Looking forward: Imaging the migration motor of Apicomplexa parasites

Abstract text

Apicomplexa parasites, a phylum that includes obligate intracellular pathogens such as Plasmodium spp, Toxoplasma gondii or Cryptosporidium spp share a repertoire of homologous structures, such as the conoid and motor proteins that are required for for motility, which is central for parasite survival and dissemination. The current view, on how Apicompexa parasites moves, is described by the linear model, that postulates that, apicomplexan parasite locomotion is a type of adhesion based motility, powered by an actin-myosin motor, located in a space of 30 nm underneath the plasma membrane, and on the outer layer of the saccule like structure called the inner membrane complex (IMC).

Although, a cumulative amount of empirical data support this model, the architecture of the motor, its actual localisation and molecular basis of migration are still largely unsolved.

Here, we systematically tagged multiple components of the gliding machinery with multifunctional reporters, such as HALO or SNAP that allow imaging of parasites using super-resolution based methods including STED, uExMIC, graphene-energy transfer (GET) biosensors and FRAP functional live imaging methods. Using this combined approach, we have started to comprehensively and objectively test whether our observations fit with the predictions from the linear model.

Our preliminary results, shows that distribution of myosin-A, actin, and other linear model components may agree with alternative configurations of the motor and alternative, mechanistic models are plausible.The data suggest a thorough revision of the current model of migration.