Title
Effects of metal ions and cosolutes on G-quadruplex topology
Author
Taiga Fujii, Peter Podbevšek, Janez Plavec, Naoki Sugimoto
Year
2016
Journal
Journal of Inorganic Biochemistry
Abstract
Topologies of G-quadruplexes depend on oligonucleotide sequences and on environmental factors, and the diversity of G-quadruplex topologies complicates investigation of functions of these nucleic acid structures. To investigate how metal ions and cosolutes regulate topologies of G-quadruplexes, we stabilized the antiparallel conformation by insertion of 2′-deoxyxanthosine and 8-oxo-2′-deoxyguanosine into selected positions of an oligonucleotide. Thermodynamic analyses of the oligonucleotide revealed that Na+ stabilized the antiparallel G-quadruplex, whereas K+ destabilized this topology. This result suggests that metal ions selectively stabilize G-quadruplex topologies with cavities between G-quartet planes of certain sizes. In the presence of KCl in 20 wt% poly(ethylene glycol) with average molecular weight of 200, the antiparallel basket-type G-quadruplex conformation was not stabilized compared with the dilute condition. In the presence of NaCl, the cosolute did stabilize the G-quadruplex with respect to the dilute condition. The presented data show that metal ions and cosolutes regulate topologies of G-quadruplexes through mechanisms that depend on sizes of metal ion cavities and hydration states.
Instrument
J-1500
Keywords
Circular dichroism, DNA structure, Chemical stability, Ligand binding, Thermal stability, Biochemistry