EXPRESSION OF THE PLASMODIAL NUTRIENT CHANNEL ON OOCYTES

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This is a proposal to isolate and characterize the nutrient-permeable ion channel on the intraerythrocytic malaria parasite, P. falciparum. This channel was first described by the applicant and his colleagues [1, appendix] and may be essential for parasite survival because it permits the parasite to acquire amino acids and monosaccharides from the red blood cell (RBC). This channel was identified by using the patch clamp method to measure ion channel activity on the parasitophorous vacuole membrane (PVM), the outer of two membranes surrounding the parasite. The applicant now proposes to express this channel on Xenopus oocytes by microinjection of parasite mRNA. Expressed channels will then be used to measure K+, lactate, and ATP4- permeabilities, examine channel regulation, and investigate possible blockers. If expression on oocytes is unsuccessful, an alternative approach, reconstitution into lipid bilayers, will allow the same detailed characterization. These studies should address fundamental questions on parasite nutrient trafficking and may have profound implications for the treatment of malaria: an identified channel blocker may prevent nutrient acquisition and, therefore, kill parasites through starvation. The applicant has decided to focus his long-term research efforts on the mechanisms of plasmodial survival within the RBC. He has considerable experience with methods used to study membrane transport and will, with this award, develop a foundation in the methods of molecular biology.