Functional and biophysical analyses of the class XIV Toxoplasma gondii Myosin D
- 150 Downloads
The obligate intracellular parasite Toxoplasma gondii uses gliding motility to migrate across the biological barriers of the host and to invade cells. This unique form of locomotion requires an intact actin cytoskeleton and involves at least one motor protein (TgMyoA) that belongs to the class XIV of the myosin superfamily. TgMyoA is anchored in the inner membrane complex and is essential for the gliding motion, host cell invasion and egress of T. gondii tachyzoites. TgMyoD is the smallest T. gondii myosin and is structurally very closely related to TgMyoA. We show here that TgMyoD exhibits similar transient kinetic properties as the fast single-headed TgMyoA. To determine if TgMyoD also contributes to parasite gliding motility, the TgMyoD gene was disrupted by double homologous recombination. In contrast to TgMyoA, TgMyoD gene is dispensable for tachyzoite propagation and motility. Parasites lacking TgMyoD glide normally and their virulence is not compromised in mice. The fact that TgMyoD is predominantly expressed in bradyzoites explains the absence of a phenotype observed with myodko in tachyzoites and does not exclude a role of this motor in gliding that would be restricted to the cyst forming but nevertheless motile stage of the parasite.
KeywordsATPase Activity Toxoplasma Gondii Host Cell Invasion Double Homologous Recombination Phosphoenol Pyruvic Acid
- mant ATP
N-methylanthraniloyl derivatives of 2′deoxy-ATP
- Keeley A and Soldati D (2004) The glideosome: a molecular machine powering motility and host-cell invasion by Apicomplexa Trends Cell. Biology 14: 528–532Google Scholar
- Malnasi-Csizmadia A, Pearson DS, Kovacs M, Woolley RJ, Geeves MA and Bagshaw CR (2001) Kinetic resolution of a conformational transition and the ATP hydrolysis step using relaxation methods with a Dictyostelium myosin II mutant containing a single tryptophan residue.Biochemistry 40(42): 12727–12737PubMedCrossRefGoogle Scholar