scholarly journals Differential Drug Efflux or Accumulation Does Not Explain Variation in the Chloroquine Response of Plasmodium falciparum Strains Expressing the Same Isoform of Mutant PfCRT

2011 ◽  
Vol 55 (5) ◽  
pp. 2310-2318 ◽  
Author(s):  
Adele M. Lehane ◽  
Donelly A. van Schalkwyk ◽  
Stephanie G. Valderramos ◽  
David A. Fidock ◽  
Kiaran Kirk
Keyword(s):  
Plasmodium Falciparum ◽  
Inhibitory Concentration ◽  
Chloroquine Resistance ◽  
Mutant Form ◽  
Digestive Vacuole ◽  
Biochemical Basis ◽  
Content Type ◽  
Chloroquine Resistance Transporter ◽  
The Difference ◽  
Mutant Forms

ABSTRACTMutant forms of thePlasmodium falciparumchloroquine resistance transporter (PfCRT) mediate chloroquine resistance by effluxing the drug from the parasite's digestive vacuole, the acidic organelle in which chloroquine exerts its parasiticidal effect. However, different parasites bearing the same mutant form of PfCRT can vary substantially in their chloroquine susceptibility. Here, we have investigated the biochemical basis for the difference in chloroquine response among transfectant parasite lines having different genetic backgrounds but bearing the same mutant form of PfCRT. Despite showing significant differences in their chloroquine susceptibility, all lines with the mutant PfCRT showed a similar chloroquine-induced H+leak from the digestive vacuole, indicative of similar rates of PfCRT-mediated chloroquine efflux. Furthermore, all lines showed similarly reduced levels of drug accumulation. Factors other than chloroquine efflux and accumulation therefore influence the susceptibility to this drug in parasites expressing mutant PfCRT. Furthermore, in some but not all strains bearing mutant PfCRT, the 50% inhibitory concentration (IC50) for chloroquine and the degree of resistance compared to that of recombinant control parasites varied with the length of the parasite growth assays. In these parasites, the 50% inhibitory concentration for chloroquine measured in 72- or 96-h assays was significantly lower than that measured in 48-h assays. This highlights the importance of considering the first- and second-cycle activities of chloroquine in future studies of parasite susceptibility to this drug.

scholarly journals Mutation in the Plasmodium falciparum CRT Protein Determines the Stereospecific Activity of Antimalarial Cinchona Alkaloids

2012 ◽  
Vol 56 (10) ◽  
pp. 5356-5364 ◽  
Author(s):  
Carol E. Griffin ◽  
Jonathan M. Hoke ◽  
Upeka Samarakoon ◽  
Junhui Duan ◽  
Jianbing Mu ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Antimalarial Activity ◽  
Cinchona Alkaloids ◽  
Chloroquine Resistance ◽  
Digestive Vacuole ◽  
Content Type ◽  
Chloroquine Resistance Transporter ◽  
Clonal Lines

ABSTRACTTheCinchonaalkaloids are quinoline aminoalcohols that occur as diastereomer pairs, typified by (−)-quinine and (+)-quinidine. The potency of (+)-isomers is greater than the (−)-isomersin vitroandin vivoagainstPlasmodium falciparummalaria parasites. They may act by the inhibition of heme crystallization within the parasite digestive vacuole in a manner similar to chloroquine. Earlier studies showed that a K76I mutation in the digestive vacuole-associated protein, PfCRT (P. falciparumchloroquine resistance transporter), reversed the normal potency order of quinine and quinidine towardP. falciparum. To further explore PfCRT-alkaloid interactions in the malaria parasite, we measured thein vitrosusceptibility of eight clonal lines ofP. falciparumderived from the 106/1 strain, each containing a uniquepfcrtallele, to fourCinchonastereoisomer pairs: quinine and quinidine; cinchonidine and cinchonine; hydroquinine and hydroquinidine; 9-epiquinine and 9-epiquinidine. Stereospecific potency of theCinchonaalkaloids was associated with changes in charge and hydrophobicity of mutable PfCRT amino acids. In isogenic chloroquine-resistant lines, the IC50ratio of (−)/(+) CA pairs correlated with side chain hydrophobicity of the position 76 residue. Second-site PfCRT mutations negated the K76I stereospecific effects: charge-change mutations C72R or Q352K/R restored potency patterns similar to the parent K76 line, while V369F increased susceptibility to the alkaloids and nullified stereospecific differences between alkaloid pairs. Interactions between key residues of the PfCRT channel/transporter with (−) and (+) alkaloids are stereospecifically determined, suggesting that PfCRT binding plays an important role in the antimalarial activity of quinine and otherCinchonaalkaloids.

scholarly journals Saquinavir Inhibits the Malaria Parasite's Chloroquine Resistance Transporter

2012 ◽  
Vol 56 (5) ◽  
pp. 2283-2289 ◽  
Author(s):  
Rowena E. Martin ◽  
Alice S. Butterworth ◽  
Donald L. Gardiner ◽  
Kiaran Kirk ◽  
James S. McCarthy ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Heterologous Expression ◽  
Protease Inhibitors ◽  
Chloroquine Resistance ◽  
Content Type ◽  
Chloroquine Resistance Transporter ◽  
Resistant Phenotype ◽  
Transgenic Parasites

ABSTRACTThe antiretroviral protease inhibitors (APIs) ritonavir, saquinavir, and lopinavir, used to treat HIV infection, inhibit the growth ofPlasmodium falciparumat clinically relevant concentrations. Moreover, it has been reported that these APIs potentiate the activity of chloroquine (CQ) against this parasitein vitro. The mechanism underlying this effect is not understood, but the degree of chemosensitization varies between the different APIs and, with the exception of ritonavir, appears to be dependent on the parasite exhibiting a CQ-resistant phenotype. Here we report a study of the role of theP. falciparumchloroquine resistance transporter (PfCRT) in the interaction between CQ and APIs, using transgenic parasites expressing different PfCRT alleles and using theXenopus laevisoocyte system for the heterologous expression of PfCRT. Our data demonstrate that saquinavir behaves as a CQ resistance reverser and that this explains, at least in part, its ability to enhance the effects of CQ in CQ-resistantP. falciparumparasites.

scholarly journals Molecular Mechanisms of Drug Resistance in Plasmodium falciparum Malaria

2020 ◽  
Vol 74 (1) ◽  
pp. 431-454
Author(s):  
Kathryn J. Wicht ◽  
Sachel Mok ◽  
David A. Fidock
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Mechanisms ◽  
Artemisinin Resistance ◽  
Plasmodium Falciparum Malaria ◽  
Drug Binding ◽  
Chloroquine Resistance ◽  
Digestive Vacuole ◽  
Vacuole Membrane ◽  
Chloroquine Resistance Transporter ◽  
Antimalarial Resistance

Understanding and controlling the spread of antimalarial resistance, particularly to artemisinin and its partner drugs, is a top priority. Plasmodium falciparum parasites resistant to chloroquine, amodiaquine, or piperaquine harbor mutations in the P. falciparum chloroquine resistance transporter (PfCRT), a transporter resident on the digestive vacuole membrane that in its variant forms can transport these weak-base 4-aminoquinoline drugs out of this acidic organelle, thus preventing these drugs from binding heme and inhibiting its detoxification. The structure of PfCRT, solved by cryogenic electron microscopy, shows mutations surrounding an electronegative central drug-binding cavity where they presumably interact with drugs and natural substrates to control transport. P. falciparum susceptibility to heme-binding antimalarials is also modulated by overexpression or mutations in the digestive vacuole membrane–bound ABC transporter PfMDR1 ( P. falciparum multidrug resistance 1 transporter). Artemisinin resistance is primarily mediated by mutations in P. falciparum Kelch13 protein (K13), a protein involved in multiple intracellular processes including endocytosis of hemoglobin, which is required for parasite growth and artemisinin activation. Combating drug-resistant malaria urgently requires the development of new antimalarial drugs with novel modes of action.

scholarly journals 3-Halo Chloroquine Derivatives Overcome Plasmodium falciparum Chloroquine Resistance Transporter-Mediated Drug Resistance in P. falciparum

2015 ◽  
Vol 59 (12) ◽  
pp. 7891-7893 ◽  
Author(s):  
Sonia Edaye ◽  
Dagobert Tazoo ◽  
D. Scott Bohle ◽  
Elias Georges
Keyword(s):  
Drug Resistance ◽  
Plasmodium Falciparum ◽  
Chloroquine Resistance ◽  
Content Type ◽  
Chloroquine Resistance Transporter ◽  
Highly Effective

ABSTRACTPolymorphism in thePlasmodium falciparumchloroquine resistance transporter (PfCRT) was shown to cause chloroquine resistance. In this report, we examined the antimalarial potential of novel 3-halo chloroquine derivatives (3-chloro, 3-bromo, and 3-iodo) against chloroquine-susceptible and -resistantP. falciparum. All three derivatives inhibited the proliferation ofP. falciparum; with 3-iodo chloroquine being most effective. Moreover, 3-iodo chloroquine was highly effective at potentiating and reversing chloroquine toxicity of drug-susceptible and -resistantP. falciparum.

scholarly journals Characterization of the Chloroquine Resistance Transporter Homologue in Toxoplasma gondii

2014 ◽  
Vol 13 (11) ◽  
pp. 1360-1370 ◽  
Author(s):  
Sally D. Warring ◽  
Zhicheng Dou ◽  
Vern B. Carruthers ◽  
Geoffrey I. McFadden ◽  
Giel G. van Dooren
Keyword(s):  
Toxoplasma Gondii ◽  
Protein Composition ◽  
Chloroquine Resistance ◽  
Digestive Vacuole ◽  
Content Type ◽  
Apicomplexan Parasites ◽  
Chloroquine Resistance Transporter ◽  
Transporter Family ◽  
New Information ◽  
Family Protein

ABSTRACT Mutations in the Plasmodium falciparum chloroquine resistance transporter ( Pf CRT) protein confer resistance to the antimalarial drug chloroquine. Pf CRT localizes to the parasite digestive vacuole, the site of chloroquine action, where it mediates resistance by transporting chloroquine out of the digestive vacuole. Pf CRT belongs to a family of transporter proteins called the chloroquine resistance transporter family. CRT family proteins are found throughout the Apicomplexa, in some protists, and in plants. Despite the importance of Pf CRT in drug resistance, little is known about the evolution or native function of CRT proteins. The apicomplexan parasite Toxoplasma gondii contains one CRT family protein. We demonstrate that T. gondii CRT ( Tg CRT) colocalizes with markers for the vacuolar (VAC) compartment in these parasites. The Tg CRT-containing VAC is a highly dynamic organelle, changing its morphology and protein composition between intracellular and extracellular forms of the parasite. Regulated knockdown of Tg CRT expression resulted in modest reduction in parasite fitness and swelling of the VAC, indicating that Tg CRT contributes to parasite growth and VAC physiology. Together, our findings provide new information on the role of CRT family proteins in apicomplexan parasites.

scholarly journals A Computational Study of Molecular Mechanism of Chloroquine Resistance by Chloroquine Resistance Transporter Protein of Plasmodium falciparum via Molecular Modeling and Molecular Simulations

Physchem ◽  
2021 ◽  
Vol 1 (3) ◽  
pp. 232-242
Author(s):  
Chandan Patel ◽  
Dipankar Roy
Keyword(s):  
Plasmodium Falciparum ◽  
Molecular Modeling ◽  
Molecular Mechanism ◽  
Computational Study ◽  
Chloroquine Resistance ◽  
Drug Efflux ◽  
Digestive Vacuole ◽  
Transporter Protein ◽  
Chloroquine Resistance Transporter ◽  
Protonated Forms

The molecular mechanism of chloroquine resistance by the chloroquine resistance transporter protein of Plasmodium sp. is explored using molecular modeling and computational methods. The key mutation, lysine(K)-76 to threonine(T) (LYS76THR) in the transporter protein pertains to increased recognition of the protonated forms of the antimalarial drug. Such enhanced affinity can promote drug efflux from host digestive vacuole, rendering aminoquinoline-based treatment ineffective.

scholarly journals The impact of HIV-associated immunosuppression on the Plasmodium falciparum chloroquine resistance transporter gene (PfCRT) of HIV patients in Akure, Nigeria

2020 ◽  
Vol 44 (1) ◽  
Author(s):  
Iyabo Adepeju Simon-Oke ◽  
Adeola Olanireti Ade-Alao ◽  
Foluso Ologundudu
Keyword(s):  
Plasmodium Falciparum ◽  
Malaria Prevalence ◽  
Cd4 Count ◽  
Chloroquine Resistance ◽  
Hiv Care ◽  
Transporter Gene ◽  
Hiv Patients ◽  
Chloroquine Resistance Transporter ◽  
Hiv Test ◽  
Low Prevalence

Abstract Background The study evaluated the prevalence of malaria and Plasmodium falciparum chloroquine resistance transporter gene (PfCRT) in HIV patients attending Specialist Hospital, Akure. This study was carried out between April and June 2019. Three hundred and seventeen (317) patients attending the antiretroviral clinic (ART) were involved, out of which 89 (28.08%) were males and 228 (71.92%) were females. HIV test was done using the Unigold® HIV test kit, malaria test was done using thick and thin blood smear, CD4 test was done using the Partec® CD4 counter and PCR was used to detect the presence of plasmodium falciparum mutant gene. The data obtained from this analysis was subjected to Pearson’s Chi-square test. Results The overall result showed low prevalence of malaria (23.03%) in the sampled patients. Highest malaria prevalence (31.0%) was recorded in HIV patients with CD4 count between 200–500 cells/μl of blood, with the males recording 24.7% malaria prevalence. The age group 20–29 years recorded the highest prevalence of 27.3%. A higher prevalence 91.1% of PfCRT gene in HIV-positive and (40.0%) in HIV-negative patients was recorded with 100% prevalence in patients with CD4 count ≤ 200. This shows that the low prevalence of malaria recorded in this study could be credited to good health-seeking attitude of HIV patients and the upscale of HIV care and treatment centres. Conclusion The high prevalence of PfCRT gene shows that treatment of malaria with chloroquine is still being practised despite the availability of artemisinin-based combination therapy (ACTs) as the recommended regimen for malaria treatment.

scholarly journals Molecular Characterization of the CytochromebGene andIn VitroAtovaquone Susceptibility of Plasmodium falciparum Isolates from Kenya

2015 ◽  
Vol 59 (3) ◽  
pp. 1818-1821 ◽  
Author(s):  
Luicer A. Ingasia ◽  
Hoseah M. Akala ◽  
Mabel O. Imbuga ◽  
Benjamin H. Opot ◽  
Fredrick L. Eyase ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Genetic Polymorphism ◽  
Molecular Characterization ◽  
Mutant Allele ◽  
Inhibitory Concentration ◽  
Wild Type Allele ◽  
Wild Type ◽  
Western Kenya ◽  
Content Type

ABSTRACTThe prevalence of a genetic polymorphism(s) at codon 268 in the cytochromebgene, which is associated with failure of atovaquone-proguanil treatment, was analyzed in 227Plasmodium falciparumparasites from western Kenya. The prevalence of the wild-type allele was 63%, and that of the Y268S (denoting a Y-to-S change at position 268) mutant allele was 2%. There were no pure Y268C or Y268N mutant alleles, only mixtures of a mutant allele(s) with the wild type. There was a correlation between parasite 50% inhibitory concentration (IC50) and parasite genetic polymorphism; mutant alleles had higher IC50s than the wild type.

scholarly journals Reduced Polymorphism in the Kelch Propeller Domain in Plasmodium vivax Isolates from Cambodia

2014 ◽  
Vol 59 (1) ◽  
pp. 730-733 ◽  
Author(s):  
Jean Popovici ◽  
Sokheng Kao ◽  
Leanghor Eal ◽  
Sophalai Bin ◽  
Saorin Kim ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Plasmodium Vivax ◽  
Preliminary Data ◽  
Mutant Allele ◽  
Chloroquine Resistance ◽  
Wild Type ◽  
Nonsynonymous Mutation ◽  
Content Type

ABSTRACTPolymorphism in the ortholog gene of thePlasmodium falciparumK13 gene was investigated inPlasmodium vivaxisolates collected in Cambodia. All of them were Sal-1 wild-type alleles except two (2/284, 0.7%), andP. vivaxK12 polymorphism was reduced compared to that of theP. falciparumK13 gene. Both mutant allele isolates had the same nonsynonymous mutation at codon 552 (V552I) and were from Ratanak Kiri province. These preliminary data should encourage additional studies for associating artemisinin or chloroquine resistance and K12 polymorphism.

scholarly journals Survey of Plasmodium falciparum multidrug resistance-1 and chloroquine resistance transporter alleles in Haiti

2013 ◽  
Vol 12 (1) ◽  
pp. 426 ◽  
Author(s):  
Maha A ElBadry ◽  
Alexandre Existe ◽  
Yves S Victor ◽  
Gladys Memnon ◽  
Mark Fukuda ◽  
...  
Keyword(s):  
Plasmodium Falciparum ◽  
Multidrug Resistance ◽  
Chloroquine Resistance ◽  
Chloroquine Resistance Transporter
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