Characterizing mixed single chain amphiphile-based coacervates as a robust protocell system

Prebiotic soup would have been a dilute pool of various constituent chemicals that would have reacted with each other to form biologically relevant precursors during life’s origin. In this milieu, compartments formed by liquid-liquid phase separation (LLPS) are thought to have facilitated concentration of chemicals, thereby catalyzing their reactions. Towards this, various LLPS-based systems have been studied as model protocells. Relevantly, fatty acid-based (decanoic acid) coacervates have recently been explored as model protocells. As far as protocell research is concerned, fatty acids have been studied much more extensively in the context of vesicle-forming entities when compared to them resulting in coacervate systems. Furthermore, exogenous delivery and endogenous synthesis of fatty acids suggest the prevalence of single chain amphiphiles (SCAs) on the early Earth, with a greater abundance of the shorter chain length moieties. In this backdrop, we set out to fabricate robust coacervate-based protocells using SCAs that would have been readily present in a chemically heterogeneous prebiotic soup, and which could thrive under various prebiotically relevant selection pressures. Towards this, we characterized a mixed amphiphile-based coacervate system composed of nonanoic acid (NA), nonanol (NOH) and tyramine (Tyra), which could form coacervates over a broad range of pHs, temperatures, and salt concentrations. This is noteworthy as compositionally heterogenous vesicles have also been shown to have advantages over pure fatty acid vesicles. Additionally, we also demonstrate RNA sequestration in these coacervates that gets enhanced upon addition of cationic amino acids, emphasizing the importance of co-solute interactions in the prebiotic soup. Lastly, we also demonstrate nonenzymatic template-directed primer extension in these coacervates, suggesting the potential functional role of these compartments during life’s origin.