(269e) Gating Protocell Permeability to RNA

We are interested in designing simple models of primitive cells in order to study how cellular life may have emerged from prebiotic chemistry. An integral feature of the artificial cell is the coordination of both membrane biophysical processes and genetic replication; the coupling of which would enable RNA replication alongside membrane division and advance the design of a synthetic cell. Short polynucleotide transport through vesicle membranes is expected to be a key step in facilitating nonenzymatic RNA replication inside vesicle membranes. While nucleotide monophosphates have been shown to permeate certain fatty acid membranes, the permeability of larger polynucleotides, like dinucleotide and trinucleotide oligomers, has not been extensively explored. Using monoacyl fatty acids to construct model membranes and short RNA polynucleotides, we studied how membrane composition, polynucleotide size, and divalent cations affect polynucleotide permeability through vesicle membranes. We find that RNA as large as a trinucleotide oligomer, can penetrate fatty acid vesicle membranes. We observe that membrane permeability can be further enhanced by exposing vesicles to short durations of heat, all the while maintaining membrane stability. Finally, using the conditions we found optimized membrane permeability, we demonstrate that chemically activated RNA trinucleotides transport across vesicle membranes to nonenzymatically copy template strands encapsulated in the interior of fatty acid vesicles. Our results showing that membrane permeability to short RNA oligomers can be gated with divalent cations and heat exposure provides insight into the environmental conditions that may have promoted genetic replication in a primitive cell. In addition, the construction of a temperature responsive membrane that enables polynucleotide passage can advance the design of vesicle bioreactors or sensors that utilize short oligonucleotides as substrates.