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

Guilherme Curty Lechuga; Paloma Napoleão-Pêgo; Larissa Rodrigues Gomes; Andressa da Matta Durans; David William Provance Jr; Salvatore Giovanni De-Simone

doi:10.3390/microorganisms9081750

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

Microorganisms. 2021 Aug 17;9(8):1750. doi: 10.3390/microorganisms9081750.

Authors

Guilherme Curty Lechuga¹, Paloma Napoleão-Pêgo¹, Larissa Rodrigues Gomes¹, Andressa da Matta Durans¹, David William Provance Jr^{1

2}, Salvatore Giovanni De-Simone^{1

3}

Affiliations

¹ FIOCRUZ, Center for Technological Development in Health (CDTS), National Institute of Science and Technology for Innovation on Neglected Diseases Populations (INCT-IDPN), Rio de Janeiro 21040-900, Brazil.
² FIOCRUZ, Interdisciplinary Medical Research Laboratory, Oswaldo Cruz Institute, Rio de Janeiro 21040-900, Brazil.
³ Department of Cellular and Molecular Biology, Biology Institute, Federal Fluminense University, Niterói 24020-141, Brazil.

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.

Keywords: B-cell epitope; SPOT synthesis; Trypanosoma cruzi; flagellar pocket; nicastrin; presenilin; transmembrane motif; type I transmembrane glycoprotein; vesicular trafficking; γ-secretase.

Abstract

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