A HECT Ubiquitin-Protein Ligase as a Novel Candidate Gene for Altered Quinine and Quinidine Responses in Plasmodium falciparum

Abstract

The emerging resistance to quinine jeopardizes the efficacy of a drug that has been used in the treatment of malaria for several centuries. To identify factors contributing to differential quinine responses in the human malaria parasite Plasmodium falciparum, we have conducted comparative quantitative trait locus analyses on the susceptibility to quinine and also its stereoisomer quinidine, and on the initial and steady-state intracellular drug accumulation levels in the F1 progeny of a genetic cross. These data, together with genetic screens of field isolates and laboratory strains associated differential quinine and quinidine responses with mutated pfcrt, a segment on chromosome 13, and a novel candidate gene, termed MAL7P1.19 (encoding a HECT ubiquitin ligase). Despite a strong likelihood of association, episomal transfections demonstrated a role for the HECT ubiquitin-protein ligase in quinine and quinidine sensitivity in only a subset of genetic backgrounds, and here the changes in IC50 values were moderate (approximately 2-fold). These data show that quinine responsiveness is a complex genetic trait with multiple alleles playing a role and that more experiments are needed to unravel the role of the contributing factors.

Balancing drug resistance and growth rates via compensatory mutations in the Plasmodium falciparum chloroquine resistance transporter

“…F), a centuries‐old drug used to treat severe malaria. Quinine resistance is known to be multifactorial, with quantitative trait loci analyses implicating mutant pfcrt and pfmdr1 as major determinants (Ferdig et al ., ; Sanchez et al ., 2011; 2014). Our data support the hypothesis that the direction and magnitude of the effect of mutant pfcrt on quinine response depends on the genetic background and PfCRT haplotype (Cooper et al ., 2002; 2007; Sidhu et al ., ; Lakshmanan et al ., ).…”

Antimalarial drug resistance: linking Plasmodium falciparum parasite biology to the clinic

“…Both PfCRT and PfMDR1 also are known to contribute to quinine resistance, which so far remains partial and which might also involve an enzyme involved in protein ubiquitination 183 (Supplementary Table 1). PfCRT- or PfMDR1-mediated changes in P. falciparum susceptibility to CQ, AQ or mefloquine are often accompanied by altered parasite susceptibility to quinine 184 , but in ways that can be unpredictable (i.e., leading to cross-resistance, or, inversely, to hypersensitivity).…”

Protein Degradation Systems as Antimalarial Therapeutic Targets

“…Expression of an extra copy of pfap2-mu harboring a S160N mutation increased P. falciparum in vitro sensitivity to chloroquine and quinine [82]. A separate study associated the HECT E3 ligase P. falciparum ubiquitin transferase (PfUT) (PF3D7_0704600) variant harboring a Y1387F mutation, in the presence of the K76T mutation in the P. falciparum chloroquine resistance transporter (PfCRT), with quinine resistance [83]. The molecular mechanisms underlying how mutations in PfUT could contribute to quinine resistance remain to be identified.…”