The crystal structures of the Brucella protein TcpB and the TLR adaptor protein TIRAP show structural differences in microbial TIR mimicry.

Experimental Data Snapshot

  • Resolution: 2.30 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.213 

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Crystal structures of the Toll/Interleukin-1 receptor (TIR) domains from the Brucella protein TcpB and host adaptor TIRAP reveal mechanisms of molecular mimicry.

Snyder, G.A.Deredge, D.Waldhuber, A.Fresquez, T.Wilkins, D.Z.Smith, P.T.Durr, S.Cirl, C.Jiang, J.Jennings, W.Luchetti, T.Snyder, N.Sundberg, E.J.Wintrode, P.Miethke, T.Xiao, T.S.

(2014) J Biol Chem 289: 669-679

  • DOI: https://doi.org/10.1074/jbc.M113.523407
  • Primary Citation of Related Structures:  
    4LQC, 4LQD

  • PubMed Abstract: 

    The Toll/IL-1 receptor (TIR) domains are crucial innate immune signaling modules. Microbial TIR domain-containing proteins inhibit Toll-like receptor (TLR) signaling through molecular mimicry. The TIR domain-containing protein TcpB from Brucella inhibits TLR signaling through interaction with host adaptor proteins TIRAP/Mal and MyD88. To characterize the microbial mimicry of host proteins, we have determined the X-ray crystal structures of the TIR domains from the Brucella protein TcpB and the host adaptor protein TIRAP. We have further characterized homotypic interactions of TcpB using hydrogen/deuterium exchange mass spectrometry and heterotypic TcpB and TIRAP interaction by co-immunoprecipitation and NF-κB reporter assays. The crystal structure of the TcpB TIR domain reveals the microtubule-binding site encompassing the BB loop as well as a symmetrical dimer mediated by the DD and EE loops. This dimerization interface is validated by peptide mapping through hydrogen/deuterium exchange mass spectrometry. The human TIRAP TIR domain crystal structure reveals a unique N-terminal TIR domain fold containing a disulfide bond formed by Cys(89) and Cys(134). A comparison between the TcpB and TIRAP crystal structures reveals substantial conformational differences in the region that encompasses the BB loop. These findings underscore the similarities and differences in the molecular features found in the microbial and host TIR domains, which suggests mechanisms of bacterial mimicry of host signaling adaptor proteins, such as TIRAP.

  • Organizational Affiliation

    From the Laboratory of Immunology, NIAID, National Institutes of Health, Bethesda, Maryland 20892.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
A, B
148Brucella melitensisMutation(s): 2 
Gene Names: NC_003317
Find proteins for Q8YF53 (Brucella melitensis biotype 1 (strain ATCC 23456 / CCUG 17765 / NCTC 10094 / 16M))
Explore Q8YF53 
Go to UniProtKB:  Q8YF53
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupQ8YF53
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 2.30 Å
  • R-Value Free: 0.263 
  • R-Value Work: 0.210 
  • R-Value Observed: 0.213 
  • Space Group: P 21 21 21
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 67.45α = 90
b = 67.3β = 90
c = 60.31γ = 90
Software Package:
Software NamePurpose
XDSdata scaling
XDSdata reduction

Structure Validation

View Full Validation Report

Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2013-12-04
    Type: Initial release
  • Version 1.1: 2014-04-09
    Changes: Database references
  • Version 1.2: 2024-02-28
    Changes: Data collection, Database references