|In a major step toward creating artificial life, researchers from the
Scripps Research Institute in La Jolla, California, have developed a
living organism that incorporates both natural and artificial DNA and is
capable of creating entirely new, synthetic proteins. The work brings
scientists closer to the development of designer proteins made to order
in a laboratory.
Previous work by the team showed that it was possible to expand the
genetic alphabet of natural DNA beyond its current four letters:
adenine(A), cytosine(C), guanine (G) and thymine(T). In 2014, the
researchers created a strain of E. coli bacteria that contained two
unnatural letters, X and Y. In the latest work, they have shown that
this partially synthetic form of E. coli can take instructions from this
hybrid genetic alphabet to make new proteins.
The creation of semi-synthetic organisms might raise concerns of hybrid
life forms spreading beyond the lab, but according to the researchers
the system they used makes such an escape unlikely.
For example, in natural DNA, base pairs are attracted to each other
through the bonding of hydrogen atoms. However, the X and Y bases are
attracted through an entirely different process, which prevents them
from accidentally bonding with natural bases. And because cells cannot
make their own X and Y without the addition of certain chemicals, the
semi-synthetic organisms cannot live outside of a laboratory.