ZAP // Dall-E-2
Scientists are arguing for the need to adjust our knowledge about exactly how genes arose.
For some time, there was a consensus about the order in which amino acids were “added” to the box of Lego bricks that build our genes.
According to , according to genetic researchers at the University of Arizona, our previous assumptions may reflect prejudices in our understanding of the biotic sources (cheers) and abiotic (not alive).
In other words, our current working model of the history of genes may be undervaluing the protolife inicial (which included precursors such as RNA and peptides), compared to what emerged with and after the beginning of life.
Our understanding of these extremely ancient times will always be incomplete, but it is important that we continue to investigate the early Earth. Scientists explain that any improvements in this understanding could not only allow us to better understand our own history, but also help us search for the beginnings of life in other parts of the Universe.
In this article, in the scientific journal Proceedings of the National Academy of Scienceresearchers led by senior author Joanna Masel and by the first author Sawsan Wehbi explain that the vital parts of our proteins (also known as amino acids) date back four billion years — the last universal common ancestor of all life on Earth.
These chains of dozens or more amino acids, called protein domainsare “like a wheel” on a car, said Wehbi in a .
“It’s a part that can be used on a lot of different cars, and wheels have been around a lot longer than cars.”
The group used software expertise and data from the National Center for Biotechnology Information to build a evolutionary tree of these protein domainswhich were only theorized or observed in the 1970s. Our knowledge of these details has grown by leaps and bounds.
One of the great paradigm shifts proposed by this investigation is the idea that we should rethink the order in which 20 genetic amino acids essentials emerged from the broth of the primitive Earth.
Scientists argue that the current model places too much importance on frequency at which an amino acid appeared in a primitive life form, leading to a theory that the amino acid found at the highest saturation must have appeared first.
This fact fits with existing research, such as one from 2017 that suggests that our amino acids represent the best of the best and not just a “frozen accident” of circumstances.
In the article, scientists state that amino acids may even have come from different parts of the young Earthrather than the entire Earth with a uniform environment.
Tryptophan, the “sleepy” amino acid found in Thanksgiving turkey, was one of those that most caught the attention of scientists (its letter designation is W). “There is a scientific consensus that W was the last of the 20 canonical amino acids to be added to the genetic code,” the scientists wrote.
But they found 1.2% W in the pre-LUCA data and just 0.9% after LUCA. These values may seem small, but it is a difference of 25%.
Why would the last amino acid to emerge be most common before the branching of all resulting life? The team theorized that the chemical explanation could point to an even older version of the idea of genetics. As with all things evolutionary, there is no intuitive reason why a successful thing should be the only one of its kind or family to exist.
“A gradual construction of the current code ea competition between old codes may have occurred simultaneously”, the scientists conclude. And, tantalizingly, “the ancient codes may also have used non-canonical amino acids”.
These could have arisen around the alkaline hydrothermal vents believed to have played a key role in the origin of life, despite the fact that the resulting life forms did not live there for long.
To apply this theory to the rest of the Universe, you don’t have to go very far either. “THE biotic synthesis of aromatic amino acids may be possible at the water-rock interface of Enceladus’ subsurface ocean,” the scientists explain.
Teresa Oliveira Campos, ZAP //
