P. falciparum cpn20 is a bona fide co-chaperonin that can replace GroES in E. coli.
P. falciparum cpn20 is a bona fide co-chaperonin that can replace GroES in E. coli.
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DOI：
10.1371/journal.pone.0053909
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发表时间：
2013
期刊：
影响因子：
3.7
通讯作者：
Weiss C
中科院分区：
文献类型：
--
作者：
Vitlin Gruber A;Nisemblat S;Zizelski G;Parnas A;Dzikowski R;Azem A;Weiss C
人类疟疾是当今世界上最普遍和最具破坏性的热带寄生虫病之一。病原体恶性疟原虫含有一种不同寻常的重要细胞器，称为质外体。抑制这种退化的叶绿体会导致寄生虫的第二代死亡，这也是抗生素治疗疟疾的机制。为了更好地了解这个细胞器的生物化学，我们克隆了一个推测为20 kDa的辅助伴侣蛋白Pf-cpn20，它定位于质外体。虽然这种蛋白质与植物叶绿体中发现的cpn20同源，但它作为辅助伴侣的功能在过去受到了质疑。在本研究中，我们使用圆二色谱和分析超速离心法对Pf-cpn20进行了结构分析，然后使用两种不同的方法来研究该蛋白作为辅助伴侣的能力。在第一种方法中，我们纯化了重组的Pf-cpn20，并在体外测试了它作为GroEL的辅助伴侣的能力，而在第二种方法中，我们检测了Pf-cpn20补充大肠杆菌中基本细菌辅助伴侣的能力。我们的结果表明，PF-cpn20在体外完全具有作为辅助伴侣的功能。此外，寄生的辅助伴侣蛋白在常温和热休克温度下都能取代大肠杆菌中的Groes。因此，Pf-cpn20在伴侣蛋白介导的蛋白质折叠中起到辅助伴侣的作用。疟疾蛋白在大肠杆菌中的功能表明，这个简单的系统可以作为进一步分析恶性疟原虫Pf-cpn20和其他伴侣蛋白的工具。
Human malaria is among the most ubiquitous and destructive tropical, parasitic diseases in the world today. The causative agent, Plasmodium falciparum, contains an unusual, essential organelle known as the apicoplast. Inhibition of this degenerate chloroplast results in second generation death of the parasite and is the mechanism by which antibiotics function in treating malaria. In order to better understand the biochemistry of this organelle, we have cloned a putative, 20 kDa, co-chaperonin protein, Pf-cpn20, which localizes to the apicoplast. Although this protein is homologous to the cpn20 that is found in plant chloroplasts, its ability to function as a co-chaperonin was questioned in the past. In the present study, we carried out a structural analysis of Pf-cpn20 using circular dichroism and analytical ultracentrifugation and then used two different approaches to investigate the ability of this protein to function as a co-chaperonin. In the first approach, we purified recombinant Pf-cpn20 and tested its ability to act as a co-chaperonin for GroEL in vitro, while in the second, we examined the ability of Pf-cpn20 to complement an E. coli depletion of the essential bacterial co-chaperonin GroES. Our results demonstrate that Pf-cpn20 is fully functional as a co-chaperonin in vitro. Moreover, the parasitic co-chaperonin is able to replace GroES in E. coli at both normal and heat-shock temperatures. Thus, Pf-cpn20 functions as a co-chaperonin in chaperonin-mediated protein folding. The ability of the malarial protein to function in E. coli suggests that this simple system can be used as a tool for further analyses of Pf-cpn20 and perhaps other chaperone proteins from P. falciparum.
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