Cloning and characterization of ferredoxin and ferredoxin-NADP+ reductase from human malaria parasite
Cloning and characterization of ferredoxin and ferredoxin-NADP+ reductase from human malaria parasite
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DOI：
10.1093/jb/mvm046
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发表时间：
2007-03-01
影响因子：
2.7
通讯作者：
Hase, Toshiharu
中科院分区：
文献类型：
--
作者：
Kimata-Ariga, Yoko;Kurisu, Genji;Hase, Toshiharu
人类疟疾寄生虫(恶性疟原虫)拥有一种由质体衍生的细胞器，称为顶体，据信该细胞器利用对寄生虫生存至关重要的新陈代谢。我们克隆和研究了植物型铁氧还蛋白(Fd)和Fd-NADP(+)还原酶(FNR)的生化性质，这是一个潜在的氧化还原系统，可能为依赖Fd的疟疾寄生虫质外体代谢途径提供还原动力。重组恶性疟原虫Fd和FnR蛋白由人工合成的密码子改变后在大肠杆菌中优先使用的基因表达。Fd的氧化还原电位比植物的叶型和根型Fd的氧化还原电位要大得多，这有利于电子从分解代谢产生的NADPH流向质外体中Fd的假定方向。经X射线结晶学分析，恶性疟原虫FD的主干结构与植物FDS非常相似，表面电荷分布显示出与植物FDS相似的几个酸性区域和该FD所独有的一些碱性区域。恶性疟原虫FNR能在依赖NADPH的细胞色素c还原的重组系统中选择性地将电子传递给恶性疟原虫FD。这些结果表明，NADPH-FNR-FD级联在人疟疾寄生虫的顶体中是起作用的。
The human malaria parasite (Plasmodium falciparum) possesses a plastid-derived organelle called the apicoplast, which is believed to employ metabolisms crucial for the parasite's survival. We cloned and studied the biochemical properties of plant-type ferredoxin (Fd) and Fd-NADP(+) reductase (FNR), a redox system that potentially supplies reducing power to Fd-dependent metabolic pathways in malaria parasite apicoplasts. The recombinant P. falciparum Fd and FNR proteins were produced by synthetic genes with altered codon usages preferred in Escherichia coli. The redox potential of the Fd was shown to be considerably more positive than those of leaf-type and root-type Fds from plants, which is favourable for a presumed direction of electron flow from catabolically generated NADPH to Fd in the apicoplast. The backbone structure of P. falciparum Fd, as solved by X-ray crystallography, closely resembles those of Fds from plants, and the surface-charge distribution shows several acidic regions in common with plant Fds and some basic regions unique to this Fd. P. falciparum FNR was able to transfer electrons selectively to P. falciparum Fd in a reconstituted system of NADPH-dependent cytochrome c reduction. These results indicate that an NADPH-FNR-Fd cascade is operative in the apicoplast of human malaria parasites.