Cation-mediated energy transfer in G-quadruplexes revealed by an internal fluorescent probe.
A single pyridine unit incorporated into G-quadruplex DNA has revealed efficient energy transfer reactions in cation-containing G-quadruplexes. 8-(2-Pyridyl)-2'-deoxyguanosine, "2PyG", is a highly sensitive internal fluorescent probe of G-quadruplex folding and energy transfer. 2PyG was minimally disruptive to G-quadruplex folding and exhibited intense fluorescence, even when it was base-stacked with other guanine residues. Using 2PyG we have quantified energy transfer efficiencies within G-quadruplex structures prepared under conditions of excess Na(+)/K(+) (110 mM) or in 40% polyethylene glycol (PEG) under salt deficient conditions. G-quadruplex structures containing coordinated cations exhibited efficient DNA-to-probe energy transfer reactions (η(t) = 0.11-0.41), while PEG-folded G-quadruplexes exhibited very little energy transfer (η(t) = 0.02-0.07). Experiments conducted using unmodified G-quadruplexes suggest that cation coordination at the O(6) position of guanine residues results in enhanced quantum yields of G-quadruplex nucleobases that, in turn, serve as efficient energy donors to 2PyG. Given the growing interest in G-quadruplex-based devices and materials, these results will provide important design principles toward harnessing the potentially useful photophysical properties of G-quadruplex wires and other G-rich structures.
Institute of Organic Chemistry, University of Zürich, Winterthurerstrasse 190, CH-8057, Switzerland.
Anaëlle
A
Dumas
Nathan W
NW
Luedtke
D002412:Cations / Q000737:chemistry; D003849:Deoxyguanosine / Q000031:analogs & derivatives* / Q000737:chemistry; D004735:Energy Transfer; D005456:Fluorescent Dyes / Q000737:chemistry*; D054856:G-Quadruplexes; D011188:Potassium / Q000737:chemistry; D012964:Sodium / Q000737:chemistry
C557779:8-(2-pyridyl)-2-deoxyguanosine; D002412:Cations; D005456:Fluorescent Dyes; D012964:Sodium; D003849:Deoxyguanosine; D011188:Potassium