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Updated: Apr 7, 2026

Using Microfluidics and Fluorescence Microscopy to Study the Assembly Dynamics of Single Actin Filaments and Bundles
Published on: May 5, 2022
Disassembly activity of actin-depolymerizing factor (ADF) is associated with distinct cellular processes in
Silvia Haase1, Dennis Zimmermann2, Maya A Olshina1
1Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
Actin-depolymerizing factor (ADF) proteins are vital for apicomplexan parasites. This study reveals genus-specific differences in ADF function, impacting parasite development but not motility.
Area of Science:
- Parasitology
- Molecular Biology
- Cell Biology
Background:
- Actin-depolymerizing factor (ADF)/cofilin proteins are essential for apicomplexan parasite motility and survival.
- The precise mechanisms of ADF function in these parasites are not fully understood.
Purpose of the Study:
- To comparatively analyze the activities of ADF proteins from *Toxoplasma gondii* and *Plasmodium falciparum*.
- To investigate the functional conservation and genus-specific adaptations of ADF proteins in apicomplexan parasites.
Main Methods:
- Utilized a conditional *T. gondii* ADF-knockout line complemented with *T. gondii* and *P. falciparum* ADF variants.
- Performed phenotypic analysis of parasite growth, motility, and organelle segregation.
- Conducted biochemical assays to assess actin depolymerization and filament severing activities.
Main Results:
- *P. falciparum* ADF1 fully restored native *T. gondii* ADF activity, indicating functional conservation.
- Mutation of a key lysine residue (Lys-72) in *Pf*ADF1 had no effect on parasite phenotypes.
- Complementing with a *Tg*ADF mutant lacking the corresponding lysine residue (Lys-68) severely impaired organelle segregation.
- Biochemical analyses showed reduced actin filament disassembly by lysine mutants, but not severing.
Conclusions:
- Actin filament disassembly is crucial for apicomplexan parasite development, but not motility.
- Genus-specific coevolution exists between ADF proteins and their native actin in apicomplexan parasites.
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