title: DNA mechatronic devices switched by K⁺ and by Sr²⁺ are structurally, topologically, and electronically distinct.
abstract: DNAs and RNAs that fold via the formation of guanine quartets form G-quadruplexes that are often highly diverse in terms of architecture and topology. G-quadruplexes are specifically stabilized by metal cations such as K(+) and Sr(2+), but not Li(+). DNA duplexes that incorporate two separated clusters of G•G mismatches ("P-duplexes") can function as electronic switches, capable of toggling reversibly from a poorly conductive conformer (E) with only Li(+) in the solution to a G-quadruplex incorporating conformer of higher conductivity (C) in the presence of K(+). Herein, we report results from fluorescence energy transfer, circular dichroism, charge conduction, and chemical footprinting experiments, which cumulatively demonstrate that P-duplex E↔C transitions are genuinely mechatronic, with causally coupled mechanical and electronic states. We show, further, that the K(+) - and the Sr(2+)-fuelled E↔C switching of a given P-duplex are structurally, topologically, and electronically distinct from each other. A single DNA P-duplex can thus exist in at least three distinguishable mechatronic states in aqueous solution.
authors.affiliation: Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, B C V5A 1S6, Canada.
authors.forename: Yu Chuan
authors.initials: YC
authors.lastname: Huang
authors.affiliation: Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, B C V5A 1S6, Canada.|Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Hua-Zhong
authors.initials: HZ
authors.lastname: Yu
authors.affiliation: Department of Molecular Biology & Biochemistry, Simon Fraser University, Burnaby, B C V5A 1S6, Canada.|Department of Chemistry, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada.
authors.forename: Dipankar
authors.initials: D
authors.lastname: Sen
mesh_terms: D004247:DNA / Q000737:chemistry*; D054856:G-Quadruplexes; D011188:Potassium / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry*
chemical_list: D004247:DNA; D011188:Potassium; D013324:Strontium
keywords: DNA; DNA machine; G-quadruplex; P-duplexes; contractile switch; hole conduction; synapsable DNA