Traffic, membrane distribution and shedding of a virulence factor of Trypanosoma cruzi: the trans-sialidase

LANTOS, ANDRES; MUCCI, JUAN; NIYOGI SAYANTANEE,; ARAOZ, BEATRIZ; BOSSI, MARIANO L.; DOCAMPO, ROBERTO; CAMPETELLA, OSCAR

Workshop; EMBO, Current advances in membrane trafficking: Implications for polarity and diseases; 2014

trans-sialidase is a key virulence factor for T. cruzi, the etiological agent of Chagas disease. The enzyme is involved in crucial aspects of the parasite?s life cycle and also generates several abnormalities in the immune system of the infected mammal. TS is a GPI-anchored protein (GPI-AP) located in the plasma membrane of trypomastigotes which is shed to the milieu. In this work we show how TS is delivered to the plasma membrane via de contractile vacuole complex (CVC) during differentiation of intracellular amastigotes into trypomastigotes. TS is transported from the CVC to the plasma membrane ushered by the small GTPase Rab11. Expression of a dominant negative mutant for Rab11 prevents TS from locating to the plasma membrane and also reduces T. cruzi infection. Infection reduction is rescued by addition of recombinant TS to the culture medium. In the plasma membrane TS appears in discrete domains which are barely separated one from another when observed under a confocal microscope. To have a better insight of TS distribution we performed super-resolution (GSDIM) imaging of these domains and have determined that TS domains are about 50nm thick and separated 150-250 nm from each other, thus validating confocal observations We evaluated whether TS belongs to detergent resistant domains (DRDs) and found that they do not given that they are susceptible to detergent extraction. However other GPI-AP in trypomastigotes, such as mucins, do belong to DRDs and correspondingly do not colocalize with TS in the trypomastigote?s membrane. Lastly, TS is shed to the milieu in exosomes and only appears as a soluble protein after digestion with recombinant PI-PLC. This suggests that there is no functional native PI-PLC in T. cruzi trypomastigotes.