Analysis of the glycome and identification of the enzymes involved in the glycosylation of Sulfolobus solfataricus

Glycosylation is one of the most prevalent post-translational modifications in proteins. Long believed a prerogative of eukaryotes, it is now clear that also Bacteria and Archaea show both N- and O-glycosylation. In recent years, substantial progresses are being made in understanding bacterial glycosylation while much less is known of this in Archaea despite the fact that the first prokaryotic N-glycosylated protein was discovered over three decades ago in the haloarchaeon Halobacterium salinarum1. N-glycosylated proteins in Archaea are more prevalent than in Bacteria, and, in the formers, glycosylation mechanism displays unique features and a sort of mixture of bacterial- and eukaryal-like traits2, such as monomeric oligosyltransferases and dolichol phosphate carrier respectively. Most of the studies on the biosynthesis and the nature of N-glycosylation has been performed mostly in Euryarchaea3. In Crenarchaea the study of the steps and the components of the machinery involved in glycosylation and of the nature of the glycosylated proteins is still in its infancy. However, preliminary results indicate that glycosylation in these organisms is indispensable for cell survival4 and even more widespread than in Euryarchaea5. Here, we report our recent studies on the enzymes from the hyperthermophilic crenarchaeon Sulfolobus solfataricus involved in the synthesis, maturation and degradation of the glycan components of the glycoproteins6. Moreover, sugar composition and structure of the glycoproteins from S. solfataricus are analysed by glycoproteomic analysis.