Differential expression of proteolytic enzymes in endosymbiont-harboring Crithidia species.

Crithidia oncopelti, Crithidia deanei and Crithidia desouzai are flagellates of the Trypanosomatidae family that present bacterium-like endosymbionts in their cytoplasm. Gelatin-SDS-PAGE analysis was used to characterize cell-associated and extracellular proteinases in these organisms. Our survey indicates that the proteolytic profiles of C. deanei and C. desouzai are identical; that C. oncopelti displays a distinct zymogram; and that species naturally lacking endosymbionts have a more complex extracellular proteolytic activity, which illustrates the heterogeneity of this genus. This is the first report on the presence of cysteine proteinases in the culture supernatant of monoxenic trypanosomatids, and by the use of wild and aposymbiotic strains from C. deanei we also demonstrated that the prokaryote endosymbiont somehow alters quantitatively the expression of extracellular proteinases in this trypanosomatid.