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Kinetics of pyrophosphate-driven proton uptake by acidocalcisomes of Leptomonas wallacei

Authors :
Moraes Moreira, Bernardo Luiz
Soares Medeiros, Lia Carolina A.
Miranda, Kildare
de Souza, Wanderley
Hentschel, Joachim
Plattner, Helmut
Barrabin, Hector
Source :
Biochemical & Biophysical Research Communications. Sep2005, Vol. 334 Issue 4, p1206-1213. 8p.
Publication Year :
2005

Abstract

Abstract: In this work, we show the kinetics of pyrophosphate-driven H+ uptake by acidocalcisomes in digitonin-permeabilized promastigotes of Leptomonas wallacei. The vacuolar proton pyrophosphatase activity was optimal in the pH range of 7.5–8.0, was inhibited by imidiodiphosphate, and was completely dependent on K+ and PPi. H+ was released with the addition of Ca2+, suggesting the presence of a Ca2+/H+ antiport. In addition, X-ray elemental mapping associated with energy-filtering transmission electron microscopy showed that most of the Ca, Na, Mg, P, K, Fe, and Zn were located in acidocalcisomes. L. wallacei immunolabeled with antibodies against Trypanosoma cruzi pyrophosphatase show intense fluorescence in cytoplasmatic organelles of size and distribution similar to the acidocalcisomes. Altogether, the results show that L. wallacei acidocalcisomes possess a H+-pyrophosphatase with characteristics of type I V-H+-PPase. However, we did not find any evidence, either for the presence of H+-ATPases or for Na+/H+ exchangers in these acidocalcisomes. [Copyright &y& Elsevier]

Details

Language :
English
ISSN :
0006291X
Volume :
334
Issue :
4
Database :
Academic Search Index
Journal :
Biochemical & Biophysical Research Communications
Publication Type :
Academic Journal
Accession number :
18186468
Full Text :
https://doi.org/10.1016/j.bbrc.2005.06.205