A newly discovered protein export machine in malaria parasites

Several hundred malaria parasite proteins are exported beyond an encasing vacuole and into the cytosol of the host erythrocyte, a process that is central to the virulence and viability of the causative Plasmodium species. The trafficking machinery responsible for this export is unknown. Here we identify in Plasmodium falciparum a translocon of exported proteins (PTEX), which is located in the vacuole membrane. The PTEX complex is ATP-powered, and comprises heat shock protein 101 (HSP101; a ClpA/B-like ATPase from the AAA+ superfamily, of a type commonly associated with protein translocons), a novel protein termed PTEX150 and a known parasite protein, exported protein 2 (EXP2). EXP2 is the potential channel, as it is the membrane-associated component of the core PTEX complex. Two other proteins, a new protein PTEX88 and thioredoxin 2 (TRX2), were also identified as PTEX components. As a common portal for numerous crucial processes, this translocon offers a new avenue for therapeutic intervention. Malaria parasite virulence During intracellular infection of erythrocytes, malaria parasites reside in vacuoles from where they export many proteins into the host cell. These protein secretions play an important role in the virulence and viability of the Plasmodium parasite. The protein export machinery involved in this process has now been identified. Termed PTEX (for Plasmodium Translocon of EXported proteins), it is an ATP-powered complex located in the vacuole membrane, and may provide a new target for antimalarial drugs. Malaria parasites reside in vacuoles during intracellular infection of erythrocytes and export many proteins into the host cell, a process that is essential for the virulence and viability of Plasmodium . Whereas transport across the parasite membrane is known to rely on the secretory pathway, the transporter responsible for the translocation of proteins across the vacuole membrane is now identified.