View source for 5ld2


==Cryo-EM structure of RecBCD+DNA complex revealing activated nuclease domain==
<SX load='5ld2' size='340' side='right' viewer='molstar' caption='[[5ld2]], [[Resolution|resolution]] 3.83&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[5ld2]] is a 4 chain structure with sequence from [https://en.wikipedia.org/wiki/Endothia_gyrosa Endothia gyrosa] and [https://en.wikipedia.org/wiki/Escherichia_coli_K-12 Escherichia coli K-12]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=5LD2 OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=5LD2 FirstGlance]. <br>
</td></tr><tr id='method'><td class="sblockLbl"><b>[[Empirical_models|Method:]]</b></td><td class="sblockDat" id="methodDat">Electron Microscopy, [[Resolution|Resolution]] 3.83&#8491;</td></tr>
<tr id='ligand'><td class="sblockLbl"><b>[[Ligand|Ligands:]]</b></td><td class="sblockDat" id="ligandDat"><scene name='pdbligand=ANP:PHOSPHOAMINOPHOSPHONIC+ACID-ADENYLATE+ESTER'>ANP</scene>, <scene name='pdbligand=MG:MAGNESIUM+ION'>MG</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=5ld2 FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=5ld2 OCA], [https://pdbe.org/5ld2 PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=5ld2 RCSB], [https://www.ebi.ac.uk/pdbsum/5ld2 PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=5ld2 ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/RECC_ECOLI RECC_ECOLI] A helicase/nuclease that prepares dsDNA breaks (DSB) for recombinational DNA repair. Binds to DSBs and unwinds DNA via a rapid (>1 kb/second) and highly processive (>30 kb) ATP-dependent bidirectional helicase. Unwinds dsDNA until it encounters a Chi (crossover hotspot instigator, 5'-GCTGGTGG-3') sequence from the 3' direction. Cuts ssDNA a few nucleotides 3' to Chi site, by nicking one strand or switching the strand degraded (depending on the reaction conditions). The properties and activities of the enzyme are changed at Chi. The Chi-altered holoenzyme produces a long 3'-ssDNA overhang which facilitates RecA-binding to the ssDNA for homologous DNA recombination and repair. Holoenzyme degrades any linearized DNA that is unable to undergo homologous recombination (PubMed:4562392, PubMed:4552016, PubMed:123277). In the holoenzyme this subunit almost certainly recognizes the wild-type Chi sequence, when added to isolated RecB increases its ATP-dependent helicase processivity. The RecBC complex requires the RecD subunit for nuclease activity, but can translocate along ssDNA in both directions.<ref>PMID:10197988</ref> <ref>PMID:10884344</ref> <ref>PMID:123277</ref> <ref>PMID:12815437</ref> <ref>PMID:12815438</ref> <ref>PMID:1535156</ref> <ref>PMID:16041061</ref> <ref>PMID:1618858</ref> <ref>PMID:20852646</ref> <ref>PMID:23851395</ref> <ref>PMID:4268693</ref> <ref>PMID:4552016</ref> <ref>PMID:4562392</ref> <ref>PMID:7608206</ref> <ref>PMID:9192629</ref> <ref>PMID:9230304</ref> <ref>PMID:9448271</ref> <ref>PMID:9790841</ref> 
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== Publication Abstract from PubMed ==
In bacterial cells, processing of double-stranded DNA breaks for repair by homologous recombination is catalysed by AddAB, AdnAB or RecBCD-type helicase-nucleases. These enzyme complexes are highly processive, duplex unwinding and degrading machines that require tight regulation. Here, we report the structure of E.coli RecBCD, determined by cryoEM at 3.8 A resolution, with a DNA substrate that reveals how the nuclease activity of the complex is activated once unwinding progresses. Extension of the 5'-tail of the unwound duplex induces a large conformational change in the RecD subunit, that is transferred through the RecC subunit to activate the nuclease domain of the RecB subunit. The process involves a SH3 domain that binds to a region of the RecB subunit in a binding mode that is distinct from others observed previously in SH3 domains and, to our knowledge, this is the first example of peptide-binding of an SH3 domain in a bacterial system.

Mechanism for nuclease regulation in RecBCD.,Wilkinson M, Chaban Y, Wigley DB Elife. 2016 Sep 20;5. pii: e18227. doi: 10.7554/eLife.18227. PMID:27644322<ref>PMID:27644322</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 5ld2" style="background-color:#fffaf0;"></div>

==See Also==
*[[Exonuclease 3D structures|Exonuclease 3D structures]]
== References ==
<references/>
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[[Category: Endothia gyrosa]]
[[Category: Escherichia coli K-12]]
[[Category: Large Structures]]
[[Category: Chaban Y]]
[[Category: Wigley DB]]
[[Category: Wilkinson M]]