NEW YORK – Scientists have taken the first steps toward writing the blueprint of life in an alphabet unknown to nature, they have reported in the journal Nature.
Until now, biologists who synthesize DNA in the lab have used the same molecules — called bases — that are found in nature. But Floyd Romesberg of the Scripps Research Institute in La Jolla, California, and colleagues not only created two new bases, but also inserted them into a single-celled organism and found that the invented bases replicate like natural DNA, albeit more slowly.
The scientists reported that they got the organisms, the common bacteria E. coli, to replicate about 24 times over the course of 15 hours.
The accomplishment “redefines this fundamental feature of life,” wrote biologists Ross Thyer and Jared Ellefson of the University of Texas, Austin, in a commentary in Nature.
The booming field of synthetic biology holds promises for creating new antibiotics and other drugs. It has also raised concerns scientists are in some way “playing God” by creating living things that could escape from labs into the outside world where they have no natural predators and nothing to check their spread.
In the current experiment, the scientists took pains to make that impossible, according to their paper. The new bases are not found in the natural environment, Romesberg and his colleagues said, so even if organisms with man-made DNA were to escape from the lab, they could not survive, let alone infect other organisms.
In nature, DNA’s bases — designated A, T, C, and G — pair up in the double helix that is the DNA molecule. Bases determine what amino acids a particular strand of DNA codes for, and therefore what proteins (long strings of amino acids) are produced.
So far, the synthetic bases, which Romesberg’s team call X and Y, do not code for any amino acids. But in principle, they — or other man-made bases — could. Much as adding a 27th and 28th letter to the English alphabet would allow more words to be created, so adding X and Y to the natural DNA bases would allow new amino acids and proteins to be created. Unknown at this early stage is whether the new proteins would be gibberish or meaningful.
Believing that they will be useful, Romesberg co-founded a biotechnology company named Synthorx, which was officially launched Wednesday. Based in San Diego, it will focus on using synthetic biology “to improve the discovery and development of new medicines, diagnostics and vaccines,” the company said in a statement.
Synthorx has the exclusive rights to the synthetic DNA advance.