Archaea osmolytes

Table 6.1. Major Classes of Osmolytes and Their Distribution among Eukaryotes, Bacteria and Archaea. Elevated Concentrations of Osmolytes Due to Freeze-Avoidance ("Freezing") or Desiccation Stress (Artemia Embryos) Are Included...

Figure 6.2. (Upper panel) The four major classes of organic osmolytes (I) sugars and polyhydric alcohols (polyols) (II) amino acids and amino acid derivatives (III) methylated ammonium and sulfonium compounds and (IV) urea. (Figure modified after Somero and Yancey, 1997.) (Lower panel) Structures of charged osmolytes accumulated in extremely halophilic archaea (after Martin et al., 1999). Note that these osmolytes commonly represent a type of organic osmolyte that is found in many bacteria or eukaryotes to which a charged group has been attached. Typically, the charged group is anionic, for example, a phosphate or a carboxylate group.

Unique Amino Acid Composition of Proteins of Extremely Halophilic Archaea When Folding Requires Help from Osmolytes... 

Phosphorylated myo-inositol is an important moiety in biochemistry as the basis for signal transduction pathways in eukaryotes. Inositol also occurs in bacteria and archaea, not as part of a signaling pathway, but with diverse and unique uses. wvo-Inositol occurs as part of mycothiol, a molecule comparable to glutathione in mycobacteria, as part of an unusual osmolyte in hyperther-mophiles [e.g., di-myo-inositol-1,1 -phosphate (DIP)], and as the lipid head-group anchor for a series of glycosylated lipids in mycobacteria that are critical in the interaction of pathogenic mycobacteria with mammalian cells. 

Chen, L., Spiliotis, E., and Roberts, M.F., 1998, Biosynthesis of Di-myo-inositol-1,1 -phosphate, a novel osmolyte in hyperthermophilic archaea. J. Bacteriol. 180 3785-3792. 

---