Crystal structure of chagasin, the endogenous cysteine-protease inhibitor from Trypanosoma cruzi

ABSTRACT Cruzain is an essential cysteine protease of Trypanosoma cruzi and a therapeutic target for Chagas' disease. Eight dogs were infected with T. cruzi; three were treated with an inhibitor of cruzain, K777, for 14 days. Treatment with K777 abrogated myocardial damage by T. cruzi, as documented by histopathological lesion scores and serum troponin I levels.

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Upregulation of the secretory pathway in cysteine protease inhibitor-resistant Trypanosoma cruzi

Journal of Cell Science ◽

10.1242/jcs.113.8.1345 ◽

2000 ◽

Vol 113 (8) ◽

pp. 1345-1354

Author(s):

J.C. Engel ◽

C.T. Garcia ◽

I. Hsieh ◽

P.S. Doyle ◽

J.H. McKerrow

Keyword(s):

Trypanosoma Cruzi ◽

Protease Inhibitor ◽

Golgi Complex ◽

Cysteine Protease ◽

Secretory Pathway ◽

Complex Function ◽

Cysteine Protease Inhibitor ◽

Cross Resistance ◽

Structural Levels

A novel chemotherapy in development for Chagas' disease targets cruzain, the major cysteine protease of Trypanosoma cruzi. Peptidomimetic inhibitors disrupt the intracellular cycle of the parasite and rescue animals from a lethal infection. Inhibitor killing of parasites results from interruption of autocatalytic cruzain processing and transport to lysosomes, and massive accumulation of precursor protein in the Golgi complex. To further understand the mechanisms of protease processing and transport in this primitive eukaryote, and uncover potential mechanisms for resistance to these drugs, we generated cysteine-protease inhibitor (CPI)-resistant epimastigotes in vitro and investigated the mechanisms involved at the biochemical and structural levels. Resistance to 20-fold the lethal CPI concentration, achieved after a year of gradual drug increase, was accompanied by a modest decrease in growth rate. A marked increase in the number of vesicles trafficking from the Golgi complex to the flagellar pocket occurs in resistant cells. No mature protease reaches lysosomes though accumulation of endocytosed gold particles in lysosomes appears to be normal. Higher molecular mass cruzain species, consistent with complexes of cruzain precursors and inhibitor, are secreted by CPI-resistant parasites into the culture supernatant. Release of these cruzain precursors may be facilitated by an enhanced acidification of trans-Golgi cisternae in resistant parasites. The pH within Golgi cisternae is higher in control epimastigotes and most mature cruzain is lysosomal. Cruzain activity is negligible in CPI-resistant epimastigote extracts compared to the parental clone. Activity is restored following withdrawal of the inhibitor. No cross-resistance to the therapeutic drugs nifurtimox and benznidazole occurred and, conversely, parasites resistant to these drugs were sensitive to CPI. Protease inhibitors are thus potential therapeutical alternatives in cases of nifurtimox/benznidazole resistance. Cumulatively, these results suggest that CPI-resistance induces upregulation of Golgi complex function and post-Golgi secretory pathway, and release of precursors before the enzyme reaches its site of biologic activity.

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Cysteine protease inhibitors alter Golgi complex ultrastructure and function in Trypanosoma cruzi

Journal of Cell Science ◽

10.1242/jcs.111.5.597 ◽

1998 ◽

Vol 111 (5) ◽

pp. 597-606 ◽

Cited By ~ 6

Author(s):

J.C. Engel ◽

P.S. Doyle ◽

J. Palmer ◽

I. Hsieh ◽

D.F. Bainton ◽

...

Keyword(s):

Trypanosoma Cruzi ◽

Protease Inhibitor ◽

Protease Inhibitors ◽

Golgi Complex ◽

Cysteine Protease ◽

Intracellular Localization ◽

Fluorescent Microscopy ◽

Brefeldin A ◽

Cysteine Protease Inhibitor ◽

Cysteine Protease Inhibitors

Cruzain, the major cysteine protease of the protozoan parasite Trypanosoma cruzi, is a target of rational drug design for chemotherapy of Chagas' disease. The precise biological role of cruzain in the parasite life cycle and the mechanism involved in the trypanocidal effect of cysteine protease inhibitors are still unclear. Here we report biological and ultrastructural alterations caused by cysteine protease inhibitors in T. cruzi epimastigotes. Cruzain, a glycoprotein that transits the Golgi-endosomal pathway, localized to pre-lysosomes/lysosomes in the posterior end of untreated epimastigotes by fluorescent microscopy utilizing either a biotinylated cysteine protease inhibitor to tag the active site, or a specific anti-cruzain antibody. Radiolabeled or biotinylated cysteine protease inhibitors bound exclusively to cruzain in intact epimastigotes confirming that cruzain is accessible to, and is targeted by the inhibitors. Treatment of T. cruzi epimastigotes with specific cysteine protease inhibitors arrested growth, altered the intracellular localization of cruzain, and induced major alterations in the Golgi complex. Following treatment, cruzain accumulated in peripheral dilations of Golgi cisternae. There was a concomitant 70% reduction in gold-labeled cruzain transported to lysosomes. Cisternae abnormalities in the Golgi compartment were followed by distention of ER and nuclear membranes. Brefeldin A increased the number and size of cisternae in epimastigotes. Pre-treatment of epimastigotes with cysteine protease inhibitors followed by exposure to brefeldin A induced a more rapid appearance of the cysteine protease inhibitor-induced Golgi alterations. Our results suggest that cysteine protease inhibitors prevent the normal autocatalytic processing and trafficking of cruzain within the Golgi apparatus. Accumulation of cruzain may decrease mobility of Golgi membranes and result in peripheral distention of cisternae. These major alterations of the Golgi complex parallel the death of T. cruzi epimastigotes.

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1 H, 15 N and 13C assignments of the cysteine protease inhibitor Chagasin from Trypanosoma cruzi

Journal of Biomolecular NMR ◽

10.1007/s10858-006-0014-x ◽

2006 ◽

Vol 36 (S1) ◽

pp. 30-30

Author(s):

Rodolpho do Aido-Machado ◽

Didier Salmon ◽

Anne Diehl ◽

Martina Leidert ◽

Oliver Schmetzer ◽

...

Keyword(s):

Trypanosoma Cruzi ◽

Protease Inhibitor ◽

Cysteine Protease ◽

Cysteine Protease Inhibitor

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A New Cruzipain-Mediated Pathway of Human Cell Invasion by Trypanosoma cruzi Requires Trypomastigote Membranes

Infection and Immunity ◽

10.1128/iai.72.10.5892-5902.2004 ◽

2004 ◽

Vol 72 (10) ◽

pp. 5892-5902 ◽

Cited By ~ 72

Author(s):

Isabela M. Aparicio ◽

Julio Scharfstein ◽

Ana Paula C. A. Lima

Keyword(s):

Trypanosoma Cruzi ◽

Protease Inhibitor ◽

Host Cell ◽

Cell Invasion ◽

Cysteine Protease ◽

Mammalian Cells ◽

Host Cells ◽

Cysteine Protease Inhibitor ◽

Host Cell Invasion ◽

Different Strains

ABSTRACT The intracellular protozoan Trypanosoma cruzi causes Chagas' disease, a chronic illness associated with cardiomyopathy and digestive disorders. This pathogen invades mammalian cells by signaling them through multiple transduction pathways. We previously showed that cruzipain, the main cysteine protease of T. cruzi, promotes host cell invasion by activating kinin receptors. Here, we report a cruzipain-mediated invasion route that is not blocked by kinin receptor antagonists. By testing different strains of T. cruzi, we observed a correlation between the level of cruzipain secreted by trypomastigotes and the capacity of the pathogen to invade host cells. Consistent with a role for cruzipain, the cysteine protease inhibitor N-methylpiperazine-urea-Phe-homophenylalanine-vinylsulfone-benzene impaired the invasion of human smooth muscle cells by strains Dm28c and X10/6 but not by the G isolate. Cruzipain-rich supernatants of Dm28c trypomastigotes enhanced the infectivity of isolate G parasites twofold, an effect which was abolished by the cysteine protease inhibitor l-trans-epoxysuccinyl-leucylamido-(4-guanidino)butane and by thapsigargin, a drug that induces depletion of the intracellular Ca2+ stores. The enhancement due to Dm28 supernatants was abolished upon cruzipain immunodepletion, and the activity was restored by purified cruzipain. In contrast, supernatants from isolate G trypomastigotes (with low levels of cruzipain) or supernatants from Dm28c epimastigotes or purified cruzipain alone did not enhance parasite invasion, indicating that the protease is required but not sufficient to engage this invasion pathway. We provide evidence that activation of this pathway requires cruzipain-mediated processing of a trypomastigote molecule associated with parasite-shed membranes. Our results couple cruzipain to host cell invasion through a kinin-independent route and further suggest that high-level cruzipain expression may contribute to parasite infectivity.

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