Biology subjects

Bower-Lepts, C.

Publications and source records attributed to Bower-Lepts, C..

3 recordsLinked to original sources

bioRxiv2026

A Plasmodium falciparum PX1 haplotype is associated with reduced susceptibility to artemisinin and lumefantrine

Effective control of falciparum malaria depends on the sustained efficacy of frontline antimalarial drugs, particularly artemether-lumefantrine (AL), the most widely used therapy in Africa. However, the emergence of artemisinin partial resistance and reduced lumefantrine susceptibility in eastern Africa threaten malaria control and elimination. Robust genetic markers of decreased susceptibility to lumefantrine remain elusive, and our understanding of artemisinin resistance is incomplete. We report results of a Plasmodium falciparum genetic cross between a drug-sensitive line and a Ugandan strain exhibiting reduced susceptibility to dihydroartemisinin and lumefantrine. Targeted deep sequencing of progeny pools and 460 recombinant progeny clones derived under drug pressures revealed distinct haplotypic signatures. Drug-selection experiments identified genetic polymorphisms in Plasmodium falciparum px1, encoding a phosphoinositide-binding protein, as the strongest correlates of reduced susceptibility to dihydroartemisinin and lumefantrine. The PX1 PIN haplotype (L1222P, M1701I, D1705N) recently discovered in Ugandan parasites was highly enriched following dihydroartemisinin or lumefantrine treatment of pooled mixtures of genetically diverse Ugandan clinical isolates. This haplotype was associated with reduced susceptibility to dihydroartemisinin and lumefantrine, compared to wild-type sequence, in culture-adapted Ugandan P. falciparum lines. These results confirm that PX1 mutations were selected across geographically distinct Ugandan parasite backgrounds. Long-term competitive fitness assays demonstrated that PX1 mutations confer asexual blood-stage parasites with a growth advantage, potentially explaining a rapid rise of PX1 PIN alleles over the last two decades in Uganda. Overall, our data suggest the PX1 PIN haplotype is a robust marker of reduced AL susceptibility in African P. falciparum, enabling surveillance of emerging drug resistance.

microbiology↗

bioRxiv2026

Double Mutations in Plasmodium falciparum Kelch13 drive resistance to next-generation artemisinin derivatives in malaria parasites

New antimalarial compounds are urgently required to overcome artemisinin partial resistance that has emerged in Asia and now Africa. Ozonides are promising next-generation artemisinins that offer the improved pharmacokinetic property of a prolonged in vivo half-life. To assess the potential for parasite resistance to ozonides in an artemisinin-resistant background, we subjected Cambodian Kelch13 (K13) mutant parasites to increasing artefenomel (OZ439) pressure up to in vivo physiological concentrations. Whole-genome sequencing identified a novel non-propeller K13 A212T mutation in OZ439-resistant parasites. Gene editing and drug susceptibility assays revealed that the K13 double mutation R539T+A212T is a determinant of OZ439 resistance. In extended parasite recovery assays, this resistance mechanism was associated with accelerated parasite recrudescence following OZ439 or OZ277 exposure. This phenotype was also observed in K13 C580Y+A212T double mutant parasites. Global metabolomic profiling revealed no changes in the levels of hemoglobin-derived peptides in OZ439-resistant parasites, suggesting that resistance is not associated with drug activation. Instead, double mutant parasites exhibited increased levels of metabolites linked to glutathione, nucleotide, and aspartate-glutamate metabolism, suggesting a higher capacity for redox regulation to tolerate drug-induced oxidative damage. Our findings demonstrate that ozonide resistance can emerge through a novel K13 mutation on the background of existing artemisinin-resistance k13 alleles.

microbiology↗

bioRxiv2019

Targeting the trypanosome kinetochore with CLK1 protein kinase inhibitors

The kinetochore is a macromolecular structure that assembles on the centromeres of chromosomes and provides the major attachment point for spindle microtubules during mitosis. In Trypanosoma brucei the proteins that make up the kinetochore are highly divergent, with the inner kinetochore comprising at least 20 distinct and essential proteins (KKT1-20) that include four protein kinases, CLK1 (KKT10), CLK2 (KKT19), KKT2 and KKT3. We performed a phenotypic screen of T. brucei bloodstream forms with a Novartis kinase-focused inhibitor library, which identified a number of selective inhibitors with potent pan-kinetoplastid activity. Deconvolution of an amidobenzimidazole series using a selection of 37 T. brucei mutants that over-express known essential protein kinases identified CLK1 as the primary target. Biochemical studies show that the irreversible competitive inhibition of CLK1 is dependent on a Michael acceptor forming an irreversible bond with C215 in the ATP binding pocket, a residue that is not present in human CLK1, thereby providing selectivity. Chemical inhibition of CLK1 impairs inner kinetochore recruitment and compromises cell cycle progression, leading to cell death. We show that KKT2 is a substrate for CLK1 and identify phosphorylation of S508 to be essential for KKT2 function and for kinetochore assembly. We propose that CLK1 is part of a novel signalling cascade that controls kinetochore function via phosphorylation of the inner kinetochore protein kinase KKT2. This work highlights a novel drug target for trypanosomatid parasitic protozoa and a new chemical tool for investigating the function of their divergent kinetochores.

microbiology↗