The actomyosin interface contains an evolutionary conserved core and an ancillary interface involved in specificity

Area of Science:

• Structural Biology
• Parasitology
• Biochemistry

Background:

• Malaria, caused by Plasmodium falciparum, relies on atypical gliding motility for infection.
• Actomyosin interactions are fundamental to this motility, but their atomic details were unknown.
• Understanding these interactions is key to developing new anti-malarial strategies.

Purpose of the Study:

• To determine the atomic structure of the Plasmodium falciparum actomyosin system.
• To elucidate the detailed interactions driving the parasite's force and motion.
• To compare the Plasmodium falciparum actomyosin structure with that of higher eukaryotes.

Main Methods:

• Electron cryomicroscopy (cryo-EM) was used to resolve the actomyosin structure.
• The structure was determined at the Rigor state, representing the end of the powerstroke.
• Comparative analysis with other actomyosin complexes was performed.

Main Results:

• The atomic structure of the Plasmodium falciparum actomyosin system was determined.
• The myosin motor's footprint on actin is conserved across eukaryotes, despite Plasmodium-specific variations.
• A conserved core interface and an ancillary interface were identified, regulating motor positioning.

Conclusions:

• The study provides unprecedented atomic insights into Plasmodium falciparum gliding motility.
• Conserved and divergent features of the actomyosin interface are highlighted.
• These findings offer a structural basis for understanding parasite movement and infectivity.