Plasmodium falciparum: cloned and expressed CIDR domains of PfEMP1 bind to chondroitin sulfate A.
Adherence of erythrocytes infected with mature asexual Plasmodium falciparum parasites (iRBC) to microvascular endothelial cells contributes to the pathology of P. falciparum malaria. It has been shown that the variant P. falciparum erythrocyte membrane protein 1 (PfEMP1) confers adhesion to a wide range of cell surface receptors. Previously, the cysteine-rich interdomain region (CIDR) of PfEMP1 has been identified as binding site to CD36. We provide evidence that the same region can also mediate binding to chondroitin sulfate A (CSA). CIDR domains of two different parasite strains were expressed in Escherichia coli as a 6xHis-tagged protein. Purified recombinant protein bound to Chinese hamster ovary (CHO) cells which naturally express chondroitin sulfate A. Treatment of wild-type CHO cells with chondroitinase ABC reduced binding up to 94.4%. Competitive binding using soluble CSA inhibited binding to CHO cells by up to 100% at 2 mg/ml and by 62.4% at 0.5 mg/ml, whereas 1 mg/ml heparan sulfate had only a little effect (18.1%). In contrast, a recombinant 6xHis-tagged DBL1 domain showed no binding to wild-type CHO cells. Such an approach of analyzing various domains of PfEMP1 as recombinant proteins may elucidate their functions and may lead to novel anti-adherence therapeutics, especially for maternal malaria infections.
Swiss Tropical Institute, Basel, CH 4002, Switzerland.
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Degen
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Weiss
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Beck
D000595:Amino Acid Sequence; D000818:Animals; D001667:Binding, Competitive; D016466:CHO Cells; D002448:Cell Adhesion; D019765:Chondroitin ABC Lyase / Q000378:metabolism; D002809:Chondroitin Sulfates / Q000378:metabolism*; D003001:Cloning, Molecular; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D005434:Flow Cytometry; D008969:Molecular Sequence Data; D010963:Plasmodium falciparum / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011485:Protein Binding; D015800:Protozoan Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment; D014162:Transfection
D015800:Protozoan Proteins; D011994:Recombinant Proteins; C085731:erythrocyte membrane protein 1, Plasmodium falciparum; D002809:Chondroitin Sulfates; D019765:Chondroitin ABC Lyase