title: The C-terminus of Toxoplasma RON2 provides the crucial link between AMA1 and the host-associated invasion complex.
abstract: 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.
authors.affiliation: Department of Microbiology and Immunology, Stanford University School of Medicine, Stanford, California, United States of America.
authors.forename: Jessica S
authors.initials: JS
authors.lastname: Tyler
authors.forename: John C
authors.initials: JC
authors.lastname: Boothroyd
mesh_terms: D020816:Amino Acid Motifs; D000818:Animals; D000953:Antigens, Protozoan / Q000378:metabolism* / Q000502:physiology; D002478:Cells, Cultured; D006790:Host-Parasite Interactions / Q000276:immunology / Q000502:physiology; D006801:Humans; D011485:Protein Binding / Q000502:physiology; D017434:Protein Structure, Tertiary / Q000502:physiology; D015800:Protozoan Proteins / Q000737:chemistry* / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D014122:Toxoplasma / Q000276:immunology / Q000378:metabolism / Q000502:physiology*; D014123:Toxoplasmosis / Q000469:parasitology / Q000473:pathology
chemical_list: C506564:AMA1 protein, Toxoplasma gondii; D000953:Antigens, Protozoan; D015800:Protozoan Proteins