title: A novel dense granule protein, GRA22, is involved in regulating parasite egress in Toxoplasma gondii.
abstract: The intracellular protozoan parasite Toxoplasma gondii is capable of invading any nucleated cell and replicates within a parasitophorous vacuole (PV). This microenvironment is modified by secretory proteins from organelles named rhoptries and dense granules. In this report, we identify a novel dense granule protein, which we refer to as GRA22. GRA22 has no significant homology to any other known proteins. GRA22 possesses a signal peptide at the N-terminal end which is responsible for dense granule and PV localization. The RH strain GRA22 contains 12 copies of tandem repeats consisting each of 21 amino acids located between the 42nd and 293rd amino acid residues from a full length of 624 amino acids. On the other hand, ME49 strain GRA22 has 10 copies of tandem repeats. The Neospora caninum GRA22 ortholog completely lacks this repetitive sequence. GRA22 knock out parasites show a similar growth rate as the parental strain. However, the timing of egress is earlier than that of the parental strain. These results suggest that GRA22 is involved in regulating parasite egress in T. gondii.
authors.affiliation: National Research Center for Protozoan Diseases (NRCPD), Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
authors.forename: Tadashi
authors.initials: T
authors.lastname: Okada
authors.forename: Dini
authors.initials: D
authors.lastname: Marmansari
authors.forename: Zeng-mei
authors.initials: ZM
authors.lastname: Li
authors.forename: Altanchimeg
authors.initials: A
authors.lastname: Adilbish
authors.forename: Shishenkov
authors.initials: S
authors.lastname: Canko
authors.forename: Akio
authors.initials: A
authors.lastname: Ueno
authors.forename: Haruhi
authors.initials: H
authors.lastname: Shono
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Furuoka
authors.forename: Makoto
authors.initials: M
authors.lastname: Igarashi
mesh_terms: D000818:Animals; D002460:Cell Line; D055786:Gene Knockout Techniques; D005816:Genetic Complementation Test; D054884:Host-Pathogen Interactions; D006801:Humans; D021382:Protein Sorting Signals; D015800:Protozoan Proteins / Q000235:genetics / Q000378:metabolism*; D020449:Repetitive Sequences, Amino Acid; D014122:Toxoplasma / Q000235:genetics / Q000502:physiology*
chemical_list: D021382:Protein Sorting Signals; D015800:Protozoan Proteins