The cryo-EM structure of the Plasmodium falciparum 20S proteasome and its use in the fight against malaria
The cryo-EM structure of the Plasmodium falciparum 20S proteasome and its use in the fight against malaria
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DOI：
10.1111/febs.13780
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发表时间：
2016-12-01
期刊：
影响因子：
5.4
通讯作者：
da Fonseca, Paula C. A.
中科院分区：
文献类型：
--
作者：
Li, Hao;Bogyo, Matthew;da Fonseca, Paula C. A.
恶性疟原虫是导致最严重疟疾的寄生虫。它对现有抗疟药物的抗药性日益增强，是对人类健康的一个重大威胁，因此迫切需要制定新的治疗战略来防治疟疾。蛋白酶体是所有真核生物中必需的蛋白酶复合物。因此，疟原虫20 S蛋白酶体的抑制对于所有感染和发育阶段的寄生虫都是高毒性的。蛋白酶体抑制剂作为治疗剂和传播阻断剂都具有抗疟潜力，但为了具有治疗应用，它们必须特异性靶向疟原虫蛋白酶体而不是其人类对应物。X射线晶体学已被广泛用于确定酵母和哺乳动物20 S蛋白酶体与配体的结构。然而，疟原虫蛋白酶体的结晶是具有挑战性的，因为只有少量的复合物可以直接从寄生虫中纯化。此外，大多数蛋白酶体-抑制剂复合物的X射线结构需要用高浓度的配体浸泡晶体，从而阻止了抑制剂亚基特异性的分析。相反，我们选择确定恶性疟原虫20 S蛋白酶体结构，在一个新的合理设计的寄生虫特异性抑制剂的存在下，通过高分辨率电子冷冻显微镜和单颗粒分析。由此产生的地图，在约3.6埃的分辨率，允许抑制剂/酶的相互作用的直接分子分析。在这里，我们提出了这种结构的概述，以及它如何提供有价值的信息，可用于帮助设计改进的蛋白酶体抑制剂，有可能被开发为下一代抗疟疾药物。
Plasmodium falciparum is the parasite responsible for the most severe form of malaria. Its increasing resistance to existing antimalarials represents a major threat to human health and urges the development of new therapeutic strategies to fight malaria. The proteasome is a protease complex essential in all eukaryotes. Accordingly, inhibition of the Plasmodium 20S proteasome is highly toxic for the parasite at all of its infective and developmental stages. Proteasome inhibitors have antimalarial potential both as curative and transmission blocking agents, but in order to have therapeutic application, they must specifically target the Plasmodium proteasome and not its human counterpart. X-ray crystallography has been widely used to determine structures of yeast and mammalian 20S proteasomes with ligands. However, crystallisation of the Plasmodium proteasome is challenging, as only small quantities of the complex can be directly purified from the parasite. Furthermore, most X-ray structures of proteasome-inhibitor complexes require soaking of crystals with high concentrations of ligand, thus preventing analysis of inhibitor subunit specificity. Instead we chose to determine the Plasmodium falciparum 20S proteasome structure, in the presence of a new rationally designed parasite-specific inhibitor, by high-resolution electron cryo-microscopy and single particle analysis. The resulting map, at a resolution of about 3.6 angstrom, allows a direct molecular analysis of inhibitor/enzyme interactions. Here we present an overview of this structure, and how it provides valuable information that can be used to assist in the design of improved proteasome inhibitors with the potential to be developed as next-generation antimalarial drugs.