Fosmidomycin Uptake into Plasmodium and Babesia-Infected Erythrocytes Is Facilitated by Parasite-Induced New Permeability Pathways

Parasitologie, Fachbereich Biologie, Philipps-Universität, Marburg, Germany.
PLoS ONE (Impact Factor: 3.23). 05/2011; 6(5):e19334. DOI: 10.1371/journal.pone.0019334
Source: PubMed


Highly charged compounds typically suffer from low membrane permeability and thus are generally regarded as sub-optimal drug candidates. Nonetheless, the highly charged drug fosmidomycin and its more active methyl-derivative FR900098 have proven parasiticidal activity against erythrocytic stages of the malaria parasite Plasmodium falciparum. Both compounds target the isoprenoid biosynthesis pathway present in bacteria and plastid-bearing organisms, like apicomplexan parasites. Surprisingly, the compounds are inactive against a range of apicomplexans replicating in nucleated cells, including Toxoplasma gondii.
Since non-infected erythrocytes are impermeable for FR90098, we hypothesized that these drugs are taken up only by erythrocytes infected with Plasmodium. We provide evidence that radiolabeled FR900098 accumulates in theses cells as a consequence of parasite-induced new properties of the host cell, which coincide with an increased permeability of the erythrocyte membrane. Babesia divergens, a related parasite that also infects human erythrocytes and is also known to induce an increase in membrane permeability, displays a similar susceptibility and uptake behavior with regard to the drug. In contrast, Toxoplasma gondii-infected cells do apparently not take up the compounds, and the drugs are inactive against the liver stages of Plasmodium berghei, a mouse malaria parasite.
Our findings provide an explanation for the observed differences in activity of fosmidomycin and FR900098 against different Apicomplexa. These results have important implications for future screens aimed at finding new and safe molecular entities active against P. falciparum and related parasites. Our data provide further evidence that parasite-induced new permeability pathways may be exploited as routes for drug delivery.

    • "An essential molecule that needs to be present in the extraerythrocytic medium appears to be pantothenic acid (Saliba et al., 1998). The observation that infected RBC, unlike noninfected RBC, show an increased permeability for a variety of molecules that have no metabolically relevant function, such as certain synthetic sphingomyelin derivatives (Ansorge et al., 1995) or the drug fosmidomycin (Baumeister et al., 2011) raise the possibility that NPP are non-specific side effects of the infection rather than biologically relevant pathways that have undergone specific selection processes. Despite several mechanistic explanations that were suggested since the first discovery of NPP, the prevailing view has remained the involvement of transport proteins located in the RBCM (Baumeister et al., 2006Baumeister et al., , 2003). "
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    ABSTRACT: The mammalian red blood cell is a terminally differentiated cell that lacks a genetic programme and that has only a very limited metabolic capacity. Nonetheless, it serves as habitat for two parasites belonging to the monophyletic group of Apicomplexa, namely Plasmodium and Babesia. Studies of the parasitized red blood cell have revealed several properties that are unknown in the non-infected cell and that are difficult to conceptualize based on our view of red blood cell function. Here we review the current knowledge on host cell invasion and nutrient acquisition by these parasites. We attempt to dissect the factors that are directly contributed by the parasites from those that exist but have remained undetected in the non-infected cell. Copyright © 2015. Published by Elsevier GmbH.
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    • "ls outside of the inner ellipse ) . How do these compounds reach their intracellular targets to produce parasite killing ? As discussed below , three of these compounds , blasticidin S , leu - peptin , and fosmidomycin , cross the host erythrocyte mem - brane through a parasite - induced channel ( Hill et al . , 2007 ; Lisk et al . , 2008 , 2010 ; Baumeister et al . , 2011 ; Nair et al . , 2011 ) . Three approved antimalarial drugs , doxycycline , azithromycin , and lumefantrine , are predicted to be poorly absorbed ( filled circles outside outer ellipse , Figure 1A ) , but their uptake by infected cells has not been directly studied ; each has known problems with oral absorption , with facilitated or act"
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    ABSTRACT: Drugs represent the primary treatment available for human malaria, as caused by Plasmodium spp. Currently approved drugs and antimalarial drug leads generally work against parasite enzymes or activities within infected erythrocytes. To reach their specific targets, these chemicals must cross at least three membranes beginning with the host cell membrane. Uptake at each membrane may involve partitioning and diffusion through the lipid bilayer or facilitated transport through channels or carriers. Here, we review the features of available antimalarials and examine whether transporters may be required for their uptake. Our computational analysis suggests that most antimalarials have high intrinsic membrane permeability, obviating the need for uptake via transporters; a subset of compounds appear to require facilitated uptake. We also review parasite and host transporters that may contribute to drug uptake. Broad permeability channels at the erythrocyte and parasitophorous vacuolar membranes of infected cells relax permeability constraints on antimalarial drug design; however, this uptake mechanism is prone to acquired resistance as the parasite may alter channel activity to reduce drug uptake. A better understanding of how antimalarial drugs reach their intracellular targets is critical to prioritizing drug leads for antimalarial development and may reveal new targets for therapeutic intervention.
    Full-text · Article · May 2015 · Frontiers in Pharmacology
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    • "Jomaa et. al. demonstrated that the antibiotic fosmidomycin and its derivative FR-900098, which are specific inhibitors of this pathway, are effective against malaria and babesiosis [3, 12]. The 1-deoxy-D-xylulose 5-phosphate/ 2-C-methyl-D-erythritol4-phosphate (DOXP/MEP) pathway of isopentenyl pyrophosphate (IPP) biosynthesis begins with the formation of DOXP through the action of the 1-deoxy-D-xylulose-5-phosphate synthase (DXS), which is the first-and rate limiting step catalyzing the formation of DOXP, by condensation of pyruvate with D-glyceraldehyde 3-phosphate (or D-glyceraldehyde) [27]. "
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    ABSTRACT: The 1-deoxy-D-xylulose-5-phosphate synthase (DXS) enzyme has been characterized in other species, but not in the genus Babesia, which causes major losses in the livestock industries worldwide. Therefore, we isolated, clonedand expressed the wild-type B. bovis dxs cDNA in Escherichia coli and evaluated its enzymatic activity in vitro. DNA sequence analysis revealed an open reading frame of 2061 bp capable of encoding a polypeptide of 686 amino acid residues with a calculated isoelectric point of pH 6.93 and a molecular mass of 75 kDa. The expressed soluble recombinant fusion DXS protein was approximately 78 kDa, which is similar to the native enzyme identified from the parasite merozoite using anti-rDXS serum. The recombinant fusion DXS enzyme exhibited Km values of 380 ± 46 µM and 790 ± 52 µM for D,L-glyceraldehyde 3-phosphate and pyruvate, respectively. In this work, we present the first cloning, expression and characterization of DXS enzyme from B. bovis.
    Full-text · Article · Apr 2014 · Journal of Veterinary Medical Science
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