Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells

Trichomonas vaginalis is a protozoan parasite that causes trichomoniasis, the most common nonviral neglected sexually transmitted disease worldwide. Biomarkers and therapeutic targets, including specific trichomonad cysteine proteases (CPs) and their endogenous inhibitors, have been identified to di...

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Main Authors: Verónica Aranda-Chan, Montserrat Gutiérrez-Soto, Claudia Ivonne Flores-Pucheta, Octavio Montes-Flores, Rossana Arroyo, Jaime Ortega-López
Format: Article
Language:English
Published: Frontiers Media S.A. 2025-03-01
Series:Frontiers in Parasitology
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Online Access:https://www.frontiersin.org/articles/10.3389/fpara.2025.1512012/full
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author Verónica Aranda-Chan
Montserrat Gutiérrez-Soto
Claudia Ivonne Flores-Pucheta
Octavio Montes-Flores
Rossana Arroyo
Jaime Ortega-López
author_facet Verónica Aranda-Chan
Montserrat Gutiérrez-Soto
Claudia Ivonne Flores-Pucheta
Octavio Montes-Flores
Rossana Arroyo
Jaime Ortega-López
author_sort Verónica Aranda-Chan
collection DOAJ
description Trichomonas vaginalis is a protozoan parasite that causes trichomoniasis, the most common nonviral neglected sexually transmitted disease worldwide. Biomarkers and therapeutic targets, including specific trichomonad cysteine proteases (CPs) and their endogenous inhibitors, have been identified to diagnose and treat this disease. Trichocystatin 2 (TC-2) was previously identified as one of the three endogenous inhibitors of the parasite’s cathepsin L-like CPs, including TvCP39, which is involved in T. vaginalis cytotoxicity and is a potential therapeutic target. TC-2 contains five cysteines, including four located in the N-terminal sequence. These cysteines may be responsible for the formation of multimers of the recombinant protein expressed in E. coli. To determine whether these cysteines are responsible for the formation of TC-2 multimers and the effect of the N-terminus on CP inhibition, a recombinant TC-2 mutant was expressed, purified, characterized, and compared with the recombinant wild-type TC-2 protein. In silico and experimental analyses revealed that wild-type and mutant TC-2 proteins presented similar results in terms of secondary and tertiary structure prediction and high thermal stability. However, compared with that of wild-type TC-2, multimer formation was significantly reduced in the mutant lacking the four N-terminal cysteines, leading to a significant reduction in papain inhibition but not in trichomonal CP activity. These results support the hypothesis that the four cysteines located in the N-terminal region are responsible for aggregation, and their deletion affected the interaction of TC-2 with papain without affecting its inhibitory activity on homologous target proteases that are crucial for T. vaginalis virulence. Our results provide essential data supporting the use of TC-2 as a potential therapeutic target.
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spelling doaj-art-403edd0302c24cf099dba07c7ec2c0e12025-08-20T02:56:24ZengFrontiers Media S.A.Frontiers in Parasitology2813-24242025-03-01410.3389/fpara.2025.15120121512012Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cellsVerónica Aranda-Chan0Montserrat Gutiérrez-Soto1Claudia Ivonne Flores-Pucheta2Octavio Montes-Flores3Rossana Arroyo4Jaime Ortega-López5Departmento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoDepartmento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoDepartmento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoDepartmento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoDepartamento de Infectómica y Patogénesis Molecular, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoDepartmento de Biotecnología y Bioingeniería, Centro de Investigación y de Estudios Avanzados del Instituto Politécnico Nacional (Cinvestav), Mexico City, MexicoTrichomonas vaginalis is a protozoan parasite that causes trichomoniasis, the most common nonviral neglected sexually transmitted disease worldwide. Biomarkers and therapeutic targets, including specific trichomonad cysteine proteases (CPs) and their endogenous inhibitors, have been identified to diagnose and treat this disease. Trichocystatin 2 (TC-2) was previously identified as one of the three endogenous inhibitors of the parasite’s cathepsin L-like CPs, including TvCP39, which is involved in T. vaginalis cytotoxicity and is a potential therapeutic target. TC-2 contains five cysteines, including four located in the N-terminal sequence. These cysteines may be responsible for the formation of multimers of the recombinant protein expressed in E. coli. To determine whether these cysteines are responsible for the formation of TC-2 multimers and the effect of the N-terminus on CP inhibition, a recombinant TC-2 mutant was expressed, purified, characterized, and compared with the recombinant wild-type TC-2 protein. In silico and experimental analyses revealed that wild-type and mutant TC-2 proteins presented similar results in terms of secondary and tertiary structure prediction and high thermal stability. However, compared with that of wild-type TC-2, multimer formation was significantly reduced in the mutant lacking the four N-terminal cysteines, leading to a significant reduction in papain inhibition but not in trichomonal CP activity. These results support the hypothesis that the four cysteines located in the N-terminal region are responsible for aggregation, and their deletion affected the interaction of TC-2 with papain without affecting its inhibitory activity on homologous target proteases that are crucial for T. vaginalis virulence. Our results provide essential data supporting the use of TC-2 as a potential therapeutic target.https://www.frontiersin.org/articles/10.3389/fpara.2025.1512012/fulltrichocystatin-2Trichomonas vaginalisprotein aggregationcysteine protease inhibitorscytotoxicity
spellingShingle Verónica Aranda-Chan
Montserrat Gutiérrez-Soto
Claudia Ivonne Flores-Pucheta
Octavio Montes-Flores
Rossana Arroyo
Jaime Ortega-López
Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
Frontiers in Parasitology
trichocystatin-2
Trichomonas vaginalis
protein aggregation
cysteine protease inhibitors
cytotoxicity
title Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
title_full Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
title_fullStr Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
title_full_unstemmed Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
title_short Trichocystatin-2 from Trichomonas vaginalis: role of N-terminal cysteines in aggregation, protease inhibition, and trichomonal cysteine protease-dependent cytotoxicity on HeLa cells
title_sort trichocystatin 2 from trichomonas vaginalis role of n terminal cysteines in aggregation protease inhibition and trichomonal cysteine protease dependent cytotoxicity on hela cells
topic trichocystatin-2
Trichomonas vaginalis
protein aggregation
cysteine protease inhibitors
cytotoxicity
url https://www.frontiersin.org/articles/10.3389/fpara.2025.1512012/full
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