Artificial DNA

What is the concept of “the RNA world”? What are the new ways to manipulate DNA? What tools do you need to create a new type of life? Professor of Biomedical Engineering at Boston University Maxim Frank-Kamenetskii explains how science fiction becomes real.

Since the double helix was discovered scientists always wondered why this particular chemistry was used by nature for this most important task in living organisms – the storage of genetic information. They always wondered whether it is just by accident, that it just was the first which worked, or it’s really something you cannot even replace, that it is the only way to do it. We know, of course, that in addition to DNA there’s RNA. And the most accepted view right now is that before life evolved to what we know now, consisting of DNA’s genetic material, proteins are molecules which execute all reactions in the cell. Originally, RNA was the most important molecule.

Chemists started synthesizing all kinds of analogs, trying to figure out whether they can play the role of DNA. One of these, a very successful analog was synthesized and put forward in the very beginning of 1991 by Peter Nielsen, a professor at Copenhagen University and his colleagues. It was a significantly different molecule than DNA; it has the same basis as DNA. Everybody remembers that DNA strands consist of sugar phosphate backbone and basis – ATGC, which are attached to this backbone. And this Peter Nielsen group completely changed the backbone. The backbone in the molecule which they put forward which is called PNA (peptide nucleic acid) has the same basis as DNA, but the sugar phosphate backbone is replaced by peptide backbone, which is not exactly the same as backbone of protein molecule, but very similar.

We have studied this for many years, because I started collaborating with Peter Nielsen very early when he had just put forward his idea of PNA. We studied PNA and our interest was to figure out what kind of structure PNA can form with DNA, mostly with double stranded DNA. PNA was the first example when we were able to “invade” the double helix. What PNA does with DNA – it has so high affinity to one of the two complementary DNA strands, that it just grips the strand, and the other complementary DNA strand becomes looped out. It really opens up the double helix.