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ARTICLE

Cysteine proteinases of Trypanosoma cruzi: from digestive enzymes to programmed cell death mediators

by GREGOR KOSEC, VANINA ALVAREZ, JUAN J. CAZZULO**

* Jozef Stefan Institute, Jamova 39, SI 1000 Ljubljana, Slovenia.
** Instituto de Investigaciones Biotecnologicas (IIB-INTECH), Universidad Nacional de General San Martin – CONICET. Av. Gral. Paz 5445, (1650) San Martín, Buenos Aires, Argentina.
¶ These authors contributed equally to the present work.
Address correspondence to: Dr. Juan José Cazzulo. E-mail: jcazzulo@iib.unsam.edu.ar Fax: (+54-11) 4752 9639

BIOCELL 2006, 30(3), 479-490. https://doi.org/10.32604/biocell.2006.30.479

Abstract

Trypanosoma cruzi, the parasite causing Chagas disease, contains a number of proteolytic enzymes. The recent completion of the genome sequence of the T. cruzi CL Brener clone suggests the presence of 70 cysteine peptidases, 40 serine peptidases (none of them from the chymotrypsin family), about 250 metallopeptidases (most leishmanolysin homologues), 25 threonine peptidases, and only two aspartyl peptidases, none of them from the pepsin family. The cysteine peptidases belong to 7 families of Clan CA, 3 families of Clan CD, and one each of Clans CE and CF. In Clan CA, the C1 family is represented by cruzipains 1 and 2, biochemically well characterized, as well as cathepsin B and two other cathepsins. There are a number of homologues to calpains (family C2), probably non-functional, lacking the Ca-binding domain. Family C54 includes the Atg4 proteinases (autophagins), which seem to be involved in the autophagic process. Clan CD includes family C14, the metacaspases. We have expressed the metacaspases TcMCA3 and TcMCA5, and obtained indirect evidence of their participation in programmed cell death induced by fresh human serum in the parasite. More experiments are required to better define their role in apoptosis.

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