-E,. Norberg, T., Lindh, F., Lundskog, B. B., Arnqvist, A., Hammarström, L., Borén, T. (2002) Helicobacter pylori SabA adhesin in persistent infection and chronic inflammation. Science 297, 573-578
Aspholm-Hurtig, M., Dailide, G., Lahmann, M., Kalia, A., Ilver, D., Roche, N., Vikström, S., Sjöström, R., Lindén, S., Bäckström, A., Arnqvist, A., Mahdavi, J., Nilsson, U. J., Velapatiño, B., Gilman, R. H., Gerhard, M., Alarcon, T., López-Brea, M., Nakazawa, T., Fox, J. G,, Correa, P., Dominguez-Bello, M. G., Perez-Perez, G. I., Blaser, M. J., Normark, S., Carlstedt, I., Oscarson, S., Teneberg, S., Berg, D. E., Borén, T. (2004) Functional adaptation of BabA, the Helicobacter pylori blood-group antigen binding adhesin. Science 305, 519-522
Unemo, M., Aspholm-Hurtig, M., Ilver, D., Borén, T., Bergström, J., Danielsson, D., Teneberg, S. (2005) The sialic acid binding SabA adhesin of Helicobacter pylori is essential for nonopsonic activation of human neutrophils. J. Biol. Chem. 280, 15390-15397