© 2015 by The American Society for Biochemistry and Molecular Biology, Inc. The malaria parasite Plasmodium falciparum apicoplast indirect aminoacylation pathway utilizes a non-discriminating glutamyl-tRNA synthetase to synthesize Glu-tRNAGln and a glutaminyl-tRNA amidotransferase to convert Glu-tRNAGln to Gln-tRNAGln. Here, we show that Plasmodium falciparum and other apicomplexans possess a unique heterodimeric glutamyltRNA amidotransferase consisting of GatA and GatB subunits (GatAB). We localized the P. falciparum GatA and GatB subunits to the apicoplast in blood stage parasites and demonstrated that recombinant GatAB converts Glu-tRNAGln to Gln-tRNAGln in vitro. We demonstrate that the apicoplast GatAB-catalyzed reaction is essential to the parasite blood stages because we could not delete the Plasmodium berghei gene encoding GatA in blood stage parasites in vivo. A phylogenetic analysis placed the split between Plasmodium GatB, archaeal GatE, and bacterial GatB prior to the phylogenetic divide between bacteria and archaea. Moreover, Plasmodium GatA also appears to have emerged prior to the bacterial-archaeal phylogenetic divide. Thus, although GatAB is found in Plasmodium, it emerged prior to the phylogenetic separation of archaea and bacteria.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): FIC/2010/09
Acknowledgements: We thank Geoffrey McFadden for providing anti-ACP antibody, J. Lapointe and A. Weiner for plasmids expressingCCA-adding enzyme, and Y. M. Hou for the pGFIB vector. We thankMR4 for providing P. falciparum 3D7 parasites contributed by DanCarucci and Alister Craig. The unpublished P. berghei genomesequence data were produced by the Pathogen Sequencing Group atthe Wellcome Trust Sanger Institute and can be obtained on line. Theunpublished C. velia and V. brassicaformis ortholog sequences weregraciously provided by Arnab Pain and Hifzur Ansari of King AbdullahUniversity of Science and Technology. The Chromera and Vitrellasequencing project was funded by a King Abdullah University of Scienceand Technology OCRF (GCR) award (FIC/2010/09) to ArnabPain. We also thank Jonathan Eisen and Dongying Wu for their consultingon the phylogenetic analyses.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.