Plasmodium Apicoplast Gln-tRNAGln Biosynthesis Utilizes a Unique GatAB Amidotransferase Essential for Erythrocytic Stage Parasites

• Published in: The Journal of biological chemistry Vol. 290; no. 49; pp. 29629 - 29641
• Main Authors: Mailu, Boniface M., Li, Ling, Arthur, Jen, Nelson, Todd M., Ramasamy, Gowthaman, Fritz-Wolf, Karin, Becker, Katja, Gardner, Malcolm J.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 04.12.2015; American Society for Biochemistry and Molecular Biology
• Subjects: Antimalarials - chemistry; apicoplast; Apicoplasts - metabolism; Cell Nucleus - metabolism; Computational Biology; Enzymology; Erythrocytes - parasitology; GATA Transcription Factors - metabolism; Gene Deletion; glutamyl-tRNA amidotransferase; glutamyl-tRNA synthetase; Green Fluorescent Proteins - metabolism; Humans; malaria; Malaria - metabolism; Malaria - parasitology; Models, Molecular; Nitrogenous Group Transferases - metabolism; nucleic acid; nucleic acid enzymology; Phylogeny; plasmodium; Plasmodium falciparum - metabolism; Protein Structure, Tertiary; Protozoan Proteins - metabolism; Recombinant Proteins - metabolism; RNA, Transfer, Amino Acyl - biosynthesis; RNA, Transfer, Gln - genetics; transfer RNA (tRNA); transfer RNA (tRNA); plasmodium; nucleic acid enzymology; glutamyl-tRNA synthetase; nucleic acid; glutamyl-tRNA amidotransferase; malaria; apicoplast
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M115.655100

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 glutamyl-tRNA 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-tRNAGlnin 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. Background:Plasmodium apicoplast protein synthesis is essential for parasite survival, yet few of the enzymes involved have been biochemically characterized. Results: Nucleus-encoded apicoplast GatAB glutamyl-tRNA amidotransferase forms Gln-tRNAGln in concert with a non-discriminating glutamyl-tRNA synthetase. Conclusion: Formation of apicoplast Gln-tRNAGln is via indirect aminoacylation. Significance: The apicoplast indirect aminoacylation pathway is a potential drug target.