View source for 1sc7


==Human DNA Topoisomerase I (70 Kda) In Complex With The Indenoisoquinoline MJ-II-38 and Covalent Complex With A 22 Base Pair DNA Duplex==
<StructureSection load='1sc7' size='340' side='right'caption='[[1sc7]], [[Resolution|resolution]] 3.00&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1sc7]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Homo_sapiens Homo sapiens]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1SC7 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=1SC7 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">X-ray diffraction, [[Resolution|Resolution]] 3&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=M38:4-(5,11-DIOXO-5H-INDENO[1,2-C]ISOQUINOLIN-6(11H)-YL)BUTANOATE'>M38</scene>, <scene name='pdbligand=PG4:TETRAETHYLENE+GLYCOL'>PG4</scene>, <scene name='pdbligand=PTR:O-PHOSPHOTYROSINE'>PTR</scene>, <scene name='pdbligand=TGP:5-THIO-2-DEOXY-GUANOSINE+PHOSPHONIC+ACID'>TGP</scene></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=1sc7 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1sc7 OCA], [https://pdbe.org/1sc7 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=1sc7 RCSB], [https://www.ebi.ac.uk/pdbsum/1sc7 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=1sc7 ProSAT]</span></td></tr>
</table>
== Evolutionary Conservation ==
[[Image:Consurf_key_small.gif|200px|right]]
Check<jmol>
  <jmolCheckbox>
    <scriptWhenChecked>; select protein; define ~consurf_to_do selected; consurf_initial_scene = true; script "/wiki/ConSurf/sc/1sc7_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview03.spt</scriptWhenUnchecked>
    <text>to colour the structure by Evolutionary Conservation</text>
  </jmolCheckbox>
</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/main_output.php?pdb_ID=1sc7 ConSurf].
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== Publication Abstract from PubMed ==
Human topoisomerase I (top1) is the molecular target of a diverse set of anticancer compounds, including the camptothecins, indolocarbazoles, and indenoisoquinolines. These compounds bind to a transient top1-DNA covalent complex and inhibit the resealing of a single-strand nick that the enzyme creates to relieve superhelical tension in duplex DNA. (Hertzberg, R. P.; et al. Biochem. 1989, 28, 4629-4638. Hsiang, Y. H.; et al. J. Biol. Chem 1985, 260, 14873-14878. Champoux, J. J. Annu. Rev. Biochem. 2001, 70, 369-413. Stewart, L.; et al. Science 1998, 729, 1534-1541.) We report the X-ray crystal structures of the human top1-DNA complex bound with camptothecin and representative members of the indenoisoquinoline and indolocarbazole classes of top1 poisons. The planar nature of all three structurally diverse classes allows them to intercalate between DNA base pairs at the site of single-strand cleavage. All three classes of compounds have a free electron pair near Arg364, a residue that if mutated confers resistance to all three classes of drugs. The common intercalative binding mode is augmented by unexpected chemotype-specific contacts with amino acid residues Asn352 and Glu356, which adopt alternative side-chain conformations to accommodate the bound compounds. These new X-ray structures explain how very different molecules can stabilize top1-DNA covalent complexes and will aid the rational design of completely novel structural classes of anticancer drugs.

Structures of three classes of anticancer agents bound to the human topoisomerase I-DNA covalent complex.,Staker BL, Feese MD, Cushman M, Pommier Y, Zembower D, Stewart L, Burgin AB J Med Chem. 2005 Apr 7;48(7):2336-45. PMID:15801827<ref>PMID:15801827</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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<div class="pdbe-citations 1sc7" style="background-color:#fffaf0;"></div>

==See Also==
*[[Topoisomerase 3D structures|Topoisomerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Homo sapiens]]
[[Category: Large Structures]]
[[Category: Burgin AB]]
[[Category: Cushman M]]
[[Category: Feese MD]]
[[Category: Pommier Y]]
[[Category: Staker BL]]
[[Category: Stewart L]]
[[Category: Zembower D]]