Okada Tadashi, Marmansari Dini, Li Zeng-mei, Adilbish Altanchimeg, Canko Shishenkov, Ueno Akio, Shono Haruhi, Furuoka Hidefumi, Igarashi Makoto
National Research Center for Protozoan Diseases (NRCPD), Obihiro University of Agriculture and Veterinary Medicine, Obihiro, Hokkaido 080-8555, Japan.
Mol Biochem Parasitol. 2013 May;189(1-2):5-13. doi: 10.1016/j.molbiopara.2013.04.005. Epub 2013 Apr 23.
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.
细胞内原生动物寄生虫刚地弓形虫能够侵入任何有核细胞，并在寄生泡（PV）内进行复制。这种微环境会被来自名为棒状体和致密颗粒的细胞器分泌的蛋白质所改变。在本报告中，我们鉴定出一种新型致密颗粒蛋白，我们将其称为GRA22。GRA22与任何其他已知蛋白均无显著同源性。GRA22在N末端具有一个信号肽，该信号肽负责其在致密颗粒和寄生泡中的定位。RH株的GRA22含有12个串联重复序列，每个重复序列由21个氨基酸组成，位于全长624个氨基酸的第42至293个氨基酸残基之间。另一方面，ME49株的GRA22有10个串联重复序列。犬新孢子虫的GRA22直系同源物完全缺乏这种重复序列。敲除GRA22的寄生虫显示出与亲代菌株相似的生长速率。然而，逸出的时间比亲代菌株更早。这些结果表明，GRA22参与调控刚地弓形虫的寄生虫逸出过程。
