Imidazopyridazine Inhibitors of Plasmodium falciparum Calcium-Dependent Protein Kinase 1 Also Target Cyclic GMP-Dependent Protein Kinase and Heat Shock Protein 90 To Kill the Parasite at Different Stages of Intracellular Development.
Imidazopyridazine Inhibitors of Plasmodium falciparum Calcium-Dependent Protein Kinase 1 Also Target Cyclic GMP-Dependent Protein Kinase and Heat Shock Protein 90 To Kill the Parasite at Different Stages of Intracellular Development.
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DOI：
10.1128/aac.01748-15
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发表时间：
2015-12-28
影响因子：
4.9
通讯作者：
Holder AA
中科院分区：
文献类型：
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作者：
Green JL;Moon RW;Whalley D;Bowyer PW;Wallace C;Rochani A;Nageshan RK;Howell SA;Grainger M;Jones HM;Ansell KH;Chapman TM;Taylor DL;Osborne SA;Baker DA;Tatu U;Holder AA
咪唑并哒嗪化合物是钙依赖性蛋白激酶1（CDPK 1）和恶性疟原虫体外生长的有效ATP竞争性抑制剂。在这里，我们表明，这些化合物可以分为两类，这取决于核和R2取代基之间的芳香族连接基的性质。第1类化合物具有嘧啶连接体，并抑制寄生虫生长在晚期的滋养体，而第2类化合物具有非嘧啶连接体，并抑制滋养体阶段的生长，这表明两类化合物的作用模式不同。该化合物还抑制环GMP（cGMP）依赖性蛋白激酶（PKG），其对这种酶的效力大大降低了在ATP结合位点的酶的看门人残基的取代。1类化合物对表达修饰的PKG的寄生虫系的有效性也显著降低，表明这些化合物主要通过抑制PKG而不是CDPK 1杀死寄生虫。HSP 90被鉴定为2类化合物的结合配偶体，并且代表性化合物结合至HSP 90的N-末端结构域中的ATP结合位点。减少CDPK 1的看门人残基的大小，使酶的抑制碰撞激酶抑制剂，然而，寄生虫线表达的修饰的酶显示这些化合物的敏感性没有变化。总之，这些发现表明CDPK 1可能不是进一步开发抑制剂的合适靶标，并且咪唑并哒嗪杀死寄生虫的主要机制是通过抑制PKG或HSP 90。
Imidazopyridazine compounds are potent, ATP-competitive inhibitors of calcium-dependent protein kinase 1 (CDPK1) and of Plasmodium falciparum parasite growth in vitro. Here, we show that these compounds can be divided into two classes depending on the nature of the aromatic linker between the core and the R2 substituent group. Class 1 compounds have a pyrimidine linker and inhibit parasite growth at late schizogony, whereas class 2 compounds have a nonpyrimidine linker and inhibit growth in the trophozoite stage, indicating different modes of action for the two classes. The compounds also inhibited cyclic GMP (cGMP)-dependent protein kinase (PKG), and their potency against this enzyme was greatly reduced by substitution of the enzyme's gatekeeper residue at the ATP binding site. The effectiveness of the class 1 compounds against a parasite line expressing the modified PKG was also substantially reduced, suggesting that these compounds kill the parasite primarily through inhibition of PKG rather than CDPK1. HSP90 was identified as a binding partner of class 2 compounds, and a representative compound bound to the ATP binding site in the N-terminal domain of HSP90. Reducing the size of the gatekeeper residue of CDPK1 enabled inhibition of the enzyme by bumped kinase inhibitors; however, a parasite line expressing the modified enzyme showed no change in sensitivity to these compounds. Taken together, these findings suggest that CDPK1 may not be a suitable target for further inhibitor development and that the primary mechanism through which the imidazopyridazines kill parasites is by inhibition of PKG or HSP90.