A team of researchers led by Associate Professor Yan Jie from the Department of Physics at the National University of Singapore (NUS) Faculty of Science has identified three new distinct overstretched deoxyribonucleic acid (DNA) structures caused by mechanical stretching. This discovery provides a clear answer to a long-running debate among scientists over the nature of DNA overstretching.
Debate on Possible DNA Structural Transitions
Recent single-molecule studies revealed that mechanical stretching could induce transitions to elongated DNA structures. Three possible elongated DNA structures have been proposed, namely: a single-stranded DNA under tension, DNA bubbles consisting two parallel, separated single-stranded DNA under tension, and a new form of base-paired double-stranded DNA. The existence of the three transitions has been heavily discussed among scientists for some 17 years.
To fully understand the nature of DNA overstretching, the team led by Assoc Prof Yan, which comprises members from NUS, the University of Minnesota and the Massachusetts Institute of Technology, explored the possible structural transitions.
Three Distinct Transitions Revealed
In their recent study, the researchers systematically investigated the three possible transitions induced by mechanical stretching, with methods to control DNA construct, temperature, force and salt concentration. Their data successfully identified all the three proposed structures and fully characterised their respective thermo-mechanical properties. These findings were first published on the online version of the Proceedings of the National Academy of Sciences on 19 February 2013.
These findings complete the picture about the structures of DNA under tension, providing a conclusion to the 17-year-old debate.
An illustration of three distinct elongated DNA structures produced by mechanical stretching (Image credi
|Contact: Sarah LOKE|
National University of Singapore