Add two letters to the human genetic code

American scientists have just announced the addition of two letters to the genetic code for the first time.

A team of experts at the Scripps Research Institute in California has altered the structure of a bacterium, causing it to fuse and reproduce two DNA components that do not exist in nature.

This experiment shows that the letters in DNA, which have existed for hundreds of millions of years, can be expanded through human intervention.

According to scientist Floyd Romesberg, life on Earth in all its diversity is encoded by two unique pairs of genetic base codes, AT and CG. The team's experiment is to add a third, man-made pair to the helix diagram, with the goal of creating proteins that never existed before.

The new DNA base pair needs to fit along the natural genetic code in the DNA code and not disrupt replication or transcription, the first step in making a protein.

During this process, the DNA “zipper” is opened, segments of it are copied to provide a template, and then closed. To ensure that the inserted base pairs are not attacked and rejected by the cell’s DNA repair mechanism, the team created a circular DNA strand (plasmid), consisting of the natural combination of AT and CG, as well as an unnatural pair of genetic code bases – d5SICs and dNaM. The plasmid was then inserted into a common bacterium – Escherichia coli.

However, when a base pair of DNA does not exist in nature, the molecular building blocks that help replicate it in cells do not exist either. The team solved this challenge by adding building blocks that inhibit E. coli bacteria.

The researchers also genetically engineered the E. coli to secrete an algal protein that pushes obstacles around the cell membrane. The results showed that the new plasmid replicated smoothly with very few errors—a must for healthy DNA—and that unnatural base pairs were not removed from the genetic code. The next step was to insert the new letters into RNA (ribonucleic acid), a thin derivative of DNA that breaks down into proteins.

Biologists Ross Thyer and Jared Ellefson of the University of Texas at Austin warn of concerns surrounding DNA tampering and the potential to create synthetic organisms. Efforts to expand the genetic alphabet have raised questions about the universality of DNA and could draw criticism of related research./.

According to Vietnam+