Localization of the ATP-binding cassette (ABC) transport proteins PfMRP1, PfMRP2, and PfMDR5 at the Plasmodium falciparum plasma membrane

Jeroen MW van den Heuvel,Reginald A Kavishe,Adrian JF Luty,Jan B Koenderink,Frans GM Russel,Marga van de Vegte-Bolmer

doi:10.1186/1475-2875-8-205

Abstract

BackgroundThe spread of drug resistance has been a major obstacle to the control of malaria. The mechanisms underlying drug resistance in malaria seem to be complex and multigenic. The current literature on multiple drug resistance against anti-malarials has documented PfMDR1, an ATP-binding cassette (ABC) protein, as an important determinant of resistance. In the Plasmodium falciparum genome, there are several ABC transporters some of which could be putative drug transporting proteins. In order to understand the molecular mechanisms underlying drug resistance, characterization of these transporters is essential. The aim of this study was to characterize and localize putative ABC transporters.MethodsIn the plasmoDB database, 16 members of the P. falciparum ABC family can be identified, 11 of which are putative transport proteins. A phylogenetic analysis of the aligned NBDs of the PfABC genes was performed. Antibodies against PfMRP1 (PfABCC1), PfMRP2 (PfABCC2), and PfMDR5 (PfABCB5) were generated, affinity purified and used in immunocytochemistry to localize the proteins in the asexual stages of the parasite.ResultsThe ABC family members of P. falciparum were categorized into subfamilies. The ABC B subfamily was the largest and contained seven members. Other family members that could be involved in drug transport are PfABCC1, PfABCC2, PfABCG1, and PfABCI3. The expression and localization of three ABC transport proteins was determined. PfMRP1, PfMRP2, and PfMDR5 are localized to the plasma membrane in all asexual stages of the parasite.ConclusionIn conclusion, 11 of the 16 ABC proteins in the P. falciparum genome are putative transport proteins, some of which might be involved in drug resistance. Moreover, it was demonstrated that three of these proteins are expressed on the parasite's plasma membrane.

Highlights

The spread of drug resistance has been a major obstacle to the control of malaria
PfMDR1 (PFE1150w), PfMDR2 (PF14_0455), and PfMRP1 (PFA0590w) are hits that have been described in literature by several groups [810], but the other family members have not been the subject of investigation yet
There are five ATP-binding cassette (ABC) family members that do not contain a trans-membrane domain (TMD). Three of these belong to the E and F subfamilies, whereas the other two members were classified in the I subfamily that was introduced for the plant ABC proteins recently [20]

Summary

Introduction

The spread of drug resistance has been a major obstacle to the control of malaria. The mechanisms underlying drug resistance in malaria seem to be complex and multigenic. The current literature on multiple drug resistance against anti-malarials has documented PfMDR1, an ATP-binding cassette (ABC) protein, as an important determinant of resistance. The transport proteins responsible for this type of resistance are socalled multidrug resistance proteins (MDR/MRP), most of which belong to the superfamily of ATP binding cassette (ABC) proteins, one of the largest protein families. Many of these plasma membrane proteins actively pump out a wide range of structurally and functionally diverse amphipathic drugs, thereby decreasing the intracellular drug accumulation and resulting in drug resistance [1,2]. Apart from their normal physiological role, ABC transporters are involved in various diseases either by a mutation or through an altered mode of their expression [3,4]

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