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| | {{STRUCTURE_1a6h| PDB=1a6h | SCENE= }} | | {{STRUCTURE_1a6h| PDB=1a6h | SCENE= }} |
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| - | '''DNA QUADRUPLEX CONTAINING GCGC TETRAD, NMR, 4 STRUCTURES'''
| + | ===DNA QUADRUPLEX CONTAINING GCGC TETRAD, NMR, 4 STRUCTURES=== |
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| - | ==Overview==
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| - | Both X-ray and NMR structural studies have defined the polymorphic nature of G-quadruplexes generated through mutual stacking of G.G.G.G tetrads by guanine rich telomeric sequences. Recently, the fragile X syndrome d(C-G-G)n triplet nucleotide repeat has been shown to form a stable quadruplex of undefined structure in monovalent cation solution. We have undertaken a structural characterization of the d(G-C-G-G-T3-G-C-G-G) undecanucleotide to elucidate the structural alignments associated with quadruplex formation by this oligomer which contains sequence elements associated with the fragile X syndrome triplet repeat. d(G-C-G-G-T3-G-C-G-G) in Na+ cation solution forms a quadruplex through dimerization of two symmetry related hairpins with the lateral connecting T3 loops positioned at opposite ends of the quadruplex. This novel NMR-molecular dynamics based solution structure contains internal G.C.G.C tetrads sandwiched between terminal G.G.G.G tetrads. Watson-Crick G.C base-pairs within individual hairpins dimerize through their major groove edges using bifurcated hydrogen bonds to form internal G(anti).C(anti).G(anti).C(anti) tetrads. Adjacent strands are anti-parallel to each other around the symmetric G-quadruplex which contains two distinct narrow and two symmetric wide grooves. By contrast, the terminal G-tetrads adopt G(syn).G(anti).G(syn).G(anti) alignments. The structure of the d(G-C-G-G-T3-G-C-G-G) quadruplex with its multi-layer arrangement of G.G.G.G and G.C.G.C tetrads greatly expands on our current knowledge of quadruplex folding topologies. Our results establish the pairing alignments that can be potentially utilized by the fragile X syndrome triplet repeat to form quadruplex structures through dimerization of hairpin stems. The formation of novel G.C.G.C tetrads through dimerization of Watson-Crick G.C base-pairs is directly relevant to the potential pairing alignments of helical stems in genetic recombination.
| + | The line below this paragraph, {{ABSTRACT_PUBMED_7500339}}, adds the Publication Abstract to the page |
| | + | (as it appears on PubMed at http://www.pubmed.gov), where 7500339 is the PubMed ID number. |
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| | + | {{ABSTRACT_PUBMED_7500339}} |
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| | ==About this Structure== | | ==About this Structure== |
| - | This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=228d 228d]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A6H OCA]. | + | This structure supersedes the now removed PDB entry [http://oca.weizmann.ac.il/oca-bin/send-pdb?obs=1&id=228d 228d]. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A6H OCA]. |
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| | ==Reference== | | ==Reference== |
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| | [[Category: Fragile x syndrome]] | | [[Category: Fragile x syndrome]] |
| | [[Category: Gcgc tetrad]] | | [[Category: Gcgc tetrad]] |
| - | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 09:53:20 2008'' | + | |
| | + | ''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Mon Jun 30 16:14:48 2008'' |
Revision as of 13:14, 30 June 2008
Template:STRUCTURE 1a6h
DNA QUADRUPLEX CONTAINING GCGC TETRAD, NMR, 4 STRUCTURES
Template:ABSTRACT PUBMED 7500339
About this Structure
This structure supersedes the now removed PDB entry 228d. Full experimental information is available from OCA.
Reference
Solution structure of a DNA quadruplex containing the fragile X syndrome triplet repeat., Kettani A, Kumar RA, Patel DJ, J Mol Biol. 1995 Dec 8;254(4):638-56. PMID:7500339
Page seeded by OCA on Mon Jun 30 16:14:48 2008
