2XUR

The G157C mutation in the Escherichia coli sliding clamp specifically affects initiation of replication

Summary for 2XUR

• Entry DOI: 10.2210/pdb2xur/pdb
• Descriptor: DNA POLYMERASE III SUBUNIT BETA (2 entities in total)
• Functional Keywords: replication, transferase, dna-directed dna polymerase
• Biological source: ESCHERICHIA COLI
• Cellular location: Cytoplasm: P0A988
• Total number of polymer chains: 2
• Total formula weight: 83273.34

Authors

Johnsen, L.,Morigen,Dalhus, B.,Bjoras, M.,Flaatten, I.,Waldminghaus, T.,Skarstad, K. (deposition date: 2010-10-20, release date: 2011-02-16, Last modification date: 2023-12-20)

Primary citation

Johnsen, L.,Flaatten, I.,Morigen,Dalhus, B.,Bjoras, M.,Waldminghaus, T.,Skarstad, K.
The G157C Mutation in the Escherichia Coli Sliding Clamp Specifically Affects Initiation of Replication.
Mol.Microbiol., 79:433-, 2011

PubMed Abstract: 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 β 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 β 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 β clamp, was apparently unaffected. The result indicates that some aspects of β clamp activity are specific to the origin. It is possible that the origin specific activities of β contribute to regulation of initiation frequency.

PubMed: 21219462
DOI: 10.1111/J.1365-2958.2010.07453.X

Experimental method

X-RAY DIFFRACTION (1.9 Å)