The ATP-mediated formation of the YgjD-YeaZ-YjeE complex is required for the biosynthesis of tRNA t super(6)A in Escherichia coli

• Published in: Nucleic acids research 2015-02, Vol.43 (3), p.1804-1817
• Main Authors: Zhang, Wenhua, Collinet, Bruno, Perrochia, Ludovic, Durand, Dominique, van Tilbeurgh, Herman
• Format: Article
• Language: English
• Subjects: Escherichia coli
• ISSN: 0305-1048; 1362-4962
• DOI: 10.1093/nar/gku1397

The essential and universal N super(6)-threonylcarbamoylade nosine (t super(6)A) modification at position 37 of ANN-decoding tRNAs plays a pivotal role in translational fidelity through enhancement of the cognate codon recognition and stabilization of the codon-anticodon interaction. In Escherichia coli, the YgjD (TsaD), YeaZ (TsaB), YjeE (TsaE) and YrdC (TsaC) proteins are necessary and sufficient for the in vitro biosynthesis of t super(6)A, using tRNA, ATP, L-threonine and bicarbonate as substrates. YrdC synthesizes the short-lived L-threonylcarbamoyladenylate (TCA), and YgjD, YeaZ and YjeE cooperate to transfer the L-threonylcarbamoyl-moiety from TCA onto adenosine at position 37 of substrate tRNA. We determined the crystal structure of the heterodimer YgjD-YeaZ at 2.3 Aa, revealing the presence of an unexpected molecule of ADP bound at an atypical site situated at the YgjD-YeaZ interface. We further showed that the ATPase activity of YjeE is strongly activated by the YgjD-YeaZ heterodimer. We established by binding experiments and SAXS data analysis that YgjD-YeaZ and YjeE form a compact ternary complex only in presence of ATP. The formation of the ternary YgjD-YeaZ-YjeE complex is required for the in vitro biosynthesis of t super(6)A but not its ATPase activity.