Experimental Data Snapshot

  • Resolution: 1.60 Å
  • R-Value Free: 0.277 
  • R-Value Observed: 0.202 

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The structure of plasmid-encoded transcriptional repressor CopG unliganded and bound to its operator.

Gomis-Ruth, F.X.Sola, M.Acebo, P.Parraga, A.Guasch, A.Eritja, R.Gonzalez, A.Espinosa, M.del Solar, G.Coll, M.

(1998) EMBO J 17: 7404-7415

  • DOI: https://doi.org/10.1093/emboj/17.24.7404
  • Primary Citation of Related Structures:  
    1B01, 2CPG

  • PubMed Abstract: 

    The structure of the 45 amino acid transcriptional repressor, CopG, has been solved unliganded and bound to its target operator DNA. The protein, encoded by the promiscuous streptococcal plasmid pMV158, is involved in the control of plasmid copy number. The structure of this protein repressor, which is the shortest reported to date and the first isolated from a plasmid, has a homodimeric ribbon-helix-helix arrangement. It is the prototype for a family of homologous plasmid repressors. CopG cooperatively associates, completely protecting several turns on one face of the double helix in both directions from a 13-bp pseudosymmetric primary DNA recognition element. In the complex structure, one protein tetramer binds at one face of a 19-bp oligonucleotide, containing the pseudosymmetric element, with two beta-ribbons inserted into the major groove. The DNA is bent 60 degrees by compression of both major and minor grooves. The protein dimer displays topological similarity to Arc and MetJ repressors. Nevertheless, the functional tetramer has a unique structure with the two vicinal recognition ribbon elements at a short distance, thus inducing strong DNA bend. Further structural resemblance is found with helix-turn-helix regions of unrelated DNA-binding proteins. In contrast to these, however, the bihelical region of CopG has a role in oligomerization instead of DNA recognition. This observation unveils an evolutionary link between ribbon-helix-helix and helix-turn-helix proteins.

  • Organizational Affiliation

    Institut de Biologia Molecular de Barcelona, CSIC, Jordi Girona, 18-26, 08034 Barcelona, Spain.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B, C
45Streptococcus agalactiaeMutation(s): 0 
Find proteins for P13920 (Streptococcus agalactiae)
Explore P13920 
Go to UniProtKB:  P13920
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP13920
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.60 Å
  • R-Value Free: 0.277 
  • R-Value Observed: 0.202 
  • Space Group: C 2 2 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.19α = 90
b = 102.49β = 90
c = 40.21γ = 90
Software Package:
Software NamePurpose
CCP4model building
MOSFLMdata reduction
CCP4data scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 1999-11-19
    Type: Initial release
  • Version 1.1: 2008-04-26
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2023-12-27
    Changes: Data collection, Database references, Derived calculations