Amino Acid Specific Nonenzymatic Montmorillonite-Promoted RNA Polymerization

Understanding prebiotic RNA synthesis is essential to both the RNA world and RNA-protein co-evolution theories of the origin of life. Nonenzymatic templated RNA synthesis occurs in solution or by montmorillonite clay heterogenous catalysis but the high magnesium concentrations required are deleterious to protocell membranes. Here, we explore a multicomponent environmental system consisting of amino acids, RNA mononucleotides and montmorillonite at various Mg²⁺ concentrations. We show that specific alpha amino acids, especially those that were prebiotically most relevant, act as prebiotic coenzymes and further enhance montmorillonite-catalyzed polymerization in a cooperative mechanism to produce even longer RNA oligomers. Significantly, and different from template-directed nonenzymatic RNA polymerization by primer extension, added Mg²⁺ is not required for montmorillonite-catalyzed polymerization, especially as enhanced by specific amino acids. Thus amino acid specific montmorillonite-catalyzed RNA polymerization is compatible with protocell membranes and could occur in a wider variety of geochemical environments of various Mg²⁺ concentrations.