Four new DNA bases synthesized

Source: phys.org

By: John Nicolas Olitin 

Ever since the beginning of life a couple billion years ago, genetic information is believed to be stored in the DNA as a string of only four bases or letters–Guanine (G), Cytosine (C), Adenine (A), and Thymine (T).

Just recently, researchers have created a DNA that contains not just the four natural bases but also four synthetic ones.

In a study published on February 22, in the journal Science, a research team led by Steven Brenner from the Foundation of Applied Molecular Evolution (FfAME) in the US has synthesized four additional nucleotide bases, namely P, Z, S, and B, wherein P pairs with Z, and S pairs with B. This essentially doubles the “letters” comprising the DNA, and thus increasing the information density over standard DNA.

The DNA system composed of the four natural bases and the four artificial ones is called “hachimoji” DNA (meaning “eight letters” in Japanese). It functions the same as normal DNA, is found to be stable, and can be transcribed into RNA.

However, according to Brenner, in order to determine if hachimoji has the ability to support life, it has to be self-sustaining–a crucial factor that the research team was unable to test without the risk of creating a biohazard in the process.

This is not the first time that artificial nucleotides have been synthesized. In a 2011 study also led by Brenner, an expanded genetic information system composed of the four standard nucleotides, and two additional nonstandard nucleotides (P and Z) were also developed.

With a more diverse set of genetic components, scientists can, in theory, create DNA or RNA sequences that can function better than regular DNA, aside from storage of information.

Furthermore, hachimoji DNA can potentially be used to create novel proteins. For instance, a protein is now being developed based on strands of DNA including P-Z that were observed to be better at binding to cancer cells as compared to regular DNA. This protein can then be included as part of an anti-cancer drug.

In addition to its medical applications, this discovery expands the scope of the structures that we might encounter as we search for life in the cosmos, as well as provide insights as we seek answers to mysteries regarding life’s origin.

Reference:

Warren, M. (2019, February 28). Life’s genetic alphabet doubled. Nature, 566(436). doi:10.1038/d41586-019-00650-8