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

Abstract

Nicastrin (NICT) is a transmembrane protein physically associated with the polytypical aspartyl protease presenilin that plays a vital role in the correct localization and stabilization of presenilin to the membrane-bound γ-secretase complex. This complex is involved in the regulation of a wide range of cellular events, including cell signaling and the regulation of endocytosed membrane proteins for their trafficking and protein processing. Methods: In Trypanosoma cruzi, the causal agent of the Chagas disease, a NICT-like protein (Tc/NICT) was identified with a short C-terminus orthologous to the human protein, a large ectodomain (ECD) with numerous glycosylation sites and a single-core transmembrane domain containing a putative TM-domain (457GSVGA461) important for the γ-secretase complex activity. Results: Using the Spot-synthesis strategy with Chagasic patient sera, five extracellular epitopes were identified and synthetic forms were used to generate rabbit anti-Tc/NICT polyclonal serum that recognized a ~72-kDa molecule in immunoblots of T. cruzi epimastigote extracts. Confocal microscopy suggests that Tc/NICT is localized in the flagellar pocket, which is consistent with data from our previous studies with a T. cruzi presenilin-like protein. Phylogenetically, Tc/NICT was localized within a subgroup with the T. rangeli protein that is clearly detached from the other Trypanosomatidae, such as T. brucei. These results, together with a comparative analysis of the selected peptide sequence regions between the T. cruzi and mammalian proteins, suggest a divergence from the human NICT that might be relevant to Chagas disease pathology. As a whole, our data show that a NICT-like protein is expressed in the infective and replicative stages of T. cruzi and may be considered further evidence for a γ-secretase complex in trypanosomatids.

Comparative membrane proteomic analysis of Tritrichomonas foetus isolates

“…Nicastrin, a transmembrane protein, is involved in the regulation of a wide range of cellular events, including cell signaling. The nicastrin protein of T. cruzi identified five IgG-binding epitopes involved in host immune recognition 88 . The Ptype ATPase subfamilies it has been related to trypanosomatids growth, adaptation, infectivity, and survival.…”

Angiostrongylus cantonensis an Atypical Presenilin: Epitope Mapping, Characterization, and Development of an ELISA Peptide Assay for Specific Diagnostic of Angiostrongyliasis

“…Our group has been working for some years on the characterization of GSC proteins from lower eukaryotes [53,54] and we observed that this group of proteins has a very low homology (~20-30%) to each other, a fact that has made their identification difficult in genomics and proteomics [55,56] projects. However, on the other hand, this information points out that these proteins are more likely to have specific epitopes under the immunological point of view.…”

Characterization and Cellular Localization of a SFT-2/Got-1- like Transporter Protein of <em>Leishmania infantum</em>

“…Although much is known about the involvement of presenilins with signal transduction in humans, very little is known in unicellular organisms and parasites. Recently, the PS-like protein [24] and some components of the GSC [25] was characterized in Trypanosoma cruzi and other parasites [26] by our group. During our characterization studies of this group of membrane protein in Leishmania sp, we did not identify any protein with significant similarity to Pen-2.…”