A sodium-potassium switch in the formation of four-stranded G4-DNA

Sen, Dipankar; Gilbert, Walter

doi:10.1038/344410a0

Cited by 794 publications

(710 citation statements)

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“…At low temperatures, K+ stabilized conformations that did not lead to G-wire formation. These structures were most likely hairpin dimers (G'2-DNA), which is consistent with previous reports (Sundquist & Klug, 1989;Sen & Gilbert, 1990). Although Na+ may facilitate the formation of the same conformations as K+, it may not stabilize them as well as K+.…”

Section: Discussionsupporting

confidence: 92%

“…Many G-rich telomeric oligomers can form a family of related structures containing G-quartets (G-DNA). For example, a single repeat of the Tetrahymena telomeric G-strand sequence TGGGGT will adopt a four-stranded parallel quadruplex (Aboul-ela et al, 1992) while two repeats, (T2G4)2, can adopt either a four-stranded parallel quadruplex known as G4-DNA or an anti-parallel hairpin dimer quadruplex known as G'2-DNA (Sen & Gilbert, 1990). For the two repeat molecules, the preference of one conformation over the other is most influenced by the monovalent cation present (Na+ or K+) and DNA concentration.…”

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“…For the two repeat molecules, the preference of one conformation over the other is most influenced by the monovalent cation present (Na+ or K+) and DNA concentration. The ability of different monovalent cations to affect G-DNA conformation has been termed the Na+/K+ switch (Sen & Gilbert, 1990).…”

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confidence: 99%

“…K+ facilitates the formation of G'2-DNA by G-rich sequences due to its superior stabilizing ability. However, in Na+ the same sequences will adopt the G'2-DNA conformation but will also be found in the more stable G4-DNA conformation (Sen & Gilbert, 1990). The length of the G-rich oligomer also affects which conformation it will adopt.…”

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G-Wires: Self-Assembly of a Telomeric Oligonucleotide, d(GGGGTTGGGG), into Large Superstructures

Marsh¹,

Henderson²

1994

Biochemistry

157

150

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The telomeric DNA oligonucleotide 5'-G4T2G4-3' (Tet 1.5) spontaneously assembles into large superstructures we have termed G-wires. G-wires can be resolved by gel electrophoresis as a ladder pattern.The self-association of Tet 1.5 is noncovalent and exhibits characteristics of G4-DNA, a parallel fourstranded structure stabilized by guanine tetrads. Formation of G-wires is dependent upon the presence of Na+ and/or K+, and once formed, G-wires are resistant to denaturation. The results described here extend our understanding of the structural potential of G-rich nucleic acids and may provide insight into the * To whom correspondence should be addressed.

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Section: Discussionsupporting

confidence: 92%

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confidence: 99%

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G-Wires: Self-Assembly of a Telomeric Oligonucleotide, d(GGGGTTGGGG), into Large Superstructures

Marsh¹,

Henderson²

1994

Biochemistry

157

150

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“…Sen and Gilbert observed that the formation of the four-stranded parallel quadruplexes was anomalously dependent on the species of alkali metal cation in the solution. They proposed that the bimolecular foldback quadruplexes were "overstabilized" intermediates and expected that all of the quadruplexes that were formed by single-or double-folded strands could finally be converted to four-stranded parallel structures [30]. Miura et al, using Raman spectroscopy, detected the transition of the antiparallel bimolecular [d(G 4 G 4 )] 2 to the parallel four-stranded structure in the solution containing Na ϩ and K ϩ by changing the K ϩ /Na ϩ ratio [31].…”

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Bimolecular quadruplexes and their transitions to higher-order molecular structures detected by ESI-FTICR-MS

Guo

Liu

2007

J. Am. Soc. Mass Spectrom.

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Four individual quadruplexes, which are self-assembled in ammonium acetate solution from telomeric sequences of closely related DNA strands-d(G 4 T 4 G 4 ), d(G 3 T 4 G 4 ), d(G 3 T 4 G 3 ), and d(G 4 T 4 G 3 )-have been detected in the gas phase using electrospray ionization Fourier transform ion cyclotron resonance mass spectrometry (ESI-FTICR-MS). The bimolecular quadruplexes associate with the same number of NH 4 ϩ in the gas phase as NMR shows that they do in solution. The quadruplex structures formed in solution are maintained in the gas phase. Furthermore, the mass spectra show that the bimolecular quadruplexes generated by the strands d( Of particular interest is a telomeric DNA that consists of repeating sequences, such as TTAGGG in vertebrates and TTTTGGGG in Oxytricha. These sequences have been proven to fold into quadruplexes in vitro and potentially have the function of inhibiting telomerase activities. The telomerase, a reverse enzyme expressed in more than 80% of tumor cells, responds for the replication of the telomeric DNA and has been considered as a target for anticancer drug design [4,5]. Guanine-rich oligonucleotides can also self-associate into higher-order structures, such as supermolecular G-wires [6], which serve as artificial ion channels and ion receptors and which have a wide range of applications in medicine, materials science, and nanotechnology [2,7,8].DNA quadruplex structures can be formed from one, two, or four oligonucleotide strands and are stabilized by coordinated monovalent cations acting between adjacent G-quartets [1, 9 -11]. The strands with single repeating guanine sequences usually arrange themselves from the 5= to the 3= end in parallel four-stranded quadruplexes, whereas the strands with more than two tracks of repeating guanine units can form a number of quadruplexes that are distinguished by their strand number, strand orientation, and loop types. The structural topologies of DNA quadruplexes also drastically change with slight changes of the DNA sequences, with the nature of the cationic species and with their concentrations in solution. As a result, the structures of DNA quadruplexes are far from being fully recognized and have been of concern to researchers because of their potential implications in biological and structural applications.Development in electrospray ionization mass spectrometry (ESI-MS) has been shown to be superior in the analysis of DNA noncovalent complexes in terms of speed, sensitivity, stoichiometry, and specificity compared to other analytical techniques [12]. Previous work by ourselves and others have shown that some specific DNA conformations, such as hairpins, triplexes, and quadruplexes formed in solution, can survive in the gas phase [13][14][15][16][17][18][19][20]. This prompted us to explore the structural properties of DNA quadruplexes with ESI-MS so as to add new information concerning them.

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