Abstract
Actin polymerization in Apicomplexa protozoa is central to parasite motility and host cell invasion. Toxofilin has been characterized as a protein that sequesters actin monomers and caps actin filaments in Toxoplasma gondii. Herein, we show that Toxofilin properties in vivo as in vitro depend on its phosphorylation. We identify a novel parasitic type 2C phosphatase that binds the Toxofilin/G-actin complex and a casein kinase II-like activity in the cytosol, both of which modulate the phosphorylation status of Toxofilin serine53. The interplay of these two molecules controls Toxofilin binding of G-actin as well as actin dynamics in vivo. Such functional interactions should play a major role in actin sequestration, a central feature of actin dynamics in Apicomplexa that underlies the spectacular speed and nature of parasite gliding motility.
Publication types
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Research Support, Non-U.S. Gov't
MeSH terms
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Actin Capping Proteins
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Actins / metabolism*
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Amino Acid Sequence
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Animals
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Casein Kinase II
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Dichlororibofuranosylbenzimidazole / pharmacology
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Enzyme Inhibitors / pharmacology
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Microfilament Proteins* / metabolism
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Molecular Sequence Data
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Phosphoprotein Phosphatases / metabolism*
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Phosphorylation
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Protein Serine-Threonine Kinases / antagonists & inhibitors
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Protein Serine-Threonine Kinases / metabolism*
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Protozoan Proteins
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Sequence Alignment
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Serine / metabolism
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Toxoplasma / drug effects
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Toxoplasma / enzymology*
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Toxoplasma / metabolism
Substances
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Actin Capping Proteins
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Actins
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Enzyme Inhibitors
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Microfilament Proteins
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Protozoan Proteins
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toxofilin protein, Toxoplasma gondii
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Serine
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Dichlororibofuranosylbenzimidazole
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Casein Kinase II
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Protein Serine-Threonine Kinases
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Phosphoprotein Phosphatases