Scientists at the Salk Institute have achieved a significant breakthrough in understanding Darwinian evolution at the molecular level thanks to RNA.
RNA might hold the keys to the origins of life on Earth. In a recent study, researchers from the Salk Institute unveiled an RNA enzyme capable of precisely replicating other RNA strands while allowing the emergence of new variants. This remarkable ability to evolve places RNA at the heart of the earliest forms of evolution, suggesting a prebiotic world dominated by these molecules before the appearance of DNA and proteins.
This concept, known under the name of the "RNA world" hypothesis, proposes that life began in an environment where RNA played a central role, not only in storing genetic information but also in facilitating the chemical reactions essential to life. The discovery of an RNA enzyme capable of replicating other RNA strands with high precision lends significant support to this hypothesis.
At the core of this research is replication fidelity. Scientists have long sought to understand how genetic information could be copied with enough accuracy to allow life to develop and diversify. The RNA enzymes recently developed by the team at the Salk Institute introduce crucial mutations that significantly improve this accuracy, paving the way for understanding the evolution of the earliest forms of life.
The RNA sequences replicated by a polymerase of lesser fidelity drift from their original sequence and lose their function over time, whereas those catalyzed by a polymerase of higher fidelity retain their function and evolve towards more fit sequences.
Credit: Salk Institute Experiments have shown that not only could these enzymes faithfully replicate functional RNA molecules, but they also allowed the emergence of new variants, thus increasing their evolutionary fitness. This phenomenon illustrates how Darwinian evolution, described by Charles Darwin as "descent with modification," could have manifested at the molecular level well before the emergence of complex cellular life.
The study also reveals how natural selection could have functioned at a fundamental level, laying the groundwork for the diversity and complexity of life we observe today. By better understanding the role of RNA in the early stages of evolution, scientists hope to recreate RNA-based life under laboratory conditions, thus providing new insights into the origins of life on Earth and possibly on other planets.
This research underscores the crucial importance of replication fidelity in evolution and opens exciting avenues for future explorations into the origins of life. The possibility of creating autonomous RNA-based life in the laboratory could be within our reach in the coming decades, marking a significant milestone in our understanding of life itself.