2Q97

Complex of mammalian actin with toxofilin from toxoplasma gondii

Experimental Data Snapshot

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.229 

wwPDB Validation 3D Report Full Report


This is version 1.2 of the entry. See complete history. 

Literature

Toxofilin from Toxoplasma gondii forms a ternary complex with an antiparallel actin dimer

Lee, S.H., Hayes, D.B., Rebowski, G., Tardieux, I., Dominguez, R.

(2007) Proc.Natl.Acad.Sci.Usa 104: 16122-16127

  • DOI: 10.1073/pnas.0705794104

  • PubMed Abstract: 

    • Many human pathogens exploit the actin cytoskeleton during infection, including Toxoplasma gondii, an apicomplexan parasite related to Plasmodium, the agent of malaria. One of the most abundantly expressed proteins of T. gondii is toxofilin, a monome ...

    Many human pathogens exploit the actin cytoskeleton during infection, including Toxoplasma gondii, an apicomplexan parasite related to Plasmodium, the agent of malaria. One of the most abundantly expressed proteins of T. gondii is toxofilin, a monomeric actin-binding protein (ABP) involved in invasion. Toxofilin is found in rhoptry and presents an N-terminal signal sequence, consistent with its being secreted during invasion. We report the structure of toxofilin amino acids 69-196 in complex with the host mammalian actin. Toxofilin presents an extended conformation and interacts with an antiparallel actin dimer, in which one of the actins is related by crystal symmetry. Consistent with this observation, analytical ultracentrifugation analysis shows that toxofilin binds two actins in solution. Toxofilin folds into five consecutive helices, which form three relatively independent actin-binding sites. Helices 1 and 2 bind the symmetry-related actin molecule and cover its nucleotide-binding cleft. Helices 3-5 bind the other actin and constitute the primary actin-binding region. Helix 3 interacts in the cleft between subdomains 1 and 3, a common binding site for most ABPs. Helices 4 and 5 wrap around actin subdomain 4, and residue Gln-134 of helix 4 makes a hydrogen-bonding contact with the nucleotide in actin, both of which are unique features among ABPs. Toxofilin dramatically inhibits nucleotide exchange on two actin molecules simultaneously. This effect is linked to the formation of the antiparallel actin dimer because a construct lacking helices 1 and 2 binds only one actin and inhibits nucleotide exchange less potently.

    Organizational Affiliation: 

    Department of Physiology, University of Pennsylvania School of Medicine, 3700 Hamilton Walk, Philadelphia, PA 19104-6085, USA.




Macromolecules

Find similar proteins by: Sequence  |  Structure

Entity ID: 1
MoleculeChainsSequence LengthOrganismDetails
Actin, alpha skeletal muscle
A
375Oryctolagus cuniculusMutation(s): 0 
Gene Names: ACTA1 (ACTA)
Find proteins for P68135 (Oryctolagus cuniculus)
Go to Gene View: ACTA1
Go to UniProtKB:  P68135
Entity ID: 2
MoleculeChainsSequence LengthOrganismDetails
Toxofilin
T
129Toxoplasma gondiiMutation(s): 0 
Gene Names: toxofilin
Find proteins for Q9NG25 (Toxoplasma gondii)
Go to UniProtKB:  Q9NG25
Small Molecules
Ligands 2 Unique
IDChainsName / Formula / InChI Key2D Diagram3D Interactions
ATP
Query on ATP
Download SDF File 
Download CCD File 
A
ADENOSINE-5'-TRIPHOSPHATE
C10 H16 N5 O13 P3
ZKHQWZAMYRWXGA-KQYNXXCUSA-N
 Ligand Interaction
CA
Query on CA
Download SDF File 
Download CCD File 
A
CALCIUM ION
Ca
BHPQYMZQTOCNFJ-UHFFFAOYSA-N
 Ligand Interaction
Modified Residues  1 Unique
IDChainsTypeFormula2D DiagramParent
HIC
Query on HIC
A
L-PEPTIDE LINKINGC7 H11 N3 O2HIS
Experimental Data & Validation

Experimental Data

  • Method: X-RAY DIFFRACTION
  • Resolution: 2.5 Å
  • R-Value Free: 0.284 
  • R-Value Work: 0.229 
  • Space Group: P 41 2 2
Unit Cell:
Length (Å)Angle (°)
a = 54.523α = 90.00
b = 54.523β = 90.00
c = 363.100γ = 90.00
Software Package:
Software NamePurpose
AMoREphasing
HKL-2000data scaling
HKL-2000data reduction
REFMACrefinement

Structure Validation

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Entry History 

Deposition Data

Revision History 

  • Version 1.0: 2007-10-16
    Type: Initial release
  • Version 1.1: 2011-07-13
    Type: Version format compliance
  • Version 1.2: 2011-08-24
    Type: Atomic model