Hochschule Bonn-Rhein-Sieg, Von Liebig Strasse 20, 53359, Rheinbach, Germany.
Amino Acids. 2010 Feb;38(2):461-9. doi: 10.1007/s00726-009-0405-x. Epub 2009 Dec 1.
An important issue facing global health today is the need for new, effective and affordable drugs against malaria, particularly in resource-poor countries. Moreover, the currently available antimalarials are limited by factors ranging from parasite resistance to safety, compliance, cost and the current lack of innovations in medicinal chemistry. Depletion of polyamines in the intraerythrocytic phase of P. falciparum is a promising strategy for the development of new antimalarials since intracellular levels of putrescine, spermidine and spermine are increased during cell proliferation. S-adenosyl-methionine-decarboxylase (AdoMETDC) is a key enzyme in the biosynthesis of spermidine. The AdoMETDC inhibitor CGP 48664A, known as SAM486A, inhibited the separately expressed plasmodial AdoMETDC domain with a Km( i ) of 3 microM resulting in depletion of spermidine. Spermidine is an important precursor in the biosynthesis of hypusine. This prompted us to investigate a downstream effect on hypusine biosynthesis after inhibition of AdoMETDC. Extracts from P. falciparum in vitro cultures that were treated with 10 microM SAM 486A showed suppression of eukaryotic initiation factor 5A (eIF-5A) in comparison to the untreated control in two-dimensional gel electrophoresis. Depletion of eIF-5A was also observed in Western blot analysis with crude protein extracts from the parasite after treatment with 10 microM SAM486A. A determination of the intracellular polyamine levels revealed an approximately 27% reduction of spemidine and a 75% decrease of spermine while putrescine levels increased to 36%. These data suggest that inhibition of AdoMetDc provides a novel strategy for eIF-5A suppression and the design of new antimalarials.
今天，全球健康面临的一个重要问题是需要新的、有效和负担得起的抗疟药物，特别是在资源匮乏的国家。此外，目前可用的抗疟药物受到多种因素的限制，包括寄生虫耐药性、安全性、顺应性、成本以及药物化学领域目前缺乏创新。在疟原虫的红细胞内期，多胺的耗竭是开发新的抗疟药物的一个有前途的策略，因为在细胞增殖过程中，腐胺、亚精胺和精胺的细胞内水平增加。S-腺苷甲硫氨酸脱羧酶（AdoMETDC）是亚精胺生物合成中的关键酶。AdoMETDC 抑制剂 CGP 48664A（称为 SAM486A）以 3μM 的 Km(i)抑制分别表达的疟原虫 AdoMETDC 结构域，导致亚精胺耗竭。亚精胺是 Hypusine 生物合成的重要前体。这促使我们在 AdoMETDC 抑制后研究其对 Hypusine 生物合成的下游影响。与未经处理的对照相比，用 10μM SAM486A 处理的体外培养的疟原虫提取物在二维凝胶电泳中显示出真核起始因子 5A（eIF-5A）的抑制。在用 10μM SAM486A 处理寄生虫粗蛋白提取物后，通过 Western blot 分析也观察到 eIF-5A 的耗竭。细胞内多胺水平的测定显示，亚精胺减少约 27%，精胺减少 75%，而腐胺水平增加到 36%。这些数据表明，AdoMetDc 的抑制为 eIF-5A 抑制和新的抗疟药物设计提供了一种新的策略。
