Journal Article

Diverse mutational pathways converge on saturable chloroquine transport via the malaria parasite’s chloroquine resistance transporter

Rowena E. Martin, Michael Lanzer, Valerie Goh, Cecilia P. Sanchez, Rosa V. Marchetti, Sebastiano Bellanca, Sashika N. Richards, Robert L. Summers, Kiaran Kirk, Tegan J. Dolstra, Wilfred D. Stein, Anurag Dave, Megan N. Nash, Robyn L. Schenk

2014

Overview

Mutations in the chloroquine resistance transporter (PfCRT) are the primary determinant of chloroquine (CQ) resistance in the malaria parasite Plasmodium falciparum . A number of distinct PfCRT haplotypes, containing between 4 and 10 mutations, have given rise to CQ resistance in different parts of the world. Here we present a detailed molecular analysis of the number of mutations (and the order of addition) required to confer CQ transport activity upon the PfCRT as well as a kinetic characterization of diverse forms of PfCRT. We measured the ability of more than 100 variants of PfCRT to transport CQ when expressed at the surface of Xenopus laevis oocytes. Multiple mutational pathways led to saturable CQ transport via PfCRT, but these could be separated into two main lineages. Moreover, the attainment of full activity followed a rigid process in which mutations had to be added in a specific order to avoid reductions in CQ transport activity. A minimum of two mutations sufficed for (low) CQ transport activity, and as few as four conferred full activity. The finding that diverse PfCRT variants are all limited in their capacity to transport CQ suggests that resistance could be overcome by reoptimizing the CQ dosage.

• Publisher: National Academy of Sciences,National Acad Sciences
• Subject: Amino Acid Sequence / Animals / Biological Sciences / Biological Transport / chloroquine / Chloroquine - metabolism / Drug Resistance / Gene expression / Haplotypes / Kinetics / Malaria / Malaria, Falciparum - metabolism / Membrane Transport Proteins - chemistry / Membrane Transport Proteins - genetics / Membrane Transport Proteins - metabolism / Molecular biology / Molecular Sequence Data / Mutant Proteins - chemistry / Mutant Proteins - metabolism / Mutation / Mutation - genetics / Oocytes / Parasites / Parasites - metabolism / Parasitic protozoa / Plasmodium falciparum / Plasmodium falciparum - metabolism / PNAS Plus / Protozoan Proteins - chemistry / Protozoan Proteins - genetics / Protozoan Proteins - metabolism / Recombinant Proteins - metabolism / Structure-Activity Relationship / Transfection / Vector-borne diseases / Xenopus laevis