We all know that DNA is the molecule that contains genetic information, but few of us know the mysteries it holds. Interestingly, it is a very simple structure that breaks with some of the basic premises of chemistry . For example, no one would think that two negatively charged skeletons could come together rather than repel each other, or that the transmission of such valuable information would be left to links that can be broken by water. More surprising is the fact that a combination of four nitrogenous bases, paired two by two (adenine, A, with thymine, T, and guanine, G, with cytosine, C), is simply responsible for all the great variety of organisms alive present on our planet.
The existence of these four nitrogenous bases is due to chance: they were formed and combined according to the conditions existing on Earth at that time. For this reason, scientists such as Professor P. Schultz ask themselves “what life would be like if God had worked on the seventh day”. Could there be a DNA with a genetic alphabet of more than four letters, for example? If another chemistry of life is viable, there could be other types of organisms than the ones we know on our planet: what would this life be like? Would we be able to recognize it if we found it? Such is the relevance of the answer to these questions that even NASA invests in projects related to the chemistry of nucleic acids.
Expanding the genetic alphabet
To know if another chemistry of life is possible, it is necessary to determine the essential conditions that a molecule must meet to store and transmit genetic information. Numerous research groups have made changes to the structure of DNA and the need for negative charges in the skeleton to maintain the well-known double helix structure has been proven. The bases or letters, however, have allowed more types of modifications and various research groups have managed to expand the genetic alphabet , even creating a semisynthetic organism with a couple more letters, according to a study published in the journal Nature in 2014 .
On the other hand, the translation of genetic information follows the premises set by the genetic code to convert an RNA sequence into the amino acid sequence of a protein. This genetic code has been modified and microorganisms capable of introducing unnatural amino acids into proteins that have new functions have been created. Now, the groups of Professors Romesberg and Schultz, from The Scripps Research Institute are working collaboratively to create an organism with a broader genetic alphabet that is capable of storing more information, transmitting it and translating it. If successful, it would be the first step towards the creation of artificial life with the capacity for its own evolution and they would have shown that we must look beyond the work that God completed in 6 days.
Empar Vengut i Climent is a researcher at the Department of Organic and Pharmaceutical Chemistry at the University of Seville. Article written in collaboration with the UCC + i of the University of Seville.
