Are biological processes involving DNA, like transcription, facilitated by a local and spontaneous denaturation of the double stranded molecule? This question is matter of debate in the field of single molecule studies in particular. Using a rigorous analysis of single molecule data obtained by massive parallelization of the Tethered Particle Motion (TPM) technique, researchers from the Institut de Pharmacologie et Biologie Structurale have shown that before complete DNA denaturation, temperature modifies the thermal fluctuations without leading to opening of the DNA over several base pairs, stable over time. This study was published in Nucleic Acids Research, on January 23rd, 2017.
Figure: Influence of the temperature on (A) the TPM signal and (B) the characteristic length of the DNA fluctuations noted Lp, scaling as the DNA rigidity. The measurements (colored marks) are given for three linear DNA molecules of about 2 kbp with distinct sequences. While the TPM signal shows a strong decrease with temperature, the fluctuation length, it allows to extract, varies only slightly with temperature. This behavior corresponds to a DNA maintaining a constant rigidity. The strong dependence observed by other research groups (black and grey marks) is more likely to result from an incomplete analysis of TPM raw data.
This work was performed in collaboration with researchers from the Laboratoire de Physique Théorique and from the Laboratoire de Microbiologie et Génétique Moléculaire de Toulouse and was funded by CNRS, University Toulouse 3 and the ANR-11-NANO-010 ‘TPM on a Chip’.
Brunet, A., Salomé, L., Rousseau, P., Destainville, N., Manghi, M. and Tardin, C. (2017) How does temperature impact the conformation of single DNA molecules below melting temperature? Nucleic Acids Res 10.1093/nar/gkx1285
Research: Catherine Tardin
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