title: Characterisation of the drug transport properties of the Plasmodium falciparum chloroquine resistance transporter through expression in Xenopus laevis oocytes
creator: Dave, Anurag
subject: ddc-570
subject: 570 Life sciences
description: With an annual mortality of around a million people, most of whom are children, malaria remains a major health hazard in our times. Amongst the drugs used to treat malaria, compounds such as chloroquine (CQ) and quinine (QN) are no longer the first line antimalarials in use because of the spread of drug resistant Plasmodium falciparum, in particular that of the chloroquine resistant (CQR) strains.  Central to CQR malaria is the Plasmodium falciparum chloroquine transporter (PfCRT), a trans-membrane protein located in the digestive vacuolar membrane of the parasite. It has been shown in the past that mutations in this protein are linked to an enhanced efflux of CQ from the digestive vacuole, which is the basis of CQR in P. falciparum. As part of this study, PfCRT was expressed in oocytes of Xenopus laevis, in order to understand the relationship between mutant pfcrt and transport of quinoline drugs. A number of naturally occurring and lab-constructed pfcrt mutants were expressed in oocytes, and transport measured for CQ, QN and its stereoisomer quinidine (QD). The data obtained showed that apart from being a carrier for CQ, mutant PfCRT exhibited saturable and verapamil-sensitive uptake of QN and QD, suggesting that PfCRT is a carrier for QN and QD as well. Using polymorphic pfcrt alleles, it was observed that mutations in pfcrt can influence the apparent Michaelis-Menten constant for CQ. While all mutant pfcrt alleles showed uptake of CQ albeit with differences, only the Dd2 and GB4 alleles showed transport for QN and QD, indicating that pfcrt mutations may also influence the substrate specificity. Mutants generated for the Ecu1110 alleles showed that only three mutations can suffice for CQ transport. Amino acid substitution in the Dd2 allele revealed a role for residue 326 in quinoline substrate selectivity. Taken together, the data argue in favour of a model where PfCRT acts as a carrier for quinolines such as CQ and QN, whose kinetic parameters are dependent on the actual combination of mutant residues present.  
date: 2011
type: Dissertation
type: info:eu-repo/semantics/doctoralThesis
type: NonPeerReviewed
format: application/pdf
identifier: https://archiv.ub.uni-heidelberg.de/volltextserverhttps://archiv.ub.uni-heidelberg.de/volltextserver/12130/1/Anurag_Dave_dissertation.pdf
identifier: DOI:10.11588/heidok.00012130
identifier: urn:nbn:de:bsz:16-opus-121300
identifier:   Dave, Anurag  (2011) Characterisation of the drug transport properties of the Plasmodium falciparum chloroquine resistance transporter through expression in Xenopus laevis oocytes.  [Dissertation]     
relation: https://archiv.ub.uni-heidelberg.de/volltextserver/12130/
rights: info:eu-repo/semantics/openAccess
rights: http://archiv.ub.uni-heidelberg.de/volltextserver/help/license_urhg.html
language: eng