Journal article

Publication year: 2018

Pages: 4049-4067

Journal: Journal of Molecular Biology

Volume number: 430

Issue number: 21

ISSN: 0022-2836

eISSN: 1089-8638

DOI Link: https://doi.org/10.1016/j.jmb.2018.07.030

Publisher: Elsevier

Abstract: 
The enzyme 6-phosphogluconate dehydrogenase (6PGD) of the malaria parasite Plasmodium falciparum catalyzes the third step of the pentose phosphate pathway converting 6-phosphogluconate (6PG) to ribulose 5-phosphate. The NADPH produced by 6PGD is crucial for antioxidant defense and redox regulation, and ribose 5-phosphate is essential for DNA and RNA synthesis in the rapidly growing parasite. Thus, 6PGD represents an attractive antimalarial drug target. In this study, we present the X-ray structures of Pf6PGD in native form as well as in complex with 6PG or nicotinamide adenine dinucleotide phosphate (NADP(+)) at resolutions of 2.8, 1.9, and 2.9 angstrom, respectively. The overall structure of the protein is similar to structures of 6PGDs from other species; however, a flexible loop close to the active site rearranges upon binding of 6PG and likely regulates the conformation of the cofactor NADP(+). Upon binding of 6PG, the active site loop adopts a closed conformation. In the absence of 6PG, the loop opens and NADP(+) is bound in a waiting position, indicating that the cofactor and 6PG bind independently from each other. This sequential binding mechanism was supported by kinetic studies on the homodimeric wild-type Pf6PGD. Furthermore, the function of the Plasmodium-specific residue W104L mutant was characterized by site-directed mutagenesis. Notably, the activity of Pf6PGD was found to be post-translationally redox regulated via S-nitrosylation, and screening the Medicines for Malaria Venture Malaria Box identified several compounds with IC(50)s in the low micromolar range. Together with the three-dimensional structure of the protein, this is a promising starting point for further drug discovery approaches. (C) 2018 Elsevier Ltd. All rights reserved.

Harvard Citation style: Haeussler, K., Fritz-Wolf, K., Reichmann, M., Rahlfs, S. and Becker, K. (2018) Characterization of Plasmodium falciparum 6-Phosphogluconate Dehydrogenase as an Antimalarial Drug Target, Journal of Molecular Biology, 430(21), pp. 4049-4067. https://doi.org/10.1016/j.jmb.2018.07.030

APA Citation style: Haeussler, K., Fritz-Wolf, K., Reichmann, M., Rahlfs, S., & Becker, K. (2018). Characterization of Plasmodium falciparum 6-Phosphogluconate Dehydrogenase as an Antimalarial Drug Target. Journal of Molecular Biology. 430(21), 4049-4067. https://doi.org/10.1016/j.jmb.2018.07.030