A single-molecule platform for investigation of interactions between G-quadruplexes and small-molecule ligands
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Koirala, Deepak, Soma Dhakal, Beth Ashbridge, et al. "A Single-Molecule Platform for Investigation of Interactions between G-Quadruplexes and Small-Molecule Ligands" Nature Chemistry 3, no. 10 (2011): 782–87. https://doi.org/10.1038/nchem.1126.
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This version of the article has been accepted for publication, after peer review (when applicable) and is subject to Springer Nature’s AM terms of use, but is not the Version of Record and does not reflect post-acceptance improvements, or any corrections. The Version of Record is available online at: https://doi.org/10.1038/nchem.1126
Abstract
Ligands that stabilize the formation of telomeric DNA G-quadruplexes have potential as cancer treatments, because the G-quadruplex structure cannot be extended by telomerase, an enzyme over-expressed in many cancer cells. Understanding the kinetic, thermodynamic and mechanical properties of small-molecule binding to these structures is therefore important, but classical ensemble assays are unable to measure these simultaneously. Here, we have used a laser tweezers method to investigate such interactions. With a force jump approach, we observe that pyridostatin promotes the folding of telomeric G-quadruplexes. The increased mechanical stability of pyridostatin-bound G-quadruplex permits the determination of a dissociation constant K </sub>d</sub> of 490 ± 80 nM. The free-energy change of binding obtained from a Hess-like process provides an identical K </sub>d</sub> for pyridostatin and a K </sub>d</sub> of 42 ± 3 µM for a weaker ligand RR110. We anticipate that this single-molecule platform can provide detailed insights into the mechanical, kinetic and thermodynamic properties of liganded bio-macromolecules, which have biological relevance.