Toxoplasmosis: evolution of infection machinery

February 16, 2024

Toxoplasmosis is an infectious disease found worldwide, caused by the single-celled parasite Toxoplasma gondii. In humans, infection poses a particular risk to pregnant woman, as it can lead to birth defects. Like the closely related malaria pathogen – Plasmodium falciparum – and other related species, T. gondii possesses special organelles, so-called rhoptries and micronemes, for infecting the host cell. In the course of their evolution, the parasites not only developed special organelles such as the rhoptries and micronemes, but also all the protein machinery required to ensure the production and functioning of the organelles. “In order to create their specific structures, the parasites had to repurpose some proteins and add others,” explains LMU parasitologist Elena Jimenez-Ruiz.

Toxoplasmosis is an infectious disease found worldwide, caused by the single-celled parasite Toxoplasma gondii. In humans, infection poses a particular risk to pregnant woman, as it can lead to birth defects. Like the closely related malaria pathogen – Plasmodium falciparum – and other related species, T. gondii possesses special organelles, so-called rhoptries and micronemes, for infecting the host cell. A team led by Professor Markus Meissner, Chair of Experimental Parasitology at LMU, and Professor Joel Dacks from the University of Alberta (Canada) has now investigated the evolution of this infection machinery and identified an organelle-specific protein, which could become a promising target for new therapeutic approaches.

In the course of their evolution, the parasites not only developed special organelles such as the rhoptries and micronemes, but also all the protein machinery required to ensure the production and functioning of the organelles. The so-called organelle paralogy hypothesis (OPH) proposes that the current diversity of cell organelles came about due to the duplication and subsequent diversification over evolutionary time of certain genes that code organelle identity. “In order to create their specific structures, the parasites had to repurpose some proteins and add others,” explains LMU parasitologist Elena Jimenez-Ruiz.