Structure of the Plasmodium falciparum M17 aminopeptidase and significance for the design of drugs targeting the neutral exopeptidases
Structure of the Plasmodium falciparum M17 aminopeptidase and significance for the design of drugs targeting the neutral exopeptidases
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DOI：
10.1073/pnas.0911813107
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发表时间：
2010-02-09
影响因子：
11.1
通讯作者：
Whisstock, James C.
中科院分区：
文献类型：
--
作者：
McGowan, Sheena;Oellig, Christine A.;Whisstock, James C.
由于抗药性寄生虫的迅速出现，目前的疟疾治疗和预防措施受到严重挑战。人类疟疾寄生虫恶性疟原虫表达两种中性氨基肽酶PFA-M1和PFA-M17，它们的功能是调节红细胞内生长和发育所需的细胞内氨基酸池。这些酶对寄生虫的生存至关重要，是有效的治疗靶点。我们先前报道了单体PFA-M1的X射线晶体结构，并提出了底物进入和活性中心释放游离氨基酸的机制。在这里，我们介绍了六聚体亮氨酸氨基肽酶PFA-M17的X射线晶体结构，PFA-M17单独和与两种具有抗疟疾活性的抑制剂复合。PFA-M17六聚体的六个活性部位呈盘状排列，向内取向形成一个中心催化腔；位于催化腔六个入口处的柔性环起到调节底物访问的作用。与PFA-M1形成鲜明对比的是，PFA-M17具有狭窄且疏水的初级特异性口袋，这是其高度受限的底物特异性的原因。我们还解释了这些酶中的金属结合中心(两个在PFA-M17中，一个在PFA-M1中)在底物和药物结合中的重要作用。我们对PFA-M1和PFA-M17活性部位的详细了解现在使我们能够合理地开发一种独特的双靶点和/或联合抗疟疾疗法。
Current therapeutics and prophylactics for malaria are under severe challenge as a result of the rapid emergence of drug-resistant parasites. The human malaria parasite Plasmodium falciparum expresses two neutral aminopeptidases, PfA-M1 and PfA-M17, which function in regulating the intracellular pool of amino acids required for growth and development inside the red blood cell. These enzymes are essential for parasite viability and are validated therapeutic targets. We previously reported the x-ray crystal structure of the monomeric PfA-M1 and proposed a mechanism for substrate entry and free amino acid release from the active site. Here, we present the x-ray crystal structure of the hexameric leucine aminopeptidase, PfA-M17, alone and in complex with two inhibitors with antimalarial activity. The six active sites of the PfA-M17 hexamer are arranged in a disc-like fashion so that they are orientated inwards to form a central catalytic cavity; flexible loops that sit at each of the six entrances to the catalytic cavern function to regulate substrate access. In stark contrast to PfA-M1, PfA-M17 has a narrow and hydrophobic primary specificity pocket which accounts for its highly restricted substrate specificity. We also explicate the essential roles for the metal-binding centers in these enzymes (two in PfA-M17 and one in PfA-M1) in both substrate and drug binding. Our detailed understanding of the PfA-M1 and PfA- M17 active sites now permits a rational approach in the development of a unique class of two-target and/or combination antimalarial therapy.