title: Sr(2+) induces unusually stable d(GGGTGGGTGGGTGGG) quadruplex dimers.
abstract: Guanine-rich sequences are able to form quadruplexes consisting of G-quartet structural units. Quadruplexes play an important role in the regulation of gene expression and have therapeutic and biotechnological potential. The HIV-1 integrase inhibitor, (GGGT)4 , and its variants demonstrate unusually high thermal stability. This property has been exploited in the use of quadruplex formation to drive various endergonic reactions of nucleic acids such as isothermal DNA amplification. Quadruplex stability is mainly determined by cations, which specifically bind into the inner core of the structure. In the present work, we report a systematic study of a variant of the HIV-1 integrase inhibitor, GGGTGGGTGGGTGGG (G3T), in the presence of alkali and alkaline-earth cations. We show that Sr(2+) -G3T is characterized by the highest thermal stability and that quadruplex formation requires only one Sr(2+) ion that binds with low micromolar affinity. These concentrations are sufficient to drive robust isothermal quadruplex priming DNA amplification reaction. The Sr(2+) -quadruplexes are also able to form unusually stable dimers through end-to-end stacking. The multimerization can be induced by a combination of quadruplex forming cations (i.e., K(+) or Sr(2+) ) and non-specific Mg(2+) .
authors.affiliation: Institute of Biophysics, Ilia State University, Tbilisi, 0162, Republic of Georgia.
authors.forename: Levan
authors.initials: L
authors.lastname: Lomidze
authors.affiliation: Department of Chemistry and Biochemistry, Center for RNA Biology, The Ohio State University, Columbus, OH, 43210.
authors.forename: Sean
authors.initials: S
authors.lastname: Kelley
authors.affiliation: Institute of Biophysics, Ilia State University, Tbilisi, 0162, Republic of Georgia.
authors.forename: Shota
authors.initials: S
authors.lastname: Gogichaishvili
authors.affiliation: Institute of Biophysics, Ilia State University, Tbilisi, 0162, Republic of Georgia.
authors.forename: Nunu
authors.initials: N
authors.lastname: Metreveli
authors.affiliation: Department of Chemistry and Biochemistry, Center for RNA Biology, The Ohio State University, Columbus, OH, 43210.
authors.forename: Karin
authors.initials: K
authors.lastname: Musier-Forsyth
authors.affiliation: Institute of Biophysics, Ilia State University, Tbilisi, 0162, Republic of Georgia.|Department of Chemistry and Biochemistry, Center for RNA Biology, The Ohio State University, Columbus, OH, 43210.
authors.forename: Besik
authors.initials: B
authors.lastname: Kankia
mesh_terms: D019428:HIV Integrase Inhibitors / Q000737:chemistry*; D009690:Nucleic Acid Conformation; D009838:Oligodeoxyribonucleotides / Q000737:chemistry*; D013324:Strontium / Q000737:chemistry*
chemical_list: D019428:HIV Integrase Inhibitors; D009838:Oligodeoxyribonucleotides; D013324:Strontium
keywords: G3T quadruplex; QPA amplification; Sr2+ cations; dimerization