Membrane plasticity induced by myo-inositol derived archaeal lipids: chemical synthesis and biophysical characterization.

Archaeal membrane lipids have specific structures that allow Archaea to withstand extreme conditions of temperature and pressure. In order to understand the molecular parameters that govern such resistance, the synthesis of 1,2-di-O-phytanyl-sn-glycero-3-phosphoinositol (DoPhPI), an archaeal lipid derived from myo-inositol, is reported. Benzyl protected myo-inositol was first prepared and then transformed to phosphodiester derivatives using a phosphoramidite based-coupling reaction with archaeol. Aqueous dispersions of DoPhPI alone or mixed with DoPhPC can be extruded and form small unilamellar vesicles, as detected by DLS. Neutron, SAXS, and solid-state NMR demonstrated that the water dispersions could form a lamellar phase at room temperature that then evolves into cubic and hexagonal phases with increasing temperature. Phytanyl chains were also found to impart remarkable and nearly constant dynamics to the bilayer over wide temperature ranges. All these new properties of archaeal lipids are proposed as providers of plasticity and thus means for the archaeal membrane to resist extreme conditions.