A novel role of rab11 in trafficking GPI-anchored trans-sialidase to the plasma membrane of trypanosoma cruzi

Abstract

Trypanosoma cruzi, the causative agent of Chagas disease, is a unicellular parasite that possesses a contractile vacuole complex (CVC). This organelle is usually present in free-living protists and is mainly involved in osmoregulation. However, in some organisms, like for example Dictyostelium discoideum, other roles include calcium homeostasis and transference of proteins to the plasma membrane. T. cruzi plasma membrane is very rich in glycosylphosphatidylinositol anchored proteins (GPI-AP) and a very important group of GPI-AP is that of the trans-sialidases. These enzymes catalyze the transfer of sialic acid from host glycoconjugates to mucins present in the surface of the parasite and are important for host cell invasion among other functions. We recently reported that a pathway dependent on the Rab GTPase Rab11 is involved in the traffic of trans-sialidases to the plasma membrane through the CVC of the infective stages of the parasite and that preventing this traffic results in considerable reduction in the ability of T. cruzi to infect host cells. We also found that traffic of other GPI-anchored proteins is also through the CVC but uses a Rab11-independent pathway. These represent unconventional pathways of GPIanchored protein traffic to the plasma membrane.