Phosphatidylinositol 3-Monophosphate Is Involved in Toxoplasma Apicoplast Biogenesis
Figure 2
PI3P-binding module disturbs apicoplast biogenesis.
(A) The expression of ddFYVE in intracellular FNR-RFP/ddFYVE expressing parasites was induced by the addition of 1 µM Shield-1 and the localization of both markers was analyzed at the indicated time of incubation. Arrowheads indicate the formation of a PI3P-containing compartment next to the apicoplast and at the base of V-shaped dividing apicoplasts. DNA-, ddFYVE- and FNR labels in residual bodies (arrows) and tachyzoites that have lost their apicoplast, but retain the PI3P-containing compartment at the sub-apical pole (open triangles) are indicated. The lowest panel shows the cytosolic staining of ddFYVEm and the persistence of the apicoplast 18 h after Shield-1 induction. (B) Time-lapse microscopy of FNR-RFP/ddFYVE parasites. Elapsed time after addition of 1 µM Shield-1 is indicated. Early during apicoplast replication, ddFYVE remained concentrated near the apicoplast (190 min). When apicoplasts started to separate (240 min), a portion of FRN label remained associated with the ddFYVE compartment (open triangle). After completion of daughter cell formation (300 min), all ddFYVE label and part of FNR label accumulated in the residual body (arrow). The arrowhead points to the parasite that has lost the FNR label. (C) Two hours after Shield-1 induction, the accumulation of ddFYVE is observed at the base of the V-shaped elongated apicoplasts.