title: Calcium-dependent phosphorylation alters class XIVa myosin function in the protozoan parasite Toxoplasma gondii.
abstract: Class XIVa myosins comprise a unique group of myosin motor proteins found in apicomplexan parasites, including those that cause malaria and toxoplasmosis. The founding member of the class XIVa family, Toxoplasma gondii myosin A (TgMyoA), is a monomeric unconventional myosin that functions at the parasite periphery to control gliding motility, host cell invasion, and host cell egress. How the motor activity of TgMyoA is regulated during these critical steps in the parasite's lytic cycle is unknown. We show here that a small-molecule enhancer of T. gondii motility and invasion (compound 130038) causes an increase in parasite intracellular calcium levels, leading to a calcium-dependent increase in TgMyoA phosphorylation. Mutation of the major sites of phosphorylation altered parasite motile behavior upon compound 130038 treatment, and parasites expressing a nonphosphorylatable mutant myosin egressed from host cells more slowly in response to treatment with calcium ionophore. These data demonstrate that TgMyoA undergoes calcium-dependent phosphorylation, which modulates myosin-driven processes in this important human pathogen.
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405.
authors.forename: Qing
authors.initials: Q
authors.lastname: Tang
authors.affiliation: Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Nicole
authors.initials: N
authors.lastname: Andenmatten
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602.
authors.forename: Miryam A
authors.initials: MA
authors.lastname: Hortua Triana
authors.affiliation: Vermont Genetics Network Proteomics Facility, University of Vermont, Burlington, VT 05405 Department of Biology, University of Vermont, Burlington, VT 05405.
authors.forename: Bin
authors.initials: B
authors.lastname: Deng
authors.affiliation: Wellcome Trust Centre for Molecular Parasitology, Institute of Infection, Immunity and Inflammation, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, United Kingdom.
authors.forename: Markus
authors.initials: M
authors.lastname: Meissner
authors.affiliation: Center for Tropical and Emerging Global Diseases and Department of Cellular Biology, University of Georgia, Athens, GA 30602.
authors.forename: Silvia N J
authors.initials: SN
authors.lastname: Moreno
authors.affiliation: Department of Biology, University of Vermont, Burlington, VT 05405.
authors.forename: Bryan A
authors.initials: BA
authors.lastname: Ballif
authors.affiliation: Department of Microbiology and Molecular Genetics, University of Vermont College of Medicine, Burlington, VT 05405 Gary.Ward@uvm.edu.
authors.forename: Gary E
authors.initials: GE
authors.lastname: Ward
mesh_terms: D002118:Calcium / Q000378:metabolism*; D003600:Cytosol / Q000378:metabolism; D009218:Myosins / Q000378:metabolism / Q000502:physiology*; D010766:Phosphorylation; D015800:Protozoan Proteins / Q000378:metabolism / Q000502:physiology*; D014122:Toxoplasma / Q000378:metabolism* / Q000502:physiology
chemical_list: D015800:Protozoan Proteins; D009218:Myosins; D002118:Calcium