Add salt, add sugar: N-glycosylation in Haloferax volcanii

Although performed by members of all three domains of life, the archaeal version of N-glycosylation remains the least understood. Studies on Haloferax volcanii have, however, begun to correct this situation. A combination of bioinformatics, molecular biology, biochemical and mass spectrometry approaches have served to delineate the Agl pathway responsible for N-glycosylation of the S-layer glycoprotein, a reporter of this post-translationalmodification in Hfx. volcanii.More recently, differential N-glycosylation of the S-layer glycoprotein as a function of environmental salinity was demonstrated, showing that this post-translational modification serves an adaptive role in Hfx. volcanii. Furthermore, manipulation of the Agl pathway, together with the capability of Hfx. volcanii to N-glycosylate nonnative proteins, forms the basis for establishing this species as a glyco-engineering platform. In the present review, these and other recent findings are addressed.