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

Saliba, K. J., Allen, R. J. W., Zissis, S., Bray, Patrick, Ward, Stephen ORCID: and Kirk, K. (2003) 'Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase'. Journal of Biological Chemistry, Vol 278, Issue 8, pp. 5605-5612.

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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 A, 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.

Item Type: Article
Additional Information: This research was originally published in Journal of Biological Chemistry. Saliba K, Allen R, Zissis S, Bray P, Ward S, Kirk K. Acidification of the malaria parasite's digestive vacuole by a H+-ATPase and a H+-pyrophosphatase. Journal of Biological Chemistry 2003. Vol 278:pp 5605-5612. © the American Society for Biochemistry and Molecular Biology
Subjects: QU Biochemistry > Enzymes > QU 136 Hydrolases
QU Biochemistry > Cells and Genetics > QU 350 Cellular structures
QX Parasitology > Protozoa > QX 135 Plasmodia
WH Hemic and Lymphatic Systems > Hematologic Diseases. Immunologic Factors. Blood Banks > WH 150 Erythrocytes
Faculty: Department: Groups (2002 - 2012) > Molecular & Biochemical Parasitology Group
Digital Object Identifer (DOI):
Depositing User: Lynn Roberts-Maloney
Date Deposited: 03 Jul 2013 09:31
Last Modified: 17 Jul 2020 10:57


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