iFrankenstein here we come.
At the Scripps Research Institute in LaJolla, California scientists have successfully created two new bases of Deoxyribonucleic Acid and inserted them into a single celled organism. The E. coli did replicate slowly but normally over a fifteen hour period approximately 24 times. The bases do not code for any amino acids but are named X and Y.
“What we have done,”says Floyd Romesberg, study leader of the project, “is successfully store increased information in the DNA of a living cell.” Romesberg has now co-founded, Synthorox, a biotechnology company. The public company statement partially reads, “to improve the discovery and development of new medicines, diagnostics and vaccines.”
“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 Floyd E. Romesberg, who led the research team. “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.”
When thinking how DNA works imagine a zipper being zipped up and down with matching pairs of DNA. In a press release from the Scripps Research Institute it reports that “any new pair of DNA bases would have to bind with an affinity comparable to that of the natural nucleoside base-pairs adenine – thymine and cytosine – guanine. Such new bases also would have to line up stably alongside the natural bases in a zipper-like stretch of DNA.”
In the new study, the team synthesized a stretch of circular DNA known as a plasmid and inserted it into cells of the common bacterium E. coli. The plasmid DNA contained natural T-A and C-G base pairs along with the best-performing unnatural base pair Romesberg’s laboratory had discovered, two molecules known as d5SICS and dNaM. The goal was to get the E. coli cells to replicate this semi-synthetic DNA as normally as possible.
The greatest hurdle may be reassuring to those who fear the uncontrolled release of a new life form: the molecular building blocks for d5SICS and dNaM are not naturally in cells. Thus, to get the E. coli to replicate the DNA containing these unnatural bases, the researchers had to supply the molecular building blocks artificially, by adding them to the fluid solution outside the cell.
Then, to get the building blocks, known as nucleoside triphosphates, into the cells, they had to find special triphosphate transporter molecules that would do the job.
The researchers eventually were able to find a triphosphate transporter, made by a species of microalgae, that was good enough at importing the unnatural triphosphates. “That was a big breakthrough for us—an enabling breakthrough,” said Malyshev.