Design of a basigin‐mimicking inhibitor targeting the malaria invasion protein RH5

Abstract

Many human pathogens use host cell‐surface receptors to attach and invade cells. Often, the host‐pathogen interaction affinity is low, presenting opportunities to block invasion using a soluble, high‐affinity mimic of the host protein. The Plasmodium falciparum reticulocyte‐binding protein homolog 5 (RH5) provides an exciting candidate for mimicry: it is highly conserved and its moderate affinity binding to the human receptor basigin (KD ≥1 μM) is an essential step in erythrocyte invasion by this malaria parasite. We used deep mutational scanning of a soluble fragment of human basigin to systematically characterize point mutations that enhance basigin affinity for RH5 and then used Rosetta to design a variant within the sequence space of affinity‐enhancing mutations. The resulting seven‐mutation design exhibited 1900‐fold higher affinity (KD approximately 1 nM) for RH5 with a very slow binding off rate (0.23 h−1) and reduced the effective Plasmodium growth‐inhibitory concentration by at least 10‐fold compared to human basigin. The design provides a favorable starting point for engineering on‐rate improvements that are likely to be essential to reach therapeutically effective growth inhibition.

Deep mutational scanning of proteins in mammalian cells

“…An important biomedical application of DMS is the engineering of therapeutic proteins. 138 DMS in phage and yeast has been widely used for the affinity maturation of antibodies, chimeric antigen receptors (CARs), peptides/small proteins, and decoy receptors for the treatment of viral infections, 139 , 140 parasitic infections, 141 cancer, 18 , 39 and other diseases. 142 DMS is also commonly used for antibody epitope mapping 19 , 143 and for the identification of potential escape variants in the context of viral infections.…”