Figure 4.

Structure-based multiple sequence alignment of seven APH enzymes and Rv3168 (PDB codes: 1L8T, 1ND4, 3HAM, 3TDV, 3SG8, 3TYK, 3I0O, 3ATT). Secondary structural elements are shown above the alignment with nomenclature corresponding to APH(2″) enzymes. Residues are color-coded based on location: nucleoside pocket (blue), triphosphate pocket (yellow), catalytic pocket (green), and specificity pocket (purple). The catalytic aspartate is highlighted in red. Conserved residues are indicated with a star. Residues with a gray background were found in structurally identical locations, and in cases where two subsets of enzymes have different structurally conserved elements, a tan background was used in addition to gray. Residues with a white background represent structural elements or conformations specific to a single enzyme. Inserts are shown as purple boxes, with the number displayed indicating the number of residues inserted at that location.