This invention provides prokaryotic glycosyltransferases, including a bifunctional sialyltransferase that has both an .alpha.2,3- and an .alpha.2,8-activity. A .beta.1,4-GalNAc transferase and a .beta.1,3-galactosyltransferase are also provided by the invention, as are other glycosyltransferases and enzymes involved in synthesis of lipooligosaccharide (LOS). The glycosyltransferases can be obtained from, for example, Campylobacter species, including C. jejuni. In additional embodiments, the invention provides nucleic acids that encode the glycosyltransferases, as well as expression vectors and host cells for expressing the glycosyltransferases.