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Updated: Sep 29, 2026
Understanding the Development of Compensatory Pathways in a Mutant Malaria Parasite Harbouring Hypomorphic Allele of Plant-Like Kinases
Published on: November 22, 2024
Analysis of the antimalarial drug resistance protein Pfcrt expressed in yeast
Hanbang Zhang1, Ellen M Howard, Paul D Roepe
1Department of Chemistry, Lombardi Cancer Center, Georgetown University, 37th and O Streets, Washington, D. C. 20057-1227, USA.
Abstract:
Mutations in the novel membrane protein Pfcrt were recently found to be essential for chloroquine resistance (CQR) in Plasmodium falciparum, the parasite responsible for most lethal human malaria (Fidock, D. A., Nomura, T., Talley, A. K., Cooper, R. A., Dzekunov, S. M., Ferdig, M. T., Ursos, L. M., Sidhu, A. B., Naude, B., Deitsch, K. W., Su, X. Z., Wootton, J. C., Roepe, P. D., and Wellems, T. E. (2000) Mol. Cell 6, 861-871). Pfcrt is localized to the digestive vacuolar membrane of the intraerythrocytic parasite and may function as a transporter. Study of this putative transport function would be greatly assisted by overexpression in yeast followed by characterization of membrane vesicles. Unfortunately, the very high AT content of malarial genes precludes efficient heterologous expression. Thus, we back-translated Pfcrt to design idealized genes with preferred yeast codons, no long poly(A) sequences, and minimal stem-loop structure. We synthesized a designed gene with a two-step PCR method, fused this to N- and C-terminal sequences to aid membrane insertion and purification, and now report efficient expression of wild type and mutant Pfcrt proteins in the plasma membrane of Saccharomyces cerevisiae and Pichia pastoris yeast. To our knowledge, this is the first successful expression of a full-length malarial parasite integral membrane protein in yeast. Purified membranes and inside-out plasma membrane vesicle preparations were used to analyze wild type versus CQR-conferring mutant Pfcrt function, which may include effects on H(+) transport (Dzekunov, S., Ursos, L. M. B., and Roepe, P. D. (2000) Mol. Biochem. Parasitol. 110, 107-124), and to perfect a rapid purification of biotinylated Pfcrt. These data expand on the role of Pfcrt in conferring CQR and define a productive route for analysis of important P. falciparum transport proteins and membrane associated vaccine candidates.
Insights
Researchers engineered the Plasmodium falciparum chloroquine resistance (Pfcrt) gene for efficient expression in yeast. This breakthrough enables detailed study of Pfcrt
Area of Science:
- Malaria research
- Molecular parasitology
- Protein expression
Background:
- Mutations in Pfcrt are crucial for chloroquine resistance in Plasmodium falciparum, the parasite causing severe malaria.
- Pfcrt is a membrane protein in the parasite's digestive vacuole, potentially acting as a transporter.
- Studying Pfcrt's function requires its overexpression, but high AT content in malaria genes hinders heterologous expression.
Purpose of the Study:
- To overcome challenges in expressing Plasmodium falciparum genes in yeast.
- To enable functional analysis of wild-type and mutant Pfcrt proteins.
- To develop a method for studying malaria parasite membrane proteins.
Main Methods:
- Designed an idealized Pfcrt gene with optimized yeast codons and reduced structural elements.
- Synthesized the designed gene using a two-step PCR method.
- Expressed the designed Pfcrt gene in Saccharomyces cerevisiae and Pichia pastoris, analyzing membrane vesicles.
Main Results:
- Achieved efficient expression of full-length wild-type and mutant Pfcrt in yeast plasma membranes, a first for malarial integral membrane proteins.
- Purified membranes and vesicles allowed analysis of Pfcrt function, including potential H+ transport.
- Developed a rapid purification method for biotinylated Pfcrt.
Conclusions:
- The engineered Pfcrt gene facilitates the study of chloroquine resistance mechanisms.
- This approach provides a viable method for analyzing Plasmodium falciparum transport proteins.
- Enables further research into membrane-associated vaccine candidates for malaria.
