FRET peptides reveal differential proteolytic activation in intraerythrocytic stages of the malaria parasites Plasmodium berghei and Plasmodium yoelii

• Published in: International journal for parasitology Vol. 41; no. 3-4; pp. 363 - 372
• Main Authors: da Cruz, Laura Nogueira, Alves, Eduardo, Leal, Mônica Teixeira, Juliano, Maria A., Rosenthal, Philip J., Juliano, Luiz, Garcia, Celia R.S.
• Format: Journal Article
• Language: English
• Published: Kidlington Elsevier Ltd 01-03-2011; [Oxford; New York]: Elsevier Science; Elsevier
• Subjects: Animals; Biological and medical sciences; Ca2+ modulation; Calcium - metabolism; Calcium - pharmacology; Calcium Signaling; Enzyme Activation - drug effects; Erythrocytes - parasitology; Fluorescence Resonance Energy Transfer; FRET; Fundamental and applied biological sciences. Psychology; Human protozoal diseases; Infectious diseases; Life cycle. Host-agent relationship. Pathogenesis; Malaria; Medical sciences; Monensin - pharmacology; Nigericin - pharmacology; Parasitic diseases; Peptide Hydrolases - metabolism; Peptides - chemistry; Peptides - pharmacology; Plasmodium berghei; Plasmodium berghei - drug effects; Plasmodium berghei - enzymology; Plasmodium yoelii; Plasmodium yoelii - drug effects; Plasmodium yoelii - enzymology; Protease activity; Protozoa; Protozoal diseases; Thapsigargin - pharmacology; Plasmodium berghei; FRET; Malaria; Plasmodium yoelii; Ca2+ modulation; Protease activity; Protozoa; Apicomplexa; Protozoal disease; Peptides; Parasite; Activity; Activation; Parasitosis; Infection; Modulation; Ca
• ISSN: 0020-7519; 1879-0135
• DOI: 10.1016/j.ijpara.2010.10.009

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► Ex vivo protease activation measurements in malaria parasites using FRET peptides. ► Calcium modulation in protease activation differs within the rodent malaria parasites, Plasmodium berghei and Plasmodium yoelii. ► Differences in the protease activity profile during intraerythrocytic stages of P. berghei and P. yoelli.
Malaria is still a major health problem in developing countries. It is caused by the protist parasite Plasmodium, in which proteases are activated during the cell cycle. Ca2+ is a ubiquitous signalling ion that appears to regulate protease activity through changes in its intracellular concentration. Proteases are crucial to Plasmodium development, but the role of Ca2+ in their activity is not fully understood. Here we investigated the role of Ca2+ in protease modulation among rodent Plasmodium spp. Using fluorescence resonance energy transfer (FRET) peptides, we verified protease activity elicited by Ca2+ from the endoplasmatic reticulum (ER) after stimulation with thapsigargin (a sarco/endoplasmatic reticulum Ca2+-ATPase (SERCA) inhibitor) and from acidic compartments by stimulation with nigericin (a K+/H+ exchanger) or monensin (a Na+/H+ exchanger). Intracellular (BAPTA/AM) and extracellular (EGTA) Ca2+ chelators were used to investigate the role played by Ca2+ in protease activation. In Plasmodium berghei both EGTA and BAPTA blocked protease activation, whilst in Plasmodium yoelii these compounds caused protease activation. The effects of protease inhibitors on thapsigargin-induced proteolysis also differed between the species. Pepstatin A and phenylmethylsulphonyl fluoride (PMSF) increased thapsigargin-induced proteolysis in P. berghei but decreased it in P. yoelii. Conversely, E64 reduced proteolysis in P. berghei but stimulated it in P. yoelii. The data point out key differences in proteolytic responses to Ca2+ between species of Plasmodium.