View source for 1a36


==TOPOISOMERASE I/DNA COMPLEX==
<StructureSection load='1a36' size='340' side='right'caption='[[1a36]], [[Resolution|resolution]] 2.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[1a36]] is a 3 chain structure with sequence from [http://en.wikipedia.org/wiki/Human Human]. The January 2006 RCSB PDB [http://pdb.rcsb.org/pdb/static.do?p=education_discussion/molecule_of_the_month/index.html Molecule of the Month] feature on ''Topoisomerases''  by David S. Goodsell is [http://dx.doi.org/10.2210/rcsb_pdb/mom_2006_1 10.2210/rcsb_pdb/mom_2006_1]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=1A36 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1A36 FirstGlance]. <br>
</td></tr><tr id='activity'><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>
<tr id='resources'><td class="sblockLbl"><b>Resources:</b></td><td class="sblockDat"><span class='plainlinks'>[http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=1a36 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=1a36 OCA], [http://pdbe.org/1a36 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=1a36 RCSB], [http://www.ebi.ac.uk/pdbsum/1a36 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=1a36 ProSAT]</span></td></tr>
</table>
== 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. 
== Function ==
[[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>  
== 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/a3/1a36_consurf.spt"</scriptWhenChecked>
    <scriptWhenUnchecked>script /wiki/extensions/Proteopedia/spt/initialview01.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=1a36 ConSurf].
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== Publication Abstract from PubMed ==
The three-dimensional structure of a 70-kilodalton amino terminally truncated form of human topoisomerase I in complex with a 22-base pair duplex oligonucleotide, determined to a resolution of 2.8 angstroms, reveals all of the structural elements of the enzyme that contact DNA. The linker region that connects the central core of the enzyme to the carboxyl-terminal domain assumes a coiled-coil configuration and protrudes away from the remainder of the enzyme. The positively charged DNA-proximal surface of the linker makes only a few contacts with the DNA downstream of the cleavage site. In combination with the crystal structures of the reconstituted human topoisomerase I before and after DNA cleavage, this information suggests which amino acid residues are involved in catalyzing phosphodiester bond breakage and religation. The structures also lead to the proposal that the topoisomerization step occurs by a mechanism termed "controlled rotation."

A model for the mechanism of human topoisomerase I.,Stewart L, Redinbo MR, Qiu X, Hol WG, Champoux JJ Science. 1998 Mar 6;279(5356):1534-41. PMID:9488652<ref>PMID:9488652</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 1a36" style="background-color:#fffaf0;"></div>

==See Also==
*[[Topoisomerase|Topoisomerase]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: DNA topoisomerase]]
[[Category: Human]]
[[Category: Large Structures]]
[[Category: RCSB PDB Molecule of the Month]]
[[Category: Topoisomerases]]
[[Category: Champoux, J J]]
[[Category: Hol, W G.J]]
[[Category: Qiu, X]]
[[Category: Redinbo, M R]]
[[Category: Stewart, L]]
[[Category: Dna]]
[[Category: Isomerase-dna complex]]
[[Category: Topoisomerase i]]