Biosynthesis of Ether-Type Polar Lipids in Archaea and Evolutionary Considerations

Abstract

SUMMARY This review deals with the in vitro biosynthesis of the characteristics of polar lipids in archaea along with preceding in vivo studies. Isoprenoid chains are synthesized through the classical mevalonate pathway, as in eucarya, with minor modifications in some archaeal species. Most enzymes involved in the pathway have been identified enzymatically and/or genomically. Three of the relevant enzymes are found in enzyme families different from the known enzymes. The order of reactions in the phospholipid synthesis pathway (glycerophosphate backbone formation, linking of glycerophosphate with two radyl chains, activation by CDP, and attachment of common polar head groups) is analogous to that of bacteria. sn-Glycerol-1-phosphate dehydrogenase is responsible for the formation of the sn-glycerol-1-phosphate backbone of phospholipids in all archaea. After the formation of two ether bonds, CDP-archaeol acts as a common precursor of various archaeal phospholipid syntheses. Various phospholipid-synthesizing enzymes from archaea and bacteria belong to the same large CDP-alcohol phosphatidyltransferase family. In short, the first halves of the phospholipid synthesis pathways play a role in synthesis of the characteristic structures of archaeal and bacterial phospholipids, respectively. In the second halves of the pathways, the polar head group-attaching reactions and enzymes are homologous in both domains. These are regarded as revealing the hybrid nature of phospholipid biosynthesis. Precells proposed by Wächtershäuser are differentiated into archaea and bacteria by spontaneous segregation of enantiomeric phospholipid membranes (with sn-glycerol-1-phosphate and sn-glycerol-3-phosphate backbones) and the fusion and fission of precells. Considering the nature of the phospholipid synthesis pathways, we here propose that common phospholipid polar head groups were present in precells before the differentiation into archaea and bacteria.

Reduction in prevalence ofArchaeaafter periodontal therapy in subjects with generalized aggressive periodontitis

“…24 However, these adjunctive beneficial effects of MTZ + AMX were not observed for the Archaea domain. It should be emphasized that the metabolic processes and the cell wall structure of Archaea differ from those of bacteria, 18 and therefore some antimicrobial agents that are effective against bacteria may not be effective against Archaea. Recently, Dridi et al 32 tested in vitro the antibiotic resistance patterns of eight methanogenic Archaea.…”

“…[8][9][10][11][12][13][14][15] Archaea are a group of single-cell microorganisms that were classified, based on the sequence of ribosomal RNA genes, as a distinct group of organisms, differing greatly from Bacteria and Eukaryotes 16 in terms of genetic, biochemical, and structural features. 17,18 Several studies have shown that Archaea can be isolated from subgingival samples of periodontitis patients, 10,[12][13][14][15]19,20 infected root canals, 21,22 and in sites with peri-implantitis. 23 In addition, an association between the severity of periodontal disease and the prevalence of Archaea (Methanobrevibacter spp) has been suggested.…”

Acetaldehyde in the Alaskan subarctic snowpack

“…Plasmalogens are frequent in bacterial and archaeal membranes (Snyder, 1999) and these are found in soils and in aerosol particles (Ariya et al, 2009;Gattinger et al, 2003). Producing acetaldehyde would require the existence of plasmalogens with 2-carbon chains, while these molecules usually have much longer chains (Koga and Morii, 2007). However, the analytical methods commonly used to analyze etherlipids (Gattinger Fig.…”

Rapid discrimination of archaeal tetraether lipid cores by liquid chromatography-tandem mass spectrometry

“…Thus far, all identified members of the archaea have been found to contain glycerol diphytanyl diether and/or glycerol dibiphytanyl glycerol tetraether (GDGT) lipids in their cellular membranes [4]. The membrane lipids occur either as naked core lipids, or with phospho-and/or glyco-head groups that are introduced during biosynthesis [5]. The two saturated C 40 -biphytanyl hydrocarbon chains of the GDGT lipid cores are tethered at both ends to glycerol moieties via ether linkages, with sn-2,3 stereochemistry exhibited by each glycerol [6].…”