Dynamics and stability of polymorphic human telomeric G-quadruplex under tension.
Bottom Line: This work characterizes the equilibrium transitions of single-molecule telomeric G4 at physiological K(+) concentration.Our results show that the kinetically favored folding pathway is through a short-lived intermediate state to a longer-lived state.In addition, an ultra-long-lived form of telomeric G4 structure with a much stronger mechanical stability is identified.
Affiliation: Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.Show MeSH
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Mentions: Ultra stable vertical magnetic tweezers built in lab were used to stretch the DNA constructs using a pair of magnets on the top of the chamber (Figure 1A). The magnetic tweezers were controlled by in-house-written LabVIEW program (National Instruments). The extension change of the construct was recorded with a sampling rate of ∼200 frames per second. Force was controlled by changing the distance between the permanent magnets and flow chamber. Loading rate control was achieved by moving the magnets through a programmed trajectory. The magnetic tweezers have a spatial resolution for bead stuck on surface of ∼2 nm, and the force calibration has a relative error of <10% (32). More details of the magnetic tweezers design, the force and loading rate control, as well as the force calibration were detailed in our previous publications (32,37). All experiments were carried out at our lab room temperature of 21−23 °C.
Affiliation: Mechanobiology Institute, National University of Singapore, 5A Engineering Drive 1, 117411, Singapore.