Substitution of Pro165 in Transmembrane 4 of PfCRT Abolishes Lysosome Acidification Function in Stably Transfected HEK-293F Cells
Fadi Baakdah
Institute of Parasitology, McGill University, Ste. Anne de Bellevue, Québec, Canada.
Elias Georges *
Institute of Parasitology, McGill University, Ste. Anne de Bellevue, Québec, Canada.
*Author to whom correspondence should be addressed.
Abstract
The Plasmodium falciparum chloroquine resistance transporter (PfCRT) is localised on the parasite digestive vacuole, an organelle that maintains an acidic lumen. Here we demonstrated the isolation of HEK-293F cells stably expressing wild type 3D7 and mutant Pfcrt alleles. Immuno-fluorescence staining of HEK-293F transfectants confirms the localization of Pfcrt alleles to the lysosomal vesicles. Moreover, cells expressing mut-PfCRTETSE showed greater lysosomal acidification as demonstrated by the dramatic increase in the accumulation of two weak bases, acridine orange and CytiPainter LysoOrange dyes. Furthermore, HEK-293 cells stably expressing mut-PfCRTETSE with a single substitution of proline 165 in transmembrane 4 completely inhibited the accumulation of weak bases. Taken together, our results demonstrate the role of Pro165 in PfCRT lysosomal acidification function in HEK-293F cells.
Keywords: Proline mutations, PfCRT, heterologous expression, lysosome-acidification, Plasmodium falciparum