View source for 5bk4


==Cryo-EM structure of Mcm2-7 double hexamer on dsDNA==
<StructureSection load='5bk4' size='340' side='right' caption='[[5bk4]], [[Resolution|resolution]] 3.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5bk4]] is a 14 chain structure with sequence from [http://en.wikipedia.org/wiki/Atcc_18824 Atcc 18824]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5BK4 OCA]. For a <b>guided tour on the structure components</b> use [http://oca.weizmann.ac.il/oca-docs/fgij/fg.htm?mol=5BK4 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></td></tr>
<tr id='gene'><td class="sblockLbl"><b>[[Gene|Gene:]]</b></td><td class="sblockDat">MCM2, YBL023C, YBL0438 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824]), MCM3, YEL032W, SYGP-ORF23 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824]), MCM4, CDC54, HCD21, YPR019W, YP9531.13 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824]), MCM5, CDC46, YLR274W, L9328.1 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824]), MCM6, YGL201C ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824]), MCM7, CDC47, YBR202W, YBR1441 ([http://www.ncbi.nlm.nih.gov/Taxonomy/Browser/wwwtax.cgi?mode=Info&srchmode=5&id=4932 ATCC 18824])</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=5bk4 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5bk4 OCA], [http://pdbe.org/5bk4 PDBe], [http://www.rcsb.org/pdb/explore.do?structureId=5bk4 RCSB], [http://www.ebi.ac.uk/pdbsum/5bk4 PDBsum], [http://prosat.h-its.org/prosat/prosatexe?pdbcode=5bk4 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/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/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/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/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 ==
During replication initiation, the core component of the helicase-the Mcm2-7 hexamer-is loaded on origin DNA as a double hexamer (DH). The two ring-shaped hexamers are staggered, leading to a kinked axial channel. How the origin DNA interacts with the axial channel is not understood, but the interaction could provide key insights into Mcm2-7 function and regulation. Here, we report the cryo-EM structure of the Mcm2-7 DH on dsDNA and show that the DNA is zigzagged inside the central channel. Several of the Mcm subunit DNA-binding loops, such as the oligosaccharide-oligonucleotide loops, helix 2 insertion loops, and presensor 1 (PS1) loops, are well defined, and many of them interact extensively with the DNA. The PS1 loops of Mcm 3, 4, 6, and 7, but not 2 and 5, engage the lagging strand with an approximate step size of one base per subunit. Staggered coupling of the two opposing hexamers positions the DNA right in front of the two Mcm2-Mcm5 gates, with each strand being pressed against one gate. The architecture suggests that lagging-strand extrusion initiates in the middle of the DH that is composed of the zinc finger domains of both hexamers. To convert the Mcm2-7 DH structure into the Mcm2-7 hexamer structure found in the active helicase, the N-tier ring of the Mcm2-7 hexamer in the DH-dsDNA needs to tilt and shift laterally. We suggest that these N-tier ring movements cause the DNA strand separation and lagging-strand extrusion.

Cryo-EM structure of Mcm2-7 double hexamer on DNA suggests a lagging-strand DNA extrusion model.,Noguchi Y, Yuan Z, Bai L, Schneider S, Zhao G, Stillman B, Speck C, Li H Proc Natl Acad Sci U S A. 2017 Oct 25. pii: 201712537. doi:, 10.1073/pnas.1712537114. PMID:29078375<ref>PMID:29078375</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
</div>
<div class="pdbe-citations 5bk4" style="background-color:#fffaf0;"></div>
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Atcc 18824]]
[[Category: DNA helicase]]
[[Category: Bai, L]]
[[Category: Li, H]]
[[Category: Yuan, Z]]
[[Category: Complex]]
[[Category: Dna replication]]
[[Category: Hydrolase-dna complex]]