Protein biosynthesis changes in Trypanosoma cruzi induced by supra-optimal temperature

Early during vertebrate infection, T. cruzi is exposed to the host blood at an elevated temperature. Bearing this in mind, the pattern of protein synthesis of two parasite forms was examined. SDS-PAGE of heated organisms showed an increase in at least four proteins (103, 92, 75 and 61 kD). The temperature effect is also manifested in cells whose RNA synthesis is reduced by actinomycin D treatment. The synthesis of the ‘29 ° proteins’ is inhibited at 40 °C in organisms growing in culture medium; when the organisms were maintained in serum, the inhibition was not observed. The inhibitory effect observed at 40 °C was reversed when the temperature was shifted to 29 °C. These proteins were synthesized for 180 min at 37 °C or 360 min at 40 °C. The increased protein synthesis manifested at 37 °C had decreased 45 min after the temperature was lowered to 29 °C. When the cells were pre-incubated at 40 °C and shifted to 29 °C, the synthesis of the heat-induced proteins proceeded for at least 180 min. This pattern of heat induction in epimastigotes and trypomastigotes is the same irrespective of whether the incubation medium is LIT (for epimastigotes), M-16 (for trypomastigotes), or when serum was used for both cell types.