Scientists have created a unique bacterium with an added pair of unnatural DNA bases to its genetic material that can replicate the DNA bases as usually as it can through molecular building blocks.
“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,” said TSRI Associate Professor and leader of the research team Floyd E. Romesberg, in a press release.
“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,” he added.
Since the late 1990s, the researchers had been working to find molecular pairs that could have new, functional DNA bases and could code for newly existing proteins and organisms. In 2008, they have identified sets of nucleoside molecules capable of hooking up across a two-stranded DNA just like natural base pairs and explained how these unnatural base pairs together with the right enzymes could enable the DNA to replicate.
The following year, the team found enzymes that transcribe this half-synthetic DNA into RNA.
In the latest study, the researchers aimed to get the common bacterium E. Coli cells to replicate the half-synthetic DNA as normally as they can. To achieve this, the team had to synthesize a stretch of circular DNA or “plasmid” and insert it into the cells of the bacterium. The plasma DNA had the natural base pairs known as T-A and C-G and also had the unnatural base pair of d5SICS-dNaM which are two molecules they discovered.
The study was conducted by using a test tube. Denis A. Malyshev, member of the Romesberg team, said in a press release: “These unnatural base pairs have worked beautifully in vitro, but the big challenge has been to get them working in the much more complex environment of a living cell.”
Further details of this study can be read on the May 7 issue of Nature.
