By Holly Giles
The double helix DNA structure is an iconic image known to scientists everywhere. It is formed of the four bases tyrosine, cytosine, adenine and guanine (TCAG). The specific order of these four bases is what distinguishes man from rhino and banana and any other form of life on Earth. Until now these have been the only known building blocks of DNA, but this week scientists have developed four new blocks in the hope that this eight-letter DNA will provide an indication of the proteins made by other life forms and what they might consist of.
Behind the discovery of the “hachi-moji”, which means eight letter in Japanese, DNA molecule are Steven Benner and his team at the Foundation for Applied Molecular Evolution in Florida. The four new bases consist of S which pairs with B and P which pairs with Z.
The fact that hachi-moji DNA uses hydrogen bonds between pairs like our DNA means it could be integrated into our DNA to provide a staggering 512 codons compared to the conventional 64 we have now. The 512 codons make it possible to code for new amino acids with novel properties, which could enable everything from more powerful medicines and industrial catalysts to the possibility of electrically conductive proteins. In order to realise all the potential benefits of this discovery, tools are needed to take advantage of this new code and manipulate it optimally.
Ultimately, the most exciting implication of this data is the insight into other forms life could take. Until now we have been focusing on what we see as the essentials for life; water, oxygen and nitrogen. But these developments suggest we have been approaching any search in space from an overly anthropomorphised view, and although those elements are essential to human life they may not be to life in other forms. This data indicates life on other planets could be completely different to life as we know it and that their DNA might be at the heart of that. NASA, who funded the research, said “they hope it will help them expand the scope of their search for extra-terrestrial life”.