Reacción a "Shown a way in which RNA and amino acids might have begun to relate at the origin of life"

This is a chemically elegant, solid, carefully crafted piece of work, as is usual for Powner's group. It shows how good funding can lead to good work.

The first thing to say is that this work does not ‘solve’ the problem of the origin of life at all. Nor does it solve the problem of the origin of the ribosome or the origin of biological protein synthesis.

Rather, it raises more questions. The work shows us a chemical, not biological, route for connecting amino acids to RNA, the key molecule of life. This connection is essential in life as we know it, as it is what initiates protein biosynthesis in cellular ribosomes. In the work, it achieves this in a simple way, without the need for complex enzymatic machinery, using the chemistry of thiols and thioesters, sulphur derivatives of amino acids.

This could apparently solve the biochemical paradox in which proteins and RNA are needed to obtain the peptidyl-RNAs that give rise to new proteins, raising the question of how this cycle began, similar to the classic chicken-and-egg paradox.

The main limitation is its geochemical and prebiotic implausibility. Despite attempts to connect the binding of RNA to amino acids with plausible precursors—such as aminonitriles—and mild environmental conditions, the process is complex, requiring carefully controlled conditions and the precise concurrence of certain reagents at concentrations that are unlikely in a prebiotic environment. Therefore, despite its elegance, this pathway is, in my opinion, unlikely under natural conditions.

Furthermore, the work is based on a well-defined theoretical framework: that complex RNA had a direct prebiotic origin and that RNA-driven peptide synthesis could have preceded the evolution of the larger ribosomal subunit. This is currently highly debated.

Regardless of the theoretical framework on the origin of life, the result is a proof of concept that shows us that complex and precise enzymatic and structural control is not necessary to form an aminoacyl-RNA, as it is easily formed in the same position as its biological equivalent, with an activated amino acid in the form of a thioester and a double-stranded RNA. This suggests that, once the basic structures and conditions are established, the peptide synthesis cycle could easily start.

Other strategies have already been suggested on this point, with a similar theoretical framework, so this work is not a major breakthrough in understanding the origin of life. But it is still extremely interesting, not only from a chemical point of view, as it confirms that the union of the world of peptides and proteins and the world of RNA, necessary for life to start, is chemically possible in a relatively simple way.