Resurrection of the ancestral RH5 invasion ligand provides a molecular explanation for the origin of P. falciparum malaria in humans (original) (raw)
Fig 4
A single amino acid in RH5 is responsible for human basigin binding specialization.
(A) Structural representation of the RH5–basigin complex, with five of the six residues that differ between the introgressed RH5 and P. falciparum RH5 highlighted in yellow. Note that residue 148 was not resolved in the RH5 structure. (B) Proteins corresponding to IntRH5 and the six mutations where the amino acids have been mutated to the corresponding residue in the P. falciparum RH5 sequence were expressed and purified and the binding to either human or gorilla basigin determined by SPR. Sensorgrams of four 2-fold serial dilutions (600 to 75 nM) are shown, with the raw data shown in black and the fits to a simple 1:1 binding model in red. Representative sensorgrams from two experiments are shown. All mutants bound human basigin with comparable affinity (top row), and one (H200Y) showed no detectable binding to gorilla basigin. (C) Calculated interaction half-lives (_t_1/2) of all mutants to human and gorilla basigin. Bars represent means ± SEM from at least three different analyte concentrations. Underlying numerical data can be found in S1 Data. IntRH5, introgressed ancestral RH5; RH5, reticulocyte-binding protein homologue 5; SPR, surface plasmon resonance.