A Happy Separation
What was once thought to be possible only through nature is now being created in the lab. Scientists from The Scripps Research Institute (TSRI) announced today that they have successfully created the first-ever, fully stable semi-synthetic living organism.
In 2014, TSRI professor Floyd Romesberg and his colleagues led a study which resulted in the synthesis of a DNA base pair. A feat of its own, the team was now able to take those natural bases (A, G, C, T), and assemble a completely new bacterium. Their findings are published in the journal Proceedings of the National Academy of Sciences.
This goes beyond previous methods of creating stable creating stable single-celled creating stable single-celled organisms, as these bacteria hold an extra pair of synthetic bases in their genetic makeup called X and Y. Cell division was difficult to achieve in this past experiment as the bacterium would divide, but would not hold the synthetic base pair during the process. With this new experiment, TSRI graduate student Yorke Zhang and American Cancer Society postdoctoral fellow Brian Lamb were able to find a way for the organism to retain the base pairs.
First, they modified a tool called a nucleotide transporter, which makes it possible for the synthetic base pair to be copied across the cell membrane (when originally attempted in 2014, it made the semisynthetic organism very sick). This modification helped lead them to their success, allowing for an easier division while maintaining the X and Y bases. They then optimized their Y to make it more easily recognizable during the process.
Finally, the researchers used CRISPR-Cas9 as a sort of “spell check.” CRISPR-Cas9’s original role in bacteria is to act as an immune response. When there is a threat such as a virus, it can essentially cut and paste the genome from the invading virus onto itself, and use it on the offense if it returns.