Trypanosoma cruzi Prolyl Oligopeptidase Tc80 Is Involved in Nonphagocytic Mammalian Cell Invasion by Trypomastigotes

Abstract

Trypanosoma cruzi is an intracellular protozoan parasite able to invade a wide variety of mammalian cells. To have access to the target organs/cells, the parasite must cross the basal laminae and the extracellular matrix (ECM). We previously characterized an 80-kDa proteinase (Tc80) secreted by the infective trypomastigotes that hydrolyzes native collagens and might be involved in infection by degrading ECM components. Here, we present evidence indicating a role for Tc80 in the invasion of nonphagocytic cells. Tc80 was classified as a member of the prolyl oligopeptidase (POP) family of serine proteases and was also found to hydrolyze fibronectin. Selective inhibitors for POP Tc80 were synthesized that blocked parasite entry into cells. Blockage occurred when trypomastigotes were preincubated with irreversible inhibitors but not after host cell preincubation, and the blockage correlated with inhibition of POP Tc80 activity in treated parasites. These data and the enzyme location inside a vesicular compartment close to the flagellar pocket, a specialized domain in endocytosis/exocytosis, strongly suggest a role for POP Tc80 in the maturation of parasite protein(s) and/or, after secretion, in a local action on parasite or host cell/ECM components required for invasion.

Trypanosoma cruzi infection: a continuous invader-host cell cross talk with participation of extracellular matrix and adhesion and chemoattractant molecules

“…Recent studies have shown that an 80-kDa serine protease located inside a vesicular compartment close to the flagellar pocket was found to hydrolyze FN and, more importantly, to be a potential target for a potent selective inhibitor that blocks T. cruzi entry into host cells (8,14). Also, a new member of the T. cruzi 80-85-kDa glycoprotein family was shown to bind to LN (15).…”

Applications of Zymography (Substrate-SDS-PAGE) for Peptidase Screening in a Post-Genomic Era

“…Curiously, all the analyzed closely related parasitic trypanosomatids, as well, as Cryptobia salmonistica, reveal through gelatin-SDS-PAGE only metallo-and cysteine peptidases, which are prototypal peptidases and virulence factors. In trypanosomatids, for instance, serine peptidases can only be detected by in-solution assays or after enrichment processes (Grellier et al 2001). It is somewhat intriguing that cysteine and metallopeptidases are either not resistant to the denaturation/refold process and/or are not abundantly expressed by this free living bodonid, because they were not detected by zymography.…”

Molecular analysis of early host cell infection by Trypanosoma cruzi

“…A member of the prolyl oligopeptidase (POP) family of serine proteases, with specificity for human collagen types I and IV, has been identified in cell-free extracts of trypomastigotes, amastigotes and epimastigotes (84)(85). The 80 kDa enzyme, denominated POP Tc80, also hydrolyses fibronectin and appears to be implicated in host cell invasion.…”