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Genetic Manipulation in Δku80 Strains for Functional Genomic Analysis of Toxoplasma gondii
Published on: July 12, 2013
Protease activity of 80 kDa protein secreted from the apicomplexan parasite Toxoplasma gondii
1Department of Parasitology and Catholic Institute of Parasitic Diseases, College of Medicine, Catholic University of Korea, Seoul 137-701, Korea. skjy1261@hanmail.net
Abstract:
This study describes the characterization of 80 kDa protease showing gelationlytic property among three proteases in the excretory/secretory proteins (ESP) from Toxoplasma gondii. The protease activity was detected in the ESP but not in the somatic extract of RH tachyzoites. This protease was active only in the presence of calcium ion but not other divalent cationic ions such as Cu(2+), Zn(2+), Mg(2+), and Mn(2+), implying that Ca(2+) is critical factor for the activation of the protease. The 80 kDa protease was optimally active at pH 7.5. Its gelatinolytic activity was maximal at 37 degrees C, and significant level of enzyme activity of the protease remained after heat treatment at 56 degrees C for 30 min or 100 degrees C for 10 min. This thermostable enzyme was strongly inhibited by metal chelators, i.e., EDTA, EGTA, and 1,10- phenanthroline. Thus, the 80 kDa protease in the ESP secreted by T. gondii was classified as a calcium dependent neutral metalloprotease.
Insights
Toxoplasma gondii secretes a calcium-dependent 80 kDa metalloprotease with gelatinolytic activity. This thermostable enzyme is crucial for parasite function and represents a potential therapeutic target.
Area of Science:
- Parasitology
- Molecular Biology
- Enzymology
Background:
- Toxoplasma gondii, an obligate intracellular parasite, secretes various proteins essential for its survival and host interaction.
- Proteases play critical roles in parasitic infections, including host tissue invasion and immune evasion.
Purpose of the Study:
- To characterize a specific 80 kDa gelatinolytic protease identified in the excretory/secretory proteins (ESP) of Toxoplasma gondii tachyzoites.
- To determine the enzymatic properties, including optimal conditions, cofactor requirements, and stability, of this T. gondii protease.
Main Methods:
- Protease activity assay using gelatin zymography on ESP from T. gondii RH tachyzoites.
- Characterization of enzyme activity under varying pH, temperature, and in the presence of different divalent cations and metal chelators.
- Assessment of enzyme thermostability through heat treatment.
Main Results:
- An 80 kDa gelatinolytic protease was detected in T. gondii ESP, but not in somatic extracts.
- The protease activity was dependent on calcium ions (Ca2+) and was optimally active at pH 7.5 and 37°C.
- The enzyme exhibited significant thermostability and was inhibited by metal chelators, indicating it is a metalloprotease.
Conclusions:
- The 80 kDa protease secreted by T. gondii is a calcium-dependent neutral metalloprotease.
- Its gelatinolytic and thermostable properties suggest a significant role in T. gondii pathogenesis.
- This protease represents a potential target for anti-toxoplasmosis drug development.
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