Helicobacter pylori is an important human pathogen which causes both gastric and duodenal ulcers and is also associated with gastric cancer and lymphoma. This microorganism has been shown to express cell surface glycoconjugates including Lewis X and Lewis Y. These bacterial oligosaccharides are structurally similar to tumor-associated carbohydrate antigens found in mammals. In this study, we report the cloning of a novel a1,3-fucosyltranferase gene (HpfucT) involved in the biosynthesis of LeX within H. pylori. The deduced amino acid sequence of HpfucT consists of 478 residues with the calculated molecular mass of 56,194 daltons, which is approximately 100 amino acids longer than known mammalian a1,3/1,4 fucosyltransferases. The 52-kDa protein encoded by HpfucT was expressed in Escherichia coli CSRDE3 cells and gave rise to a1,3-fucosyltransferase activity but neither a1,4-fucosyltransferase nor a1,2-fucosyltransferase activity as characterized by radiochemical assays and cappilary zone electrophoresis. Truncation of the C-terminal 100 amino acids if HpfucT abolished the enzyme activity. An approximately 72-amino acids region of HpFucT exhibits significant sequence identity (40-45%) with the highly conserved C-terminal catalytic domain among known mammalian and chicken a1,3-fucosyltranserase. In addition, several structural features unique to HpfucT, including 10 direct repeats of seven amino acids and the lack of the transmembrane segment typical for known eukaryotic a1,3-fucosyltransferases, were revealed. Notably, the repeat region contains a leucine zipper motif previously demonstrated to be responsible for dimerization of various basic region-leucine zipper proteins, suggesting that the HpfucT protein could form dimers.
lipopolysaccharides, expression, gene, cloning, bacteria, biological, sequencing, Helicobacter pylori, pathogen, gastric, genome, Helicobacter, heterologous
NCBI PubMed ID: 9261149Journal NLM ID: 2985121RPublisher: Baltimore, MD: American Society for Biochemistry and Molecular Biology
Correspondence: diane.taylor@ualberta.ca
Institutions: Departement of Medical Microbiology and Immunology, Department of Chemistry, Departement of Biological Sciences, University of Alberta, Edmonton, AB, Canada
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