DNA is an incredible macromolecule. It is simple. It is stable. It is wrapped up with proteins called histones into incredibly dense chromosomes in our nucleus. And with 2 meters of DNA in each of our 37 trillion cells, we have a lot of it. So why do some biologists want to change our DNA? Marcus Schmidt and other Xenobiologists are considering changing our DNA into a different molecule called XNA (xeno nucleic acid). XNA is a theoretical genetic material which would replace the current 4 letter DNA code of G, C, T and A (Guanine, Cytosine, Thymine, and Arginine) with different nucleotides.
Organisms made up of an alternate genetic material would interact quite differently with DNA-based organisms; which could provide a number of advantages. For example, XNA-based organisms would not be affected by any existing virus which infect their host by inject old-fashioned DNA into new XNA chromosomes. In this way, new genetic material would act as a firewall, biologically protecting its host. DNA is also vulnerable to a variety of environmental stimuli (ultraviolet light, nuclear radiation, and certain chemicals). It is possible that an XNA could be created which is resistant to these exogenous agents.
This biological firewall provides an important safety tool for creating synthetic life. Imagine a company creates yeast which produces biofuels, or a microbe which “eats garbage”; this organism will be intensely observed and heavily regulated to control its replication. If these were XNA-based organisms, their nucleotide building blocks would not be readily available in its environment and would have to be externally supplied by a human creator/owner. Thus, its replication is completely regulated by its creator. In addition, the genetic materials would be so different that horizontal gene transfer would be impossible; allowing XNA-based organisms to interact with those made up of DNA on an ecological level, but never on a genetic level.
There is no evidence of any living organisms currently using the unnatural genetic material described above, and there is little indication that it will arise any time soon. In the short-term it seems likely that biologists will continue working only with DNA, but with many advantages of using XNA it may arise in the distant future. It may seem scary or unnatural to create such different life-forms, but if it they are safe and useful, XNA organisms could represent the future of synthetic biology.