Stability of intramolecular DNA quadruplexes: comparison with DNA duplexes
Stability of intramolecular DNA quadruplexes: comparison with DNA duplexes
We have determined the stability of intramolecular quadruplexes that are formed by a variety of G-rich sequences, using oligonucleotides containing appropriately placed fluorophores and quenchers. The stability of these quadruplexes is compared with that of the DNA duplexes that are formed on addition of complementary C-rich oligonucleotides. We find that the linkers joining the G-tracts are not essential for folding and can be replaced with nonnucleosidic moieties, though their sequence composition profoundly affects quadruplex stability. Although the human telomere repeat sequence d[G(3)(TTAG(3))(3)] folds into a quadruplex structure, this forms a duplex in the presence of the complementary C-rich strand at physiological conditions. The Tetrahymena sequence d[G(4)(T(2)G(4))(3)], the sequence d[G(3)(T(2)G(3))(3)], and sequences related to regions of the c-myc promoter d(G(4)AG(4)T)(2) and d(G(4)AG(3)T)(2) preferentially adopt the quadruplex form in potassium-containing buffers, even in the presence of a 50-fold excess of their complementary C-rich strands, though the duplex predominates in the presence of sodium. The HIV integrase inhibitor d[G(3)(TG(3))(3)] forms an extremely stable quadruplex which is not affected by addition of a 50-fold excess of the complementary C-rich strand in both potassium- and sodium-containing buffers. Replacing the TTA loops of the human telomeric repeat with AAA causes a large decrease in quadruplex stability, though a sequence with AAA in the first loop and TTT in the second and third loops is slightly more stable.
6507-6513
Risitano, A.
cf59ac40-0ade-4e18-ab7e-354b4026b8a3
Fox, K.R.
9da5debc-4e45-473e-ab8c-550d1104659f
5 August 2003
Risitano, A.
cf59ac40-0ade-4e18-ab7e-354b4026b8a3
Fox, K.R.
9da5debc-4e45-473e-ab8c-550d1104659f
Risitano, A. and Fox, K.R.
(2003)
Stability of intramolecular DNA quadruplexes: comparison with DNA duplexes.
Biochemistry, 42 (21), .
(doi:10.1021/bi026997v).
Abstract
We have determined the stability of intramolecular quadruplexes that are formed by a variety of G-rich sequences, using oligonucleotides containing appropriately placed fluorophores and quenchers. The stability of these quadruplexes is compared with that of the DNA duplexes that are formed on addition of complementary C-rich oligonucleotides. We find that the linkers joining the G-tracts are not essential for folding and can be replaced with nonnucleosidic moieties, though their sequence composition profoundly affects quadruplex stability. Although the human telomere repeat sequence d[G(3)(TTAG(3))(3)] folds into a quadruplex structure, this forms a duplex in the presence of the complementary C-rich strand at physiological conditions. The Tetrahymena sequence d[G(4)(T(2)G(4))(3)], the sequence d[G(3)(T(2)G(3))(3)], and sequences related to regions of the c-myc promoter d(G(4)AG(4)T)(2) and d(G(4)AG(3)T)(2) preferentially adopt the quadruplex form in potassium-containing buffers, even in the presence of a 50-fold excess of their complementary C-rich strands, though the duplex predominates in the presence of sodium. The HIV integrase inhibitor d[G(3)(TG(3))(3)] forms an extremely stable quadruplex which is not affected by addition of a 50-fold excess of the complementary C-rich strand in both potassium- and sodium-containing buffers. Replacing the TTA loops of the human telomeric repeat with AAA causes a large decrease in quadruplex stability, though a sequence with AAA in the first loop and TTT in the second and third loops is slightly more stable.
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Submitted date: 14 October 2002
Published date: 5 August 2003
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Local EPrints ID: 24244
URI: http://eprints.soton.ac.uk/id/eprint/24244
ISSN: 0006-2960
PURE UUID: 85dc6f87-e70f-4a63-887b-3282a92cdf29
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Date deposited: 29 Mar 2006
Last modified: 16 Mar 2024 02:36
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A. Risitano
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