Retraction Note: Branched tricarboxylic acid metabolism in Plasmodium falciparum

Nature 466, 774–778 (2010); doi:10.1038/nature09301 and corrigendum Nature 469, 432 (2011); doi:10.1038/nature09712

We retract this Letter, which reported both reductive and oxidative tricarboxylic acid (TCA) metabolism in Plasmodium falciparum parasites (‘branched TCA metabolism’). The data for metabolic labelling of TCA intermediates remain reliable, but we have come to realize that the interpretation presented is incorrect. Although there is both reductive and oxidative TCA cycle flux in P. falciparum-infected red blood cell (RBC) cultures (as we reported), new data from the Llinás and Vaidya groups (manuscript in preparation) suggests that the reductive flux occurs primarily in the RBCs and not in the parasite itself. Specifically, we have used new enrichment strategies for the parasitized RBCs that enhance our ability to measure P. falciparum-infected RBC metabolic activity without excessive interference from surrounding uninfected RBCs. On feeding ¹³C₅ glutamine, we measured both ¹³C₂-succinate and ¹³C₄-succinate in the infected RBCs, demonstrating that TCA metabolism in blood-stage P. falciparum is not branched but primarily oxidative (cyclic).