New insight into how DNA holds together revealed

The new finding comes from Chalmers University of Technology, Sweden, where molecular biologists have disproved the prevailing theory relating to how deoxyribonucleic acid (DNA), constructed of two strands (sugar molecules and phosphate groups), binds itself. For decades the common view has put this down to hydrogen bonds, holding together the two sides of the DNA structure. The new research attributes the binding to water.

The new finding came about after extensive research using spectroscopic data and optical tweezers experiments, to help reveal the molecular-level unstacking dynamics of DNA. This showed that DNA molecules have a hydrophobic interior (dry, or ‘water disliking’), in an environment consisting mainly of water. The environment is therefore hydrophilic (wet or ‘water attracting’), while the DNA molecules’ nitrogen bases are hydrophobic, pushing away the surrounding water. The research showed that when hydrophobic units are in a hydrophilic environment, they group together, to minimize their exposure to the water.

The DNA double helix

AFP/File

As for the hydrogen bonds, previously regarded as essential for holding DNA helixes together, this appear to be involved with sorting base pairs, ensuring that the pairs link together in the correct sequence.

In terms of the significance of the finding, the Gothenburg research could have implications for medicine and life sciences. One example is with cancer research, as lead scientist Bobo Feng, explains: “To understand cancer, we need to understand how DNA repairs. To understand that, we first need to understand DNA itself. So far, we have not, because we believed that hydrogen bonds were what held it together. Now, we have shown that instead it is the hydrophobic forces which lie behind it. We have also shown that DNA behaves totally differently in a hydrophobic environment. This could help us to understand DNA, and how it repairs.”

Outside of the Francis Crick Institute, a sculpture of DNA. A staggering 14 meters high and made of weathered steel, the sculpture entitled ‘Paradigm’.

Tim Sandle

The new research is outlined in the journal PNAS.The research paper is titled “Hydrophobic catalysis and a potential biological role of DNA unstacking induced by environment effects.”