Myosin II Localization in Plasmodium Falciparum Trophozoites Suggests Role in Hemoglobin-containing Vesicle Transport
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The protozoan Plasmodium falciparum causes the disease malaria, which kills hundreds of thousands of people annually. In the human host, the P. falciparum parasites infect erythrocytes and consume the host cell’s cytoplasm and hemoglobin. The process by which P. falciparum transports hemoglobin to the food vacuole for digestion is not well understood, though scientists suspect it may be similar to endocytosis in other eukaryotes. Myosin II is a eukaryotic motor protein that moves endocytosed vesicles by “walking” along actin filaments. This study investigates the P. falciparum myosin II homolog’s potential role in carrying hemoglobin-containing vesicles to the parasite food vacuole in trophozoite stage parasites by utilizing a P. falciparum cell line with GFP-tagged myosin II. Wide field fluorescent microscopy and confocal laser scanning microscopy were used to visualize the parasites and the localization of myosin II. Additionally, cytochalasin D was used to evaluate the effect of actin depolymerization on P. falciparum and myosin II localization. Myosin II was found to be localized to the food vacuole, and some movement of the protein was captured. Cytochalasin D caused accumulation of vesicles and altered the myosin II localization pattern in the parasites. Overall, the results of this study suggest that myosin II could be acting as a motor protein to transport hemoglobin-containing vesicles on actin filaments in P. falciparum trophozoites, though future research is necessary to accurately determine the role myosin II plays in these deadly parasites.