Myosin IB from Entamoeba histolytica is involved in phagocytosis of human erythrocytes

Entamoeba histolytica is a protozoan parasite that causes amoebic dysentery in humans. The disease is prevalent world,vide, Infection with E, histolyt ica results in invasion of the intestine by the parasite, followed by tissu e damage and inflammation, During this invasive process, parasites kill and phagocytose human epithelial cells, immune cells and erythrocytes, Express ion of amoebic pathogenicity requires a dynamic cytoskeleton that allows mo vement, tissue penetration and changes in parasite morphology, Myosin LB is a member of the myosin I family of motor proteins, Studies conducted both with Dictyostelium discoideum, a non-pathogenic amoeba, and with the yeast Saccharomyces cerevisiae indicate the involvement of myosin IB in cellular processes including movement, phagocytosis and endocytosis, Recently, we is olated the gene encoding myosin IB from E, histolytiea, Thus, we decided to analyze the role of myosin IB in pathogenesis of amoeba, Using a specific anti-myosin IB antibody, this protein was localized in cell regions includi ng the pseudopod, vesicles and underneath the plasma membrane. When E, hist olytica was activated for erythrophagocytosis, myosin IB was markedly recru ited to both the phagocytic cup and around internalized phagosomes. To anal yze the role of myosin IB in phagocytosis, a strain overexpressing the myos in IB gene was constructed, This strain synthesizes threefold more myosin I B than the wild-type strain, Challenge of the transfected cell line with er ythrocytes showed that these amoebae were deficient in erythrophagocytosis mainly in the uptake step, suggesting a role for myosin IB in the pathogeni c activity of a human parasite.