Import of host δ-aminolevulinate dehydratase into the malarial parasite:: Identification of a new drug target

The parasite Plasmodium berghei imports the enzyme delta -aminolevulinate dehydratase (ALAD), and perhaps the subsequent enzymes of the pathway from the host red blood cell to sustain heme synthesis. Here we have studied the mechanism of this import. A 65-kDa protein on the P. berghei membrane specifically bound to mouse red blood cell ALAD, and a 93-amino-acid fragment (ALAD-Delta NC) of the host erythrocyte ALAD was able to compete with the full-length enzyme for binding to the P. berghei membrane. ALAD-Delta NC was taken up by the infected red blood cell when added to a culture of P. falciparum and this led to a substantial decrease in ALAD protein and enzyme activity and, subsequently, heme synthesis in the parasite, resulting in its death.