Identification of EhICP1, a chagasin-like cysteine protease inhibitor of Entamoeba histolytica |
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Authors: | Riekenberg S Witjes B Sarić M Bruchhaus I Scholze H |
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Institution: | Department of Biology/Chemistry, University of Osnabrueck, 49069 Osnabrueck, Germany. |
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Abstract: | Based on the Entamoeba histolytica genome project (www.sanger.ac.uk/Project/E_histolytical/) we have identified a cysteine protease inhibitor, EhICP1 (amoebiasin 1), with significant homology to chagasin. Recombinant EhICP1 inhibited the protease activity of papain and that of a trophozoite lysate with Ki's in the picomolar range. By immunocytology, we localized the endogenous approximately 13 kDa EhICP1 in a finely dotted subcellular distribution discrete from the vesicles containing the amoebic cysteine protease, EhCP1 (amoebapain). In an overlay assay, we observed binding of recombinant EhICP1 to EhCP1. As a heptapeptide (GNPTTGF) corresponding to the second conserved chagasin motif inhibited the protease activity of both papain (K) 1.5 microM) and trophozoite extract (Ki in sub-mM range), it may be a candidate for the rational development of anti-amoebiasis drugs. |
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Keywords: | Chagasin Cysteine protease inhibitor Amoebiasin Cystatin Entamoeba histolytica |
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