Exploring the biochemical and biophysical characteristics of archaeal membranes

Presenting author: Kaja Grewe

University Regensburg, Microbiology & Archaea Centre, Universitätsstraße 31, 93053 Regensburg [DE], kaja.grewe@ur.de

Author(s):
Kaja Grewe, Henry Zivkovic, Shachar Gat, Robert Reichelt, Thorsten Bauersachs, Anne Bernheim, Petra Schwille, Dina Grohmann

Ether lipids found in archaeal membranes differ fundamentally in their biochemistry from ester lipids that constitute both eukaryotic and bacterial membranes. The unique membrane lipids of Archaea, especially the membrane-spanning tetraether lipids, are considered to be key for survival of hyperthermophilic archaea living in habitats with extreme physico-chemical parameters. Currently, the details of archaeal lipid biochemistry are poorly understood and no established model system for archaeal membranes exist.

In this study, we prepared lipid extracts from four hyperthermophilic archaea and established the formation of giant unilamellar vesicles (GUVs) to serve as an in vitro model membrane system. Additionally, we determined the lipid composition of the four archaeal lipid extracts, revealing the highly different lipid composition for each strain. The lipid composition influenced biophysical parameters like the membrane fluidity. Interestingly, archaeal membranes show phase transitions distinct from bacterial membranes. Finally, we discovered a tendency for archaeal lipids to assemble into tubular and multilamellar structures, suggesting the presence of complex lipid phases and domains within archaeal membranes both in vitro and in vivo. Taken together, we this study provides the first in-depth biophysical characterisation of archaeal membranes laying the groundwork to elucidate membrane-protein interactions in archaea.

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