A Plasmodium falciparum copper-binding membrane protein with copper transport motifs

Abstract

BackgroundCopper is an essential catalytic co-factor for metabolically important cellular enzymes, such as cytochrome-c oxidase. Eukaryotic cells acquire copper through a copper transport protein and distribute intracellular copper using molecular chaperones. The copper chelator, neocuproine, inhibits Plasmodium falciparum ring-to-trophozoite transition in vitro, indicating a copper requirement for malaria parasite development. How the malaria parasite acquires or secretes copper still remains to be fully elucidated.MethodsPlasmoDB was searched for sequences corresponding to candidate P. falciparum copper-requiring proteins. The amino terminal domain of a putative P. falciparum copper transport protein was cloned and expressed as a maltose binding fusion protein. The copper binding ability of this protein was examined. Copper transport protein-specific anti-peptide antibodies were generated in chickens and used to establish native protein localization in P. falciparum parasites by immunofluorescence microscopy.ResultsSix P. falciparum copper-requiring protein orthologs and a candidate P. falciparum copper transport protein (PF14_0369), containing characteristic copper transport protein features, were identified in PlasmoDB. The recombinant amino terminal domain of the transport protein bound reduced copper in vitro and within Escherichia coli cells during recombinant expression. Immunolocalization studies tracked the copper binding protein translocating from the erythrocyte plasma membrane in early ring stage to a parasite membrane as the parasites developed to schizonts. The protein appears to be a PEXEL-negative membrane protein.ConclusionPlasmodium falciparum parasites express a native protein with copper transporter characteristics that binds copper in vitro. Localization of the protein to the erythrocyte and parasite plasma membranes could provide a mechanism for the delivery of novel anti-malarial compounds.

A comparative transcriptomic analysis of replicating and dormant liver stages of the relapsing malaria parasite Plasmodium cynomolgi

“…Remarkably, two putative copper transporters (PcyM_1331900 and PcyM_1277100) showed high FPKM values for both liver stage schizonts and hypnozoites (highlighted in Supplementary file 10 , Figure 4B ), suggesting a role for copper homeostasis in liver stage development and quiescence. To determine whether copper was critical to P. cynomolgi liver stages, we treated infected hepatocytes with a copper chelator, neocuproine ( Choveaux et al, 2012 ; Kenthirapalan et al, 2014 ). Neocuproine treatment, initiated 1–2 hr after infection with sporozoites and continued for 6 days, indeed showed pronounced cidal effects on the viability of both liver schizonts and hypnozoites ( Figure 4C ) at the highest concentration tested.…”

Recombinant vacuolar iron transporter family homologue PfVIT from human malaria-causing Plasmodium falciparum is a Fe2+/H+exchanger

“…Despite the importance of VIT proteins to iron sequestration in many biological systems, little is understood of their mechanism of transport. Furthermore, although Plasmodium membrane proteins represent attractive potential drug targets, detailed investigation of their biochemical and biophysical properties has been hindered by lack of a source of isolated and functional recombinant proteins from the parasite 27 28 , exceptions being chloroquine resistance transporter PfCRT 29 , multi-drug resistance transporter PfMDR1 30 and copper transport protein Ctr1 31 .…”

Perturbation of copper homeostasis is instrumental in early developmental arrest of intraerythrocytic Plasmodium falciparum

“…Although there is no comprehensive understanding of copper metabolism and function in P. falciparum , the proteins involved in copper pathways and trafficking have been identified in Plasmodium spp. These include a putative copper channel, a copper transporter, a putative COX17, and a copper-transporting ATPase [ 6 , 15 , 16 ].…”