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1a8w
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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== | |
| - | + | <StructureSection load='1a8w' size='340' side='right'caption='[[1a8w]]' scene=''> | |
| - | + | == Structural highlights == | |
| - | + | <table><tr><td colspan='2'>[[1a8w]] is a 2 chain structure. Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A8W OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1A8W FirstGlance]. <br> | |
| - | + | </td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Solution NMR</td></tr> | |
| - | + | <tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[https://proteopedia.org/fgij/fg.htm?mol=1a8w FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1a8w OCA], [https://pdbe.org/1a8w PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1a8w RCSB], [https://www.ebi.ac.uk/pdbsum/1a8w PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1a8w ProSAT]</span></td></tr> | |
| - | + | </table> | |
| - | + | <div style="background-color:#fffaf0;"> | |
| - | + | == Publication Abstract from PubMed == | |
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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. | 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. | ||
| - | + | 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<ref>PMID:9737927</ref> | |
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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., Bouaziz S, Kettani A, Patel DJ | + | |
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| - | + | From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.<br> | |
| + | </div> | ||
| + | <div class="pdbe-citations 1a8w" style="background-color:#fffaf0;"></div> | ||
| + | == References == | ||
| + | <references/> | ||
| + | __TOC__ | ||
| + | </StructureSection> | ||
| + | [[Category: Large Structures]] | ||
| + | [[Category: Bouaziz S]] | ||
| + | [[Category: Kettani A]] | ||
| + | [[Category: Patel DJ]] | ||
Current revision
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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