Trypanosoma Cruzi Presenilin-like Transmembrane Aspartyl Protease: Characterization and Cellular Localization

Abstract

The increasing detection of infections of Trypanosoma cruzi, the etiological agent of Chagas disease, in non-endemic regions beyond Latin America has risen to be a major public health issue. With an impact in the millions of people, current treatments rely on antiquated drugs that produce severe side effects and are considered nearly ineffective for the chronic phase. The minimal progress in the development of new drugs highlights the need for advances in basic research on crucial biochemical pathways in T. cruzi to identify new targets. Here, we report on the T. cruzi presenilin-like transmembrane aspartyl enzyme, a protease of the aspartic class in a unique phylogenetic subgroup with T. vivax separate from protozoans. Computational analyses suggests it contains 9 transmembrane domains and an active site with the characteristic PALP motif of the A22 family. Multiple linear B-cell epitopes were identified by SPOT synthesis analysis with Chagasic patient sera. Two were chosen to generate rabbit antisera, whose signal was primarily localized to the flagellar pocket, intracellular vesicles and endoplasmic reticulum in parasites by whole cell immunofluorescence. The results suggest that the parasitic presenilin-like enzyme could have a role in the secretory pathway and serve as a biomarker for infections.

Lopinavir and Nelfinavir Induce the Accumulation of Crystalloid Lipid Inclusions within the Reservosomes of Trypanosoma cruzi and Inhibit Both Aspartyl-Type Peptidase and Cruzipain Activities Detected in These Crucial Organelles

“…Recently, a presenilin-like transmembrane aspartyl enzyme was reported in T. cruzi . The presenilin-like peptidase was detected in the flagellar pocket, endoplasmic reticulum and reservosomes [ 28 ]. Its subcellular localization suggests participation in secretion and/or endocytic trafficking.…”

“…Its subcellular localization suggests participation in secretion and/or endocytic trafficking. Interestingly, serum deprivation leads to the upregulation of T. cruzi presenilin-like protein expression but is mostly concentrated in the regions of the flagellum and the flagellar pocket region near the kinetoplast [ 28 ]. The discovery of an aspartyl peptidase by the authors in the endoplasmic reticulum and in reservosomes strengthens our previous and current findings concerning the inhibition of aspartyl peptidases by HIV-PIs and lipid storage imbalance in those organelles.…”

“…This inverse correlation led us to suppose that the aspartyl-type peptidases present in the reservosomes could somehow be (directly and/or indirectly) linked to the processes of cholesterol mobilization by the endocytic pathway in the protozoan, where the inhibition of the enzymes by HIV-PIs led to lipid accumulation in the organelles, as evidenced by TEM analyses. This assumption is reinforced by the recent work of Lechuga and coworkers [ 28 ], who suggested the participation of an aspartyl-like peptidase in secretion and/or endocytic trafficking due to its localization on the flagellar pocket, endoplasmic reticulum and reservosomes. However, we cannot exclude the possibility of other targets for HIV-PIs or even nonspecific toxic effects.…”

Epitope Mapping of the Diphtheria Toxin and Development of an ELISA-Specific Diagnostic Assay

“…To verify the diagnostic performance of the peptides, sera from ninety-two individual DTP vaccined were tested on an ELISA-peptide based assay. All 90 DTP-positive human sera and 32 mice sera reacted with the highly conserved DTx2-12 and DTx4-13 peptides but did not react with the peptides EP7 [56] from T. cruzi (PPGEDMHTRDGPRE) considered by a scale value as a good test. Both CB/DTx2-12 and CB/DTx4-13 antigens demonstrated 100% and 99.96% sensitivity, respectively and 100% specificity (Figure 3 C and D).…”

Nicastrin-Like, a Novel Transmembrane Protein from Trypanosoma cruzi Associated to the Flagellar Pocket

“…While much is known about the GSC compounds in superior eukaryotic organisms, very little is known about their role in inferior eukaryotic cells. Recently, we showed the potential for the presence of a GSC in Trypanosoma cruzi based on our characterization of a TM aspartyl protease that shows hallmarks of human PS [ 14 ]. T. cruzi is the causative agent for American trypanosomiasis, more commonly referred to as Chagas disease, and infections are typically spread by triatomine vectors that affect millions of people throughout Latin America [ 15 ].…”