tRNAs come from before the genetic code existed?
Anyway, that’s what is being reported:
The study predicted that the loading of amino acids on tRNA molecules preceded the refinement of the genetic code into codons, the regions on the messenger RNA that are read by individual tRNAs.
“For the first time, we believe we make this distinction between the evolution of the genetic code (codon discovery) and the evolution of amino acid charging,” Sun said.
There isn’t much to add to that report, since it is so sparse in detail. I just thought it was worth bringing in as an interesting news feature.
It does make sense evolutionarily, certainly. After all, the genetic code wouldn’t be of much use without tRNAs. What is more, it appears as though there was an RNA world at one time, from which DNA is thought to have appeared. So tRNA would pre-exist DNA, and at least the DNA code (if not necessarily an RNA code). Likely there would be some sort of translation going on prior to the existence of the reified genetic code, and, if this report is correct, tRNA was it.