Cysteine peptidases inHerpetomonas samuelpessoaiare modulated by temperature and dimethylsulfoxide-triggered differentiation

Abstract

SUMMARYCysteine peptidases of protozoa have been implicated in a variety of biological events, and the expression of these enzymes is modulated in response to distinct stimuli, including environmental changes and differentiation. In the present work, we have examined the expression of cysteine peptidases fromHerpetomonas samuelpessoaigrown at distinct temperatures and during dimethylsulfoxide (DMSO)-elicited differentiation. We demonstrated that a 45 kDa cysteine peptidase had its activity reduced during the parasite growth at 37°C in comparison to 26°C, and when cultured up to 72 h in the presence of DMSO. The modulation in the 45 kDa cysteine peptidase expression is connected to the differentiation process, since both temperature and DMSO are able to trigger the promastigote to paramastigote transformation inH. samuelpessoai. The possible immunological similarity ofH. samuelpessoaiproteins with well-known cysteine peptidases produced by trypanosomatid pathogens, including cruzipain (Trypanosoma cruzi) and cysteine peptidase b (cpb) fromLeishmania mexicana, was also investigated, as well as with calpain molecules. The protein cellular lysate ofH. samuelpessoaireacted with antibodies raised against cpb ofL. mexicanaand calpain ofDrosophila melanogaster; however, no reaction was observed against cruzipain. The 35 kDa cpb-like protein had its expression diminished in DMSO-treated parasites, while the 80 kDa calpain-like molecule was enhanced and an additional 30 kDa calpain-related polypeptide was exclusively observed in these cells. Fluorescence microscopy and flow cytometry analyses corroborated these data. The results described above addH. samuelpessoaito the list of parasites whose differentiation seems to be correlated with cysteine peptidase expression.