Interaction between Toxoplasma GRA7 Dense Granule Protein and the Protein from Host Macrophages

Objective To identify the protein from host macrophages which interacted with GRA7 dense granule protein of Toxoplasma gondii, and reveal the relationship between protein interaction and infection process. Methods The recombinant GRA7 protein with N-terminal GST tag were used as a bait in in vitro GST Pull-down experiment, the proteins of THP-1 monocytic macrophage cell line were captured and identified by LC-MS/MS proteomics method. The in vivo protein interaction was verified by Co-IP experiment. The overexpression of the target host protein by pc DNA3.1(+) vector in THP-1macrophage was further used to analyze the relationship between protein interaction and infection process. Results The captured THP-1 cell protein was about Mr29 000, which was identified as human carbonic anhydrase 1(h CA1). The significant in vivo protein-protein interaction between GRA7 and h CA1 was verified by Co-IP assay. The overexpression of h CA1 gene in THP-1 macrophage induced a higher propagation speed of T. gondii and the formation of the parasitophorous vacuole, but did not influence the number of the parasite. Conclusion There is a significant protein interaction between Toxoplasma GRA7 dense granule protein and h CA1 enzyme from host macrophages, which is positively related with the propagation speed of T. gondii.