Scientists Create Semi-Synthetic Organism That Contains Artificial DNA

Posted on May 9, 2014

Scientists at The Scripps Research Institute (TSRI) engineered a bacterium whose genetic material that includes an added pair of DNA letters not found in nature. Life on Earth is encoded with two pairs of DNA bases, A-T (adenine-thymine) and C-G (guanine-cytosine). The Scripps researchers made an organism that contains an additional third pair of DNA bases. The researchers created artificial chemicals, called X and Y, and inserted them into the organism, expanding the potential number of amino acids from 20 to 172. The research paper, "A semi-synthetic organism with an expanded genetic alphabet," was published here in Nature.

TSRI Associate Professor Floyd E. Romesberg, who led the research team, says in the announcement, "Life on Earth in all its diversity is encoded by only two pairs of DNA bases, A-T and C-G, and what we've made is an organism that stably contains those two plus a third, unnatural pair of bases. This shows that other solutions to storing information are possible and, of course, takes us closer to an expanded-DNA biology that will have many exciting applications - from new medicines to new kinds of nanotechnology."

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The scientists say their creation is safe. The semi-synthetic bacteria (a modified E.coli bacteria) they created cannot replicate the extra base pair outside the lab. Prof. Romesberg told BBC News, "If you spilled the flask on the ground and got them on your shoes and walked outside, the organisms would be out in the environment, but they would not have the triphosphates provided to them any longer and they wouldn't be able to replicate DNA with the unnatural base pair. As a result, the semi-synthetic component of their genome would simply revert to natural. That's a fail-safe against escape into nature."

The X and Y base pair currently provides zero function for the semi-synthetic bacteria. As Chemistry World explains, the breakthrough here is that the bacteria was able to grow and replicate with six nucleotides instead of four. BBC News reports that the scientists plan to give the artificial base pair some function in future experiments. This breakthrough at TSRI could potentially lead to new drugs, plastics and materials that are more complex and advanced than those used today.

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