Scientists Create First Organism With Expanded Genetic Code

Life's genetic map has always been made up of four natural bases represented by four letters: A, T, C and G. In a breakthrough study, scientists have created a bacterium with DNA consisting of two additional synthetic bases.

According to a report from Phys Org, a team of scientists at The Scripps Research Institute (TSRI) was successful in creating the first stable semisynthetic organism. This new bacterium still contains the four natural bases, but it features an expanded genetic code with synthetic bases dubbed X and Y.

The team first announced the development of X and Y back in 2014 with a modified E. coli bacteria holding the pair in their DNA. However, it proved to be unstable as the bacteria failed to keep the synthetic base pair when it divided.

"We've made this semisynthetic organism more life-like," senior author and TSRI professor Floyd Romesberg said. "Your genome isn't just stable for a day. Your genome has to be stable for the scale of your lifetime. If the semisynthetic organism is going to really be an organism, it has to be able to stably maintain that information."

Romesberg also told The Guardian about the reason behind the additional X and Y molecules: just in case they make it out of the laboratory. He mentioned the film Jurassic Park as a reference, a movie where the possibility of breeding was discussed despite supposed limitations in the dinosaurs' genetic makeup.

"Our failsafe is based on the availability of X and Y and the cell could never make them," Romesberg explained. "In addition, evolution works by starting with something close and then changing what it can do in small steps. Our X and Y are unlike natural DNA, so nature has nothing close to start with. We have shown many times that when you do not provide X and Y, the cells die, every time."

The research is only applicable to single cells and at this point in time, there are no applications yet. Eventually though, it can pave the way for new functions to single-celled organisms, particularly in drug discovery and medical science.

The study is published in the journal Proceedings of the National Academy of Sciences.