Volume 19, Issue 1 p. 54-69
Research article

Phylogenomic analysis of lipid biosynthetic genes of Archaea shed light on the ‘lipid divide’

Laura Villanueva

Corresponding Author

Laura Villanueva

Department of Marine Microbiology and Biogeochemistry, NIOZ, Royal Netherlands Institute for Sea Research, and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands

For correspondence. E-mail [email protected]; Tel. +31 0222369428/550; Fax +31 0222319674.Search for more papers by this author
Stefan Schouten

Stefan Schouten

Department of Marine Microbiology and Biogeochemistry, NIOZ, Royal Netherlands Institute for Sea Research, and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands

Faculty of Geosciences, Utrecht University, P.O. Box 80.021, Utrecht, 3508 TA, The Netherlands

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Jaap S. Sinninghe Damsté

Jaap S. Sinninghe Damsté

Department of Marine Microbiology and Biogeochemistry, NIOZ, Royal Netherlands Institute for Sea Research, and Utrecht University, P.O. Box 59, 1790 AB Den Burg, Texel, The Netherlands

Faculty of Geosciences, Utrecht University, P.O. Box 80.021, Utrecht, 3508 TA, The Netherlands

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First published: 26 April 2016
Citations: 33

Summary

The lipid membrane is one of the most characteristic traits distinguishing the three domains of life. Membrane lipids of Bacteria and Eukarya are composed of fatty acids linked to glycerol-3-phosphate (G3P) via ester bonds, while those of Archaea possess isoprene-based alkyl chains linked by ether linkages to glycerol-1-phosphate (G1P), resulting in the opposite stereochemistry of the glycerol phosphate backbone. This ‘lipid divide’ has raised questions on the evolution of microbial life since eukaryotes are thought to have evolved from the Archaea, requiring a radical change in membrane composition. Here, we searched for homologs of enzymes involved in membrane lipid and fatty acid synthesis in a wide variety of archaeal genomes and performed phylogenomic analyses. We found that two uncultured archaeal groups, i.e. marine euryarchaeota group II/III and ‘Lokiarchaeota’, recently discovered descendants of the archaeal ancestor leading to eukaryotes, lack the gene to synthesize G1P and, consequently, the capacity to synthesize archaeal membrane lipids. However, our analyses reveal their genetic capacity to synthesize G3P-based ‘chimeric lipids’ with either two ether-bound isoprenoidal chains or with an ester-bound fatty acid instead of an ether-bound isoprenoid. These archaea may reflect the ‘archaea-to-eukaryote’ membrane transition stage which have led to the current ‘lipid divide’.