Inhibition of Plasmodium falciparum choline kinase by hexadecyltrimethylammonium bromide:: a possible antimalarial mechanism
Inhibition of Plasmodium falciparum choline kinase by hexadecyltrimethylammonium bromide:: a possible antimalarial mechanism
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DOI：
10.1128/aac.00919-06
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发表时间：
2007-02-01
影响因子：
4.9
通讯作者：
Bandyopadhyay, Uday
中科院分区：
文献类型：
--
作者：
Choubey, Vinay;Maity, Pallab;Bandyopadhyay, Uday
胆碱激酶是肯尼迪途径（CDP-胆碱途径）中的第一种酶，用于恶性疟原虫中最重要的磷脂（磷脂酰胆碱）的生物合成。此外，胆碱激酶在捕获疟原虫体内必需的极性头组胆碱方面也发挥着关键作用。最近，恶性疟原虫胆碱激酶（PfCK）已被克隆、过表达和纯化。然而，由于缺乏合适的抑制剂，这种酶在寄生虫生长和存活中的功能尚未得到评估。纯化的重组 PfCK 使我们能够鉴定出 PfCK 的抑制剂，即十六烷基三甲基溴化铵 (HDTAB)，它与著名的抗增殖和抗利什曼药物药物十六烷基磷酸胆碱（米替福新）非常相似。 HDTAB 以剂量依赖性方式抑制 PfCK，并在体外对恶性疟原虫具有非常有效的抗疟活性。此外，HDTAB 在体内对啮齿动物疟原虫约氏疟原虫（N-67 株）表现出深刻的抗疟活性。有趣的是，发现滋养体和裂殖体阶段的寄生虫对 HDTAB 特别敏感。通过逆转录-PCR 和免疫荧光显微镜观察到，HDTAB 的阶段特异性抗疟作用与恶性疟原虫中 PfCK 的表达模式密切相关。此外，HDTAB 的抗疟活性与磷脂酰胆碱含量的降低平行，这与磷酸胆碱生成的减少相关。这些结果表明，HDTAB 抑制胆碱激酶导致磷酸胆碱减少，进而导致磷脂酰胆碱生物合成减少，导致寄生虫死亡。
Choline kinase is the first enzyme in the Kennedy pathway (CDP-choline pathway) for the biosynthesis of the most essential phospholipid, phosphatidylcholine, in Plasmodium falciparum. In addition, choline kinase also plays a pivotal role in trapping essential polar head group choline inside the malaria parasite. Recently, Plasmodium falcipamm choline kinase (PfCK) has been cloned, overexpressed, and purified. However, the function of this enzyme in parasite growth and survival has not been evaluated owing to the lack of a suitable inhibitor. Purified recombinant PfCK enabled us to identify an inhibitor of PfCK, hexadecyltrimethylammonium bromide (HDTAB), which has a very close structural resemblance to hexadecylphosphocholine (miltefosin), the well-known antiproliferative and antileishmanial drug. HDTAB inhibited PfCK in a dose-dependent manner and offered very potent antimalarial activity in vitro against Plasmodium falciparum. Moreover, HDTAB exhibited profound antimalarial activity in vivo against the rodent malaria parasite Plasmodium yoelii (N-67 strain). Interestingly, parasites at the trophozoite and schizont stages were found to be particularly sensitive to HDTAB. The stage-specific antimalarial effect of HDTAB correlated well with the expression pattern of PfCK in P.falciparum, which was observed by reverse transcription-PCR and immunofluorescence microscopy. Furthermore, the antimalarial activity of HDTAB paralleled the decrease in phosphatidylcholine content, which was found to correlate with the decreased phosphocholine generation. These results suggest that inhibition of choline kinase by HDTAB leads to decreased phosphocholine, which in turn causes a decrease in phosphatidylcholine biosynthesis, resulting in death of the parasite.