Quantitative proteomic profiling of the promastigotes and the intracellular amastigotes of Leishmania donovani isolates identifies novel proteins having a role in Leishmania differentiation and intracellular survival.

Protozoan parasites of the genus Leishmania are important human pathogens that cycle between an extracellular promastigote stage residing in the sandflies and an intracellular amastigote stage colonizing the phagolysosomal compartment of the mammalian macrophages. Here, we used the isobaric tagging method to quantify the global proteomic differences between the promastigotes and the intracellular amastigotes of three different Leishmania donovani clones derived from the THP-1 human macrophage cell line. We identified a substantial number of differentially modulated proteins involved in nutrient acquisition and energy metabolism, cell motility and cytoskeleton, transport, cell signaling and stress response. Proteins involved in vesicular trafficking and endocytosis like the rab7 GTP binding protein, GTP-binding proteins of the Ras superfamily and developmentally regulated GTP-binding protein 1 revealed enhanced expression and also a putative dynein heavy chain protein was found to be up-regulated in the amastigotes and it probably has a role in cargo transport inside the vesicles. Significantly, in the amastigotes the expression of a protein involved in glucose transport was increased eight to fifteen-fold, whereas concentrations of several proteins associated with cell motility and cytoskeleton were reduced. Thus, the quantitative proteomic analysis of L. donovani isolates sheds light on some novel proteins that may have a role in Leishmania differentiation and intracellular survival.