Distinctive kinetics and substrate specificities of plant and fungal tRNA ligases

Purine NTP analogs as substrates for the KlaTrl1 kinase reaction. Reaction mixtures (20 µL) containing 50 mM Tris-HCl, pH 8.0, 2 mM DTT, 10 mM MgCl₂, 20 nM _HOR10>p, 1 µM KlaTrl1-(385–813), and 1, 10, or 100 µM of the indicated purine NTPs were incubated at 22°C for 1 min. The extents of 5′ phosphorylation are plotted in bar graph format as a function of NTP or dNTP concentration. Each datum is the average of three separate experiments ±SEM. The chemical structures of the nucleobases are shown below the graph.