Figure 1.

aa-AMP hydrolysis by Hint1 is general. Hint1 was incubated with alpha-³²P-ATP, l-lysine, and separately with five different tRNA synthetases, with/without the cognate amino acids. The reaction was quenched at 1 min and analyzed by SDS-PAGE and autoradiography. Although lysine is present in each reaction mixture, Hint1-AMP only forms when LysRS is present, or when there is another tRNA synthetase with its cognate amino acid. An active site mutant Hint1_H114A, which was characterized in this work, was also used to coincubate with LysRS and l-Lys.