Structure of the AAA+ protease delivery protein SspB

Experimental Data Snapshot

  • Resolution: 2.20 Å
  • R-Value Free: 0.292 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 

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Structure of a delivery protein for an AAA+ protease in complex with a peptide degradation tag

Levchenko, I.Grant, R.A.Wah, D.A.Sauer, R.T.Baker, T.A.

(2003) Mol Cell 12: 365-372

  • DOI: https://doi.org/10.1016/j.molcel.2003.08.014
  • Primary Citation of Related Structures:  
    1OU8, 1OU9, 1OUL

  • PubMed Abstract: 

    Substrate selection by AAA+ ATPases that function to unfold proteins or alter protein conformation is often regulated by delivery or adaptor proteins. SspB is a protein dimer that binds to the ssrA degradation tag and delivers proteins bearing this tag to ClpXP, an AAA+ protease, for degradation. Here, we describe the structure of the peptide binding domain of H. influenzae SspB in complex with an ssrA peptide at 1.6 A resolution. The ssrA peptides are bound in well-defined clefts located at the extreme ends of the SspB homodimer. SspB contacts residues within the N-terminal and central regions of the 11 residue ssrA tag but leaves the C-terminal residues exposed and positioned to dock with ClpX. This structure, taken together with biochemical analysis of SspB, suggests mechanisms by which proteins like SspB escort substrates to AAA+ ATPases and enhance the specificity and affinity of target recognition.

  • Organizational Affiliation

    Howard Hughes Medical Institute, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
Stringent starvation protein B homolog
A, B
129Haemophilus influenzaeMutation(s): 3 
Gene Names: sspB
Find proteins for P45206 (Haemophilus influenzae (strain ATCC 51907 / DSM 11121 / KW20 / Rd))
Explore P45206 
Go to UniProtKB:  P45206
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP45206
Sequence Annotations
  • Reference Sequence
Small Molecules
Ligands 0 Unique
IDChains Name / Formula / InChI Key2D Diagram3D Interactions
Modified Residues  1 Unique
IDChains TypeFormula2D DiagramParent
Query on MSE
A, B
Experimental Data & Validation

Experimental Data

  • Resolution: 2.20 Å
  • R-Value Free: 0.292 
  • R-Value Work: 0.256 
  • R-Value Observed: 0.256 
  • Space Group: P 31 2 1
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 78.883α = 90
b = 78.883β = 90
c = 105.08γ = 120
Software Package:
Software NamePurpose
HKL-2000data reduction
SCALEPACKdata scaling

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-09-23
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance