Toxofilin, a Novel Actin-binding Protein from Toxoplasma gondii, Sequesters Actin Monomers and Caps Actin Filaments
AUTOR(ES)
Poupel, Olivier
FONTE
The American Society for Cell Biology
RESUMO
Toxoplasma gondii relies on its actin cytoskeleton to glide and enter its host cell. However, T. gondii tachyzoites are known to display a strikingly low amount of actin filaments, which suggests that sequestration of actin monomers could play a key role in parasite actin dynamics. We isolated a 27-kDa tachyzoite protein on the basis of its ability to bind muscle G-actin and demonstrated that it interacts with parasite G-actin. Cloning and sequence analysis of the gene coding for this protein, which we named Toxofilin, showed that it is a novel actin-binding protein. In in vitro assays, Toxofilin not only bound to G-actin and inhibited actin polymerization as an actin-sequestering protein but also slowed down F-actin disassembly through a filament end capping activity. In addition, when green fluorescent protein-tagged Toxofilin was overexpressed in mammalian nonmuscle cells, the dynamics of actin stress fibers was drastically impaired, whereas green fluorescent protein-Toxofilin copurified with G-actin. Finally, in motile parasites, during gliding or host cell entry, Toxofilin was localized in the entire cytoplasm, including the rear end of the parasite, whereas in intracellular tachyzoites, especially before they exit from the parasitophorous vacuole of their host cell, Toxofilin was found to be restricted to the apical end.
ACESSO AO ARTIGO
http://www.pubmedcentral.nih.gov/articlerender.fcgi?artid=14779Documentos Relacionados
- Characterization of Mayven, a Novel Actin-binding Protein Predominantly Expressed in Brain
- New actin-binding proteins from Dictyostelium discoideum
- Interactions of actin, myosin, and an actin-binding protein of chronic myelogenous leukemia leukocytes.
- Isolation of a high molecular weight actin-binding protein from baby hamster kidney (BHK-21) cells.
- Glutathione depletion triggers actin cytoskeleton changes via actin-binding proteins