Characterisation of a synthetic Archeal membrane reveals a possible new adaptation route to extreme conditions

Abstract

It has been proposed that adaptation to high temperature involved the synthesis of monolayer-forming ether phospholipids. Recently, a novel membrane architecture was proposed to explain the membrane stability in polyextremophiles unable to synthesize such lipids, in which apolar polyisoprenoids populate the bilayer midplane and modify its physico-chemistry, extending its stability domain. Here, we have studied the effect of the apolar polyisoprenoid squalane on a model membrane analogue using neutron diffraction, SAXS and fluorescence spectroscopy. We show that squalane resides inside the bilayer midplane, extends its stability domain, reduces its permeability to protons but increases that of water, and induces a negative curvature in the membrane, allowing the transition to novel non-lamellar phases. This membrane architecture can be transposed to early membranes and could help explain their emergence and temperature tolerance if life originated near hydrothermal vents. Transposed to the archaeal bilayer, this membrane architecture could explain the tolerance to high temperature in hyperthermophiles which grow at temperatures over 100 °C while having a membrane bilayer. The induction of a negative curvature to the membrane could also facilitate crucial cell functions that require high bending membranes.

Origin of cyanobacterial thylakoids via a non-vesicular glycolipid phase transition and their impact on the Great Oxygenation Event

“…These primordial lipids are all built on a three-carbon glycerol scaffold (numbered sn-1, sn-2, sn-3). On the one hand, Archaea are bounded by membranes made of isoprenoid hydrocarbon chains linked via ether bonds to an sn-2,3-glycerol phosphate backbone, and multiple derivatives with two polar heads, which can form lipid monolayers (Salvador-Castell et al, 2021;Imachi et al, 2020). On the other hand, Bacteria and Eukaryota are primarily bounded by membranes made of acyl-glycerolipids, deriving from a precursor containing fatty acids linked via ester bonds to an sn-1,2-glycerol phosphate backbone (Imachi et al, 2020).…”

Water–Sulfuric Acid Foam as a Possible Habitat for Hypothetical Microbial Community in the Cloud Layer of Venus

“…Most likely, with the increase of surface temperatures on Venus, a direct selection for (poly)extremophilic forms of microorganisms occurred. Indeed, thermophilic and halophilic Archaea and Bacteria can thrive on Earth in similar conditions [19][20][21][22]. The drying of water bodies at the significant elevation of temperature undoubtedly was accompanied by a strong increase in salt concentrations.…”

“…High molecular weight compounds include lipoproteins, lipopolysaccharides, heteropolysaccharides, proteins, polymeric, and particulate compounds. Low molecular weight compounds consist of glycolipids (rhamnolipids, sophorolipids, mannosylerythritol lipids, and trehaloselipids) and lipopeptides (e.g., surfactin, fengycin) [22,38]. The metabolic function of biosurfactants in bacteria is to allow the cells to use water-insoluble substrates by acting as natural emulsifiers.…”

Extrusion: A New Method for Rapid Formulation of High‐Yield, Monodisperse Nanobubbles

“…The formation of the vesicles/liposomes is made possible by extrusion, if the processes take place at a temperature higher than their phase transition temperature such that the lipids are in a fluid state. [ 34–37 ] While commonly utilized as a strategy for formulating liposomes, to our knowledge, the work presented here is the first to demonstrate the ability to form stable monodisperse gas‐core nanostructures using the mini‐extruder system.…”