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Conformational dynamics of G-quadruplex DNA probed by time-resolved circular dichroism

Abstract : Guanine-quadruplexes (G4) are non-canonical DNA structures that result from the hydrophobic stacking of guanine quartets stabilized by metal cations (typically Na+ and K+). There is now an increasing body of experimental evidence of their occurrence in important cell functions correlated to their folding/unfolding mechanisms. However, only few studies have addressed the dynamical aspect of their formation. In this context, we have undertaken the study of several intramolecular G4 with a novel extension of temperature-jump experiments capable to measure the thermal denaturation and the consecutive renaturation of DNA over a time window spanning a few ten milliseconds to seconds. Conformational changes have been monitored by time-resolved circular dichroism (CD), which is known to be sensitive to the chiral arrangement of guanines in the G4 scaffolds.Prior to time-resolved measurements, within the frame of a collaboration with DISCO/SOLEIL, we have performed static synchrotron radiation CD measurements on several short G4-forming sequences, such as human telomere, thrombin-binding aptamer and c-MYC promoter sequences, displaying distinct topologies. Denaturation and renaturation kinetics are found to exhibit biphasic decays with time constants of a few hundred milliseconds and a few seconds, respectively. Those kinetics depend strongly on the amplitude of the temperature jump and the concentration of cations. Taken together these observations suggest the existence of multiple folding pathways on extremely rugged landscapes.
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Submitted on : Monday, June 4, 2018 - 11:52:10 AM
Last modification on : Tuesday, September 29, 2020 - 5:19:29 AM
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  • HAL Id : tel-01806951, version 1


Marco Schmid. Conformational dynamics of G-quadruplex DNA probed by time-resolved circular dichroism. Optics [physics.optics]. Université Paris Saclay (COmUE), 2017. English. ⟨NNT : 2017SACLX107⟩. ⟨tel-01806951⟩



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