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Vertebrate telomere repeat DNAs favor external loop propeller quadruplex structures in the presence of high concentrations of potassium.

Rujan IN, Meleney JC, Bolton PH - Nucleic Acids Res. (2005)

Bottom Line: Anti-parallel quadruplex structures are favored in the presence of high concentrations, 140 mM, of sodium.External loop, also known as propeller, parallel type structures are favored in the presence of high concentrations, 100 mM, of potassium in the presence of either 5 or 140 mM sodium.These results indicate that the external loop structures may be present in vertebrate telomeres under the conditions of high potassium and low sodium concentration found in nuclei.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Department, Wesleyan University Middletown, CT 06459, USA.

ABSTRACT
The circular dichroism, CD, spectra of the telomere repeats of vertebrates, d(TTAGGG), indicate that parallel type quadruplex structures or disordered single-stranded structures are formed in low salt. Anti-parallel quadruplex structures are favored in the presence of high concentrations, 140 mM, of sodium. External loop, also known as propeller, parallel type structures are favored in the presence of high concentrations, 100 mM, of potassium in the presence of either 5 or 140 mM sodium. The cation dependence of the CD spectra of the vertebrate telomere repeat DNAs is distinctly different from that of the telomere repeats of Tetrahymena and Oxytricha as well as that of the thrombin binding aptamer. These results indicate that the external loop structures may be present in vertebrate telomeres under the conditions of high potassium and low sodium concentration found in nuclei.

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Related in: MedlinePlus

The CD spectra of d(GGGGTTTTGGGG) and d(TGGGGTTGGGGT) in the presence of 5 and 140 mM sodium are shown in the upper panels. The CD spectra of these DNAs in the presence of 5 mM sodium with 0, 1, 10 or 100 mM potassium are shown in the middle panels. In the upper panels, the CD spectra of these DNAs in the presence of 140 mM sodium with 0, 1, 10 or 100 mM potassium are shown.
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fig6: The CD spectra of d(GGGGTTTTGGGG) and d(TGGGGTTGGGGT) in the presence of 5 and 140 mM sodium are shown in the upper panels. The CD spectra of these DNAs in the presence of 5 mM sodium with 0, 1, 10 or 100 mM potassium are shown in the middle panels. In the upper panels, the CD spectra of these DNAs in the presence of 140 mM sodium with 0, 1, 10 or 100 mM potassium are shown.

Mentions: In contrast to the behavior of the DNAs containing vertebrate telomere repeats the CD spectrum of the Oxytricha repeat DNA, d(GGGGTTTTGGGG), is of the anti-parallel type under all the conditions examined, as shown in the results in Figure 6. An NMR-based study showed that the addition of potassium to this DNA alters the loop structure but not the basket type anti-parallel quartet structure (13). The structure of a DNA containing four repeats of the Oxytricha sequence has been shown to form an anti-parallel structure in the presence of 100 mM sodium (48).


Vertebrate telomere repeat DNAs favor external loop propeller quadruplex structures in the presence of high concentrations of potassium.

Rujan IN, Meleney JC, Bolton PH - Nucleic Acids Res. (2005)

The CD spectra of d(GGGGTTTTGGGG) and d(TGGGGTTGGGGT) in the presence of 5 and 140 mM sodium are shown in the upper panels. The CD spectra of these DNAs in the presence of 5 mM sodium with 0, 1, 10 or 100 mM potassium are shown in the middle panels. In the upper panels, the CD spectra of these DNAs in the presence of 140 mM sodium with 0, 1, 10 or 100 mM potassium are shown.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC1074753&req=5

fig6: The CD spectra of d(GGGGTTTTGGGG) and d(TGGGGTTGGGGT) in the presence of 5 and 140 mM sodium are shown in the upper panels. The CD spectra of these DNAs in the presence of 5 mM sodium with 0, 1, 10 or 100 mM potassium are shown in the middle panels. In the upper panels, the CD spectra of these DNAs in the presence of 140 mM sodium with 0, 1, 10 or 100 mM potassium are shown.
Mentions: In contrast to the behavior of the DNAs containing vertebrate telomere repeats the CD spectrum of the Oxytricha repeat DNA, d(GGGGTTTTGGGG), is of the anti-parallel type under all the conditions examined, as shown in the results in Figure 6. An NMR-based study showed that the addition of potassium to this DNA alters the loop structure but not the basket type anti-parallel quartet structure (13). The structure of a DNA containing four repeats of the Oxytricha sequence has been shown to form an anti-parallel structure in the presence of 100 mM sodium (48).

Bottom Line: Anti-parallel quadruplex structures are favored in the presence of high concentrations, 140 mM, of sodium.External loop, also known as propeller, parallel type structures are favored in the presence of high concentrations, 100 mM, of potassium in the presence of either 5 or 140 mM sodium.These results indicate that the external loop structures may be present in vertebrate telomeres under the conditions of high potassium and low sodium concentration found in nuclei.

View Article: PubMed Central - PubMed

Affiliation: Chemistry Department, Wesleyan University Middletown, CT 06459, USA.

ABSTRACT
The circular dichroism, CD, spectra of the telomere repeats of vertebrates, d(TTAGGG), indicate that parallel type quadruplex structures or disordered single-stranded structures are formed in low salt. Anti-parallel quadruplex structures are favored in the presence of high concentrations, 140 mM, of sodium. External loop, also known as propeller, parallel type structures are favored in the presence of high concentrations, 100 mM, of potassium in the presence of either 5 or 140 mM sodium. The cation dependence of the CD spectra of the vertebrate telomere repeat DNAs is distinctly different from that of the telomere repeats of Tetrahymena and Oxytricha as well as that of the thrombin binding aptamer. These results indicate that the external loop structures may be present in vertebrate telomeres under the conditions of high potassium and low sodium concentration found in nuclei.

Show MeSH
Related in: MedlinePlus