Chakrabarti D, Azam T, DelVecchio C, Qiu L, Park Y I, Allen C M
Department of Molecular Biology, Microbiology and Center for Diagnostics and Drug Development, University of Central Florida, Orlando 322816-2360, USA.
Mol Biochem Parasitol. 1998 Aug 1;94(2):175-84. doi: 10.1016/s0166-6851(98)00065-6.
Prenylated proteins have been shown to function in important cellular regulatory processes including signal transduction. The enzymes involved in protein prenylation, farnesyl transferase and geranylgeranyl transferase, have been recent targets for development of cancer chemotherapeutics. We have initiated a systematic study of protein prenyl transferases of the malaria parasite, Plasmodium falciparum, to determine whether these enzymes can be developed as targets for antimalarial chemotherapy. We report here the identification of protein farnesyl transferase and protein geranylgeranyl transferase-I in the malaria parasite, P. falciparum. The farnesyl transferase has been partially purified from the cytosolic fraction through ammonium sulfate precipitation and Mono-Q chromatography. Farnesyl and geranylgeranyl transferase-I activities are present at all stages of P. falciparum intraerythrocytic development with maximum specific activity in the ring stage. Geranylgeranyl transferase-I specific activity is two times that of farnesyl transferase in the ring stage. Peptidomimetics and prenyl analogues of protein farnesyl transferase substrates were tested as in vitro inhibitors of partially purified P. falciparum prenyl transferase and of malaria parasite growth. The peptidomimetics were significantly more potent inhibitors than lipid substrate analogues of both the activity of Mono-Q purified enzyme and parasite growth in intraerythrocytic cultures. Exposure of the parasite to the peptidomimetic L-745,631 also showed significant inhibition of morphological development beyond the trophozoite stage. These studies suggest the potential of designing or identifying differential inhibitors of P. falciparum and mammalian prenyl transferases as an approach to novel malaria therapy.
异戊二烯化蛋白已被证明在包括信号转导在内的重要细胞调节过程中发挥作用。参与蛋白质异戊二烯化的酶，法尼基转移酶和香叶基香叶基转移酶，是近期癌症化疗药物开发的靶点。我们已启动对疟原虫恶性疟原虫蛋白质异戊二烯基转移酶的系统研究，以确定这些酶是否可被开发为抗疟化疗的靶点。我们在此报告在恶性疟原虫中鉴定出蛋白质法尼基转移酶和蛋白质香叶基香叶基转移酶-I。通过硫酸铵沉淀和Mono-Q色谱法从胞质部分中部分纯化了法尼基转移酶。法尼基和香叶基香叶基转移酶-I活性在恶性疟原虫红细胞内发育的所有阶段均存在，在环状体阶段具有最大比活性。在环状体阶段，香叶基香叶基转移酶-I的比活性是法尼基转移酶的两倍。测试了蛋白质法尼基转移酶底物的拟肽和异戊二烯类似物作为部分纯化的恶性疟原虫异戊二烯基转移酶活性和疟原虫生长的体外抑制剂。拟肽对Mono-Q纯化酶的活性和红细胞内培养物中的疟原虫生长的抑制作用比脂质底物类似物明显更强。将疟原虫暴露于拟肽L-745,631也显示出对滋养体阶段之后的形态发育有显著抑制作用。这些研究表明设计或鉴定恶性疟原虫和哺乳动物异戊二烯基转移酶的差异抑制剂作为新型疟疾治疗方法的潜力。
