Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase

Saliba, Kevin J., Allen, Richard J. W., Zissis, Stephanie, Bray, Patrick G., Ward, Stephen A. and Kirk, Kiaran (2003) Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase. The Journal of Biological Chemistry., 278 8: 5605-5612.


Author Saliba, Kevin J.
Allen, Richard J. W.
Zissis, Stephanie
Bray, Patrick G.
Ward, Stephen A.
Kirk, Kiaran
Title Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase
Formatted title Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase
Journal name The Journal of Biological Chemistry.    (ERA 2010 Rank A*)   Check publisher's open access policy
Publication date 2003-02-21
Sub-type Article
DOI 10.1074/jbc.M208648200
Volume number 278
Issue number 8
ISSN 0021-9258
Start page 5605
End page 5612
Total pages 8
Place of publication United States
Publisher American Society for Biochemistry and Molecular Biology, Inc.
Language eng
Formatted abstract As it grows within the human erythrocyte, the malaria parasite, Plasmodium falciparum, ingests the erythrocyte cytosol, depositing it via an endocytotic feeding mechanism in the "digestive vacuole," a specialized acidic organelle. The digestive vacuole is the site of hemoglobin degradation, the storage site for hemozoin (an inert biocrystal of toxic heme), the site of action of many antimalarial drugs, and the site of proteins known to be involved in antimalarial drug resistance. The acidic pH of this organelle is thought to play a critical role in its various functions; however, the mechanisms by which the pH within the vacuole is maintained are not well understood. In this study, we have used a combination of techniques to demonstrate the presence on the P. falciparum digestive vacuole membrane of two discrete H+ pumping mechanisms, both capable of acidifying the vacuole interior. One is a V-type H+-ATPase, sensitive to concanamycin A and bafilomycin A1. The other is a H+-pyrophosphatase, which was inhibited by NaF and showed a partial dependence on K+. The operation of the H+-pyrophosphatase was dependent on the presence of a Mg2+-pyrophosphate complex, and kinetic experiments gave results consistent with free pyrophosphate acting as an inhibitor of the protein. The presence of the combination of a H+-ATPase and a H+-pyrophosphatase on the P. falciparum digestive vacuole is similar to the situation in the acidic tonoplasts (vacuoles) of plant cells.
Keyword Acidification
Article
Digestive system
Enzyme analysis
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article
Collection: Institute for Molecular Bioscience - Publications
 
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Created: Thu, 07 Apr 2011, 14:48:20 EST by Susan Allen on behalf of Institute for Molecular Bioscience