Researchers at The Scripps Research Institute at La Jolla, Calif., have created a bacterium with a genome containing artificial DNA. Scripps researchers have chemically created new nucleotides named X and Y, successfully producing the first bacterium with a six-letter DNA. Work on artificial DNA has been carried out for more than 20 years, but it is only now that that it has been successfully integrated and functional in a living cell. Scientists inserted an XY pair of nucleotides into the bacterium E. coli and watched the resulting reproduction. The bacteria reproduced normally and successfully replicated the X and Y nucleotides in addition to its regular ones. Such technology could be used to produce live vaccines that are incapable of replicating in the human body and so remain harmless while still evoking the necessary immune response.
The process they used to find the X and Y nucleotides involved chloroplasts, which are present in plants. Chloroplasts are unique in that they are able to import nucleotides from surrounding tissue; the genes controlling this process have already been determined. Romesburg and his team harnessed this ability by splicing certain genes from algae into the E. coli genome, which allowed the bacterium to import X and Y nucleotides from its surroundings.