Characterization of a novel endogenous cysteine proteinase inhibitor, trichocystatin-3 (TC-3), localized on the surface of Trichomonas vaginalis.
Int J Biochem Cell Biol
; 102: 87-100, 2018 09.
Article
en En
| MEDLINE
| ID: mdl-30016696
ABSTRACT
Trichomonas vaginalis is a flagellated protist responsible for human trichomoniasis. T. vaginalis has three genes encoding for endogenous cysteine proteinase (CP) inhibitors, known as trichocystatin-1 through trichocystatin-3 (TC-1, TC-2, and TC-3). These inhibitors belong to the cystatin family. In this study, we characterized trichocystatin-3 (TC-3), an endogenous cysteine proteinase (CP) inhibitor of T. vaginalis. TC-3 possesses a signal peptide in the N-terminus and two putative glycosylation sites (typical of family 2, cystatins) but lacks the PW motif and cysteine residues (typical of family 1, stefins). Native TC-3 was recognized as an â¼18 kDa protein band in a T. vaginalis protein extract. By confocal microscopy, endogenous TC-3 was found in the Golgi complex, cytoplasm, large vesicles, and the plasma membrane. These localizations are consistent with an in silico prediction. In addition, the purified recombinant protein (TC-3r) functions as an inhibitor of cathepsin L CPs, such as human liver cathepsin L and trichomonad CPs, present in a proteinase-resistant extract (PRE). Via a pull-down assay using TC-3r as bait and PRE, we identified several trichomonad CPs targeted by TC-3, primarily TvCP3. These CP-TC-3 interactions occur in vesicles, in the cytoplasm, and on the parasite surface. In addition, TC-3r showed a protective effect on HeLa cell monolayers by inhibiting trichomonad surface CPs involved in cellular damage. Our results show that the endogenous inhibitor TC-3 plays a key role in the regulation of endogenous CP proteolytic activity.
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Base de datos:
MEDLINE
Asunto principal:
Trichomonas vaginalis
/
Inhibidores de Cisteína Proteinasa
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
Int J Biochem Cell Biol
Asunto de la revista:
BIOQUIMICA
Año:
2018
Tipo del documento:
Article