Crystal Structure of the C-terminal Actin Binding Domain of Salmonella Invasion Protein A (SipA)

Experimental Data Snapshot

  • Resolution: 1.80 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.194 

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This is version 1.3 of the entry. See complete history


Salmonella SipA polymerizes actin by stapling filaments with nonglobular protein arms.

Lilic, M.Galkin, V.E.Orlova, A.VanLoock, M.S.Egelman, E.H.Stebbins, C.E.

(2003) Science 301: 1918-1921

  • DOI: https://doi.org/10.1126/science.1088433
  • Primary Citation of Related Structures:  

  • PubMed Abstract: 

    Like many bacterial pathogens, Salmonella spp. use a type III secretion system to inject virulence proteins into host cells. The Salmonella invasion protein A (SipA) binds host actin, enhances its polymerization near adherent extracellular bacteria, and contributes to cytoskeletal rearrangements that internalize the pathogen. By combining x-ray crystallography of SipA with electron microscopy and image analysis of SipA-actin filaments, we show that SipA functions as a "molecular staple," in which a globular domain and two nonglobular "arms" mechanically stabilize the filament by tethering actin subunits in opposing strands. Deletion analysis of the tethering arms provides strong support for this model.

  • Organizational Affiliation

    Laboratory of Structural Microbiology, Rockefeller University, New York, NY 10021, USA.

Find similar proteins by:  (by identity cutoff)  |  3D Structure
Entity ID: 1
MoleculeChains Sequence LengthOrganismDetailsImage
SipA177Salmonella enterica subsp. enterica serovar TyphimuriumMutation(s): 0 
Gene Names: SipA
Find proteins for P0CL52 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720))
Explore P0CL52 
Go to UniProtKB:  P0CL52
Entity Groups  
Sequence Clusters30% Identity50% Identity70% Identity90% Identity95% Identity100% Identity
UniProt GroupP0CL52
Sequence Annotations
  • Reference Sequence
Experimental Data & Validation

Experimental Data

  • Resolution: 1.80 Å
  • R-Value Free: 0.222 
  • R-Value Work: 0.194 
  • R-Value Observed: 0.194 
  • Space Group: P 43 21 2
Unit Cell:
Length ( Å )Angle ( ˚ )
a = 79.9α = 90
b = 79.9β = 90
c = 57.5γ = 90
Software Package:
Software NamePurpose
DENZOdata reduction
SCALEPACKdata scaling
RESOLVEmodel building

Structure Validation

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Entry History 

Deposition Data

Revision History  (Full details and data files)

  • Version 1.0: 2003-10-07
    Type: Initial release
  • Version 1.1: 2008-04-29
    Changes: Version format compliance
  • Version 1.2: 2011-07-13
    Changes: Version format compliance
  • Version 1.3: 2024-02-14
    Changes: Data collection, Database references