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However, the ancient replicase appears to have been lost in time and its role in modern biology has been taken over by more efficient protein machines.

To support the RNA world hypothesis, researchers have been seeking to re-create an equivalent of the RNA replicase in the laboratory.

While such molecular "Doppelgangers" of the ancient replicase have been discovered, both their detailed molecular structure and mode of action has remained elusive due to the difficulty of determining the structure of dynamic RNA molecules.

To better understand how the RNA replicase works, the researchers did a comprehensive mutational study to highlight the crucial elements of the RNA structure.

This analysis confirmed features of the catalytic site but also revealed the importance of two so-called kissing-loop interactions, which bind the scaffolding and the catalytic subunits together, as well as the importance of a specific RNA domain for fidelity, that is the accuracy with which the replicase copies RNA strands.