Two complementary alpha-fucosidases fromStreptococcus pneumoniaepromote complete degradation of host-derived carbohydrate antigens.Hobbs, J.K., Pluvinage, B., Robb, M., Smith, S.P., Boraston, A.B.
(2019) J Biol Chem 294: 12670-12682
- PubMed: 31266803
- DOI: 10.1074/jbc.RA119.009368
- Structures With Same Primary Citation
- PubMed Abstract:
An important aspect of the interaction between the opportunistic bacterial pathogen Streptococcus pneumoniae and its human host is its ability to harvest host glycans. The pneumococcus can degrade a variety of complex glycans, including ...
An important aspect of the interaction between the opportunistic bacterial pathogen Streptococcus pneumoniae 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 S. pneumoniae Although S. pneumoniae 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, Sp GH29 C and Sp GH95 C , that target α-(1→3/4) and α-(1→2) fucosidic linkages, respectively. X-ray crystallography studies combined with functional assays revealed that Sp GH29 C is specific for the Lewis A and Lewis X antigen motifs and that Sp GH95 C is specific for the H(O)-antigen motif. Together, these enzymes could defucosylate Lewis Y and Lewis B 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 S. pneumoniae 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 Sp GH92, we anticipate that the α-fucosidases identified here will be important factors in developing more refined models of the S. pneumoniae -host interaction.
Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8P 5C2, Canada firstname.lastname@example.org.