EPJ E Highlight - DNA’s double stranded stretch

Understanding how DNA and proteins interact could come from a better grasp of DNA’s behaviour once stretched. © Svilen Milev

Models simulate what happens to DNA strands when stretched to the breaking point

Theoretical physicists like to play with very unconventional toys. Manoel Manghi from Toulouse University in France and his colleagues have adopted a seemingly playful approach to examining what happens to a double stranded molecule of DNA when it is stretched to the breaking point, in a study about to be published in EPJ E. Instead of using optical tweezers to stretch DNA as previously done in experimental settings, the authors focused on using a theoretical model to account for the structural deformations of DNA and determine how its mechanical characteristics could explain certain biological processes.

Over fifteen years ago, scientists discovered that DNA undergoes two structural transitions when pulled from both ends. The problem is that in experimental conditions these two transitions can overlap and can therefore be difficult to observe. Instead, Manghi and colleagues relied on a standard mathematical tool referred to as a ‘coupled discrete wormlike chain-Ising model’ to simulate DNA stretching and match experimental observations.

Thanks to their theoretical approach, the authors confirmed that after overcoming initial resistance to stretching, at a force of around 65 piconewtons (pN) in strength, the DNA stretches to almost twice its original length while also becoming less rigid. They also confirmed the other known structural transition occurring at around 135 pN. Although the critical forces of both transitions depend on the DNA sequence, they found it is the second one that most depends on it.

Beyond 135pN, DNA strands start peeling apart into single stranded DNAs that are similar to those obtained when DNA is heated up and undergoes thermal denaturation. This model thus bridges the gap between force-induced mechanical stretching and thermal denaturation and could potentially help understand how DNA performs its biological functions such as interaction with proteins and how it is packaged, say, in viruses.

Mesoscopic models for DNA stretching under force: new results and comparison to experiments. M. Manghi, N. Destainville, J. Palmeri (2012), European Physical Journal E 35:110, DOI: 10.1140/epje/i2012-12110-2

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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