TgGRA23, a novel Toxoplasma gondii dense granule protein associated with the parasitophorous vacuole membrane and intravacuolar network

Tatsunori Masatani, Tomohide Matsuo, Tetsuya Tanaka, Mohamad Alaa Terkawi, Eung Goo Lee, Youn Kyoung Goo, Gabriel Oluga Aboge, Junya Yamagishi, Kei Hayashi, Kyohko Kameyama, Shinuo Cao, Yoshifumi Nishikawa, Xuenan Xuan

    Research output: Contribution to journalArticlepeer-review

    13 Citations (Scopus)

    Abstract

    Toxoplasma gondii is an intracellular protozoan parasite, which relies on a specialized compartment, the parasitophorous vacuole (PV), to survive within host cells. Dense granules within the parasite release a large variety of proteins to maintain the integrity of the vacuole structure. Here, we identified a novel dense granule protein in T. gondii, TgGRA23, which is a homolog of the Sarcocystis muris dense granule protein, SmDG32. Recombinant TgGRA23 (rTgGRA23) expressed in Escherichia coli as a glutathione S-transferase (GST) fusion protein was used to raise antisera in mice and rabbits. Immunoblotting showed that antisera from the immunized mice and rabbits reacted with parasite lysates to yield a 21-kDa native protein. In addition, immuno-electron microscopic examination showed that TgGRA23 resides in the dense granules, PV membrane and intravacuolar network of the parasite. To confirm the precise subcellular localization of TgGRA23 in T. gondii, an immunofluorescent antibody test was performed using dense granule markers. Notably, TgGRA23 co-localized with other dense granule proteins including TgGRA4 and TgGRA7, in the extracellular-stage parasites. Biochemical experiments indicated that TgGRA23 is insoluble and may form an electrostatic complex that is resistant to non-ionic detergents. Furthermore, specific antibodies to TgGRA23 were detected during the chronic stage of Toxoplasma infection in mice. Our results suggest that TgGRA23 is an as yet unknown member of the T. gondii dense granule proteins, and that it may be involved in remodeling or maintenance of the PV.

    Original languageEnglish
    Pages (from-to)372-379
    Number of pages8
    JournalParasitology International
    Volume62
    Issue number4
    DOIs
    Publication statusPublished - 2013 Aug 1

    Keywords

    • Dense granule
    • Intravacuolar network
    • Parasitophorous vacuole
    • Parasitophorous vacuole membrane
    • TgGRA23
    • Toxoplasma gondii

    ASJC Scopus subject areas

    • Parasitology
    • Infectious Diseases

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