Wu Wesley, Herrera Zachary, Ebert Danny, Baska Katie, Cho Seok H, DeRisi Joseph L, Yeh Ellen
Department of Biochemistry and Biophysics, University of California, San Francisco, San Francisco, California, USA.
Department of Biochemistry, Stanford Medical School, Stanford, California, USA.
Antimicrob Agents Chemother. 2015 Jan;59(1):356-64. doi: 10.1128/AAC.03342-14. Epub 2014 Nov 3.
The apicoplast is an essential plastid organelle found in Plasmodium parasites which contains several clinically validated antimalarial-drug targets. A chemical rescue screen identified MMV-08138 from the "Malaria Box" library of growth-inhibitory antimalarial compounds as having specific activity against the apicoplast. MMV-08138 inhibition of blood-stage Plasmodium falciparum growth is stereospecific and potent, with the most active diastereomer demonstrating a 50% effective concentration (EC50) of 110 nM. Whole-genome sequencing of 3 drug-resistant parasite populations from two independent selections revealed E688Q and L244I mutations in P. falciparum IspD, an enzyme in the MEP (methyl-d-erythritol-4-phosphate) isoprenoid precursor biosynthesis pathway in the apicoplast. The active diastereomer of MMV-08138 directly inhibited PfIspD activity in vitro with a 50% inhibitory concentration (IC50) of 7.0 nM. MMV-08138 is the first PfIspD inhibitor to be identified and, together with heterologously expressed PfIspD, provides the foundation for further development of this promising antimalarial drug candidate lead. Furthermore, this report validates the use of the apicoplast chemical rescue screen coupled with target elucidation as a discovery tool to identify specific apicoplast-targeting compounds with new mechanisms of action.
顶质体是疟原虫中发现的一种重要的质体细胞器，其中包含几个经过临床验证的抗疟药物靶点。一项化学拯救筛选从具有生长抑制作用的抗疟化合物“疟疾盒”文库中鉴定出MMV-08138对顶质体具有特异性活性。MMV-08138对恶性疟原虫血液期生长的抑制具有立体特异性且效力强大，活性最强的非对映异构体的半数有效浓度（EC50）为110 nM。对来自两个独立筛选的3个耐药寄生虫群体进行全基因组测序，发现在顶质体中参与甲基-D-赤藓糖醇-4-磷酸（MEP）类异戊二烯前体生物合成途径的一种酶——恶性疟原虫IspD中存在E688Q和L244I突变。MMV-08138的活性非对映异构体在体外直接抑制PfIspD活性，半数抑制浓度（IC50）为7.0 nM。MMV-08138是首个被鉴定出的PfIspD抑制剂，与异源表达的PfIspD一起，为进一步开发这种有前景的抗疟药物候选先导物奠定了基础。此外，本报告验证了将顶质体化学拯救筛选与靶点鉴定相结合作为一种发现工具，用于识别具有新作用机制的靶向顶质体的特异性化合物的用途。
