Comparison of human CMTr1 with human CMTr2 and trypanosome TbMTr1. (A) Superimposition of human CMTr1 (red), modeled human CMTr2 (gray), and trypanosome TbMTr1 (blue). Magenta circles indicate the base which has been removed for clarity. The position of the cap analog (light blue) and the SAM (yellow) were inserted by superimposition from the published structure (PDB 4n48). (B) Configuration of the four amino acids forming the catalytic center of human CMTr1 (red), modeled human CMTr2 (gray), and trypanosome TbMTr1 (blue). Magenta circles indicate the base which has been removed for clarity. (C) Substrate and cofactor recognition of human CMTr1 (red), modeled human CMTr2 (gray), and trypanosome TbMTr1 (blue). Amino acids contacting the cap binding are shown on top and amino acids contacting the cofactor SAM (yellow) are shown at bottom. The catalytic center is indicated by a dashed circle, and the turquoise circle indicates solvent facing. Contacts of amino acids via side chains are indicated by purple circles and via the backbone in green circles. Green and blue thin dashed lines indicate direct hydrogen bonds and hydrogen bonds via a water molecule, respectively. Magenta thick dashed lines indicate aromatic stacking. Methyl-groups are shown in yellow circles.
