Ligand-Receptor Interaction: AMA-1 Contains Small Regions Governing Bovine Erythrocyte Binding.

Apical membrane antigen 1 is a microneme protein which plays an indispensable role during Apicomplexa parasite invasion. The detailed mechanism of AMA-1 molecular interaction with its receptor on bovine erythrocytes has not been completely defined in . This study was focused on identifying the minimum AMA-1-derived regions governing specific and high-affinity binding to its target cells. Different approaches were used for detecting locus genetic variability and natural selection signatures. The binding properties of twelve highly conserved 20-residue-long peptides were evaluated using a sensitive and specific binding assay based on radio-iodination. AMA-1 ectodomain structure was modelled and refined using molecular modelling software. NetMHCIIpan software was used for calculating B- and T-cell epitopes. The gene had regions under functional constraint, having the highest negative selective pressure intensity in the Domain I encoding region. Interestingly, AMA-1-DI (YMQKFDIPRNHGSGIYVDLG and GYESVGSKSYRMPVGKCPVV) and DII (CPMHPVRDAIFGKWSGGSCV)-derived peptides had high specificity interaction with erythrocytes and bound to a chymotrypsin and neuraminidase-treatment sensitive receptor. DI-derived peptides appear to be exposed on the protein's surface and contain predicted B- and T-cell epitopes. These findings provide data (for the first-time) concerning AMA-1 functional subunits which are important for establishing receptor-ligand interactions which could be used in synthetic vaccine development.