Identification of EhICP1, a chagasin-like cysteine protease inhibitor of Entamoeba histolytica.
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.
Riekenberg
S
S
Department of Biology/Chemistry, University of Osnabrueck, 49069 Osnabrueck, Germany.
Witjes
B
B
Sarić
M
M
Bruchhaus
I
I
Scholze
H
H
D000595:Amino Acid Sequence; D000818:Animals; D003546:Cysteine Endopeptidases / Q000032:analysis / Q000378:metabolism*; D015853:Cysteine Proteinase Inhibitors / Q000737:chemistry* / Q000378:metabolism / Q000494:pharmacology*; D004748:Entamoeba histolytica / Q000737:chemistry / Q000378:metabolism*; D008969:Molecular Sequence Data; D010206:Papain / Q000037:antagonists & inhibitors; D017433:Protein Structure, Secondary; D011994:Recombinant Proteins / Q000378:metabolism; D016415:Sequence Alignment
D015853:Cysteine Proteinase Inhibitors; D011994:Recombinant Proteins; D003546:Cysteine Endopeptidases; D010206:Papain