Post-translational modifications modulate the function of most eukaryote proteins by altering their activity state, localization, turnover, and interactions with other proteins. Many important proteins, including antibodies, hormones and receptors, are glycosylated but the development of chemical and enzymatic methods for the synthesis of homogeneous glycoproteins has proved a considerable challenge.
A paper published in Science in 2004 was later retracted when it proved impossible to repeat the results but researchers at the University of Maryland School of Medicine and ETH, Zurich have now described a new process for preparing homogeneous eukaryotic glycoproteins. The method, which involves engineering and functionally transferring the glycosylation machinery from Campylobacter jejuni into Escherichia coli, provides a means of expressing glycosylated proteins with the key GlcNAc-Asn linkage. The bacterial glycans can then be trimmed and remodelled in vitro by enzymatic transglycosylation to provide N-glycosylated eukaryotic proteins. The authors believe that the new methodology, which is published in the journal Nature Biotechnology, should lead to a general platform for producing eukaryotic N-glycoproteins.