1myq
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(New page: 200px<br /><applet load="1myq" size="450" color="white" frame="true" align="right" spinBox="true" caption="1myq" /> '''An intramolecular quadruplex of (GGA)(4) tri...)
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Revision as of 20:07, 24 November 2007
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An intramolecular quadruplex of (GGA)(4) triplet repeat DNA with a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad, and its dimeric interaction
Overview
The structure of d(GGAGGAGGAGGA) containing four tandem repeats of a GGA, triplet sequence has been determined under physiological K(+) conditions., d(GGAGGAGGAGGA) folds into an intramolecular quadruplex composed of a, G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad. Four G-G segments of, d(GGAGGAGGAGGA) are aligned parallel with each other due to six successive, turns of the main chain at each of the GGA and GAGG segments. Two, quadruplexes form a dimer stabilized through a stacking interaction, between the heptads of the two quadruplexes. Comparison of the structure, of d(GGAGGAGGAGGA) with the reported structure of d(GGAGGAN) (N=G or T), containing two tandem repeats of the GGA triplet revealed that although, the two structures resemble each other to some extent, the extension of, the repeats of the GGA triplet leads to distinct structural differences:, intramolecular quadruplex for 12-mer versus intermolecular quadruplex for, 7-mer; heptad versus hexad in the quadruplex; and three sheared G:A, base-pairs versus two sheared G:A base-pairs plus one A:A base-pair per, quadruplex. It was also suggested that d(GGAGGAGGAGGA) forms a similar, quadruplex under low salt concentration conditions. This is in contrast to, the case of d(GGAGGAN) (N=G or T), which forms a duplex under low salt, concentration conditions. On the basis of these results, the structure of, naturally occurring GGA triplet repeat DNA is discussed.
About this Structure
1MYQ is a Protein complex structure of sequences from [1]. Full crystallographic information is available from OCA.
Reference
An intramolecular quadruplex of (GGA)(4) triplet repeat DNA with a G:G:G:G tetrad and a G(:A):G(:A):G(:A):G heptad, and its dimeric interaction., Matsugami A, Ouhashi K, Kanagawa M, Liu H, Kanagawa S, Uesugi S, Katahira M, J Mol Biol. 2001 Oct 19;313(2):255-69. PMID:11800555
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