Experimental Data Snapshot

  • Resolution: 1.85 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.191 

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Flexibility revealed by the 1.85 A crystal structure of the beta sliding-clamp subunit of Escherichia coli DNA polymerase III.

Oakley, A.J.Prosselkov, P.Wijffels, G.Beck, J.L.Wilce, M.C.Dixon, N.E.

(2003) Acta Crystallogr D Biol Crystallogr 59: 1192-1199

  • DOI: https://doi.org/10.1107/s0907444903009958
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    The beta subunit of the Escherichia coli replicative DNA polymerase III holoenzyme is the sliding clamp that interacts with the alpha (polymerase) subunit to maintain the high processivity of the enzyme. The beta protein is a ring-shaped dimer of 40.6 kDa subunits whose structure has previously been determined at a resolution of 2.5 A [Kong et al. (1992), Cell, 69, 425-437]. Here, the construction of a new plasmid that directs overproduction of beta to very high levels and a simple procedure for large-scale purification of the protein are described. Crystals grown under slightly modified conditions diffracted to beyond 1.9 A at 100 K at a synchrotron source. The structure of the beta dimer solved at 1.85 A resolution shows some differences from that reported previously. In particular, it was possible at this resolution to identify residues that differed in position between the two subunits in the unit cell; side chains of these and some other residues were found to occupy alternate conformations. This suggests that these residues are likely to be relatively mobile in solution. Some implications of this flexibility for the function of beta are discussed.

  • Organizational Affiliation

    Crystallography Centre, University of Western Australia, Nedlands, WA 6907, Australia.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
DNA polymerase III, beta chain
A, B
366Escherichia coliMutation(s): 0 
Gene Names: dnaN
Find proteins for P0A988 (Escherichia coli (strain K12))
Explore P0A988 
Go to UniProtKB:  P0A988
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0A988
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.85 Å
  • R-Value Free: 0.245 
  • R-Value Work: 0.188 
  • R-Value Observed: 0.191 
  • Space Group: P 1 21 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 80.012α = 90
b = 66.595β = 114.02
c = 80.779γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-09-04
    Type: Initial release
  • Version 1.1: 2008-04-28
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references, Refinement description