2xur

THE G157C MUTATION IN THE ESCHERICHIA COLI SLIDING CLAMP SPECIFICALLY AFFECTS INITIATION OF REPLICATION

spinqualitylabelsall models 2xur, resolution 1.90Å Show:Asymmetric Unit Biological Assembly Drag the structure with the mouse to rotate   Export Animated Image   Print3D Structural highlights 2xur is a 2 chain structure with sequence from Escherichia coli. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance. Activity: DNA-directed DNA polymerase, with EC number 2.7.7.7 Resources: FirstGlance, OCA, RCSB, PDBsum Function [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. 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 From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See Also DNA polymerase

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