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Preparing Lamellae from Vitreous Biological Samples Using a Dual-Beam Scanning Electron Microscope for Cryo-Electron Tomography
Published on: August 5, 2021
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In situ ultrastructures of two evolutionarily distant apicomplexan rhoptry secretion systems
Shrawan Kumar Mageswaran1, Amandine Guérin2, Liam M Theveny1
1Department of Biochemistry and Biophysics, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, USA.
Nature Communications
|August 18, 2021
Summary
Researchers revealed the conserved structure of the rhoptry secretion system in Apicomplexa parasites. This breakthrough clarifies how these pathogens inject essential proteins into host cells for infection.
Area of Science:
- Cell Biology
- Parasitology
- Structural Biology
Background:
- Apicomplexan parasites cause significant diseases like malaria and toxoplasmosis.
- Rhoptries are essential organelles for host cell invasion, but their secretion mechanism is poorly understood.
Purpose of the Study:
- To elucidate the conserved architecture and mechanism of the rhoptry secretion system in Apicomplexa.
- To provide an ultrastructural framework for understanding effector delivery by these parasites.
Main Methods:
- Cryo-electron tomography and subtomogram averaging were used to visualize the rhoptry secretion system.
- Genetic manipulation (protein depletion) was employed to study the functional role of components like Nd9.
Main Results:
- Identified conserved helical filaments shaping rhoptries and an apical vesicle (AV) anchored by the rhoptry secretory apparatus (RSA).
- Demonstrated that RSA disruption impairs AV anchoring and rhoptry secretion.
- Proposed a model for apical vesicle reloading and discharging of multiple rhoptries involving microtubules.
Conclusions:
- The study provides a detailed ultrastructural framework for rhoptry-mediated host cell invasion in Apicomplexa.
- Understanding this system is crucial for developing strategies against apicomplexan-borne diseases.
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