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Glutathione transport: A new role for PfCRT in chloroquine resistance

Patzewitz, Eva-Maria, Salcedo-Sora, J. Enrique, Wong, Eleanor H., Sethia, Sonal, Stocks, Paul A., Maughan, Spencer C., Murray, James Augustus Henry, Krishna, Sanjeev, Bray, Patrick G., Ward, Stephen A. and Müller, Sylke 2013. Glutathione transport: A new role for PfCRT in chloroquine resistance. Antioxidants & Redox Signaling 19 (7) , pp. 683-695. 10.1089/ars.2012.4625

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Abstract

Aims: Chloroquine (CQ) kills Plasmodium falciparum by binding heme, preventing its detoxification to hemozoin in the digestive vacuole (DV) of the parasite. CQ resistance (CQR) is associated with mutations in the DV membrane protein P. falciparum chloroquine resistance transporter (PfCRT), mediating the leakage of CQ from the DV. However, additional factors are thought to contribute to the resistance phenotype. This study tested the hypothesis that there is a link between glutathione (GSH) and CQR. Results: Using isogenic parasite lines carrying wild-type or mutant pfcrt, we reveal lower levels of GSH in the mutant lines and enhanced sensitivity to the GSH synthesis inhibitor l-buthionine sulfoximine, without any alteration in cytosolic de novo GSH synthesis. Incubation with N-acetylcysteine resulted in increased GSH levels in all parasites, but only reduced susceptibility to CQ in PfCRT mutant-expressing lines. In support of a heme destruction mechanism involving GSH in CQR parasites, we also found lower hemozoin levels and reduced CQ binding in the CQR PfCRT-mutant lines. We further demonstrate via expression in Xenopus laevis oocytes that the mutant alleles of Pfcrt in CQR parasites selectively transport GSH. Innovation: We propose a mechanism whereby mutant pfcrt allows enhanced transport of GSH into the parasite's DV. The elevated levels of GSH in the DV reduce the level of free heme available for CQ binding, which mediates the lower susceptibility to CQ in the PfCRT mutant parasites. Conclusion: PfCRT has a dual role in CQR, facilitating both efflux of harmful CQ from the DV and influx of beneficial GSH into the DV. Antioxid. Redox Signal. 19, 683–695.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Biosciences
Subjects: Q Science > QH Natural history > QH301 Biology
Publisher: Mary Ann Liebert
ISSN: 1523-0864
Funders: Wellcome Trust, European Community’s Seventh Framework Programme, MRC, BBSRC
Last Modified: 04 Jun 2017 05:39
URI: http://orca.cf.ac.uk/id/eprint/52657

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