Fig. 2.

¹H, ¹⁵N chemical shift assignment of the imino and amino groups of E. coli tRNA^Asp(GUC). (a) Sequence and L-shape 2D representation of modified E. coli tRNA^Asp(GUC). Modified residues are represented in red. The nature of interactions between base pairs is described according to the classification by Leontis and Westhof (Leontis and Westhof 2001). (b) (¹H,¹⁵N)-BEST-TROSY spectrum and assignment of the imino groups of unmodified and modified E. coli tRNA^Asp. Signals from the unmodified sample are represented in blue and signals from the modified sample are in red. Asterisks denote peaks in the modified sample that correspond to a subpopulation in which U65 is not modified into Ψ65. (c) (¹H,¹⁵N)-BEST-TROSY-HNN-COSY spectrum showing correlations across hydrogen bonds in the modified tRNA^Asp. (d) (¹H,¹⁵N)-CPMG-NOESY-HSQC enabling the chemical shift assignment of the amino groups in the modified tRNA^Asp. (e) (¹H,¹⁵N)-HSQC spectrum showing the chemical shift assignment of the NH₂-amino groups of modified tRNA^Asp