The effect of dolichol on the structure and phase behaviour of phospholipid model membranes

Abstract

The effect of dolichol C(95) on the structure and thermotropic phase behaviour of dipalmitoylphosphatidylcholine, dipalmitoylphosphatidylethanolamine and stearoyloleoylphosphatidylethanolamine has been examined by synchrotron X-ray diffraction and differential scanning calorimetry. The presence of dolichol C(95) had no detectable effects on the temperature of either the gel to ripple or the ripple to liquid-crystal phase transition of dipalmitoylphosphatidylcholine. A proportionate increase of a few degrees in the temperature of the gel to lamellar liquid-crystal phase transition is observed in dispersions of dipalmitoylphosphatidylethanolamine and significantly there is a decrease in the temperature of the lamellar to non-lamellar phase transition of stearoyloleoylphosphatidylethanolamine. There was no significant change in the bilayer repeat spacing of all three mixed dispersions in gel phase in the presence of up to 20 mol% dolichol C(95). Electron density calculations showed that there was no change of bilayer thickness of dipalmitoylphosphatidylcholine with incorporation of up to 7.5 mol% dolichol C(95). These data suggest that effect of dolichol on the phospholipid model membranes depend on both the head group and the hydrocarbon chains of the phospholipid molecules. The presence of dolichol in phosphatidylcholine bilayers conforms to a model in which the polyisoprene compound is phase separated into a central domain sandwiched between the two monolayers in gel phase. In bilayers of phosphatidylethanolamines dolichol tends to stabilize the bilayers in gel phase at low temperatures and destabilize the bilayers in lamellar disordered structure at high temperatures. Non-lamellar structures coexist with lamellar disordered phase over a wide temperature range suggesting that dolichol is enriched in domains of non-lamellar structure and depleted from lamellar phase. These findings are useful to understand the function of dolichol in cell membranes.

Polyprenols Are Synthesized by a Plastidial cis-Prenyltransferase and Influence Photosynthetic Performance

“…The incorporation of polyprenols into model membrane systems in vitro is well known to alter their membrane physico-chemical properties (Vigo et al, 1984;Valtersson et al, 1985;Schroeder et al, 1987;Janas et al, 1994;Wang et al, 2008;Sévin and Sauer, 2014). However, in vivo evidence to support these observations is lacking.…”

At the membrane frontier: A prospectus on the remarkable evolutionary conservation of polyprenols and polyprenyl-phosphates

“…A variety of techniques have been used to address this question including nuclear magnetic resonance (NMR) spectroscopy, differential scanning calorimetry, small angle X-ray diffraction, electrophysiology, and freeze-fracture electron microscopy [101–112]. From these studies, there is considerable evidence that polyisoprenols increase membrane fluidity, ion permeability and the propensity of membranes to adopt a non-bilayer, hexagonal II conformation (Fig.…”

Lipid bilayer nanodisc platform for investigating polyprenol-dependent enzyme interactions and activities

“…Prior studies on polyprenol-dependent pathways have principally focused on redacted experimental systems representing two of the three key variables. For example, the effect of varying the substrate polyprenol groups has been studied using glycan assembly enzymes that have been solubilized from the native lipid bilayer with detergent (16)(17)(18); and interactions of polyprenyl-linked compounds with model membrane systems, such as liposomes, in the absence of membrane-bound proteins have been investigated using biophysical techniques, including computational modeling and NMR spectroscopy (19)(20)(21)(22)(23)(24).…”