1k4t

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{{STRUCTURE_1k4t| PDB=1k4t | SCENE= }}
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==HUMAN DNA TOPOISOMERASE I (70 KDA) IN COMPLEX WITH THE POISON TOPOTECAN AND COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX==
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===HUMAN DNA TOPOISOMERASE I (70 KDA) IN COMPLEX WITH THE POISON TOPOTECAN AND COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX===
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<StructureSection load='1k4t' size='340' side='right' caption='[[1k4t]], [[Resolution|resolution]] 2.10&Aring;' scene=''>
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{{ABSTRACT_PUBMED_12426403}}
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== Structural highlights ==
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<table><tr><td colspan='2'>[[1k4t]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K4T OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1K4T FirstGlance]. <br>
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==Disease==
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</td></tr><tr><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=HG:MERCURY+(II)+ION'>HG</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=TTC:(S)-10-[(DIMETHYLAMINO)METHYL]-4-ETHYL-4,9-DIHYDROXY-1H-PYRANO[3,4 6,7]INOLIZINO[1,2-B]-QUINOLINE-3,14(4H,12H)-DIONE'>TTC</scene>, <scene name='pdbligand=TTG:2-(1-DIMETHYLAMINOMETHYL-2-HYDROXY-8-HYDROXYMETHYL-9-OXO-9,11-DIHYDRO-INDOLIZINO[1,2-B]QUINOLIN-7-YL)-2-HYDROXY-BUTYRIC+ACID'>TTG</scene><br>
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<tr><td class="sblockLbl"><b>[[Non-Standard_Residue|NonStd Res:]]</b></td><td class="sblockDat"><scene name='pdbligand=PTR:O-PHOSPHOTYROSINE'>PTR</scene>, <scene name='pdbligand=TGP:5-THIO-2-DEOXY-GUANOSINE+PHOSPHONIC+ACID'>TGP</scene></td></tr>
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<tr><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[1a35|1a35]], [[1a31|1a31]], [[1a36|1a36]], [[1k4s|1k4s]]</td></tr>
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<tr><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/DNA_topoisomerase DNA topoisomerase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=5.99.1.2 5.99.1.2] </span></td></tr>
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<tr><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1k4t FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1k4t OCA], [http://www.rcsb.org/pdb/explore.do?structureId=1k4t RCSB], [http://www.ebi.ac.uk/pdbsum/1k4t PDBsum]</span></td></tr>
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<table>
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== Disease ==
[[http://www.uniprot.org/uniprot/TOP1_HUMAN TOP1_HUMAN]] Note=A chromosomal aberration involving TOP1 is found in a form of therapy-related myelodysplastic syndrome. Translocation t(11;20)(p15;q11) with NUP98.
[[http://www.uniprot.org/uniprot/TOP1_HUMAN TOP1_HUMAN]] Note=A chromosomal aberration involving TOP1 is found in a form of therapy-related myelodysplastic syndrome. Translocation t(11;20)(p15;q11) with NUP98.
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== Function ==
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[[http://www.uniprot.org/uniprot/TOP1_HUMAN TOP1_HUMAN]] Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(3'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 5'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 5'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone (By similarity). Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells.<ref>PMID:2833744</ref> <ref>PMID:19168442</ref> <ref>PMID:14594810</ref> <ref>PMID:16033260</ref>
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== Evolutionary Conservation ==
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[[Image:Consurf_key_small.gif|200px|right]]
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Check<jmol>
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<jmolCheckbox>
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<scriptWhenChecked>select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/k4/1k4t_consurf.spt"</scriptWhenChecked>
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<scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.spt</scriptWhenUnchecked>
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<text>to colour the structure by Evolutionary Conservation</text>
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</jmolCheckbox>
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</jmol>, as determined by [http://consurfdb.tau.ac.il/ ConSurfDB]. You may read the [[Conservation%2C_Evolutionary|explanation]] of the method and the full data available from [http://bental.tau.ac.il/new_ConSurfDB/chain_selection.php?pdb_ID=2ata ConSurf].
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<div style="clear:both"></div>
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<div style="background-color:#fffaf0;">
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== Publication Abstract from PubMed ==
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We report the x-ray crystal structure of human topoisomerase I covalently joined to double-stranded DNA and bound to the clinically approved anticancer agent Topotecan. Topotecan mimics a DNA base pair and binds at the site of DNA cleavage by intercalating between the upstream (-1) and downstream (+1) base pairs. Intercalation displaces the downstream DNA, thus preventing religation of the cleaved strand. By specifically binding to the enzyme-substrate complex, Topotecan acts as an uncompetitive inhibitor. The structure can explain several of the known structure-activity relationships of the camptothecin family of anticancer drugs and suggests that there are at least two classes of mutations that can produce a drug-resistant enzyme. The first class includes changes to residues that contribute to direct interactions with the drug, whereas a second class would alter interactions with the DNA and thereby destabilize the drug-binding site.
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==Function==
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The mechanism of topoisomerase I poisoning by a camptothecin analog.,Staker BL, Hjerrild K, Feese MD, Behnke CA, Burgin AB Jr, Stewart L Proc Natl Acad Sci U S A. 2002 Nov 26;99(24):15387-92. Epub 2002 Nov 8. PMID:12426403<ref>PMID:12426403</ref>
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[[http://www.uniprot.org/uniprot/TOP1_HUMAN TOP1_HUMAN]] Releases the supercoiling and torsional tension of DNA introduced during the DNA replication and transcription by transiently cleaving and rejoining one strand of the DNA duplex. Introduces a single-strand break via transesterification at a target site in duplex DNA. The scissile phosphodiester is attacked by the catalytic tyrosine of the enzyme, resulting in the formation of a DNA-(3'-phosphotyrosyl)-enzyme intermediate and the expulsion of a 5'-OH DNA strand. The free DNA strand then undergoes passage around the unbroken strand thus removing DNA supercoils. Finally, in the religation step, the DNA 5'-OH attacks the covalent intermediate to expel the active-site tyrosine and restore the DNA phosphodiester backbone (By similarity). Regulates the alternative splicing of tissue factor (F3) pre-mRNA in endothelial cells.<ref>PMID:2833744</ref><ref>PMID:19168442</ref><ref>PMID:14594810</ref><ref>PMID:16033260</ref>
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==About this Structure==
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From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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[[1k4t]] is a 4 chain structure with sequence from [http://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1K4T OCA].
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</div>
==See Also==
==See Also==
*[[Topoisomerase|Topoisomerase]]
*[[Topoisomerase|Topoisomerase]]
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== References ==
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==Reference==
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<references/>
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<ref group="xtra">PMID:012426403</ref><references group="xtra"/><references/>
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__TOC__
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</StructureSection>
[[Category: DNA topoisomerase]]
[[Category: DNA topoisomerase]]
[[Category: Homo sapiens]]
[[Category: Homo sapiens]]

Revision as of 15:47, 29 September 2014

HUMAN DNA TOPOISOMERASE I (70 KDA) IN COMPLEX WITH THE POISON TOPOTECAN AND COVALENT COMPLEX WITH A 22 BASE PAIR DNA DUPLEX

1k4t, resolution 2.10Å

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