View source for 6eyc


==Re-refinement of the MCM2-7 double hexamer using ISOLDE==
<StructureSection load='6eyc' size='340' side='right' caption='[[6eyc]], [[Resolution|resolution]] 3.80&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[6eyc]] is a 6 chain structure. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=6EYC OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=6EYC FirstGlance]. <br>
</td></tr><tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat"><scene name='pdbligand=ADP:ADENOSINE-5-DIPHOSPHATE'>ADP</scene>, <scene name='pdbligand=ZN:ZINC+ION'>ZN</scene></td></tr>
<tr id='related'><td class="sblockLbl"><b>[[Related_structure|Related:]]</b></td><td class="sblockDat">[[3ja8|3ja8]]</td></tr>
<tr id='activity'><td class="sblockLbl"><b>Activity:</b></td><td class="sblockDat"><span class='plainlinks'>[http://en.wikipedia.org/wiki/DNA_helicase DNA helicase], with EC number [http://www.brenda-enzymes.info/php/result_flat.php4?ecno=3.6.4.12 3.6.4.12] </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=6eyc FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=6eyc OCA], [http://pdbe.org/6eyc PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=6eyc RCSB], [http://www.ebi.ac.uk/pdbsum/6eyc PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=6eyc ProSAT]</span></td></tr>
</table>
== Function ==
[[http://www.uniprot.org/uniprot/MCM7_YEAST MCM7_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  [[http://www.uniprot.org/uniprot/MCM5_YEAST MCM5_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity; specifically the MCM2-MCM5 association is proposed to be reversible and to mediate a open ring conformation which may facilitate DNA loading. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  [[http://www.uniprot.org/uniprot/MCM2_YEAST MCM2_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity; specifically the MCM2-MCM5 association is proposed to be reversible and to mediate a open ring conformation which may facilitate DNA loading. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Necessary for cell growth.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  [[http://www.uniprot.org/uniprot/MCM4_YEAST MCM4_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Required for S phase execution.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  [[http://www.uniprot.org/uniprot/MCM3_YEAST MCM3_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Necessary for cell growth.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  [[http://www.uniprot.org/uniprot/MCM6_YEAST MCM6_YEAST]] Acts as component of the MCM2-7 complex (MCM complex) which is the putative replicative helicase essential for 'once per cell cycle' DNA replication initiation and elongation in eukaryotic cells. The active ATPase sites in the MCM2-7 ring are formed through the interaction surfaces of two neighboring subunits such that a critical structure of a conserved arginine finger motif is provided in trans relative to the ATP-binding site of the Walker A box of the adjacent subunit. The six ATPase active sites, however, are likely to contribute differentially to the complex helicase activity. Once loaded onto DNA, double hexamers can slide on dsDNA in the absence of ATPase activity. Required for the entry in S phase and for cell division.<ref>PMID:19896182</ref> <ref>PMID:19910535</ref>  
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
This paper introduces ISOLDE, a new software package designed to provide an intuitive environment for high-fidelity interactive remodelling/refinement of macromolecular models into electron-density maps. ISOLDE combines interactive molecular-dynamics flexible fitting with modern molecular-graphics visualization and established structural biology libraries to provide an immersive interface wherein the model constantly acts to maintain physically realistic conformations as the user interacts with it by directly tugging atoms with a mouse or haptic interface or applying/removing restraints. In addition, common validation tasks are accelerated and visualized in real time. Using the recently described 3.8 A resolution cryo-EM structure of the eukaryotic minichromosome maintenance (MCM) helicase complex as a case study, it is demonstrated how ISOLDE can be used alongside other modern refinement tools to avoid common pitfalls of low-resolution modelling and improve the quality of the final model. A detailed analysis of changes between the initial and final model provides a somewhat sobering insight into the dangers of relying on a small number of validation metrics to judge the quality of a low-resolution model.

ISOLDE: a physically realistic environment for model building into low-resolution electron-density maps.,Croll TI Acta Crystallogr D Struct Biol. 2018 Jun 1;74(Pt 6):519-530. doi:, 10.1107/S2059798318002425. Epub 2018 Apr 11. PMID:29872003<ref>PMID:29872003</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 6eyc" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: DNA helicase]]
[[Category: Croll, T I]]
[[Category: Dna-directed dna polymerase]]
[[Category: Multienzyme complex]]
[[Category: Nuclear protein]]
[[Category: Nucleus]]