1Q5Z

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

• PDB DOI: https://doi.org/10.2210/pdb1Q5Z/pdb

• Classification: CELL INVASION
• Organism(s): Salmonella enterica subsp. enterica serovar Typhimurium
• Expression System: Escherichia coli BL21(DE3)
• Mutation(s): No 


• Deposited: 2003-08-11 Released: 2003-10-07 
• Deposition Author(s): Stebbins, C.E., Lilic, M., Galkin, V.E., Orlova, A., VanLoock, M.S., Egelman, E.H.

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Experimental Data Snapshot

• Method: X-RAY DIFFRACTION
• Resolution: 1.80 Å
• R-Value Free: 0.222 
• R-Value Work: 0.194 
• R-Value Observed: 0.194 

Literature

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

• PubMed: 14512630 
• DOI: https://doi.org/10.1126/science.1088433
• Primary Citation of Related Structures:  
  1Q5Z


• 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.

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Organizational Affiliation: 

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

Biological Assembly 1  

Global Symmetry: Asymmetric - C1 
Global Stoichiometry: Monomer - A1 

Biological assembly 1 assigned by authors.

Macromolecule Content

• Total Structure Weight: 19.45 kDa 
• Atom Count: 1,356 
• Modelled Residue Count: 145 
• Deposited Residue Count: 177 
• Unique protein chains: 1

Macromolecules

Entity ID: 1
Molecule	Chains	Sequence Length	Organism	Details	Image
SipA	A	177	Salmonella enterica subsp. enterica serovar Typhimurium	Mutation(s): 0  Gene Names: SipA
UniProt
Find proteins for P0CL52 (Salmonella typhimurium (strain LT2 / SGSC1412 / ATCC 700720)) Explore P0CL52  Go to UniProtKB:  P0CL52

Experimental Data & Validation

Experimental Data

• Method: X-RAY DIFFRACTION
• 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 = 79.9	α = 90
b = 79.9	β = 90
c = 57.5	γ = 90

Software Package:

Software Name	Purpose
DENZO	data reduction
SCALEPACK	data scaling
SOLVE	phasing
RESOLVE	model building
CNS	refinement
RESOLVE	phasing

Structure Validation

Entry History 

Deposition Data

• Released Date: 2003-10-07 
Deposition Author(s): Stebbins, C.E., Lilic, M., Galkin, V.E., Orlova, A., VanLoock, M.S., Egelman, E.H.

Revision History  

• 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