Soldati D, Lassen A, Dubremetz J F, Boothroyd J C
Zentrum für Molekulare Biologie Heidelberg, Germany.
Mol Biochem Parasitol. 1998 Oct 30;96(1-2):37-48. doi: 10.1016/s0166-6851(98)00090-5.
Secretion in the obligate intracellular parasite, Toxoplasma gondii, occurs through a number of regulated compartments. Among these are the apical organelles known as rhoptries which release their contents as part of the invasion process. We are interested in the processing, targeting and ultimate function of rhoptry proteins (and have focused our analyses on rhoptry protein 1 (ROP1). In this paper, we address the issue of processing: using a number of engineered forms of the ROP1 gene (introduced into a ROP1- background), we show that ROP1 is synthesized as a pre-pro-protein that is subject to proteolytic cleavages to remove the pre-sequence and the 'pro' region, at the N-terminus. Using brefeldin A (BFA) and reduced temperature we show that this processing occurs late in the secretory pathway of the parasite. Immunolocalization studies with epitope-tagged constructs indicate that processing is apparently occurring in the nascent rhoptries of dividing parasites. The results are discussed in the context of the targeting and possible function of the ROP1 protein.
专性细胞内寄生虫刚地弓形虫的分泌过程通过多个受调控的区室进行。其中包括被称为棒状体的顶端细胞器，它们在入侵过程中释放其内容物。我们对棒状体蛋白的加工、靶向定位及最终功能感兴趣（并且我们的分析聚焦于棒状体蛋白1（ROP1））。在本文中，我们探讨加工问题：通过使用多种工程改造形式的ROP1基因（导入ROP1基因缺失背景中），我们发现ROP1是以前原蛋白的形式合成的，该前原蛋白在N端会经历蛋白水解切割以去除前导序列和“原”区域。使用布雷菲德菌素A（BFA）和降低温度，我们发现这种加工发生在寄生虫分泌途径的后期。用表位标签构建体进行的免疫定位研究表明，加工显然发生在正在分裂的寄生虫的新生棒状体中。我们结合ROP1蛋白的靶向定位和可能的功能对结果进行了讨论。
