1. Evidence for Regulation of Hemoglobin Metabolism and Intracellular Ionic Flux by the Plasmodium falciparum Chloroquine Resistance Transporter.
- Author
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Lee AH, Dhingra SK, Lewis IA, Singh MK, Siriwardana A, Dalal S, Rubiano K, Klein MS, Baska KS, Krishna S, Klemba M, Roepe PD, Llinás M, Garcia CRS, and Fidock DA
- Subjects
- Amodiaquine pharmacology, Antimalarials pharmacology, Artemisinins pharmacology, Calcium metabolism, Cells, Cultured, Erythrocytes metabolism, Erythrocytes parasitology, Gene Expression, Humans, Ion Transport drug effects, Ionophores pharmacology, Membrane Transport Proteins metabolism, Monensin pharmacology, Mutation, Nigericin pharmacology, Plasmodium falciparum genetics, Plasmodium falciparum metabolism, Protozoan Proteins metabolism, Pyrrolidinones pharmacology, Chloroquine pharmacology, Drug Resistance, Multiple genetics, Erythrocytes drug effects, Hemoglobins metabolism, Host-Parasite Interactions, Membrane Transport Proteins genetics, Plasmodium falciparum drug effects, Protozoan Proteins genetics
- Abstract
Plasmodium falciparum multidrug resistance constitutes a major obstacle to the global malaria elimination campaign. Specific mutations in the Plasmodium falciparum chloroquine resistance transporter (PfCRT) mediate resistance to the 4-aminoquinoline drug chloroquine and impact parasite susceptibility to several partner agents used in current artemisinin-based combination therapies, including amodiaquine. By examining gene-edited parasites, we report that the ability of the wide-spread Dd2 PfCRT isoform to mediate chloroquine and amodiaquine resistance is substantially reduced by the addition of the PfCRT L272F mutation, which arose under blasticidin selection. We also provide evidence that L272F confers a significant fitness cost to asexual blood stage parasites. Studies with amino acid-restricted media identify this mutant as a methionine auxotroph. Metabolomic analysis also reveals an accumulation of short, hemoglobin-derived peptides in the Dd2 + L272F and Dd2 isoforms, compared with parasites expressing wild-type PfCRT. Physiologic studies with the ionophores monensin and nigericin support an impact of PfCRT isoforms on Ca
2+ release, with substantially reduced Ca2+ levels observed in Dd2 + L272F parasites. Our data reveal a central role for PfCRT in regulating hemoglobin catabolism, amino acid availability, and ionic balance in P. falciparum, in addition to its role in determining parasite susceptibility to heme-binding 4-aminoquinoline drugs.- Published
- 2018
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