Scientists add two extra letters to life’s genetic code

An international team of scientists from the United States, France and China have created bacteria that flourish using an expanded genetic code/alphabet.

The DNA double helix, the blueprint for all forms of life on our planet, is currently written in a code consisting of 4 letters of English alphabet (A, T, C and G). But, the scientists modified the lab organism to use two more letters, giving it a genetic code of 6 letters.

Previous studies had shown that a UBP (unnatural base pair), consisted of a couple of synthetic letters X and Y, could be incorporated into the DNA of E-coli bacteria. But, the resulting bacteria grew slowly, and the UBP was obliterated after numerous rounds of cell division.

Now, Prof. Floyd Romesberg of California’s Scripps Research Institute, and others showed that their lab bacteria can hold on for an indefinite period to the synthetic base pair as it divides.

Sharing their study’s findings, Prof. Romesberg said, “We’ve made this semisynthetic organism more life-like. 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.”

Scientists are hopeful that their research could lead to bugs that would eventually allow production of new classes of drugs to treat various diseases.

The addition of extra letters to life’s genetic code was detailed and reported in the Tuesday (Jan. 24th) edition of the journal PNAS.