3SXU

Structure of the E. coli SSB-DNA polymerase III interface

Summary for 3SXU

• Entry DOI: 10.2210/pdb3sxu/pdb
• Descriptor: DNA polymerase III subunit chi, DNA polymerase III subunit psi, SSB peptide, ... (4 entities in total)
• Functional Keywords: dna replication, chi binds to ssb and psi, transferase
• Biological source: Escherichia coli; More
• Total number of polymer chains: 3
• Total formula weight: 32858.10

Authors

Marceau, A.H.,Keck, J.L. (deposition date: 2011-07-15, release date: 2011-09-21, Last modification date: 2023-09-13)

Primary citation

Marceau, A.H.,Bahng, S.,Massoni, S.C.,George, N.P.,Sandler, S.J.,Marians, K.J.,Keck, J.L.
Structure of the SSB-DNA polymerase III interface and its role in DNA replication.
Embo J., 30:4236-4247, 2011

PubMed Abstract: Interactions between single-stranded DNA-binding proteins (SSBs) and the DNA replication machinery are found in all organisms, but the roles of these contacts remain poorly defined. In Escherichia coli, SSB's association with the χ subunit of the DNA polymerase III holoenzyme has been proposed to confer stability to the replisome and to aid delivery of primers to the lagging-strand DNA polymerase. Here, the SSB-binding site on χ is identified crystallographically and biochemical and cellular studies delineate the consequences of destabilizing the χ/SSB interface. An essential role for the χ/SSB interaction in lagging-strand primer utilization is not supported. However, sequence changes in χ that block complex formation with SSB lead to salt-dependent uncoupling of leading- and lagging-strand DNA synthesis and to a surprising obstruction of the leading-strand DNA polymerase in vitro, pointing to roles for the χ/SSB complex in replisome establishment and maintenance. Destabilization of the χ/SSB complex in vivo produces cells with temperature-dependent cell cycle defects that appear to arise from replisome instability.

PubMed: 21857649
DOI: 10.1038/emboj.2011.305

Experimental method

X-RAY DIFFRACTION (1.85 Å)