| Full text | |
| Author(s): |
Farias, Shirley L.
;
Gazarini, Marcos L.
;
Melo, Robson L.
;
Hirata, Izaura Y.
;
Juliano, Maria A.
;
Juliano, Luiz
[6]
;
Garcia, Célia R. S.
Total Authors: 7
|
| Document type: | Journal article |
| Source: | Molecular and Biochemical Parasitology; v. 141, n. 1, p. 71-79, May 2005. |
| Field of knowledge: | Biological Sciences - Biophysics |
| Abstract | |
Bloodstage malaria parasites require proteolytic activity for key processes as invasion, hemoglobin degradation and merozoite escape from red blood cells (RBCs). We investigated by confocal microscopy the presence of cysteine-protease activity elicited by calcium stimulus in Plasmodium chabaudi and Plasmodium falciparum in free trophozoites or for the later parasite within RBC using fluorescence resonance energy transfer (FRET) peptides. Peptide probes access, to either free or intraerythrocytic parasites, was also tested by selecting a range of fluorescent peptides (653-3146 Da molecular mass) labeled with Abz or FITC. In the present work we show that Ca2+ stimulus elicited by treatment with either melatonin, thapsigargin, ionomicin or nigericin, promotes an increase of substrate hydrolysis, which was blocked by the specific cysteine-protease inhibitor E-64 and the intracellular Ca2+ chelator, BAPTA. When parasites were treated with cytoplasmic Ca2+ releasing compounds, a cysteine-protease was labeled in the parasite cytoplasm by the fluorescent specific irreversible inhibitor, Ethyl-Eps-Leu-Tyr-Cap-Lys(Abz)-NH2, where Ethyl-Eps is Ethyl-(2S,3S)-oxirane-2,3-dicarboxylate. In summary, we demonstrate that P. chabaudi and P. falciparum have a cytoplasmic dependent cysteine-protease activity elicited by Ca2+. (AU) | |
| FAPESP's process: | 02/06194-7 - Molecular bases of the transduction of the signal of the cell cycle of malaria parasites |
| Grantee: | Célia Regina da Silva Garcia |
| Support Opportunities: | Research Projects - Thematic Grants |
| FAPESP's process: | 03/09994-7 - Substrates and peptidic inhibitors for proteolytic enzymes |
| Grantee: | Luiz Juliano Neto |
| Support Opportunities: | PRONEX Research - Thematic Grants |