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The significance of the biosynthesis of plant hormones in Toxoplasma gondii

弓形虫植物激素生物合成的意义

基本信息

批准号：
21590460
负责人：
NAGAMUNE Kisaburo
金额：
$ 3万
依托单位：
National Institute of Infectious Diseases
依托单位国家：
日本
项目类别：
Grant-in-Aid for Scientific Research (C)
财政年份：
2009
资助国家：
日本
起止时间：
2009 至 2011
项目状态：
已结题

项目摘要

Recently, we found that Toxoplasma gondii produces a plant hormone, abscisic acid, and that it is essential for the infection of this parasite. So, we studied the effect of other plant hormones cytokinins on Toxoplasma gondii. We found that genes encoding the enzymes for the trans-zeatin biosynthesis in plants are present in T. gondii genome. Consistently, we detected intermediates for two possible trans-zeatin-biosynthesis pathways by MS analysis. A natural cytokinin, trans-zeatin, accelerated the proliferation of T. gondii. In contrast, a synthetic cytokinin, thidiazuron, inhibited the parasite proliferation in culture. This inhibition was also observed in laboratory animals. Since cytokinins regulate the cell cycle progression by enhancing the expression of D-type cyclin in plant, we carried out flowcytometric analysis to observe the effect of cytokinins on the cell cycle progression of T. gondii. Trans-zeatin hastened the cell cycle progression from G1 to S phase while thidiazuron caused the halt there. Quantitative-PCR(qPCR) analysis revealed that trans-zeatin upregulated the expression of one cyclin like as higher plant system, whereas thidiazuron downregulated its expression. These results suggest that this cyclin plays a crucial role in controlling the cell cycle progression in T. gondii and concomitantly its proliferation. Since cytokinins are also known to regulate chloroplast development in plants, we examined whether cytokinins affect apicoplast, which is a homologous organella to chloroplast in T. gondii. Immunofluorescence microscopy and qPCR analysis revealed trans-zeatin increased the number of apicoplasts but thidiazuron extinguished apicoplast. These result suggest that cytokinins are very important molecules to regulate the cell cycle of the parasite and division of apicoplast.

最近，我们发现刚地弓形虫产生一种植物激素，脱落酸，它是感染这种寄生虫所必需的。因此，我们研究了其他植物激素细胞分裂素对弓形虫的影响。我们发现，编码转玉米素生物合成酶的基因存在于T。弓形虫基因组一致地，我们通过MS分析检测到两种可能的玉米素转生物合成途径的中间体。一种天然的细胞分裂素trans-zeatin能促进T.刚地。与此相反，合成的细胞分裂素，thidiazuron，抑制寄生虫增殖文化。在实验室动物中也观察到这种抑制作用。由于细胞分裂素是通过促进D型细胞周期蛋白的表达来调控植物细胞周期进程的，因此我们采用流式细胞术分析了细胞分裂素对T.刚地。反式玉米素可加速细胞周期由G1期进入S期，而噻苯隆则使细胞周期停滞在S期。定量PCR（qPCR）分析表明，反式玉米素上调一个细胞周期蛋白的表达，如高等植物系统，而thidiazuron下调其表达。这些结果表明，这种细胞周期蛋白在控制T细胞周期进程中起着至关重要的作用。并伴随其增殖。由于细胞分裂素也被认为是调节植物叶绿体发育，我们研究了细胞分裂素是否影响顶质体，这是一个同源的细胞器叶绿体在T。刚地。免疫荧光显微镜和qPCR分析表明，反式玉米素增加了顶质体的数量，但噻苯隆熄灭顶质体。这些结果表明，细胞分裂素是调节寄生虫细胞周期和顶质体分裂的重要分子。