A Phosphoinositide-Specific Phospholipase C of Trypanosoma Cruzi: Unique Characteristics of a Delta-Type Homologue

Abstract

The phosphoinositide-specific phospholipase C gene (TcPI-PLC  ) of the protozoan parasite Trypanosoma cruzi was cloned, sequenced, expressed in E. 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 it associates to the plasma membrane. 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 N-terminal end, lack of an apparent PH 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 [3H]myristate and [3H]palmitate, and immunoprecipitation with anti-TcPI-PLC antibody, and may constitute the first example of a new group of PI-PLCs.