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'''A K+ CATION-INDUCED CONFORMATIONAL SWITCH WITHIN A LOOP SPANNING SEGMENT OF A DNA QUADRUPLEX CONTAINING G-G-G-C REPEATS, NMR, 8 STRUCTURES''' | '''A K+ CATION-INDUCED CONFORMATIONAL SWITCH WITHIN A LOOP SPANNING SEGMENT OF A DNA QUADRUPLEX CONTAINING G-G-G-C REPEATS, NMR, 8 STRUCTURES''' | ||
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==About this Structure== | ==About this Structure== | ||
Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A8W OCA]. | |||
==Reference== | ==Reference== | ||
A K cation-induced conformational switch within a loop spanning segment of a DNA quadruplex containing G-G-G-C repeats., Bouaziz S, Kettani A, Patel DJ, J Mol Biol. 1998 Sep 25;282(3):637-52. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9737927 9737927] | A K cation-induced conformational switch within a loop spanning segment of a DNA quadruplex containing G-G-G-C repeats., Bouaziz S, Kettani A, Patel DJ, J Mol Biol. 1998 Sep 25;282(3):637-52. PMID:[http://www.ncbi.nlm.nih.gov/pubmed/9737927 9737927] | ||
[[Category: Bouaziz, S.]] | [[Category: Bouaziz, S.]] | ||
[[Category: Kettani, A.]] | [[Category: Kettani, A.]] | ||
[[Category: Patel, D J.]] | [[Category: Patel, D J.]] | ||
[[Category: | [[Category: Cation dependent conformational transition]] | ||
[[Category: | [[Category: Deoxyribonucleic acid]] | ||
[[Category: | [[Category: Dna quadruplexes targeted to hiv integrase]] | ||
[[Category: | [[Category: G-g-g-c repeat-containing dna quadruplex]] | ||
[[Category: | [[Category: K+ cation coordination site]] | ||
[[Category: | [[Category: K+ cation encapsulation within a hairpin loop]] | ||
[[Category: | [[Category: Monovalent]] | ||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Fri May 2 09:59:39 2008'' | |||
''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on | |||
Revision as of 09:59, 2 May 2008
A K+ CATION-INDUCED CONFORMATIONAL SWITCH WITHIN A LOOP SPANNING SEGMENT OF A DNA QUADRUPLEX CONTAINING G-G-G-C REPEATS, NMR, 8 STRUCTURES
OverviewOverview
We have identified a unique structural transition (in slow exchange on the NMR time scale) in the tertiary fold of the d(G-G-G-C-T4-G-G-G-C) quadruplex on proceeding from Na+ to K+ as counterion in aqueous solution. Both monovalent cation-dependent conformations exhibit certain common structural features, which include head-to-tail dimerization of two symmetry-related stem-hairpin loops, adjacent strands which are antiparallel to each other and adjacent stacked G(syn).G(anti). G(syn).G(anti) tetrads in the central core of the quadruplexes. The Na and K cation stabilized structures of the d(G-G-G-C-T4-G-G-G-C) quadruplexes differ in the conformations of the T-T-T-T loops, the relative alignment of G.C base-pairs positioned opposite each other through their major groove edges and potentially in the number of monovalent cation binding sites. We have identified potential K cation binding cavities within the symmetry-related T-T-T-G segments, suggesting the potential for two additional monovalent cation binding sites in the K cation-stabilized quadruplex relative to its Na cation-stabilized counterpart. Modeling studies suggest that the major groove edges of guanine residues in Watson-Crick G.C base-pairs could potentially be bridged by coordinated K cations in the d(G-G-G-C-T4-G-G-G-C) quadruplex in KCl solution in contrast to formation of G.C.G.C tetrads for the corresponding quadruplex in NaCl solution. Our results defining the molecular basis of a Na to K cation-dependent conformational switch in the loop spanning segment of the d(G-G-G-C-T4-G-G-G-C) quadruplex may have relevance to recent observations that specific K cation coordinated loop conformations within quadruplexes exhibit inhibitory activity against HIV integrase.
About this StructureAbout this Structure
Full crystallographic information is available from OCA.
ReferenceReference
A K cation-induced conformational switch within a loop spanning segment of a DNA quadruplex containing G-G-G-C repeats., Bouaziz S, Kettani A, Patel DJ, J Mol Biol. 1998 Sep 25;282(3):637-52. PMID:9737927 Page seeded by OCA on Fri May 2 09:59:39 2008