International Centre for Genetic Engineering and Biotechnology, New Delhi, India.
Cell Death Dis. 2011 Nov 24;2(11):e231. doi: 10.1038/cddis.2011.118.
The ATP-dependent ClpQY protease system in Plasmodium falciparum is a prokaryotic machinery in the parasite. In the present study, we have identified the complete ClpQY system in P. falciparum and elucidated its functional importance in survival and growth of asexual stage parasites. We characterized the interaction of P. falciparum ClpQ protease (PfClpQ) and PfClpY ATPase components, and showed that a short stretch of residues at the C terminus of PfClpY has an important role in this interaction; a synthetic peptide corresponding to this region antagonizes this interaction and interferes with the functioning of this machinery in the parasite. Disruption of ClpQY function by this peptide caused hindrance in the parasite growth and maturation of asexual stages of parasites. Detailed analyses of cellular effects in these parasites showed features of apoptosis-like cell death. The peptide-treated parasites showed mitochondrial dysfunction and loss of mitochondrial membrane potential. Dysfunctioning of mitochondria initiated a cascade of reactions in parasites, including activation of VAD-FMK-binding proteases and nucleases, which resulted in apoptosis-like cell death. These results show functional importance of mitochondrial proteases in the parasite and involvement of mitochondria in programmed cell death in the malaria parasites.
疟原虫中的 ATP 依赖型 ClpQY 蛋白酶系统是寄生虫中的一种原核机制。在本研究中，我们鉴定了疟原虫中的完整 ClpQY 系统，并阐明了其在无性阶段寄生虫生存和生长中的功能重要性。我们描述了疟原虫 ClpQ 蛋白酶（PfClpQ）和 PfClpY ATP 酶成分的相互作用，并表明 PfClpY 的 C 末端的一小段残基在这种相互作用中具有重要作用；与该区域相对应的合成肽拮抗这种相互作用并干扰寄生虫中这种机制的功能。该肽对 ClpQY 功能的破坏导致寄生虫生长受阻和无性阶段寄生虫的成熟受阻。对这些寄生虫中细胞效应的详细分析显示出类似细胞凋亡的细胞死亡特征。用肽处理的寄生虫表现出线粒体功能障碍和线粒体膜电位丧失。线粒体功能障碍引发寄生虫中的级联反应，包括 VAD-FMK 结合蛋白酶和核酸酶的激活，导致类似细胞凋亡的细胞死亡。这些结果表明线粒体蛋白酶在寄生虫中的功能重要性以及线粒体在疟原虫程序性细胞死亡中的参与。
