Ca2+/H+ exchange in acidic vacuoles of Trypanosoma brucei
TLDR
The use of digitonin to permeabilize the plasma membrane of Trypanosoma brucei procyclic and bloodstream trypomastigotes allowed the identification of a non-mitochondrial nigericin-sensitive Ca2+ compartment, which is tentatively named the acidocalcisome.Abstract:
The use of digitonin to permeabilize the plasma membrane of Trypanosoma brucei procyclic and bloodstream trypomastigotes allowed the identification of a non-mitochondrial nigericin-sensitive Ca2+ compartment. The proton ionophore carbonyl cyanide p-trifluoromethoxyphenylhydrazone (FCCP) was able to cause Ca2+ release from this compartment, which was also sensitive to sodium orthovanadate. Preincubation of the cells with the vacuolar H(+)-ATPase inhibitor bafilomycin A1 greatly reduced the nigericin-sensitive Ca2+ compartment. Bafilomycin A1 inhibited the initial rate of ATP-dependent non-mitochondrial Ca2+ uptake and stimulated the initial rate of nigericin-induced Ca2+ release by permeabilized procyclic trypomastigotes. ATP-dependent and bafilomycin A1- and 7-chloro-4-nitrobenz-2-oxa-1,3-diazole (NBD-Cl)-sensitive Acridine Orange uptake was demonstrated in permeabilized cells. Under these conditions Acridine Orange was concentrated in abundant cytoplasmic round vacuoles by a process inhibited by bafilomycin A1, NBD-Cl, nigericin, and Ca2+. Vanadate or EGTA significantly increased Acridine Orange uptake, while Ca2+ released Acridine Orange from these preparations, thus suggesting that the dye and Ca2+ were being accumulated in the same acidic vacuole. Acridine Orange uptake was reversed by nigericin, bafilomycin A1 and NH4Cl. The results are consistent with the presence of a Ca2+/H(+)-ATPase system pumping Ca2+ into an acidic vacuole, that we tentatively named the acidocalcisome.read more
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Acidocalcisomes ? conserved from bacteria to man
Roberto Docampo,Roberto Docampo,Wanderley de Souza,Kildare Miranda,Kildare Miranda,Peter Rohloff,Silvia N.J. Moreno,Silvia N.J. Moreno +7 more
TL;DR: Acidocalcisomes were first described in trypanosomatids and have been characterized in most detail in these species, and are linked with several functions, including storage of cations and phosphorus, polyphosphate metabolism, calciumHomeostasis, maintenance of intracellular pH homeostasis and osmoregulation.
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Molecular mechanisms of endolysosomal Ca2+ signalling in health and disease
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Mechanism of acidification of the trans-golgi network (tgn): in situ measurements of ph using retrieval of tgn38 and furin from the cell surface
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Acidocalcisomes in Toxoplasma gondii tachyzoites
Silvia N.J. Moreno,Li Zhong +1 more
TL;DR: Evidence is found that T. gondii tachyzoites possess a significant amount of Ca2+ stored in an acidic compartment, termed the acidocalcisome, as indicated by the increase in [Ca2+]i induced by bafilomycin A1 (a specific inhibitor of H(+)-ATPases), nigericin or the weak base NH4Cl, in the nominal absence of extracellular Ca2+.
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Trypanosoma cruzi contains major pyrophosphate stores, and its growth in vitro and in vivo is blocked by pyrophosphate analogs.
Julio A. Urbina,Benjamin Moreno,Stephanie Vierkotter,Eric Oldfield,Gilberto Payares,Cristina Sanoja,Brian N. Bailey,Wen Yan,David A. Scott,Silvia N.J. Moreno,Roberto Docampo +10 more
TL;DR: High field 31P nuclear magnetic resonance spectroscopy showed that inorganic pyrophosphate (P2O7 4−) is more abundant than ATP in Trypanosoma cruzi, the causative agents of Chagas' disease, and selectively inhibited the proliferation of intracellular T. cruzi amastigotes and produced a profound suppression in the number of circulating trypomastigote in mice with an acute infection.