Microneme rhomboid protease TgROM1 is required for efficient intracellular growth of Toxoplasma gondii
Microneme rhomboid protease TgROM1 is required for efficient intracellular growth of Toxoplasma gondii
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DOI：
10.1128/ec.00331-07
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发表时间：
2008-04-01
期刊：
影响因子：
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通讯作者：
Sibley, L. David
中科院分区：
文献类型：
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作者：
Brossier, Fabien;Starnes, G. Lucas;Sibley, L. David
菱形是丝氨酸蛋白酶，能在跨膜区内裂解底物。弓形虫含有六个菱形体，它们在不同的生命周期阶段表达，并定位于不同的细胞亚室。弓形虫菱形蛋白1(TgROM1)已被证明在体外具有活性，恶性疟原虫中的同源蛋白在异源系统中处理必要的微线体蛋白AMA1。我们研究了TgROM1的作用，以确定其在弓形虫体外生长中的作用。TgROM1定位于寄生虫的分泌途径，包括高尔基体和微线体，其中含有与宿主细胞入侵有关的黏附蛋白。然而，与其他微体蛋白不同的是，TgROM1在细胞入侵过程中没有释放到寄生虫表面，这表明它在细胞入侵中不起关键作用。用四环素可调控系统抑制TgROM1表明ROM1缺乏的寄生虫被野生型弓形虫所击败。与野生型细胞相比，ROM1基因缺陷的寄生虫在侵袭性方面仅有轻微的下降，但复制速度较慢。综上所述，这些结果表明ROM1是弓形虫高效细胞内生长所必需的。
Rhomboids are serine proteases that cleave their substrates within the transmembrane domain. Toxoplasma gondii contains six rhomboids that are expressed in different life cycle stages and localized to different cellular compartments. Toxoplasma rhomboid protein 1 (TgROM1) has previously been shown to be active in vitro, and the orthologue in Plasmodium falciparum processes the essential microneme protein AMA1 in a heterologous system. We investigated the role of TgROM1 to determine its role during in vitro growth of T. gondii. TgROM1 was localized in the secretory pathway of the parasite, including the Golgi apparatus and micronemes, which contain adhesive proteins involved in invasion of host cells. However, unlike other micronemal proteins, TgROM1 was not released onto the parasite surface during cell invasion, suggesting it does not play a critical role in cell invasion. Suppression of TgROM1 using the tetracycline-regulatable system revealed that ROM1-deficient parasites were outcompeted by wild-type T. gondii. ROM1-deficient parasites showed only modest decrease in invasion but replicated more slowly than wild-type cells. Collectively, these results indicate that ROM1 is required for efficient intracellular growth by T. gondii.