Conformational changes of the motif 2 loop and the ordering loop. (a, b) Overall structures of the triclinic crystal form of PylRS(c270) (PDB entry 3vqx
, molecule A). The motif 2 and ordering loops are coloured red. (c, d) Close-up stereoviews of motif 2 and the ordering loops (boxed regions in a and b). The superpositioned Cα traces of the AMP-bound (red and cyan traces; residues 277–286 and 331–337) and BocLys-AMP-bound forms (yellow and orange traces; residues 277–286 and 331–337) with those of the ligand-free (dark blue trace; residues 277–286 and 331–337; PDB entry 2e3c
) and two AMPPNP-bound forms (green and pink traces; residues 277–286 and 331–337; PDB entries 2zcd
) are shown. Arrows indicate the open-to-closed conformations of the motif 2 and ordering loops.