Glyco affinity proteomics: identification of carbohydrate-binding adhesins being potential vaccine components in case of the cancerogenic gastric colonizer helicobacter pylori

J Bergstrom, PhD, E Gustafsson, BSc, P Johansson, BSc, T Larsson, Techn, H Miller-Podraza, PhD, C Nilsson, MD, PhD, Susann Teneberg, MD, PhD, KA Karlsson, MD, PhD

Institute of Medical Biochemistry, Goteborg University, Sweden

AIM Microbes need to attach to host tissues to cause infections, most often to carbohydrate epitopes mediated by minor adhesin proteins (1). Vaccination against such adhesins may protect against infections (2). The project is using known carbohydrate binding specificities to design affinity probes for identification of adhesins against genome sequence (proteomics). METHODS A multivalent probe may be based on albumin to which the receptor saccharide and a photoactive cross-linker with biotin are coupled. After incubation of probe with living bacterial cells and photoactivation, biotin-tagged protein is enriched through streptavidin beads and electrophoresis followed by trypsin digestion, mass spectrometry of peptides and bioinformatics search against genome for a safe identity of protein (3). RESULTS The known Lewis b-binding adhesin BabA with a copy number of 500 per H. pylori bacterial cell (4) was successfully tested with this technique (3), and a sialic acid-binding adhesin was newly identified (5). CONCLUSIONS Low-abundant membrane adhesins may be rationally identified by an affinity proteomics approach. H. pylori, the colonizer behind gastric cancer, is uniquely complex with about ten separate carbohydrate-binding specificities (6). Similar to the case for urinary infection and E. coli (2), vaccination with low-abundant adhesins of H. pylori may prove to prevent colonization and thus cancer development. (1)KA Karlsson, Mol Microbiol 1998;29:1. (2)S Langermann et al J Infect Dis 2000;181:774. (3)T Larsson et al FEBS Lett 2000;469:155. (4)D Ilver et al Science 1998;279:373. (5)J Mahdavi et al submitted. (6)KA Karlsson, Glycobiology 2000;10:761.

KEY WORDS: mass spectrometry, bioinformatics, infection.

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Paper presented at the International Symposium on Predictive Oncology and Intervention Strategies; Paris, France; February 9 - 12, 2002; in the section on Carcinogenesis.