Structural comparison of TrmIs. A The electrostatic surfaces of each TrmI protein were determined using PYMOL/APBS and are colored by the electrostatic potential. The values of surface potential range from -72 kT/e (red) to +72 kT/e (blue). a MtTrmI b TtTrmI c TmTrmI d AaTrmI e PaTrmI. B Stereoview of the tetrameric architecture of AaTrmI with the SAM ligand in red sticks. The structure is shown with a 45 degree rotation around the vertical symmetry axis compared to Figure 1A. C Closer view showing the tetrameric interface in two orthogonal orientations. The main secondary structure elements are labeled. D Stereo view of the superimposition of the monomer from the six TrmI structures. The Cαs of residues 85 to 263 corresponding to the C-terminal domain (TmTrmI numbering) are superposed. PaTrmI (PDB code 3MB5), AaTrmI, HsTrmI, MtTrmI, TmTrmI and TtTrmI are drawn in green, cyan, yellow, pink, orange and purple, respectively, and SAM in red sticks. The N-and C-termini are indicated by the letters N and C, respectively. E View of one monomer of PaTrmI (PDB code 3MB5) labeled with the secondary structure elements and with the polypeptide chain colored according to the B-factors (low B-factor in blue, high B-factor in red).