scholarly journals Re-refinement of Plasmodium falciparum orotidine 5′-monophosphate decarboxylase provides a clearer picture of an important malarial drug target

2018 ◽  
Vol 74 (10) ◽  
pp. 664-668 ◽  
Author(s):  
Walter R. P. Novak ◽  
Korbin H. J. West ◽  
Lucy M. D. Kirkman ◽  
Gabriel S. Brandt
Keyword(s):  
Public Health ◽  
Plasmodium Falciparum ◽  
Drug Design ◽  
Electron Density ◽  
Antimalarial Drug ◽  
Drug Target ◽  
Antimalarial Drugs ◽  
Important Advance ◽  
Structure Based Drug Design ◽  
Monophosphate Decarboxylase

The development of antimalarial drugs remains a public health priority, and the orotidine 5′-monophosphate decarboxylase from Plasmodium falciparum (PfOMPDC) has great potential as a drug target. The crystallization of PfOMPDC with substrate bound represents an important advance for structure-based drug-design efforts [Tokuoka et al. (2008), J. Biochem. 143, 69–78]. The complex of the enzyme bound to the substrate OMP (PDB entry 2za1) would be of particular utility in this regard. However, re-refinement of this structure of the Michaelis complex shows that the bound ligand is the product rather than the substrate. Here, the re-refinement of a set of three structures, the apo enzyme and two versions of the product-bound form (PDB entries 2za1, 2za2 and 2za3), is reported. The improved geometry and fit of these structures to the observed electron density will enhance their utility in antimalarial drug design.

scholarly journals Comparison of Efficacies of Cysteine Protease Inhibitors against Five Strains of Plasmodium falciparum

2001 ◽  
Vol 45 (3) ◽  
pp. 949-951 ◽  
Author(s):  
Ajay Singh ◽  
Philip J. Rosenthal
Keyword(s):  
Plasmodium Falciparum ◽  
Protease Inhibitors ◽  
Cysteine Protease ◽  
Antimalarial Drug ◽  
Drug Target ◽  
Antimalarial Drugs ◽  
Cross Resistance ◽  
Cysteine Protease Inhibitors ◽  
Antimalarial Agents ◽  
Parasite Strains

ABSTRACT Falcipain-2, a cysteine protease and essential hemoglobinase ofPlasmodium falciparum, is a potential antimalarial drug target. We compared the falcipain-2 sequences and sensitivities to cysteine protease inhibitors of five parasite strains that differ markedly in sensitivity to established antimalarial drugs. The sequence of falcipain-2 was highly conserved, and the sensitivities of all of the strains to falcipain-2 inhibitors were very similar. Thus, cross-resistance between cysteine protease inhibitors and other antimalarial agents is not expected in parasites that are now circulating and falcipain-2 remains a promising chemotherapeutic target.

scholarly journals Mitochondrial type II NADH dehydrogenase of Plasmodium falciparum is dispensable and not the functional target of putative NDH2 quinolone inhibitors

2018 ◽  
Author(s):  
Hangjun Ke ◽  
Suresh M. Ganesan ◽  
Swati Dass ◽  
Joanne M. Morrisey ◽  
Sovitj Pou ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Drug ◽  
Drug Target ◽  
Nadh Dehydrogenase ◽  
Antimalarial Activity ◽  
Reductase Activity ◽  
Proton Pumping ◽  
Type Ii ◽  
Long Time ◽  
Specific Inhibitors

AbstractThe battle against malaria has been substantially impeded by the recurrence of drug resistance in Plasmodium falciparum, the deadliest human malaria parasite. To counter the problem, novel antimalarial drugs are urgently needed, especially those that target unique pathways of the parasite, since they are less likely to have side effects. The mitochondrial type II NADH dehydrogenase of P. falciparum, PfNDH2 (PF3D7_0915000), has been considered a good prospective antimalarial drug target for over a decade, since malaria parasites lack the conventional multi-subunit NADH dehydrogenase, or Complex I, present in the mammalian mitochondrial electron transport chain (mtETC). Instead, Plasmodium parasites contain a single subunit NDH2, which lacks proton pumping activity and is absent in humans. A significant amount of effort has been expended to develop PfNDH2 specific inhibitors, yet the essentiality of PfNDH2 has not been convincingly verified. Herein, we knocked out PfNDH2 in P. falciparum via a CRISPR/Cas9 mediated approach. Deletion of PfNDH2 does not alter the parasite’s susceptibility to multiple mtETC inhibitors, including atovaquone and ELQ-300. We also show that the antimalarial activity of the fungal NDH2 inhibitor HDQ and its new derivative CK-2-68 is due to inhibition of the parasite cytochrome bc1 complex rather than PfNDH2. These compounds directly inhibit the ubiquinol-cytochrome c reductase activity of the malarial bc1 complex. Our results call into question the validity of PfNDH2 as an antimalarial drug target.ImportanceFor a long time, PfNDH2 has been considered an attractive antimalarial drug target. However, the conclusion that PfNDH2 is essential was based on preliminary and incomplete data. Here we generate a PfNDH2 KO (knockout) parasite in the blood stages of Plasmodium falciparum, showing that the gene is not essential. We also show that previously reported PfNDH2-specific inhibitors kill the parasites primarily via targeting the cytochrome bc1 complex, not PfNDH2. Overall, we provide genetic and biochemical data that help to resolve a long-debated issue in the field regarding the potential of PfNDH2 as an antimalarial drug target.

scholarly journals Role ofPfmdr1inIn VitroPlasmodium falciparum Susceptibility to Chloroquine, Quinine, Monodesethylamodiaquine, Mefloquine, Lumefantrine, and Dihydroartemisinin

2014 ◽  
Vol 58 (12) ◽  
pp. 7032-7040 ◽  
Author(s):  
Nathalie Wurtz ◽  
Bécaye Fall ◽  
Aurélie Pascual ◽  
Mansour Fall ◽  
Eric Baret ◽  
...  
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Multidrug Resistance ◽  
Antimalarial Drug ◽  
Antimalarial Drugs ◽  
Wild Type ◽  
Antimalarial Drug Resistance ◽  
Content Type ◽  
Increased Susceptibility

ABSTRACTThe involvement ofPfmdr1(Plasmodium falciparummultidrug resistance 1) polymorphisms in antimalarial drug resistance is still debated. Here, we evaluate the association between polymorphisms inPfmdr1(N86Y, Y184F, S1034C, N1042D, and D1246Y) andPfcrt(K76T) andin vitroresponses to chloroquine (CQ), mefloquine (MQ), lumefantrine (LMF), quinine (QN), monodesethylamodiaquine (MDAQ), and dihydroartemisinin (DHA) in 174Plasmodium falciparumisolates from Dakar, Senegal. ThePfmdr186Y mutation was identified in 14.9% of the samples, and the 184F mutation was identified in 71.8% of the isolates. No 1034C, 1042N, or 1246Y mutations were detected. ThePfmdr186Y mutation was significantly associated with increased susceptibility to MDAQ (P= 0.0023), LMF (P= 0.0001), DHA (P= 0.0387), and MQ (P= 0.00002). The N86Y mutation was not associated with CQ (P= 0.214) or QN (P= 0.287) responses. ThePfmdr1184F mutation was not associated with various susceptibility responses to the 6 antimalarial drugs (P= 0.168 for CQ, 0.778 for MDAQ, 0.324 for LMF, 0.961 for DHA, 0.084 for QN, and 0.298 for MQ). ThePfmdr186Y-Y184 haplotype was significantly associated with increased susceptibility to MDAQ (P= 0.0136), LMF (P= 0.0019), and MQ (P= 0.0001). The additionalPfmdr186Y mutation increased significantly thein vitrosusceptibility to MDAQ (P< 0.0001), LMF (P< 0.0001), MQ (P< 0.0001), and QN (P= 0.0026) in wild-typePfcrtK76 parasites. The additionalPfmdr186Y mutation significantly increased thein vitrosusceptibility to CQ (P= 0.0179) inPfcrt76T CQ-resistant parasites.

scholarly journals Plasmodium falciparum Niemann-Pick Type C1-Related Protein is a Druggable Target Required for Parasite Membrane Homeostasis

2018 ◽  
Author(s):  
Eva S. Istvan ◽  
Sudipta Das ◽  
Suyash Bhatnagar ◽  
Josh R. Beck ◽  
Edward Owen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Plasmodium Falciparum ◽  
Plasma Membrane ◽  
Small Molecule ◽  
Antimalarial Drug ◽  
Drug Target ◽  
Related Protein ◽  
Immuno Electron Microscopy ◽  
Increased Sensitivity ◽  
Niemann Pick

AbstractPlasmodium parasites possess a protein with homology to Niemann-Pick Type C1 proteins (Plasmodium falciparum Niemann-Pick Type C1-Related protein, PfNCR1). We isolated parasites with resistance-conferring mutations in PfNCR1 during selections with three diverse small-molecule antimalarial compounds and show that the mutations are causative for compound resistance. PfNCR1 protein knockdown results in severely attenuated growth and confers hypersensitivity to the compounds. Compound treatment or protein knockdown leads to increased sensitivity of the parasite plasma membrane (PPM) to the amphipathic glycoside saponin and engenders digestive vacuoles (DVs) that are small and malformed. Immuno-electron microscopy and split-GFP experiments localize PfNCR1 to the PPM. Our experiments show that PfNCR1 activity is critically important for the composition of the PPM and is required for DV biogenesis, suggesting PfNCR1 as a novel antimalarial drug target.

scholarly journals The Plasmodium falciparum cytoplasmic translation apparatus: a promising therapeutic target not yet exploited by clinically approved antimalarials

2018 ◽  
Author(s):  
Christine Moore Sheridan ◽  
Valentina E. Garcia ◽  
Vida Ahyong ◽  
Joseph L. DeRisi
Keyword(s):  
Plasmodium Falciparum ◽  
Protein Synthesis ◽  
Drug Target ◽  
Malaria Parasite ◽  
Experimental Methods ◽  
Mechanisms Of Action ◽  
Antimalarial Drugs ◽  
Inhibit Protein Synthesis ◽  
Indirect Measure ◽  
Wide Range

AbstractThe continued specter of resistance to existing antimalarials necessitates the pursuit of novel targets and mechanisms of action for drug development. One class of promising targets consists of the 80S ribosome and its associated components comprising the parasite translational apparatus. Development of translation-targeting therapeutics requires a greater understanding of protein synthesis and its regulation in the malaria parasite. Research in this area has been limited by the lack of appropriate experimental methods, particularly a direct measure of parasite translation. We have recently developed and optimized the PfIVT assay, an in vitro method directly measuring translation in whole-cell extracts from the malaria parasite Plasmodium falciparum.Here, we present an extensive pharmacologic assessment of the PfIVT assay using a wide range of known inhibitors, demonstrating its utility for studying activity of both ribosomal and non-ribosomal elements directly involved in translation. We further demonstrate the superiority of this assay over a historically utilized indirect measure of translation, S35-radiolabel incorporation. Additionally, we utilize the PfIVT assay to investigate a panel of clinically approved antimalarial drugs, many with unknown or unclear mechanisms of action, and show that none inhibit translation, reaffirming Plasmodium translation to be a viable alternative drug target. Within this set, we unambiguously find that mefloquine lacks translation inhibition activity, despite having been recently mischaracterized as a ribosomal inhibitor. This work exploits a direct and reproducible assay for measuring P. falciparum translation, demonstrating its value in the continued study of protein synthesis in malaria and its inhibition as a drug target.Author summaryNovel antimalarial drugs are required to combat rising resistance to current therapies. The protein synthesis machinery of the malaria parasite Plasmodium falciparum is a promising unexploited target for antimalarial development, but its study has been hindered by use of indirect experimental methods which often produce misleading and inaccurate results. We have recently developed a direct method to investigate malaria protein synthesis utilizing whole-parasite extracts. In this work, we present an extensive characterization of the assay, using a panel of pharmacologic inhibitors with known mechanisms of action. We demonstrate the specificity of the assay in various stages of protein synthesis, as well as its improved accuracy and sensitivity in comparison to an indirect measure that has been the previous standard for the field. We further demonstrate that no current clinically available antimalarial drugs inhibit protein synthesis, emphasizing its potential as a target for drugs that will overcome existing resistance. Importantly, among the antimalarials tested was mefloquine, a widely used antimalarial that has recently been mischaracterized as an inhibitor protein synthesis. Our finding that mefloquine does not inhibit protein synthesis emphasizes the importance of using direct functional measurements when determining drug targets.

Characterization of Plasmodium falciparum 6-Phosphogluconate Dehydrogenase as an Antimalarial Drug Target

2018 ◽  
Vol 430 (21) ◽  
pp. 4049-4067 ◽  
Author(s):  
Kristina Haeussler ◽  
Karin Fritz-Wolf ◽  
Max Reichmann ◽  
Stefan Rahlfs ◽  
Katja Becker
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Drug ◽  
Drug Target ◽  
Phosphogluconate Dehydrogenase
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