The C-terminus of Toxoplasma RON2 provides the crucial link between AMA1 and the host-associated invasion complex

PLoS Pathog. 2011 Feb 10;7(2):e1001282. doi: 10.1371/journal.ppat.1001282.


Host cell invasion by apicomplexan parasites requires formation of the moving junction (MJ), a ring-like apposition between the parasite and host plasma membranes that the parasite migrates through during entry. The Toxoplasma MJ is a secreted complex including TgAMA1, a transmembrane protein on the parasite surface, and a complex of rhoptry neck proteins (TgRON2/4/5/8) described as host cell-associated. How these proteins connect the parasite and host cell has not previously been described. Here we show that TgRON2 localizes to the MJ and that two short segments flanking a hydrophobic stretch near its C-terminus (D3 and D4) independently associate with the ectodomain of TgAMA1. Pre-incubation of parasites with D3 (fused to glutathione S-transferase) dramatically reduces invasion but does not prevent injection of rhoptry bulb proteins. Hence, the entire C-terminal region of TgRON2 forms the crucial bridge between TgAMA1 and the rest of the MJ complex but this association is not required for rhoptry protein injection.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Motifs
  • Animals
  • Antigens, Protozoan / metabolism*
  • Antigens, Protozoan / physiology
  • Cells, Cultured
  • Host-Parasite Interactions* / immunology
  • Host-Parasite Interactions* / physiology
  • Humans
  • Protein Binding / physiology
  • Protein Structure, Tertiary / physiology
  • Protozoan Proteins / chemistry*
  • Protozoan Proteins / immunology
  • Protozoan Proteins / metabolism
  • Protozoan Proteins / physiology*
  • Toxoplasma / immunology
  • Toxoplasma / metabolism
  • Toxoplasma / physiology*
  • Toxoplasmosis / parasitology
  • Toxoplasmosis / pathology


  • AMA1 protein, Toxoplasma gondii
  • Antigens, Protozoan
  • Protozoan Proteins