tRNA Can Form Molecular Assemblies and Replicate Information

A team from the Ludwig-Maximilians University in Munich has shown that slight alterations in transfer-RNA molecules (tRNAs) allow them to self-assemble into a functional unit that can replicate information exponentially. Their findings were published in eLife today. 

The discovery implies that tRNAs could act as a link between replication and translation in the earliest living systems. In their experiments, lead researcher Dieter Braun and his colleagues used a set of reciprocally complementary DNA strands modeled on the characteristic form of modern tRNAs. Each was made up of two hairpins, separated by an informational sequence in the middle.

Each experiment began with a template, and this sequence dictated the form of the complementary molecule with which it can interact in the pool of available strands. The researchers went on to demonstrate that the templated binary structure can be amplified, by applying a repeating sequence of temperature fluctuations.

"It is therefore conceivable that such a replication mechanism could have taken place on a hydrothermal microsystem on the early Earth," says Braun. In particular, aqueous solutions trapped in porous rocks on the seafloor would have provided a favorable environment for such reaction cycles, since natural temperature oscillations, generated by convection currents, are known to occur in such settings. The team was also able to show that the system is capable of exponential replication. "This link between replication and translation in an early evolutionary scenario could provide a solution to the chicken-and-the-egg problem," says collaborator Alexandra Kühnlein. It could also account for the characteristic form of proto-tRNAs, and elucidate the role of tRNAs before they were co-opted for use in translation.