Credit: © 2008 NPG

RNA can act as an informational polymer and can catalyse reactions, and this inspires a popular theory that the formation of RNA alone can explain the origin of life on earth. A key part of this intriguing puzzle is how the nucleotides that make up the RNA polymer could be formed from the small molecules present in a prebiotic world.

Now, John Sutherland and co-workers from the University of Manchester, UK, have shown that a pyrimidine ribonucleotide can indeed be assembled1 from plausibly prebiotic small molecules — cyanamide, cyanoacetylene, glycoaldehyde and glyceraldehyde — provided that inorganic phosphate is present at an early stage. Although sugars and pyrimidine bases have been formed previously from such a mixture, it had been difficult to reconcile this with the fact that ribose (the sugar) could not be formed selectively — particularly in the required five-membered-ring hemiacetal form — and that coupling of the free sugar and pyrimidine base was, at best, unfavourable.

Sutherland and co-workers show that phosphate can act as a buffer and catalyst in the formation of a pyrimidine nucleotide by an alternative route. Ultimately, the researchers hope to show the production of an RNA oligomer from a plausible prebiotic mixture.