Protein Glycosylation in Archaea: A Post-Translational Modification to Enhance Extremophilic Protein Stability

摘要

Post-translational modifications account for much of the biological diversity generated at the proteome level. Of these, glycosylation is the most prevalent. Long-thought to be unique to Eukarya, it is now clear that both Bacteria and Archaea are also capable of N-glycosylation, namely the covalent linkage of oligosaccharides to select target asparagine residues. However, little had been known of this process in Archaea. As such, this project aimed at defining the N-glycosylation pathway of the halophilic archaeon Haloferax volcanii. Employing a combination of bioinformatics, genetic, biochemical and structural approaches, the funded research succeeded in identifying a group of clustered H. volcanii genes (the agl genes) encoding proteins involved in the assembly and attachment of a pentasaccharide to select asparagine residues of the S-layer glycoprotein, a reporter of N-glycosylation in this species. In addition to providing insight into N-glycosylation across evolution and the biology of extremophiles, these findings could be exploited to create archaeal strains expressing selected N-glycosylation enzyme modules. This would allow for a harnessing of the greater diversity associated with this post- translational modification in Archaea in the design of tailor-made glycoproteins.