The Plasmodium falciparum ABC transporter ABCI3 confers parasite strain-dependent pleiotropic antimalarial drug resistance

05 Jul 2021

Murithi JM, Deni I, Pasaje CFA, Okombo J, Bridgford JL, Gnädig NF, Edwards RL, Yeo T, Mok S, Burkhard AY, Coburn-Flynn O, Istvan ES, Sakata-Kato T, Gomez-Lorenzo MG, Cowell AN, Wicht KJ, Le Manach C, Kalantarov GF, Dey S, Duffey M, Laleu B, Lukens AK, Ottilie S, Vanaerschot M, Trakht IN, Gamo FJ, Wirth DF, Goldberg DE, Odom John AR, Chibale K, Winzeler EA, Niles JC, Fidock DA

Cell chemical biology
PMID: 34233174

Doi: 10.1016/j.chembiol.2021.06.006

Photo: gerasimov_foto_174/Shutterstock.com

Widespread Plasmodium falciparum resistance to first-line antimalarials underscores the vital need to develop compounds with novel modes of action and identify new druggable targets. Here, we profile five compounds that potently inhibit P. falciparum asexual blood stages. Resistance selection studies with three carboxamide-containing compounds, confirmed by gene editing and conditional knockdowns, identify point mutations in the parasite transporter ABCI3 as the primary mediator of resistance. Selection studies with imidazopyridine or quinoline-carboxamide compounds also yield changes in ABCI3, this time through gene amplification. Imidazopyridine mode of action is attributed to inhibition of heme detoxification, as evidenced by cellular accumulation and heme fractionation assays. For the copy-number variation-selecting imidazopyridine and quinoline-carboxamide compounds, we find that resistance, manifesting as a biphasic concentration-response curve, can independently be mediated by mutations in the chloroquine resistance transporter PfCRT. These studies reveal the interconnectedness of P. falciparum transporters in overcoming drug pressure in different parasite strains.

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