Background: Serogroup W-135 meningococci express a highly unusual capsular polysaccharide with sialic acid as an internal sugar conjugated by heteroglycans. Results: The capsule polymerase SiaD W-135 contains two successively active domains comprising galactosyltransferase and sialyltransferase activity in one polypeptide chain. Conclusion:The capsule polymerase SiaD W-135 is a chimeric enzyme. Significance: With the characterization of SiaD W-135 a basis has been established for its exploitation in vaccine developmental approaches.

Background: Capsule polymerases of Neisseria meningitidis serogroups W and Y comprise hexosyl-and sialyltransferase activity. Results: Hexosyltransferase activity is encoded by the predicted N-terminal GT-B fold. Sialyltransferase activity requires 168 additional amino acids upstream of the predicted C-terminal GT-B fold. Conclusion:The sialyltransferase domains of NmW/Y define a new glycosyltransferase (CAZy) family. Significance: The new CAZy family comprises sequences from distantly related species.