The present invention relates to a method of synthesizing a rhamnose polysaccharide. The invention also relates to a synthetic streptococcal polysaccharide, a streptococcal glycoconjugate, an immunogenic composition or vaccine comprising the streptococcal polysaccharide or glycoconjugate and the polysaccharide, glycoconjugate, immunogenic composition or vaccine for use in raising an immune response in an animal or for use in treating or preventing a disease, condition or infection with a streptococcal aetiology.

Disclosed herein are methods of generating proteoglycans with distinct glycan structures in engineered, non-naturally occurring eukaryotic cells. These methods make accessible a dynamic range of protein glycosylation. Compositions of engineered, non-naturally occurring cells capable of generating these proteoglycans are also disclosed herein.