How Toxoplasma hooks up

The intracellular parasite Toxoplasma gondii hides out in a specialized compartment surrounded by the parasitophorous vacuole membrane (PVM). The PVM associates with host cell organelles, possibly as a way of scavenging lipids from the host cell. Sinai and Joiner (page 95), describe a protein that mediates this association. The new work illuminates a poorly understood aspect of parasite biology, and may be relevant for understanding organelle interactions in eukaryotic cells.

Sinai and Joiner focused on the T. gondii ROP2 protein, as this protein appears on the PVM around the time that the PVM associates with mitochondria, and it contains a domain with characteristics of a mitochondrial targeting signal. In vitro, they find that the N-terminal domain of ROP2 partially translocates into the mitochondrial outer membrane, and appears to stably integrate there. The same domain also...