tRNA Synthetase Gene Sharing: Like the Movie Transformers

You’ve seen those amazing multi-purpose kitchen utensils and jackknifes that perform a dozen tasks, but it is all standard fare in biology. From the DNA molecule which stores all kinds of information (you can see examples here, here, here and here) including overlapping genes, to molecules that fulfill various roles depending on the cellular context and gene sharing, biology is the model of efficiency. Call it multi-purpose design, component reuse, optimization of information density, or whatever, it is one of biology’s biggest unsung feats and last week yet another example was published.

You may remember the two key steps in protein synthesis are transcription and translation, where (i) the DNA gene is copied and (ii) the copy is used to encode a string of amino acids, respectively. What your biology teacher did not know, however, is that one of the key enzymes in translation also is part of the massive transcription choreography.

Everyone has heard of the DNA code but few understand how it works. The copy of the DNA gene, known as messenger RNA (mRNA) consists of a string of nucleotides. Those nucleotides are taken three at a time to form a sequence of three letter words, or codons. There are 64 (4^3) different codons and transfer RNA (tRNA) molecules do the reading of these codons. Different tRNA molecules recognize different codons. The magic is that on the other end of each tRNA is glued the correct type of amino acid, corresponding to the codon that that specific tRNA will recognize.

But how did the tRNA molecules come to have the right amino acid glued on? There are enzymes that carry an amino acid and, when they find the right corresponding tRNA, they glue the amino acid onto it. So it is with these enzymes, collectively known as tRNA synthetases, where the heavy lifting occurs. They implement the DNA code.

But the new research has found that the heroics do not stop there. The scientists discovered the details of how one of the tRNA synthetases, when a phosphate group is attached to the right place, undergoes a dramatic structural and functional change. No longer is it busy gluing an amino acid to the right tRNA. Instead, it moves upstream in the assembly line process and helps to regulate the transcription activity. As one of the scientists explained:

If you think about the structural changes that occur in the synthetase we looked at in the study, it’s very much like the movie Transformers, it’s a machine that changes structure and turns into another machine that can accomplish a completely different task—like from a car to a giant robot.

Of course yet another protein is responsible for attaching the phosphate group to the right place, at the right time. But that’s another story. For now, the question is how could this tRNA synthetase have come to have this dual role?

Of course the evolution of a protein, any protein, is problematic simply because successful searches are so unlikely. The fitness landscape is rugged, pitted with myriad local minima that frustrate evolutionary searches. Even by evolutionist’s own optimistic approximations it would never occur in the lifetime of the universe.

And beyond that, there is then the problem of how tRNA synthetases in particular could have evolved. For instance, their role so heavily depends on the intricate process of translation, involving so many other molecular players. To be sure simpler versions of that process can be envisioned, but even simpler versions are complex.

It is not as though a freshly minted tRNA synthetase is going to help much if some sort of translation process is not already in place. And it is even more unlikely that such a translation process would evolve without the needed tRNA synthetases to complete the choreography. Obviously evolution requires some sort of sequence of events providing a gradual build up. But beyond speculation, we have no compelling story to tell for this miracle.

But now, on top of these massive problems, we find that tRNA synthetases can, upon a low entropy phosphorylation, transform to a completely different structure and function. Imagine the serendipity involved.

After successfully navigating the problems discussed above to construct the translation process, and after having constructed protein kinases which attach phosphate groups at convenient places, evolution’s natural selection found that one of the kinases happened to phosphorylate one of the tRNA synthetases at just the right place to perform an incredible transformation operation where the newly formed molecular machine performed just the right function in the completely different process of transcription. This is simply incredible.

Now I would be delighted to learn that I’ve stupidly overlooked some straightforward and compelling evolutionary explanation for all of this. I don’t have a dog in this fight. Perhaps evolution is true, perhaps it is false, or perhaps it is somewhere in between. I don’t care and if there is a scientific explanation of how this world of biology could have spontaneously arisen then I would gladly shout it out.

But instead of explanations all I get is pushback. It’s all my fault for attacking science, we all know evolution is true, and besides god would never make viruses anyway.

It illustrates the enormous gap between evolutionists and the evidence. For evolutionists there are no problems behind the assertion that evolution is a fact. There are only research problems of how evolution occurred. Objective, scientific evaluations of how the evidence actually bears on the theory are elusive. Religion drives science, and it matters.