Excreted/secreted proteins from trypanosome procyclic strains

Abstract

Trypanosoma secretome was shown to be involved in parasite virulence and is suspected of interfering in parasite life-cycle steps such as establishment in the Glossina midgut, metacyclogenesis. Therefore, we attempted to identify the proteins secreted by procyclic strains of T. brucei gambiense and T. brucei brucei, responsible for human and animal trypanosomiasis, respectively. Using mass spectrometry, 427 and 483 nonredundant proteins were characterized in T. brucei brucei and T. brucei gambiense secretomes, respectively; 35% and 42% of the corresponding secretome proteins were specifically secreted by T. brucei brucei and T. brucei gambiense, respectively, while 279 proteins were common to both subspecies. The proteins were assigned to 12 functional classes. Special attention was paid to the most abundant proteases (14 families) because of their potential implication in the infection process and nutrient supply. The presence of proteins usually secreted via an exosome pathway suggests that this type of process is involved in trypanosome ESP secretion. The overall results provide leads for further research to develop novel tools for blocking trypanosome transmission.

Figure 1

Protein profile of two different T. brucei strains. Coomassie blue-stained SDS-PAGE showing (from right to left) the marker (PM), secretome, and proteome from two procyclic Trypanosoma strains: Biyamina and Stib 215.

Figure 2

Classification of T. brucei proteins from two different procyclic strains into functional categories. Proteins from the two strains (Biyamina and Stib 215) were classified into 12 functional categories. The x-axis shows the following categories: (1) unassigned function, (2) folding and degradation, (3) nucleotide metabolism, (4) carbohydrate metabolism, (5) amino acid metabolism, (6) protein synthesis, (7) signaling, (8) cell cycle and organization, (9) lipid and cofactor, (10) transport, (11) redox, and (12) RNA/DNA metabolism. The y-axis shows the percentage of each category for each strain.

Figure 3

Overlap between secretomes of Biyamina and Stib procyclic strains. Proteins found in the analysis of Biyamina and Stib secretomes were compared. The red domain represents the proteins common to the two strains (279 proteins).

Figure 4

Overlap between all the proteins from procyclic secretomes (Biyamina and Stib) and total proteome [59]. Proteins found in the analysis of secretomes and T. brucei total proteome were compared. The red domain represents the proteins common in the two proteomes (284 proteins).