Capsular polysaccharides (CPSs) of Neisseria meningitidis (Nm) are directly connected to meningococcal virulence and are excellent candidates for the development of glycoconjugate vaccines. Enzyme-catalyzed synthesis is an efficient approach to obtain structurally defined complex carbohydrates. NmSiaDW is the key polymerase for synthesizing Nm serogroup W CPS. The enzyme was cloned and expressed in E. coli at a level of 150 mg purified protein per liter culture. It was used in highly efficient one-pot multienzyme (OPME) galactosylation and sialylation systems for synthesizing a library of NmW capsular oligosaccharides spanning from monosaccharide to decasaccharide in excellent yields (83–96%). The obtained size-controlled oligosaccharides allowed detailed biochemical characterization of NmSiaDW. The catalytic efficiency of the galactosyltranferase activity increased with the increase of the length of the sialoside acceptors. On the other hand, the sialyltransferase activity is independent of the length of the galactoside acceptors. In addition, acceptor substrate inhibition of the sialyltransferase activity was observed. Substrate specificity studies showed that NmSiaDW had some promiscuity towards modifications on either acceptors or donors, indicating its potential in chemoenzymatic synthesis of carbohydrate derivatives. NmSiaDW will be a powerful catalyst for synthesizing chemical biological probes and Nm serogroup W CPS vaccine candidates.

N. meningitidis capsular polysaccharide (CPS) polymerase and its application in chemoenzymatic synthesis

2019 Fall National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.