A Dibasic Motif in the Tail of a Class XIV Apicomplexan Myosin Is an Essential Determinant of Plasma Membrane Localization
- 1 April 2000
- journal article
- Published by American Society for Cell Biology (ASCB) in Molecular Biology of the Cell
- Vol. 11 (4), 1385-1400
- https://doi.org/10.1091/mbc.11.4.1385
Abstract
Obligate intracellular parasites of the phylum Apicomplexa exhibit gliding motility, a unique form of substrate-dependent locomotion essential for host cell invasion and shown to involve the parasite actin cytoskeleton and myosin motor(s). Toxoplasma gondii has been shown to express three class XIV myosins, TgM-A, -B, and -C. We identified an additional such myosin, TgM-D, and completed the sequences of a related Plasmodium falciparum myosin, PfM-A. Despite divergent structural features, TgM-A purified from parasites bound actin in an ATP-dependent manner. Isoform-specific antibodies revealed that TgM-A and recombinant mycTgM-A were localized right beneath the plasma membrane, and subcellular fractionation indicated a tight membrane association. Recombinant TgM-D also had a peripheral although not as sharply defined localization. Truncation of their respective tail domains abolished peripheral localization and tight membrane association. Conversely, fusion of the tails to green fluorescent protein (GFP) was sufficient to confer plasma membrane localization and sedimentability. The peripheral localization of TgM-A and of the GFP-tail fusion did not depend on an intact F-actin cytoskeleton, and the GFP chimera did not localize to the plasma membrane of HeLa cells. Finally, we showed that the specific localization determinants were in the very C terminus of the TgM-A tail, and site-directed mutagenesis revealed two essential arginine residues. We discuss the evidence for a proteinaceous plasma membrane receptor and the implications for the invasion process.Keywords
This publication has 58 references indexed in Scilit:
- A family of unconventional myosins from the nematode Caenorhabditis elegansJournal of Molecular Biology, 1997
- A novel class of unconventional myosins from Toxoplasma gondiiJournal of Molecular Biology, 1997
- Glycine 699 is pivotal for the motor activity of skeletal muscle myosin.The Journal of cell biology, 1996
- Toxoplasma Invasion of Mammalian Cells Is Powered by the Actin Cytoskeleton of the ParasiteCell, 1996
- The Molecular Cloning and Characterization of Drosophila melanogaster Myosin-IA and Myosin-IBJournal of Molecular Biology, 1994
- The actin binding site in the tail domain of Dictyostelium myosin 1C (myoC) resides within the glycine‐ and proline‐rich sequence (tail homology region 2)FEBS Letters, 1994
- Virulent strains of Toxoplasma gondii comprise a single clonal lineageNature, 1992
- The Drosophila ninaC locus encodes two photoreceptor cell specific proteins with domains homologous to protein kinases and the myosin heavy chain headCell, 1988
- Immunofluorescent Localization of Myosin at the Anterior Pole of the Coccidian, Toxoplasma gondi1The Journal of Protozoology, 1983
- Cleavage of Structural Proteins during the Assembly of the Head of Bacteriophage T4Nature, 1970