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Published on: June 12, 2014
Characterization of two cysteine proteases secreted by Blastocystis ST7, a human intestinal parasite
Ivan Wawrzyniak1, Catherine Texier, Philippe Poirier
1Clermont Université, Université Blaise Pascal, Laboratoire Microorganismes: Génome et Environnement, BP 10448, F-63000 Clermont-Ferrand, France.
Abstract:
Blastocystis spp. are unicellular anaerobic intestinal parasites of both humans and animals and the most prevalent ones found in human stool samples. Their association with various gastrointestinal disorders raises the questions of its pathogenicity and of the molecular mechanisms involved. Since secreted proteases are well-known to be implicated in intestinal parasite virulence, we intended to determine whether Blastocystis spp. possess such pathogenic factors. In silico analysis of the Blastocystis subtype 7 (ST7) genome sequence highlighted 22 genes coding proteases which were predicted to be secreted. We characterized the proteolytic activities in the secretory products of Blastocystis ST7 using specific protease inhibitors. Two cysteine proteases, a cathepsin B and a legumain, were identified in the parasite culture supernatant by gelatin zymographic SDS-PAGE gel and MS/MS analysis. These proteases might act on intestinal cells and disturb gut function. This work provides serious molecular candidates to link Blastocystis spp. and intestinal disorders.
Insights
Blastocystis parasites, common in human stool, may cause gut issues. Researchers identified specific secreted proteases, like cysteine proteases, in Blastocystis subtype 7, suggesting a mechanism for intestinal disorders.
Area of Science:
- Parasitology
- Molecular Biology
- Gastroenterology
Background:
- Blastocystis spp. are prevalent unicellular anaerobic intestinal parasites found in humans and animals.
- Their role in gastrointestinal disorders is debated, prompting investigation into their pathogenicity.
- Secreted proteases are known virulence factors in intestinal parasites.
Purpose of the Study:
- To investigate the presence and function of secreted proteases in Blastocystis subtype 7 (ST7).
- To identify specific proteases that may contribute to Blastocystis-associated intestinal disorders.
Main Methods:
- In silico analysis of the Blastocystis ST7 genome to identify protease-encoding genes.
- Characterization of proteolytic activities in parasite secretory products using protease inhibitors.
- Identification of specific proteases via gelatin zymography, SDS-PAGE, and MS/MS analysis.
Main Results:
- The Blastocystis ST7 genome contains 22 predicted secreted protease genes.
- Proteolytic activity was confirmed in the parasite's culture supernatant.
- Two cysteine proteases, cathepsin B and legumain, were identified in the supernatant.
Conclusions:
- Blastocystis ST7 secretes cysteine proteases, including cathepsin B and legumain.
- These identified proteases are potential virulence factors that may contribute to intestinal cell damage and gut dysfunction.
- This study provides molecular candidates linking Blastocystis spp. to intestinal disorders.
