Efficient synthesis and protein conjugation of β-(1→6)-d-N-acetylglucosamine oligosaccharides from the polysaccharide intercellular adhesin

A wide variety of medically important biofilm forming bacteria produce similar polysaccharide intracellular adhesins (PIAs). The PIA structures consist of partially de-N-acetylated beta-(1-->6)-N-acetylglucosamine polymers. These exopolysaccharides are key components of the bacterial biofilm matrix. Here, we describe the efficient synthesis of PIA oligosaccharides using an acid reversion reaction of N-acetylglucosamine in HF.pyridine. The PIA oligosaccharides produced by this reaction can be purified to homogeneity by size exclusion chromatography. Chemistry was developed to conjugate the PIA oligosaccharides to bovine serum albumin using a new heterobifunctional linker containing a thiol and an N-methylhydroxylamine functional group. These glycoconjugates may serve as useful precursors for the development of defined conjugate vaccines against PIA producing bacterial strains.