Quadruplex Structure of D(G3T4G3) Stabilized by K+ or Na+ is an Asymmetric Hairpin Dimer
Overview
Authors
Affiliations
The ends of chromosomes contain repeats of guanine-rich sequences that can assume highly compact conformations and are presumed necessary for their biological role in chromosomal stabilization and association. We have investigated the conformational behavior of d(G3T4G3) as a function of the addition of either KCl or NaCl, in the concentration range of 50-200 mM, by using a spectrum of physical techniques and conclude that these salts induce a quadruplex species composed of two strands, each in a hairpin conformation. When salt is added, a large positive signal appears near 290 nm in the CD spectra. UV thermal denaturation curves show a single concentration-dependent transition and provide data for quantitating the thermodynamics of quadruplex formation. In electrophoresis experiments, the quadruplex structure migrates as a single species and more rapidly than the unstructured single strand. NMR spectra in the presence of KCl or NaCl indicate that the structure formed is asymmetric. Equilibrium ultracentrifugation studies confirm that these quadruplexes are composed of two strands of d(G3T4G3). Possible models for this structure are discussed.
McCarte B, Yeung O, Speakman A, Elfick A, Dunn K Biochem Biophys Rep. 2022; 31:101293.
PMID: 35677630 PMC: 9167695. DOI: 10.1016/j.bbrep.2022.101293.
Cation competition and recruitment around the c-kit1 G-quadruplex using polarizable simulations.
Salsbury A, Lemkul J Biophys J. 2021; 120(11):2249-2261.
PMID: 33794153 PMC: 8390831. DOI: 10.1016/j.bpj.2021.03.022.
Origin of Ion Specificity of Telomeric DNA G-Quadruplexes Investigated by Free-Energy Simulations.
Siebenmorgen T, Zacharias M Biophys J. 2017; 112(11):2280-2290.
PMID: 28591601 PMC: 5474742. DOI: 10.1016/j.bpj.2017.04.036.
In-cell optical imaging of exogenous G-quadruplex DNA by fluorogenic ligands.
Tseng T, Wang Z, Chien C, Chang T Nucleic Acids Res. 2013; 41(22):10605-18.
PMID: 24030712 PMC: 3905880. DOI: 10.1093/nar/gkt814.
Virgilio A, Esposito V, Citarella G, Pepe A, Mayol L, Galeone A Nucleic Acids Res. 2011; 40(1):461-75.
PMID: 21908403 PMC: 3245916. DOI: 10.1093/nar/gkr670.