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Archaeal Membrane Lipids and Applications

  1. G Dennis Sprott

Published Online: 15 AUG 2011

DOI: 10.1002/9780470015902.a0000385.pub3

eLS

eLS

How to Cite

Sprott, G. D. 2011. Archaeal Membrane Lipids and Applications. eLS. .

Author Information

  1. Institute for Biological Sciences, Ottawa, ON, Canada

Publication History

  1. Published Online: 15 AUG 2011

Abstract

Membrane lipids of Archaea are unique and distinct from those found in Eukarya and Bacteria. The polar lipids consist of isoprenoid chains, 20–40 carbons in length and usually saturated, which are attached via stable ether bonds to the glycerol carbons at the sn-2,3 positions. Polar head groups differ at the genus level of diversity and consist of mixtures of glyco groups (mainly disaccharides), and/or phospho groups primarily phosphoglycerol, phosphoserine, phosphoethanolamine or phosphoinositol. Phosphocholine headgroups are rarely found. Extremely halophilic archaea are characterised by headgroups consisting of phosphoglycerolphosphate-O-methyl, and sulfated-sugars. Some of these archaea synthesise cardiolipin analogues. The inherent stability and unique features of archaeal lipids makes them a useful biomarker for Archaea within environmental samples, including ocean sediments. The polar lipids of Archaea can be used to make liposomes (closed vesicles referred to as archaeosomes) with characteristics that are useful for applications in biotechnology. Archaeal-like polar lipids are being synthesised to optimise the properties of archaeosomes to serve as next-generation adjuvants and drug delivery systems.

Key Concepts:

  • Archaeol (2,3-diphytanyl-sn-glycerol), and variations thereof, define the polar lipids of the domain of life, Archaea.

  • The structures of polar lipids biosynthesised provide a useful taxonomic feature to assign an isolate to the Genus level of classification.

  • New polar lipid structures are being reported as the field expands to encompass novel isolates.

  • These unique polar and neutral isoprenyl lipids can be used as biomarkers of archaea in environmental samples.

  • Archaeal lipids can serve as a rich source for novel molecules not commonly found in nature, such as β-l-gulose.

  • Archaeal polar lipid mixtures hydrate to form lipid membrane vesicles (archaeosomes) with bilayer, unilayer or a combination of uni and bilayer structure.

  • Archaeosomes are generally nonfusogenic in vitro, but fusion can be dramatic for certain compositions by exposure to the combination of acidic pH, calcium and glycosidase.

  • Archaeosomes function as safe vaccine adjuvants in mammals imparting long-lasting CD8+ T-cell immunity and antibody responses.

  • Isoprenoid lipids that retain the key archaeal-lipid features are being synthesised to optimise their properties as vaccine adjuvants and delivery systems.

Keywords:

  • archaea;
  • membrane lipids;
  • archaeol;
  • caldarchaeol;
  • biomarkers;
  • archaeosomes;
  • adjuvants;
  • drug delivery