Proteomic analysis of Trypanosoma cruzi epimastigotes subjected to heat shock

Abstract

Trypanosoma cruzi is exposed to sudden temperature changes during its life cycle. Adaptation to these variations is crucial for parasite survival, reproduction, and transmission. Some of these conditions may change the pattern of genetic expression of proteins involved in homeostasis in the course of stress treatment. In the present study, the proteome of T. cruzi epimastigotes subjected to heat shock and epimastigotes grow normally was compared by two-dimensional gel electrophoresis followed by mass spectrometry for protein identification. Twenty-four spots differing in abundance were identified. Of the twenty-four changed spots, nineteen showed a greater intensity and five a lower intensity relative to the control. Several functional categories of the identified proteins were determined: metabolism, cell defense, hypothetical proteins, protein fate, protein synthesis, cellular transport, and cell cycle. Proteins involved in the interaction with the cellular environment were also identified, and the implications of these changes are discussed.

Figure 1

T. cruzi epimastigotes mobility and morphology after heat shock. (a) T. cruzi of the strain Ninoa in log phase growth were incubated at 28, 37, or 42°C for 1 to 6 h. Aliquots of each culture were taken each hour, and the number of mobile and immobile parasites was determined in a hemocytometer by observation in a microscope. The data are representative of three independent experiments and are shown as the mean ± SD. (b) Epimastigotes Giemsa-stained in log phase growth incubated at 28, 37, or 42°C for 3 h are shown.

Figure 2

2-DE polyacrylamide gels of control and heat-treated parasite extracts. (a) and (b) Silver-stained 2-DE gels of soluble proteins (300 μg per gel) from T. cruzi epimastigotes at normal growth (28°C, 3 h) (a) or heat shock (42°C, 3 h) temperatures (b). The proteins were firstly separated in a pH range of 3–10 NL and then on 10% SDS-PAGE. An average of 506 ± 73 spots were found in gels from parasites incubated at 28°C, and gels obtained from heat-shocked parasites had an average of 521 ± 31 spots. The molecular standards are indicated in kDa. The gels are representative of three independent experiments. In 2-DE gel from 42°C, the spots indicated by numbers were identified by MS (Table 1). (c) and (d) Master gels of control (c) or heat shock conditions (d). Three gel images obtained from different experiments from each condition (28°C or 42°C) were aligned and matched each other to generate an average master gel using the PDQuest software.