Scientists at the Scripps Research Institute announced Wednesday they have created a strain of common E. coli bacteria with synthetic genetic components.
The DNA that is the basis of all life is made up of four chemical bases — adenine, cytosine, guanine and thymine, known by the letters A, C, G and T. Combinations of these four make up all the instructions for creating proteins in every organism.
What the Scripps scientists succeeded in doing is to create a strain of E. coli with two unnatural chemical bases, which they dubbed “X” and “Y,” in its DNA.
In a study published in the journal Nature, the researchers explained that their “semi-synthetic” strain of E. coli is the first to both contain the unnatural bases in its DNA and use the bases to instruct cells to make a new protein.
“I would not call this a new lifeform—but it’s the closest thing anyone has ever made,” said Scripps Professor Floyd Romesberg, who led the study. “This is the first time ever a cell has translated a protein using something other than G, C, A or T.”
The protein produced in this process was a variant of green fluorescent protein, a naturally glowing marker often used in genetic experiments, which contained different unnatural amino acids incorporated at a selected site.
“This was the smallest possible change we could make to the way life works—but it is the first ever,” said Romesberg.
With the addition of X and Y, an organism could code for up to 152 new amino acids. The researchers hope these amino acids could become building blocks for new medicines.