Parasitic motility has been a fascination of mine as my thesis characterized microtubule-based motor proteins in Trypanosoma brucei, the causative agent of Human African Trypanosomiasis (HAT) and the animal wasting disease na’gana. Here is a video of that motion.
The American Chemical Society has just released a publication characterizing biophysical characteristics involved in the gliding motion of the parasite Toxoplasma gondii. Plasmodium parasites (the causative agents of malaria) and Toxoplasma parasites use the same cellular machinery to achieve this gliding. The authors use sophisticated microscopy techniques (reflection interference microscopy and expansion microscopy) to build their observational model describing cytoskeletal changes that occur to allow the characteristic motion of left-handed gliding. The authors summarize:
“We propose that the acto-myoA motor directs the traction force which allows transient energy storage by the microtubule cytoskeleton and therefore sets the thrust force required for T. gondii tachyzoite vital helical gliding capacity.”
AUTHORS:
Georgios Pavlou, Bastien Touquet, Luis Vigetti, Patricia Renesto, Alexandre Bougdour, Delphine Debarre, Martial Balland, Isabelle Tardieux*
ABSTRACT:
Among the eukaryotic cells that navigate through fully developed metazoan tissues, protozoans from the Apicomplexa phylum have evolved motile developmental stages that move much faster than the fastest crawling cells owing to a peculiar substrate-dependent type of motility, known as gliding. Best-studied models are the Plasmodium sporozoite and the Toxoplasma tachyzoite polarized cells for which motility is vital to achieve their developmental programs in the metazoan hosts. The gliding machinery is shared between the two parasites and is largely characterized. Localized beneath the cell surface, it includes actin filaments, unconventional myosin motors housed within a multimember glideosome unit, and apically secreted transmembrane adhesins. In contrast, less is known about the force mechanisms powering cell movement. Pioneered biophysical studies on the sporozoite and phenotypic analysis of tachyzoite actin-related mutants have added complexity to the general view that force production for parasite forward movement directly results from the myosin-driven rearward motion of the actin-coupled adhesion sites. Here, we have interrogated how forces and substrate adhesion–de-adhesion cycles operate and coordinate to allow the typical left-handed helical gliding mode of the tachyzoite. By combining quantitative traction force and reflection interference microscopy with micropatterning and expansion microscopy, we unveil at the millisecond and nanometer scales the integration of a critical apical anchoring adhesion with specific traction and spring-like forces. We propose that the acto-myoA motor directs the traction force which allows transient energy storage by the microtubule cytoskeleton and therefore sets the thrust force required for T. gondii tachyzoite vital helical gliding capacity.
ACS Nano 2020, XXXX, XXX, XXX-XXX
Online Publication Date: May 20, 2020
https://doi.org/10.1021/acsnano.0c01893