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1nzm

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{{STRUCTURE_1nzm| PDB=1nzm | SCENE= }}
{{STRUCTURE_1nzm| PDB=1nzm | SCENE= }}
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'''NMR structure of the parallel-stranded DNA quadruplex d(TTAGGGT)4 complexed with the telomerase inhibitor RHPS4'''
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===NMR structure of the parallel-stranded DNA quadruplex d(TTAGGGT)4 complexed with the telomerase inhibitor RHPS4===
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==Overview==
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The NMR structure of the parallel-stranded DNA quadruplex d(TTAGGGT)(4), containing the human telomeric repeat, has been determined in solution in complex with a fluorinated pentacyclic quino[4,3,2-kl]acridinium cation (RHPS4). RHPS4 has been identified as a potent inhibitor of telomerase at submicromolar levels (IC(50) value of 0.33(+/-0.13)microM), exhibiting a wide differential between telomerase inhibition and acute cellular toxicity. All of the data point to RHPS4 exerting its chemotherapeutic potency through interaction with, and stabilisation of, four-stranded G-quadruplex structures. RHPS4 forms a dynamic interaction with d(TTAGGGT)(4), as evident from 1H and 19F linewidths, with fast exchange between binding sites induced at 318 K. Perturbations to DNA chemical shifts and 24 intermolecular nuclear Overhauser effects (NOEs) identify the 5'-ApG and 5'-GpT steps as the principle intercalation sites; a structural model has been refined using NOE-restrained molecular dynamics. The central G-tetrad core remains intact, with drug molecules stacking at the ends of the G-quadruplex. The partial positive charge on position 13-N of the acridine ring appears to act as a "pseudo" potassium ion and is positioned above the centre of the G-tetrad in the region of high negative charge density. In both ApG and GpT intercalation sites, the drug is seen to converge to the same orientation in which the pi-system of the drug overlaps primarily with two bases of each G-tetrad. The drug is held in place by stacking interactions with the G-tetrads; however, there is some evidence for a more dynamic, weakly stabilised A-tetrad that stacks partially on top of the drug at the 5'-end of the sequence. Together, the interactions of RHPS4 increase the t(m) of the quadruplex by approximately 20 degrees C. There is no evidence for drug intercalation within the G-quadruplex; however, the structural model strongly supports end-stacking interactions with the terminal G-tetrads.
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(as it appears on PubMed at http://www.pubmed.gov), where 14596797 is the PubMed ID number.
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{{ABSTRACT_PUBMED_14596797}}
==About this Structure==
==About this Structure==
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Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NZM OCA].
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Full experimental information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1NZM OCA].
==Reference==
==Reference==
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[[Category: Telomere]]
[[Category: Telomere]]
[[Category: Ttagggt repeat]]
[[Category: Ttagggt repeat]]
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Sat May 3 03:10:57 2008''
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''Page seeded by [http://oca.weizmann.ac.il/oca OCA ] on Tue Jul 29 16:36:03 2008''

Revision as of 13:36, 29 July 2008

Image:1nzm.png

Template:STRUCTURE 1nzm

NMR structure of the parallel-stranded DNA quadruplex d(TTAGGGT)4 complexed with the telomerase inhibitor RHPS4

Template:ABSTRACT PUBMED 14596797

About this Structure

Full experimental information is available from OCA.

Reference

Drug recognition and stabilisation of the parallel-stranded DNA quadruplex d(TTAGGGT)4 containing the human telomeric repeat., Gavathiotis E, Heald RA, Stevens MF, Searle MS, J Mol Biol. 2003 Nov 14;334(1):25-36. PMID:14596797

Page seeded by OCA on Tue Jul 29 16:36:03 2008

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