The heat-shock response in Trypanosoma cruzi and Crithidia fasciculata

Molecular aspects of heat-shock response were investigated in monogenetic and digenetic members of the Trypanosomatidae and the data obtained compared. Trypanosoma cruzi and Crithidia fasciculata differ in the number of heat-shock proteins (HSPs) induced and in the range of supra-optimal temperature induction of these proteins. Whereas low molecular weight Hsps were induced by high temperature in Crithidia, this effect was only seen in T. cruzi after ethanol treatment. The 61 kDa peptide of T. cruzi, induced by heat, was characterized as a HSP60 family member by Western blot using a Mycobacterium polyclonal anti-HSP60 antibody. The HSP61 aa. sequence, deduced from the isolated HSP60 gene and its mRNA product were characterized. The predicted aa. sequence has shown the presence of a mitochondrial peptide leader and no large domains of aa. sequence conservation were found when compared to other known HSP60, in contrast to what is observed in HSP70. Furthermore, the HSP60 gene is apparently conserved in T. cruzi, C. fascilulata and Leishmania as suggested by genomic Southern blot analysis.

Heat shock proteins in Trypanosoma cruzi: identification and localization of HSP70 and HSP60 proteins and structure of HSP60 genes (brief report)

To identify the members of the HSP70 and HSP60 families of Trypanosoma cruzi, we analysed 35S methionine epimastigote cells by two dimensional Western blot. At 29 degrees C, an HSP70 monoclonal antibody (anti-D. melanogaster) recognized eight isotypes. At least five of these were heat-induced. Polyclonal antibody against the 65 KDa antigen (anti-M. tuberculosis) recognized three isotypes with identical molecular weights, but different microliters. Only one isoform was heat induced. The cellular distribution of HSP70 and HSP60 was studied by immunoelectron microscopy. Anti-HSP70 reactive protein was localized in the cytoplasm, mitochondria and nucleus, while anti-HSP60 protein was found in the mitochondrion and in close association with the kinetoplast. To characterize the HSP60 gene and its proteins, we isolated a genomic T. cruzi clone encoding the HSP60 gene. T. cruzi HSP60 genes could be shown to be organized in 2100 nt tandem arrays. RELP in the HSP60 genes revealed that at least three different types of HSP60 genes were encoded in the T cruzi genome. The predicted open reading frame measured exhibits about 50 percent identity to other HSP60 described. Expression of these HSP60 genes could not be induced by 2 hours heat shock at 37 degrees C. Post-transcriptional mechanisms may be responsible for HSP60 induction in T. cruzi