The protozoan parasite Toxoplasma gondii expresses two functional plant-like glycolytic enzymes -: Implications for evolutionary origin of apicomplexans
The protozoan parasite Toxoplasma gondii expresses two functional plant-like glycolytic enzymes -: Implications for evolutionary origin of apicomplexans
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DOI：
10.1074/jbc.274.35.24888
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发表时间：
1999-08-27
影响因子：
4.8
通讯作者：
Tomavo, S
中科院分区：
文献类型：
--
作者：
Dzierszinski, F;Popescu, O;Tomavo, S
最近在顶复门中发现了一种退化的非光合质体（“顶质体”），这大大改变了我们对这些寄生虫进化起源的看法。系统发育分析和存在的四个周围膜的顶质体提供了重要的支持的假设，apicomplexans获得了他们的顶质体次生内共生，可能是从一个绿色的。这表明编码预测的绿色藻类或相关光合谱系的蛋白质同源物的基因可能已经通过从携带顶质体的祖先转移进入顶复门寄生虫的细胞核。我们在这里描述了编码两种弓形虫糖酵解酶，葡萄糖-6-磷酸异构酶（G6-PI）和烯醇化酶的互补DNA，它们与陆地植物对应物具有相当大的同一性。弓形虫的两个cDNA都补充了缺乏G6-PI和烯醇化酶基因的大肠杆菌突变体，并导致活性酶的表达。在药物无法治疗的弓形虫包囊缓殖子中，G6-PI和烯醇化酶基因在转录和蛋白质水平上过表达或仅表达。此外，三维模型和蛋白质组学证实，G6-PI和烯醇化酶的T，刚地，恶性疟原虫，和陆地植物密切相关。由于这些糖酵解酶是植物同源物，不同于动物的糖酵解酶，它们将有助于追踪顶复门的进化起源，并可能为顶复门寄生虫引起的疾病提供新的化疗靶点。
The recent discovery of a vestigial, nonphotosynthetic plastid ("apicoplast") in the Apicomplexa has considerably modified our perception of the evolutionary origin of these parasites. Phylogenetic analysis and the presence of four surrounding membranes of the apicoplast provide important support for the hypothesis that apicomplexans have acquired their apicoplast by secondary endosymbiosis, probably from a green alga. This suggests that genes encoding predicted homologs of proteins of green algae or related photosynthetic lineages could have entered the nucleus of apicomplexan parasites by transfer from the ancestor harboring the apicoplast, We describe here complementary DNAs encoding two Toxoplasma gondii glycolytic enzymes, glucose-6-phosphate isomerase (G6-PI) and enolase, which have considerable identities with land plant counterparts. Both cDNAs of T, gondii complement Escherichia coli mutants lacking G6-PI and enolase genes and lead to the expression of active enzymes. In the drug untreatable encysted bradyzoites of T, gondii, G6-PI and enolase genes are overexpressed or exclusively expressed at both transcriptional and protein levels. Moreover, three-dimensional models and protein phylogeny confirmed that G6-PIs and enolases of T, gondii, Plasmodium falciparum, and land plants are closely related. Because these glycolytic enzymes are plant homologs, which differ from those of animals, they will be useful to trace the evolutionary origin of Apicomplexa and might offer novel chemotherapeutic targets in diseases caused by apicomplexan parasites.