Cysteine peptidases in the tomato trypanosomatid Phytomonas serpens: Influence of growth conditions, similarities with cruzipain and secretion to the extracellular environment

Biological Roles of Peptidases in Trypanosomatids

“…However, all the cysteine peptidases are active at acidic pH and completely restrained by E-64, a powerful cysteine peptidase inhibitor. In addition, the cysteine peptidases produced by these flagellates were exclusively detected in the parasite cellular extracts, except for C. desouzai, C. deanei [23] and P. serpens [16,20], whose cysteine peptidase activities were also characterized in the extracellular medium. At least in P. serpens, both cellular and extracellular cysteine peptidases were able to degrade several proteinaceous substrates, suggesting a possible participation of these enzymes in parasite nutrition [16,20].…”

“…In addition, the cysteine peptidases produced by these flagellates were exclusively detected in the parasite cellular extracts, except for C. desouzai, C. deanei [23] and P. serpens [16,20], whose cysteine peptidase activities were also characterized in the extracellular medium. At least in P. serpens, both cellular and extracellular cysteine peptidases were able to degrade several proteinaceous substrates, suggesting a possible participation of these enzymes in parasite nutrition [16,20]. Moreover, a 40 kDa cysteine peptidase synthesized by P. serpens cells cleaved a 115 kDa surface polypeptide located at the surface of a salivary gland from Oncopeltus fasciatus, a phytophagous insect, implicating a possible participation of this cysteine peptidase in interaction processes [20].…”

“…At least in P. serpens, both cellular and extracellular cysteine peptidases were able to degrade several proteinaceous substrates, suggesting a possible participation of these enzymes in parasite nutrition [16,20]. Moreover, a 40 kDa cysteine peptidase synthesized by P. serpens cells cleaved a 115 kDa surface polypeptide located at the surface of a salivary gland from Oncopeltus fasciatus, a phytophagous insect, implicating a possible participation of this cysteine peptidase in interaction processes [20]. Corroborating the preceding statement, cysteine peptidase inhibitors were capable of blocking the adhesion process between P. serpens promastigote cells and salivary glands of O. fasciatus [16].…”

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

“…Also, these traditionally ''non-mammalian and non-pathogenic'' microorganisms have been used as experimental models of the Trypanosomatidae family for exploring their basic mechanisms at the genetic, physiological, ultrastructural and biochemical levels. In the same way, several research groups have described common structures/molecules produced by monoxenous and heteroxenous parasites belonging to the Trypanosomatidae family (Lopes et al 1981;Breganó et al 2003;Santos et al 2006Santos et al , 2007Elias et al 2008). Interestingly, Herpetomonas species have been detected not only in insects, but repeatedly in plants and mammals, including immunosuppressed humans, mainly in HIV-infected individuals, in whom the parasites caused either visceral or cutaneous lesions (reviewed by Chicharro and Alvar, 2003;Morio et al 2008), showing the ability to develop digenetic life style under certain conditions.…”

Molecular and Proteolytic Profiles of Trypanosoma cruzi Sylvatic Isolates from Rio de Janeiro-Brazil

“…The enzyme has been shown to be lysossomal, and is located in an epimastigote-specific pre-lysossomal organelle called the 'reservossome', which contains proteins that are digested during differentiation to metacyclic trypomastigotes (Soares et al, 1992). Some authors have suggested a second location of enzyme isoforms in the plasma membrane, associated with a glycosylphosphatidylinositol (GPI) anchor (Elias et al, 2008). These isoforms were present in epimastigotes, amastigotes and trypomastigotes, and reacted with polyclonal anti-cruzipain sera, thereby becoming an immunodominant antigen that is recognized by the sera of human patients with chronic Chagas disease (Martínez et al, 1991).…”