Characterization of proteolytic activities of Giardia lamblia with the ability to cleave His-tagged N-terminal sequences

• Published in: Molecular and biochemical parasitology 2019-03, Vol.228, p.16-26
• Main Authors: de la Mora-de la Mora, José Ignacio, Enríquez-Flores, Sergio, Fernández-Lainez, Cynthia, Gutiérrez-Castrellón, Pedro, Olivos-García, Alfonso, González-Canto, Augusto, Hernández, Roberto, Luján, Hugo D., García-Torres, Itzhel, López-Velázquez, Gabriel
• Format: Article
• Language: English
• Subjects: Cathepsin; Cysteine protease; Giardiasis; PAR; Triosephosphate isomerase
• ISSN: 0166-6851; 1872-9428
• DOI: 10.1016/j.molbiopara.2019.01.001

•The study of proteolytic activities in Giardia is important to understand the factors that control the host-parasite interaction.•We developed a protein-construct to test the proteolytic properties in Giardia lamblia.•Crude extracts of Giardia trophozoites show cleavage activity on NH-terminal with cleavage site of a viral protease or thrombin.•A chromatographic fraction containing one cathepsin B is able to exert some of the observed cleavage activity.•The chromatographic fraction with the cathepsin B is able to aggregate human platelets. Giardia lamblia is one of the most common protozoan infectious agents in the world and is responsible for diarrheal disease and chronic postinfectious illness. During the host-parasite interaction, proteases are important molecules related to virulence, invasion, and colonization, not only for Giardia but also for other parasites. We aimed to characterize the cysteine protease activity detected in trophozoite lysates. This proteolytic activity showed the ability to cleave NH-terminal sequences with either a recognition sequence for a viral protease or a recognition sequence for thrombin. This cleavage activity was detected in nonencysting trophozoites and increased with the progression of encystation. This activity was also detected in excretion/secretion products of axenic trophozoites and in trophozoites cocultured with differentiated Caco-2 cells. Based on size exclusion chromatography, we obtained a fraction enriched in low- to medium-molecular-weight proteins that was capable of exerting this cleavage activity and aggregating human platelets. Finally, our results suggest that this proteolytic activity is shared with other protozoan parasites.