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Title: FRET peptides reveal differential proteolytic activation in intraerythrocytic stages of the malaria parasites Plasmodium berghei and Plasmodium yoelii
Authors: Cruz, Laura Nogueira da
Alves, Eduardo
Leal, Monica Teixeira
Juliano, Maria Aparecida [UNIFESP]
Rosenthal, Philip J.
Juliano, Luiz [UNIFESP]
Garcia, Célia Regina da Silva
Universidade de São Paulo (USP)
Universidade Federal de São Paulo (UNIFESP)
Univ Calif San Francisco
Keywords: Malaria
Plasmodium berghei
Plasmodium yoelii
Protease activity
Ca(2+) modulation
Issue Date: 1-Mar-2011
Publisher: Elsevier B.V.
Citation: International Journal for Parasitology. Oxford: Elsevier B.V., v. 41, n. 3-4, p. 363-372, 2011.
Abstract: 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. Ca(2+) 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 Ca(2+) in their activity is not fully understood. Here we investigated the role of Ca(2+) in protease modulation among rodent Plasmodium spp. Using fluorescence resonance energy transfer (FRET) peptides, we verified protease activity elicited by Ca(2+) from the endoplasmatic reticulum (ER) after stimulation with thapsigargin (a sarco/endoplasmatic reticulum Ca(2+)-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) Ca(2+) chelators were used to investigate the role played by Ca(2+) 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 Ca(2+) between species of Plasmodium. (C) 2011 Australian Society for Parasitology Inc. Published by Elsevier B.V. All rights reserved.
ISSN: 0020-7519
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