Post-translation modification in Archaea: lessons fromHaloferax volcaniiand other haloarchaea

Abstract

As an ever-growing number of genome sequences appear, it is becoming increasingly clear that factors other than genome sequence impart complexity to the proteome. Of the various sources of proteomic variability, post-translational modifications most greatly serve to expand the variety of proteins found in the cell. Likewise, modulating the rates at which different proteins are degraded also results in a constantly changing cellular protein profile. While both strategies for generating proteomic diversity are adopted by organisms across evolution, the responsible pathways and enzymes in Archaea are often less well described than are their eukaryotic and bacterial counterparts. Studies on halophilic archaea, in particular Haloferax volcanii, originally isolated from the Dead Sea, are helping to fill the void. In this review, recent developments concerning post-translational modifications and protein degradation in the haloarchaea are discussed.

N-Linked Glycosylation in Archaea: a Structural, Functional, and Genetic Analysis

“…salinarum, the haloarchaeal N-glycosylation process is currently best understood for Hfx. volcanii (6,63,64). Indeed, in the last few years, substantial progress has been made in deciphering the process of N-glycosylation in Hfx.…”

“…volcanii, a complicated picture has emerged. At least three N-glycan structures have been reported to be attached to the S-layer glycoprotein when the organism is cultured at different salt concentrations and in different laboratories (64,85,94,176). When cultured in medium containing 3.5 M NaCl, Mengele and Sumper (176) described S-layer protein Nglycans composed of different sugars.…”

Identification of Genes Involved in the Biosynthesis of the Third and Fourth Sugars of the Methanococcus maripaludis Archaellin N-Linked Tetrasaccharide

“…Although N-glycosylation is widely distributed in Archaea, studies combining both genetic and structural information about N-glycosylation pathways are focused mainly on a few model species (2,9,12), such as the mesophilic methanogens Methanococcus voltae and Methanococcus maripaludis (13)(14)(15)(16)(17), the thermoacidophile Sulfolobus acidocaldarius (9,(18)(19)(20), and the halophiles Haloferax volcanii and Haloarcula marismortui (2,11,(21)(22)(23)(24)(25)(26). As seen for many archaeal traits, the archaeal N-glycosylation pathway appears as a partial amalgam of the pathway found in eukaryotes and bacteria (1,2,27).…”

Modifying Post‐Translational Modifications: A Strategy Used by Archaea for Adapting to Changing Environments?

“…Today, it is known that Archaea perform a plethora of post-translational modifications (PTMs), including glycosylation, phosphorylation, and acetylation. [19][20][21][22][23][24][25] Table 2 lists PTMs recognized to date in Archaea and examples of species in which such modifications have been reported. In many instances, the presence of PTMs has been implicated in the ability of archaeal proteins to withstand the extremes that they encounter.…”