Proteomic analysis revealed alterations of the Plasmodium falciparum metabolism following salicylhydroxamic acid exposure

Abstract

Objectives: Although human respiratory metabolism is characterized by the mitochondrial electron transport chain, some organisms present a "branched respiratory chain." This branched pathway includes both a classical and an alternative respiratory chain. The latter involves an alternative oxidase. Though the Plasmodium falciparum alternative oxidase is not yet identified, a specific inhibitor of this enzyme, salicylhydroxamic acid (SHAM), showed a drug effect on P. falciparum respiratory function using oxygen consumption measurements. The present study aimed to highlight the metabolic pathways that are affected in P. falciparum following SHAM exposure.

Design: A proteomic approach was used to analyze the P. falciparum proteome and determine the metabolic pathways altered following SHAM treatment. To evaluate the SHAM effect on parasite growth, the phenotypic alterations of P. falciparum after SHAM or/and hyperoxia exposure were observed.

Results: After SHAM exposure, 26 proteins were significantly deregulated using a fluorescent two dimensional-differential gel electrophoresis. Among these deregulated proteins, some were particularly involved in energetic metabolism. And the combinatory effect of SHAM/hyperoxia seems deleterious for the growth of P. falciparum.

Conclusion: Our results indicated that SHAM appears to activate glycolysis and decrease stress defense systems. These data provide a better understanding of parasite biology.

Keywords: Plasmodium falciparum; glycolysis; hyperoxia; proteomic; salicylhydroxamic acid.

Figure 1

Morphologic alterations of Plasmodium falciparum following salicylhydroxamic acid (SHAM) pressure. Phenotypic changes of P. falciparum asexual blood stages were observed during two parasite cycles under (A) normoxia, (B) hyperoxia (ie, 21% oxygen), (C) SHAM/hyperoxia conditions, and (D) SHAM pressure. The parasitemia and parasitic stages were evaluated by blood smears at 0, 24, 32, 48, and 78 hours. After SHAM addition following hyperoxic exposure, significant morphological alterations were observed during the two cycles of parasites. The different intraerythrocytic stages and their corresponding percentages are indicated as follows: ring (R), trophozoites (T), schizonts (S), and parasite’s death (D).

Figure 2

Salicylhydroxamic acid (SHAM) effect on Plasmodium falciparum 3D7 strain proteome. Representative data from a two dimensional-differential gel electrophoresis experiment using a 10% homogenous sodium dodecyl sulfate polyacrylamide gel with pH range 3–10 are shown. The proteins from untreated P. falciparum parasites or treated parasites with 250 μM SHAM were labeled with Cy3 and Cy5, respectively. As determined by DeCyder 6.5 software, protein spots that were up- and down-expressed on P. falciparum under SHAM treatment (|FC| ≥ 1.5, P ≤ 0.05 t-test) were marked with master numbers (Table 1). Bold and italicized numbers correspond, respectively, to identified proteins from P. falciparum and Homo sapiens.

Figure 3

A schematic representation of the Plasmodium falciparum metabolic pathways perturbed under salicylhydroxamic acid treatment. Glycolysis and mitochondrial respiratory chain pathways based on the Ginsburg website are represented.