Furuya T, Kashuba C, Docampo R, Moreno S N
Laboratory of Molecular Parasitology, Department of Pathobiology, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61802, USA.
J Biol Chem. 2000 Mar 3;275(9):6428-38. doi: 10.1074/jbc.275.9.6428.
The phosphoinositide (PI)-specific phospholipase C gene (TcPI-PLC) of the protozoan parasite Trypanosoma cruzi was cloned, sequenced, expressed in Escherichia coli, and the protein product (TcPI-PLC) was shown to have enzymatic characteristics similar to those of mammalian delta-type PI-PLCs. The TcPI-PLC gene is expressed at high levels in the epimastigote and amastigote stages of the parasite, and its expression is induced during the differentiation of trypomastigotes into amastigotes, where TcPI-PLC associates with the plasma membrane and increases its catalytic activity. In contrast to other PI-PLCs described so far, the deduced amino acid sequence of TcPI-PLC revealed some unique features such as an N-myristoylation consensus sequence at its amino-terminal end, lack of an apparent pleckstrin homology domain and a highly charged linker region between the catalytic X and Y domains. TcPI-PLC is lipid modified in vivo, as demonstrated by metabolic labeling with [(3)H]myristate and [(3)H]palmitate and fatty acid analysis of the immunoprecipitated protein, and may constitute the first example of a new group of PI-PLCs.
原生动物寄生虫克氏锥虫的磷酸肌醇（PI）特异性磷脂酶C基因（TcPI-PLC）被克隆、测序，并在大肠杆菌中表达，其蛋白产物（TcPI-PLC）显示出与哺乳动物δ型PI-PLCs相似的酶学特性。TcPI-PLC基因在寄生虫的上鞭毛体和无鞭毛体阶段高水平表达，并且在锥鞭毛体向无鞭毛体分化过程中其表达被诱导，在该过程中TcPI-PLC与质膜结合并增加其催化活性。与迄今描述的其他PI-PLCs不同，TcPI-PLC的推导氨基酸序列显示出一些独特特征，如在其氨基末端有一个N-肉豆蔻酰化共有序列、缺乏明显的普列克底物蛋白同源结构域以及在催化X和Y结构域之间有一个高度带电的连接区。如用[（3）H]肉豆蔻酸和[（3）H]棕榈酸进行代谢标记以及对免疫沉淀蛋白进行脂肪酸分析所证明的，TcPI-PLC在体内被脂质修饰，并且可能构成一组新的PI-PLCs中的首个例子。
