Mineral–Lipid Interactions in the Origins of Life

Protocells, the first life-like entities, likely contained three molecular components: a membrane, an information-carrying molecule, and catalytic molecules. Minerals have a wide range of properties that might have contributed to the synthesis and self-assembly of these molecular components. Minerals could have mediated the formation and concentration of prebiotic organic monomers, catalyzed their polymerization into biomolecules, and catalyzed protometabolic pathways, leading to protocell self-assembly. This review considers the following major aspects of protocell membrane-mineral interactions: (i) the effect of dissolved cations on the stability of mixed fatty acid and phospholipid vesicles; (ii) the rate of lipid self-assembly to vesicles; and (iii) the role of photocatalytic minerals in harvesting light energy to drive electron transfer reactions across membranes in the development of protometabolism. Mixed FA and PL vesicle systems exhibit greater stability to divalent cations than pure FA membranes. Dissolved magnesium and other divalent cations act as an environmental selection pressure for the transition of mixed FA–PL membranes to PL-enriched membranes Minerals increase the initial rate of vesicle formation depending on the surface charge and particle size of the mineral. Minerals play a key role as a catalyst to drive energetics in a model protocell or across its membrane. The structure–activity relationship between mineral properties and organics under different environmental conditions are crucial for extrapolating probabilities of the origin of life on other solid worlds.