X-ray structure of the tetrameric mutant of the B1 domain of streptococcal protein G

Experimental Data Snapshot

  • Resolution: 2.50 Å
  • R-Value Free: 0.283 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 

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This is version 1.5 of the entry. See complete history


Core mutations switch monomeric protein GB1 into an intertwined tetramer.

Kirsten Frank, M.Dyda, F.Dobrodumov, A.Gronenborn, A.M.

(2002) Nat Struct Biol 9: 877-885

  • DOI: https://doi.org/10.1038/nsb854
  • Primary Citation of Related Structures:  
    1MPE, 1MVK

  • PubMed Abstract: 

    The structure of a mutant immunoglobulin-binding B1 domain of streptococcal protein G (GB1), which comprises five conservative changes in hydrophobic core residues, was determined by NMR spectroscopy and X-ray crystallography. The oligomeric state and quaternary structure of the mutant protein are drastically changed from the wild type protein. The mutant structure consists of a symmetric tetramer, with intermolecular strand exchange involving all four units. Four of the five secondary structure elements present in the monomeric wild type GB1 structure are retained in the tetrameric structure, although their intra- and intermolecular interactions are altered. Our results demonstrate that through the acquisition of a moderate number of pivotal point mutations, proteins such as GB1 are able to undergo drastic structural changes, overcoming reduced stability of the monomeric unit by multimerization. The present structure is an illustrative example of how proteins exploit the breadth of conformational space.

  • Organizational Affiliation

    Laboratories of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Immunoglobulin G binding protein G
A, B, C, D, E
A, B, C, D, E, F, G, H, I, J, K, L
56Streptococcus sp. 'group GMutation(s): 6 
Gene Names: SPG
Find proteins for P06654 (Streptococcus sp. group G)
Explore P06654 
Go to UniProtKB:  P06654
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP06654
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.50 Å
  • R-Value Free: 0.283 
  • R-Value Work: 0.237 
  • R-Value Observed: 0.237 
  • Space Group: P 21 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 76.1α = 90
b = 210.4β = 90
c = 55.3γ = 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: 2002-10-30
    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: 2017-10-11
    Changes: Refinement description
  • Version 1.4: 2021-10-27
    Changes: Database references, Derived calculations
  • Version 1.5: 2024-02-14
    Changes: Data collection