Journal article

Publication year: 2004

Pages: 211-220

Journal: Molecular and Biochemical Parasitology

Volume number: 136

Issue number: 2

ISSN: 0166-6851

DOI Link: https://doi.org/10.1016/j.molbiopara.2004.04.001

Publisher: Elsevier

Abstract: 
For coping with energetic and synthetic challenges, parasites require high activities of adenylate kinase (AK; ATP + AMP double left right arrow 2 ADP) and GTP:AMP phosphotransferase (GAK; GTP + AMP double left right arrow GDP + ADP). These enzymes were identified in erythrocytic stages of Plasmodium falciparum. The genes encoding PfAK and PfGAK are located on chromosomes 10 and 4, respectively. Molecular cloning and heterologous expression in E. coli yielded enzymatically active proteins of 28.9 (PfAK) and 28.0 kDa (PfGAK). Recombinant PfAK resembles authentic PfAK in its biochemical characteristics including the possible association with a stabilizing protein and the high specificity for AMP as the mononucleotide substrate. Specificity is less stringent for the triphosphate, with ATP as the best substrate (75 U/mg; k(cat) = 2160 min(-1) at 25 degreesC). PfAK contains the sequence of the amphiphatic helix that is known to mediate translocation of the cytosolic protein into the mitochondrial intermembrane space.PfGAK exhibits substrate preference for GTP and AMP (100 U/mg; k(cat) = 2800 min(-1) at 25degreesC); notably, there is no detectable activity with ATP. In contrast to its human orthologue (AK3), PfGAK contains a zinc finger motif and binds ionic iron. The dinucleoside pentaphosphate compounds AP(5)A and GP(5)A inhibited PfAK and PfGAK, respectively, with K-i values of approximately 0.2 muM which is more than 250-fold lower than the K-M values determined for the nucleotide substrates. The disubstrate inhibitors are useful for studying the enzymatic mechanism of PfAK and PfGAK as well as their function in adenine nucleotide homeostasis; in addition, the chimeric inhibitors represent interesting lead compounds for developing nucleosides to be used as antiparasitic agents. (C) 2004 Elsevier B.V. All rights reserved.

Harvard Citation style: Ulschmid, J., Rahlfs, S., Schirmer, R. and Becker, K. (2004) Adenylate kinase and GTP : AMP phosphotransferase of the malarial parasite Plasmodium falciparum central players in cellular energy metabolism, Molecular and Biochemical Parasitology, 136(2), pp. 211-220. https://doi.org/10.1016/j.molbiopara.2004.04.001

APA Citation style: Ulschmid, J., Rahlfs, S., Schirmer, R., & Becker, K. (2004). Adenylate kinase and GTP : AMP phosphotransferase of the malarial parasite Plasmodium falciparum central players in cellular energy metabolism. Molecular and Biochemical Parasitology. 136(2), 211-220. https://doi.org/10.1016/j.molbiopara.2004.04.001