title: Toxoplasma invasion of mammalian cells is powered by the actin cytoskeleton of the parasite.
abstract: Toxoplasma gondii is an obligate intracellular parasite that invades a wide range of vertebrate host cells. We demonstrate that invasion is critically dependent on actin filaments in the parasite, but not the host cell. Invasion into cytochalasin D (CD)-resistant host cells was blocked by CD, while parasite mutants invaded wild-type host cells in the presence of drug. CD resistance in Toxoplasma was mediated by a point mutation in the single-copy actin gene ACT1. Transfection of the mutant act1 allele into wild-type Toxoplasma conferred motility and invasion in the presence of CD. We conclude that host cell invasion by Toxoplasma, and likely by related Apicomplexans, is actively powered by an actin-based contractile system in the parasite.
authors.affiliation: Department of Molecular Microbiology, Washington University School of Medicine, St. Louis, Missouri, 63110, USA.
authors.forename: J M
authors.initials: JM
authors.lastname: Dobrowolski
authors.forename: L D
authors.initials: LD
authors.lastname: Sibley
mesh_terms: D008841:Actin Cytoskeleton / Q000502:physiology; D000199:Actins / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D001854:Bone Marrow Cells; D002448:Cell Adhesion / Q000187:drug effects / Q000502:physiology; D002460:Cell Line / Q000469:parasitology; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D015638:Cytochalasin D / Q000494:pharmacology; D003599:Cytoskeleton / Q000469:parasitology / Q000502:physiology; D008264:Macrophages / Q000469:parasitology; D051379:Mice; D008807:Mice, Inbred BALB C; D008969:Molecular Sequence Data; D009154:Mutation / Q000502:physiology; D014122:Toxoplasma / Q000166:cytology / Q000235:genetics / Q000469:parasitology*
chemical_list: D000199:Actins; D015638:Cytochalasin D