Membrane Properties of Branched Polyprenyl Phosphates, Postulated as Primitive Membrane Constituents

Abstract

We have postulated earlier that the highly branched isoprenoid alkanes, which are distributed widely in many sediments, may have been derived from the corresponding branched polyprenyl phosphates, potentially present in biomembranes in primitive organisms. These polyprenyl-branched polyprenyl phosphates might be derived by a simple alkylation from non-substituted polyprenyl phosphates, which we postulate to be the precursors of all membrane terpenoids. We have now synthesized a series of 6-(poly)prenyl-substituted polyprenyl phosphates and studied the formation of vesicles from these phosphates, as a function of the substituted-chain length, the position of the double bond, and pH. Nine of the branched polyprenyl phosphates containing 20-30 C-atoms do form vesicles at a 'physiological' pH; the lipophilicity/hydrophilicity ratio is as expected an important factor. We have also studied the water permeability through membranes of these branched polyprenyl phosphate vesicles by our stopped-flow/light-scattering method. These highly branched polyprenyl phosphates can more effectively reduce the water permeability than non-substituted polyprenyl phosphates: the vesicles formed by the former are more stable against mechanical stress. This reinforces our hypothesis about the origin of the sedimentary polyprenyl-substituted polyprene hydrocarbons.

The Influence of Environmental Conditions, Lipid Composition, and Phase Behavior on the Origin of Cell Membranes

“…Similar environmental and composition effects have been noted by Ourisson and coworkers for vesicles formed from phosphorylated polyprenyl lipids (Ariga et al 2005;Takajo et al 2001;Gotoh et al 2006). Lipids with at least three prenyl units form vesicles, but require highly exacting solution conditions that depend on the specific structural makeup of the polyprenyl moieties.…”

Biomimetic Synthesis and Properties of Polyprenoid

“…A series of 2-or 6-(poly)prenyl-substituted polyprenyl phosphates have been synthesized by Nagano et al (Nagano et al, 1999;Takajo et al, 2001), and we found that these higher branched polyprenyl phosphates form vesicles in water in a physiological pH domain Gotoh et al, 2006) (Fig. 9).…”

“…As a following study, we aimed to find out how "primitive" membranes made of singlechain lipids could have evolved towards a cell-wall-like structure ( Fig. 10) Gotoh et al, 2006). We have demonstrated that phytol-labeled polysaccharide pullulans coat giant vesicles made up of single-chain polyprenyl phosphates or of doublechain phospholipids present in Archea and Eukarya.…”

Membrane Self-Assembly Processes: Steps Toward the First Cellular Life

“…We note that amphiphile candidates other than fatty acids have been proposed, such as polyprenyl derivatives (Nomura et al 2001;Gotoh et al 2006;Streiff et al 2007) (see (8) in Fig. 8.2).…”