Fig. 5.

Pi-stacking interactions in binding of uracil or thymine. Amino acids that directly interact with the substrate nucleobase are shown for B. bronchiseptica WbmF and WbmG, E. coli GalE, S. venezuelae DesIV and P. aeruginosa WbpP with carbon atoms coloured yellow. UMP or dTDP from each structure is shown with carbon atoms in white. Amino acid side chains that have pi-stacking interactions with the base are labelled, and hydrogen-bonding interactions with the peptide backbone are indicated as dashed lines. Images for GalE, DesIV and WbpP were prepared using PDB files 1LRL,²⁴1R6D²³ and 1SB8,²⁵ respectively.