The malaria parasite Plasmodium falciparum has only one pyruvate dehydrogenase complex, which is located in the apicoplast
The malaria parasite Plasmodium falciparum has only one pyruvate dehydrogenase complex, which is located in the apicoplast
复制标题
DOI：
10.1111/j.1365-2958.2004.04407.x
复制
发表时间：
2005-01-01
影响因子：
3.6
通讯作者：
McFadden, GI
中科院分区：
文献类型：
--
作者：
Foth, BJ;Stimmler, LM;McFadden, GI
顶复门寄生虫的残质体（顶质体）合成脂肪酸，是一个有前途的药物靶标。在植物质体中，丙酮酸脱氢酶复合物（PDH）将丙酮酸转化为乙酰辅酶A，乙酰辅酶A是主要的脂肪酸前体，而第二个不同的PDH为线粒体中的三羧酸循环提供燃料。相比之下，存在的基因编码PDH和相关的酶复合物的基因组中的5种疟原虫和弓形虫表明，这些寄生虫只含有一个单一的PDH。PDH复合物由四个亚基（E1 α、E1 β、E2、E3）组成，通过对恶性疟原虫cDNA克隆测序，我们确定了编码完整PDH的四个基因。在顶复门寄生虫中，许多核编码的蛋白质靶向于顶质体，这是由两部分N-末端前导序列提供的，并且在所有四个PDH亚基上存在这样的N-末端序列以及系统发育分析强烈表明恶性疟原虫PDH位于顶质体中。将E1 α和E2基因的两部分前导序列与绿色荧光蛋白融合，实验证实了顶质体靶向。Western印迹分析为E1 α和E1 β PDH亚基在血液期疟原虫中的表达提供了证据。重组表达的PDH亚基E2的催化结构域在体外显示出高的酶活性，表明丙酮酸在顶质体中转化为乙酰辅酶A，可能用于脂肪酸生物合成。
The relict plastid (apicoplast) of apicomplexan parasites synthesizes fatty acids and is a promising drug target. In plant plastids, a pyruvate dehydrogenase complex (PDH) converts pyruvate into acetyl-CoA, the major fatty acid precursor, whereas a second, distinct PDH fuels the tricarboxylic acid cycle in the mitochondria. In contrast, the presence of genes encoding PDH and related enzyme complexes in the genomes of five Plasmodium species and of Toxoplasma gondii indicate that these parasites contain only one single PDH. PDH complexes are comprised of four subunits (E1alpha, E1beta, E2, E3), and we confirmed four genes encoding a complete PDH in Plasmodium falciparum through sequencing of cDNA clones. In apicomplexan parasites, many nuclear-encoded proteins are targeted to the apicoplast courtesy of two-part N-terminal leader sequences, and the presence of such N-terminal sequences on all four PDH subunits as well as phylogenetic analyses strongly suggest that the P. falciparum PDH is located in the apicoplast. Fusion of the two-part leader sequences from the E1alpha and E2 genes to green fluorescent protein experimentally confirmed apicoplast targeting. Western blot analysis provided evidence for the expression of the E1alpha and E1beta PDH subunits in blood-stage malaria parasites. The recombinantly expressed catalytic domain of the PDH subunit E2 showed high enzymatic activity in vitro indicating that pyruvate is converted to acetyl-CoA in the apicoplast, possibly for use in fatty acid biosynthesis.