A novel phosphatidylinositol-phospholipase C of Trypanosoma cruzi that is lipid modified and activated during trypomastigote to amastigote differentiation.

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.