Human Cyclophilin B forms part of a multi-protein complex during erythrocyte invasion by Plasmodium falciparum

Abstract

Invasion of human erythrocytes by Plasmodium falciparum merozoites involves multiple interactions between host receptors and their merozoite ligands. Here we report human Cyclophilin B as a receptor for PfRhopH3 during merozoite invasion. Localization and binding studies show that Cyclophilin B is present on the erythrocytes and binds strongly to merozoites. We demonstrate that PfRhopH3 binds to the RBCs and their treatment with Cyclosporin A prevents merozoite invasion. We also show a multi-protein complex involving Cyclophilin B and Basigin, as well as PfRhopH3 and PfRh5 that aids the invasion. Furthermore, we report identification of a de novo peptide CDP3 that binds Cyclophilin B and blocks invasion by up to 80%. Collectively, our data provide evidence of compounded interactions between host receptors and merozoite surface proteins and paves the way for developing peptide and small-molecules that inhibit the protein−protein interactions, individually or in toto, leading to abrogation of the invasion process.

Malaria Vaccines: Recent Advances and New Horizons

“…This soluble PfRH5-PfRipr-PfCyRPA invasion complex is required for triggering Ca 2+ release and establishing the tight junction ( Volz et al., 2016 ), with the PfP113 surface protein binding the N terminus of PfRH5 to provide an anchor to the merozoite surface ( Galaway et al., 2017 ). Further complexities surrounding PfRH5 biology have also been described, such as interactions between cyclophilin B and basigin as well as PfRhopH3 and PfRH5 ( Prakash et al., 2017 ), or PfRAP2 and basigin ( Zhang et al., 2018b ). Importantly, targeting these multiple components may improve vaccine potency; indeed antibodies against PfRH5 and PfCyRPA can synergize ( Reddy et al., 2015 ), with recent structural analyses identifying inhibitory epitopes on PfCyRPA ( Chen et al., 2017 ).…”

Stable knockout and complementation of receptor expression using in vitro cell line derived reticulocytes for dissection of host malaria invasion requirements

“…The immunophilin protein cyclophilin B was recently reported to associate with basigin to form a host multiprotein receptor complex that may be required for invasion (Prakash et al, 2017). No null erythroid phenotypes have been reported for cyclophilin B.…”

“…In addition to enabling dissection of the molecular basis of host receptors with established involvement in invasion, the ability to generate novel reticulocyte phenotypes with complete deficiency of prospective receptors provides a model for the verification or exclusion of candidate receptors identified via less direct approaches. A recent report proposed the existence of a multiprotein complex between basigin and cyclophilin B within the erythrocyte membrane, with a synthetic cyclophilin B binding peptide shown to inhibit merozoite invasion (Prakash et al, 2017). Since there have been no reports of cyclophilin B knockout red blood cells that would enable direct assessment of this hypothesis, we generated a cyclophilin B knockout BEL-A cell line, from which reticulocytes were derived.…”

A De novo Peptide from a High Throughput Peptide Library Blocks Myosin A -MTIP Complex Formation in Plasmodium falciparum

“…When the bait and target interact, RNA Polymerase is recruited to the promoter and stabilized along with the transcriptional machinery, leading to transcriptional activation of the β-galactosidase reporter gene, resulting in blue colored colonies [32,33]. The selection of colonies is based on blue-white screening that is later confirmed by multiple rounds of re-patching, re-transformation, re-co-transformation, and sequencing of the interacting peptide obtained from the dicodon library [34][35][36][37].…”

“…Mycobacterial proteins-ESAT6 and CFP10 (that are known to bind strongly with each other)-were used as the positive control, and ESAT6 and empty vector pBT nn were taken as the negative control. We have previously identified peptide binders against crucial proteins of Mycobacterium tuberculosis and Plasmodium falciparum using a similar approach [34,35]. The biophysical features like isoelectric point and grand average of hydropathicity (GRAVY) value were studied for stability ( Figure 2c).…”