This chapter discusses the chemical structures of the polar lipids in extreme halophiles, methanogens, and thermoacidophiles, then deals with the biosynthetic pathways for these lipids and their probable role in membrane structure and function, and finally discusses the evolutionary implications of their unique structures. The existence of such a large variety of unusual lipid structures in archaea raises questions concerning the biosynthetic pathways for these lipids and their function in archaeal membranes, and also concerning the evolutionary relationships within the archaea and among archaea, eubacteria and eukarya. Archaeol occurs in all three groups of archaea, extreme halophiles, methanogens and extreme thermophiles, but only in the extreme halophiles is it unaccompanied by caldarchaeol. The polar lipids of the extreme halophiles consist of one major and two or more minor phospholipids, and one major and several minor glycolipids. Metallosphaera sedula, which represents a new genus of aerobic metalmobilizing thermophilic archaea in the order Sulfolobales, was found to contain a similar pattern of caldarchaeol and nonitolcaldarchaeol-derived glycolipids, and the corresponding P-inositol phosphoglycolipids to those of Sulfolobus solfataricus.
Publication DOI: 10.1016/S0167-7306(08)60258-6Book NLM ID: 9421102Publisher: Amsterdam, New York: Elsevier
Editors: Kates M, Kushner DJ, Matheson AT
Institutions: Department of Biochemistry, University of Ottawa, Ottawa, Ont. KIN 6N5, Canada
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