Scientific Breakthrough of the Year has been awarded to researchers at Scripps Research Institute following an online public vote by Science magazine. The two scientists, Floyd Romesberg and Denis Malyshev, led a team involved in the production of an expanded genome.
The genome can be referred to as the genetic material making up an organism and is typically made up of four nucleotides, A, T, G and C, referred to as the building blocks of DNA. These nucleotides form hydrogen bonds between each other to form the base pairs AT and GC. Every triplet of nucleotides is referred to as a codon, which then subsequently encodes an amino acid. Using the different combinations of codons, there can be a total of 20 amino acids built (See Figure 1). The genetic code is limited to just 20 amino acids due to restrictions to the 4 naturally occurring nucleotides. In theory, if novel non-natural nucleotides were inserted, the number of codons and therefore amino acids could be increased to create and expanded genome.
Figure 1: Expanding the genetic alphabet: Novel nucleotides X and Y have been created to expand the number of amino acids which can be created (adapted from Synthorx).
The production of an expanded genomic alphabet was achieved by a team in Scripps following the insertion of 2 extra DNA letters (X and Y) into E. coli, resulting in a 6 letter alphabet alternative to the natural 4. The insertion of novel letters is shown above in Figure 1, which shows the enormous increase of amino acids that can be created, to 172.
This is the first example of in vivo replication of a synthetic DNA base pair and the findings were published in Nature in May. So long as the extra nucleotides are included within the media that the E. coli is growing, they will be incorporated in the genetic code. This feature serves to act as a safety feature, so if it were to ever escape the lab, it wouldn't be able to self-produce the novel expanded genome and therefore cause no harm.
The insertion of non-natural nucleotides to create an expanded alphabet is a huge scientific breakthrough and although a practical purpose has not yet been discovered, scientists are working on it. The company, Synthorx, was founded in light of these discoveries in Dr. Romesberg's Lab in Scripps.
Scientists at Synthorx have the exclusive rights to this synthetic biology technology and are now working on the development of an expanded alphabet's practical uses. A glance on the company's website reveals their aims to develop novel proteins, enzymes, RNA and DNA for various life science applications.