Receptor-ligand and parasite protein-protein interactions inPlasmodium vivax: Analysing rhoptry neck proteins 2 and 4

Abstract

Elucidating receptor-ligand and protein-protein interactions represents an attractive alternative for designing effective Plasmodium vivax control methods. This article describes the ability of P. vivax rhoptry neck proteins 2 and 4 (RON2 and RON4) to bind to human reticulocytes. Biochemical and cellular studies have shown that two PvRON2- and PvRON4-derived conserved regions specifically interact with protein receptors on reticulocytes marked by the CD71 surface transferrin receptor. Mapping each protein fragment's binding region led to defining the specific participation of two 20 amino acid-long regions selectively competing for PvRON2 and PvRON4 binding to reticulocytes. Binary interactions between PvRON2 (ligand) and other parasite proteins, such as PvRON4, PvRON5, and apical membrane antigen 1 (AMA1), were evaluated and characterised by surface plasmon resonance. The results revealed that both PvRON2 cysteine-rich regions strongly interact with PvAMA1 Domains II and III (equilibrium constants in the nanomolar range) and at a lower extent with the complete PvAMA1 ectodomain and Domains I and II. These results strongly support that these proteins participate in P. vivax's complex invasion process, thus providing new pertinent targets for blocking P. vivax merozoites' specific entry to their target cells.

Structure of Rhoptry Neck Protein 2 is essential for the interaction in vitro with Apical Membrane Antigen 1 in Plasmodium vivax

“…The result obtained for the cyclic peptide was different than previously reported by Vulliez Le Normand et al [15], however, to analyse these results it is important to highlight that the purity level of the peptides used in all experiments of this work were higher than 95%, (Additional file 1) that is required for reliable SPR experiments [32]. This result in agreement with the report from Bermudez et al [16] for a recombinant protein that contain a PvRON2 sequence in which the peptides studied were based.

Fig. 3Surface plasmon resonance studies of peptides based on PvRON2 (2035–2074) binding to PvAMA1-His 6 .

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“…Therefore, it has been hypothesized that this complex is conserved in P. vivax, and this AMA1–RON2 interaction offers potential for the development of anti-infective (vaccines and/or drugs) strategies. In fact, during the development of the present study, two other works showed the interaction of peptides and recombinant proteins based on PvRON2 and PvAMA1 [15, 16].…”

“…For this reason, PvAMA1-DII-III is able to bind to both PvAMA1 and PfAMA1 in spite of some differences in the intermolecular interactions. On the other hand, Bermudez et al [16] showed a stronger interaction of PvRON2 with PvAMA1-DII-III than with the PvAMA1 ectodomain or PvAMA1-DI-II, suggesting that other PvAMA1 regions may participate in the interaction with PvRON2. Furthermore, they also demonstrated that another PvRON2 functional region located towards the central region participates in the interaction with reticulocytes and interacts strongly with PvAMA1.…”

Protein-Protein Interactions in Malaria: Emerging Arena for Future Chemotherapeutics

“…While the process of moving junction (MJ) formation and important players involved in the process were well elucidated in P. falciparum, the other major causative agent of malaria, P. vivax, remains poorly understood, partially owing to difficulties in culturing P. vivax in vitro. Recombinant P. vivax rhoptry neck protein 2 (PvRON2), based on literature evidence of involvement of PfRON2 in MJ formation and invasion, showed that both rhoptry proteins PvRON2 and PvRON4 bound preferentially to CD71-labeled human reticulocytes rather than normocytes [26]. More importantly, the cysteine-rich C-terminal PvRON2 region strongly interacts with PvAMA1 domains II and III, similar to earlier reports of PfRON2-PfAMA1 interactions [27].…”

Genetic sequence characterization and naturally acquired immune response to Plasmodium vivax Rhoptry Neck Protein 2 (PvRON2)

“…PfRON2 and PvRON2 interact with a hydrophobic groove in AMA1 [ 52 , 53 ]. It has been recently reported that PvRON2-RI (957–1288 AA) [ 52 – 54 ] and PvRON2-RII (1850–2085 AA) [ 54 ] bind to PvAMA1 DI [ 52 , 54 ] with high affinity [ 54 ], and in both P. falciparum and P. vivax species it was observed that the residue Tyr251, which was reported to be essential for RON2 binding [ 7 , 55 ], is conserved [ 46 , 55 ].…”