Role of Sialic acid in periodontal pathogens
Much of the recent work in the laboratory has focused on the role of the important host derived sugar molecule sialic acid. Sialic acid is 9-carbon sugar that is present as the terminal glycosyl motif on a large number of human glycoproteins, lipds and gangliosides. As a result bacterial pathogens have co-opted sialic acid for several purposes that include providing nutrition, a site of adhesion, a means to modulate the host immune system and as a molecule for host mimicry via glycosylation of bacterial LPS, capsule or protein.
Sialic acid transport and harvesting
Our work on Tannerella forsythia identified not only that this fastidious anaerobic pathogen could use sialic acid as a growth factor but also the prototype member of a new family of sialic acid transporters in bacteria (Roy et al., 2010). We are currently investigating the molecular mechanisms and function of the proteins in this transport system alongside the various scavenging enzymes present in this family of bacteria.(see schematic, right and structure of binding protein below).
Role of sialidases
Several periodontal pathogens produce sialidase enzymes that are capable of the cleavage of glycosidic linkages between sialic acid and sub-terminal sugars in glyco-chains such as galactose or glucose. We have shown that for Tannerella that these are key to growth on model sialloconjugate sugars but also more recently using glycoprotein sources in biofilms (Roy et al, 2012). The work of our collaborator Professor Ashu Sharma and recent work in the lab has highlighted that these have a role in interaction with host cells which our groups are now following up.
We are also working closely with the Oral Healthcare team at GSK to investigate potential new treatments for periodontal biofilms in this area and now have a fully funded PhD project working with Ludger Ltd investigating sialidase biochemistry and structural biology.
Tannerella is not the only oral or periodontal pathogen that produces a sialidase and along with its potential role in mediating interactions with other oral bacteria in mixed biofilms might play key roles in vivo.
Collaborators in this area:
Furthermore we welcome enquiries for fellowship projects from talented individuals.