The Plasmodium falciparum proteasome is a potential antimalarial drug target. We have identified a series of amino-amide boronates that are potent and specific inhibitors of the P. falciparum 20S proteasome (Pf20S) β5 active site and that exhibit fast-acting antimalarial activity. They selectively inhibit the growth of P. falciparum compared with a human cell line and exhibit high potency against field isolates of P. falciparum and Plasmodium vivax. They have a low propensity for development of resistance and possess liver stage and transmission-blocking activity. Exemplar compounds, MPI-5 and MPI-13, show potent activity against P. falciparum infections in a SCID mouse model with an oral dosing regimen that is well tolerated. We show that MPI-5 binds more strongly to Pf20S than to human constitutive 20S (Hs20Sc). Comparison of the cryo-electron microscopy (EM) structures of Pf20S and Hs20Sc in complex with MPI-5 and Pf20S in complex with the clinically used anti-cancer agent, bortezomib, reveal differences in binding modes that help to explain the selectivity. Together, this work provides insights into the 20S proteasome in P. falciparum, underpinning the design of potent and selective antimalarial proteasome inhibitors.

恶性疟原虫蛋白酶体是一种潜在的抗疟药物靶点。我们已经鉴定出一系列氨基酰胺硼酸盐，它们是恶性疟原虫20S 蛋白酶体 ( Pf 20S) β5 活性位点的强效特异性抑制剂，具有速效抗疟活性。与人类细胞系相比，它们选择性地抑制恶性疟原虫的生长，并对恶性疟原虫和间日疟原虫的现场分离株表现出高效力。它们产生抗药性的倾向低，并具有肝脏阶段和传播阻断活性。示例性化合物 MPI-5 和 MPI-13 显示出对恶性疟原虫的有效活性具有良好耐受性的口服给药方案的SCID小鼠模型中的感染。我们表明 MPI-5 与Pf 20S 的结合比与人类组成型 20S ( Hs 20Sc) 的结合更强。Pf 20S 和Hs 20Sc 与 MPI-5 和Pf 20S 与临床使用的抗癌剂硼替佐米复合物的低温电子显微镜 (EM) 结构比较揭示了结合模式的差异，有助于解释选择性. 总之，这项工作提供了对恶性疟原虫20S 蛋白酶体的见解，为有效和选择性的抗疟蛋白酶体抑制剂的设计奠定了基础。