Trypanosoma cruzi SELECTIVELY TRANSPORT HEME OR HEME ANALOGS ALONG THE DIFFERENT LIFE-CYCLE STAGES

LUCAS PAGURA; MARCELO L MERLI; BRENDA A CIRULLI; JULIA A CRICCO

Buenos Aires

Congreso; XXVII Reunión Anual de la Scociedad Argentina de Protozoología; 2015

Sociedad Argentina de Protozoología

Trypanosoma cruzi lacks all the enzymes involved in heme biosynthesis and must incorporate it from the different hosts to supply for the heme-protein pool. We are interested in elucidating how heme is imported by the T. cruzi along its different life-cycle stages. We used fluorescent heme analogs (HAs, PP protoporphyrin and MP mesoporphyrin derivatives) to study heme transport along different life-cycle stages by confocal microscopy and direct measurement of fluorescence. These analogs cannot replace heme functions and for this reason only the imported analogs can cause a negative effect on cell growth.We observed that T. cruzi transport heme along the replicative life-cycle stages (epimastigotes and amastigotes) but heme transport was not observed in the trypomastigotes stage. Interestingly, several -but not all- HAs used to test heme transport were efficiently transported by T. cruzi. The HAs PP, ZnPP and ZnMP were taken up by the epimastigotes analyzed in this study (Dm28c and CL Brener) causing a deleterious effect on cell growth. The GaPP analog was efficiently imported by Dm28c epimastigotes, but surprisingly CL Brener did not transport it. On the other hand, SnMP was the only one HA not imported, neither by epimastigotes nor amastigotes. However all HAs competed for heme uptake, causing a reduction in the intracellular heme level. These pieces of evidence pointed out SnMP as a good candidate to study the blockage of heme transport in T. cruzi.In summary, based on our results we postulate that T. cruzi possess a selective transport system that can discriminate between structurally related compounds. The strains analyzed in this work presented a different behavior when they were expose to these HAs. This could be due to some differences in the transport system- different transporters or associated regulatory proteins, different carriers for the intracellular trafficking or differences in the regulation of heme transport.