View source for 2xur


==The G157C mutation in the Escherichia coli sliding clamp specifically affects initiation of replication==
<StructureSection load='2xur' size='340' side='right'caption='[[2xur]], [[Resolution|resolution]] 1.90&Aring;' scene=''>
== Structural highlights ==
<table><tr><td colspan='2'>[[2xur]] is a 2 chain structure with sequence from [https://en.wikipedia.org/wiki/Escherichia_coli Escherichia coli]. Full crystallographic information is available from [http://oca.weizmann.ac.il/oca-bin/ocashort?id=2XUR OCA]. For a <b>guided tour on the structure components</b> use [https://proteopedia.org/fgij/fg.htm?mol=2XUR 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]] 1.9&#8491;</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=2xur FirstGlance], [http://oca.weizmann.ac.il/oca-bin/ocaids?id=2xur OCA], [https://pdbe.org/2xur PDBe], [https://www.rcsb.org/pdb/explore.do?structureId=2xur RCSB], [https://www.ebi.ac.uk/pdbsum/2xur PDBsum], [https://prosat.h-its.org/prosat/prosatexe?pdbcode=2xur ProSAT]</span></td></tr>
</table>
== Function ==
[https://www.uniprot.org/uniprot/DPO3B_ECOLI DPO3B_ECOLI] DNA polymerase III is a complex, multichain enzyme responsible for most of the replicative synthesis in bacteria. This DNA polymerase also exhibits 3' to 5' exonuclease activity. The beta chain is required for initiation of replication once it is clamped onto DNA, it slides freely (bidirectional and ATP-independent) along duplex DNA.
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== Publication Abstract from PubMed ==
Escherichia coli cells with a point mutation in the dnaN gene causing the amino acid change Gly157 to Cys, were found to underinitiate replication and grow with a reduced origin and DNA concentration. The mutant beta clamp also caused excessive conversion of ATP-DnaA to ADP-DnaA. The DnaA protein was, however, not the element limiting initiation of replication. Overproduction of DnaA protein, which in wild-type cells leads to over-replication, had no effect in the dnaN(G157C) mutant. Origins already opened by DnaA seemed to remain open for a prolonged period, with a stage of initiation involving beta clamp loading, presumably limiting the initiation process. The existence of opened origins led to a moderate SOS response. Lagging strand synthesis, which also requires loading of the beta clamp, was apparently unaffected. The result indicates that some aspects of beta clamp activity are specific to the origin. It is possible that the origin specific activities of beta contribute to regulation of initiation frequency.

The G157C mutation in the Escherichia coli sliding clamp specifically affects initiation of replication.,Johnsen L, Flatten I, Morigen, Dalhus B, Bjoras M, Waldminghaus T, Skarstad K Mol Microbiol. 2011 Jan;79(2):433-46. doi:, 10.1111/j.1365-2958.2010.07453.x. Epub 2010 Nov 23. PMID:21219462<ref>PMID:21219462</ref>

From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
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==See Also==
*[[DNA polymerase 3D structures|DNA polymerase 3D structures]]
== References ==
<references/>
__TOC__
</StructureSection>
[[Category: Escherichia coli]]
[[Category: Large Structures]]
[[Category: Bjoras M]]
[[Category: Dalhus B]]
[[Category: Flaatten I]]
[[Category: Johnsen L]]
[[Category: Morigen]]
[[Category: Skarstad K]]
[[Category: Waldminghaus T]]