Identification of a disulfide switch in BsSco, a member of the Sco family of cytochrome c oxidase assembly proteins

Experimental Data Snapshot

  • Resolution: 1.70 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.238 
  • R-Value Observed: 0.241 

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Identification of a Disulfide Switch in BsSco, a Member of the Sco Family of Cytochrome c Oxidase Assembly Proteins

Ye, Q.Imriskova-Sosova, I.Hill, B.C.Jia, Z.

(2005) Biochemistry 44: 2934-2942

  • DOI: https://doi.org/10.1021/bi0480537
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    BsSco is a membrane-associated protein from Bacillus subtilis characterized by the sequence CXXXCP, which is conserved in yeast and human mitochondrial Sco proteins, and their bacterial homologues. BsSco is involved in the assembly of the Cu(A) center in cytochrome c oxidase and may play a role in the transfer of copper to this site. We have characterized the soluble domain of BsSco by biochemical, spectroscopic, and structural approaches. Soluble BsSco is monomeric in solution, and the two conserved cysteines are involved in an intramolecular cystine bridge. The cystine bridge is easily reduced, and circular dichroism spectroscopy shows no large-scale changes in BsSco's secondary structure upon reduction. The crystal structure of soluble BsSco, determined at 1.7 A resolution, reveals typical elements of a thioredoxin fold. The CXXXCP motif, in which Cys45 and Cys49 are conserved, is located in a turn structure on the surface of the protein. In various native and His135Ala mutant structures, both disulfide-bonded and non-disulfide-bonded forms of CXXXCP are observed. However, despite extensive attempts, copper has not been found near or beyond the CXXXCP motif, a presumptive copper-binding site. Another potential copper binding residue, His135, is located in a highly flexible loop parallel to the CXXXCP loop but is more than 10 A from Cys45 and Cys49. If these three residues are to coordinate copper, a conformational change is necessary. The structural identification of a disulfide switch demonstrates that BsSco has the capability to fill a redox role in Cu(A) assembly.

  • Organizational Affiliation

    Department of Biochemistry, Queen's University, Kingston, Ontario K7L 3N6, Canada.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Hypothetical protein ypmQ
A, B
174Bacillus subtilisMutation(s): 0 
Gene Names: ypmQ
Find proteins for P54178 (Bacillus subtilis (strain 168))
Explore P54178 
Go to UniProtKB:  P54178
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP54178
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 2 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Query on CD

Download Ideal Coordinates CCD File 
C [auth A],
D [auth A],
E [auth A],
F [auth A],
O [auth B]
Query on CA

Download Ideal Coordinates CCD File 
G [auth A]
H [auth A]
I [auth A]
J [auth A]
K [auth A]
G [auth A],
H [auth A],
I [auth A],
J [auth A],
K [auth A],
L [auth A],
M [auth A],
N [auth A],
P [auth B],
Q [auth B],
R [auth B],
S [auth B],
T [auth B],
U [auth B]
Experimental Data & Validation

Experimental Data

  • Resolution: 1.70 Å
  • R-Value Free: 0.289 
  • R-Value Work: 0.238 
  • R-Value Observed: 0.241 
  • Space Group: P 32 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 68.033α = 90
b = 68.033β = 90
c = 191.733γ = 120
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: 2005-03-01
    Type: Initial release
  • Version 1.1: 2008-04-30
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Derived calculations, Version format compliance
  • Version 1.3: 2017-10-11
    Changes: Data collection
  • Version 2.0: 2020-06-17
    Changes: Database references, Polymer sequence