Interactions between the ROP18 kinase and host cell proteins that aid in the parasitism of Toxoplasma gondii

Serine/threonine kinases secreted from rhoptry organelles are important virulence factors for Toxoplasma gondii. Among rhoptry proteins, the ROP18 kinase has been identified as a key virulence determinant mediating pathogenesis in T. gondii; however, the molecular mechanisms by which this kinase exerts its pathogenic action remain poorly understood. In this study, the interactions between the ROP18 kinase of Toxoplasma gondii and the host cell proteins were analyzed using a yeast two-hybrid technique. The cMyc-ROP1825–251 fusion proteins expressed by pGBKT7 plasmids in AH109 yeast were bound to host cell proteins from a human fetal brain cDNA library transformed to AH109 yeast using a mating method. Using these selection procedures, we identified seven host proteins that had not previously been reported to interact with ROP18 such as DDB1, TOR1AIP1, integrin, SLC3A2, TPST2, DERL2 and OCIAD1. These host proteins are associated with DNA repair, transcriptional regulation, translation modification, protein degradation and cell adhesion. Our data strongly support the hypothesis that the secreted kinase ROP18 is involved in several complex cellular pathways for the invasion and commandeering of host functions.

Our data strongly support the hypothesis that the secreted kinase ROP18 is involved in several complex cellular pathways for the invasion and commandeering of host functions.Figure optionsDownload as PowerPoint slideHighlights
► RT-PCR amplification of full length ROP18 and its mutants.
► Test of the autonomous activating activity and expression of the “bait” fusion protein.
► Use ROP1825–251 aa as “bait” to screen of the human fetal brain cDNA library.
► These host proteins interacting with ROP18 are associated with proteins in many signal pathway.