title: TgM2AP participates in Toxoplasma gondii invasion of host cells and is tightly associated with the adhesive protein TgMIC2.
abstract: Like other members of the medically important phylum Apicomplexa, Toxoplasma gondii is an obligate intracellular parasite that secretes several classes of proteins involved in the active invasion of target host cells. Proteins in apical secretory organelles known as micronemes have been strongly implicated in parasite attachment to host cells. TgMIC2 is a microneme protein with multiple adhesive domains that bind target cells and is mobilized onto the parasite surface during parasite attachment. Here, we describe a novel parasite protein, TgM2AP, which is physically associated with TgMIC2. TgM2AP complexes with TgMIC2 within 15 min of synthesis and remains associated with TgMIC2 in the micronemes, on the parasite surface during invasion and in the culture medium after release from the parasite plasma membrane. TgM2AP is proteolytically processed initially when its propeptide is removed during transit through the golgi and later while it occupies the parasite surface after discharge from the micronemes. We show that TgM2AP is a member of a protein family expressed by coccidian parasites including Neospora caninum and Eimeria tenella. This phylogenic conservation and association with a key adhesive protein suggest that TgM2AP is a fundamental component of the T. gondii invasion machinery.
authors.affiliation: W. Harry Feinstone Department of Molecular Microbiology and Immunology, Johns Hopkins University School of Public Health, 615 N. Wolfe St., Baltimore, MD 21205, USA.
authors.forename: K E
authors.initials: KE
authors.lastname: Rabenau
authors.forename: A
authors.initials: A
authors.lastname: Sohrabi
authors.forename: A
authors.initials: A
authors.lastname: Tripathy
authors.forename: C
authors.initials: C
authors.lastname: Reitter
authors.forename: J W
authors.initials: JW
authors.lastname: Ajioka
authors.forename: F M
authors.initials: FM
authors.lastname: Tomley
authors.forename: V B
authors.initials: VB
authors.lastname: Carruthers
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D003001:Cloning, Molecular; D015180:Electrophoresis, Gel, Two-Dimensional; D005347:Fibroblasts; D019084:Fluorescent Antibody Technique, Indirect; D006801:Humans; D008565:Membrane Proteins; D008969:Molecular Sequence Data; D008970:Molecular Weight; D011485:Protein Binding; D011499:Protein Processing, Post-Translational; D015800:Protozoan Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D022142:Secretory Vesicles / Q000378:metabolism; D016415:Sequence Alignment; D014122:Toxoplasma / Q000378:metabolism* / Q000502:physiology*; D014123:Toxoplasmosis / Q000469:parasitology*
chemical_list: C408878:MIC2 protein, Toxoplasma gondii; D008565:Membrane Proteins; D015800:Protozoan Proteins; C450759:TgM2AP protein, Toxoplasma gondii