An important aspect of the interaction between the opportunistic bacterial pathogen and its human host is its ability to harvest host glycans. The pneumococcus can degrade a variety of complex glycans， including N- and O-linked glycans， glycosaminoglycans， and carbohydrate antigens， an ability that is tightly linked to the virulence of Although is known to use a sophisticated enzyme machinery to attack the human glycome， how it copes with fucosylated glycans， which are primarily histo-blood group antigens， is largely unknown. Here， we identified two pneumococcal enzymes， SpGH29C and SpGH95C， that target α-(1→3/4) and α-(1→2) fucosidic linkages， respectively. X-ray crystallography ... More
An important aspect of the interaction between the opportunistic bacterial pathogen and its human host is its ability to harvest host glycans. The pneumococcus can degrade a variety of complex glycans， including N- and O-linked glycans， glycosaminoglycans， and carbohydrate antigens， an ability that is tightly linked to the virulence of Although is known to use a sophisticated enzyme machinery to attack the human glycome， how it copes with fucosylated glycans， which are primarily histo-blood group antigens， is largely unknown. Here， we identified two pneumococcal enzymes， SpGH29C and SpGH95C， that target α-(1→3/4) and α-(1→2) fucosidic linkages， respectively. X-ray crystallography studies combined with functional assays revealed that SpGH29C is specific for the LewisA and LewisX antigen motifs， and that SpGH95C is specific for the H(O)-antigen motif. Together， these enzymes could defucosylate LewisY and LewisB antigens in a complementary fashion. In vitro reconstruction of glycan degradation cascades disclosed that the individual or combined activities of these enzymes expose the underlying glycan structure， promoting the complete deconstruction of a glycan that would otherwise be resistant to pneumococcal enzymes. These experiments expand our understanding of the extensive capacity of to process host glycans and the likely roles of α-fucosidases in this. Overall， given the importance of enzymes that initiate glycan breakdown in pneumococcal virulence， such as the neuraminidase NanA and the mannosidase SpGH92， we anticipate that the α-fucosidases identified here will be important factors in developing more refined models of the -host interaction.
