Figure 2

The overall structure of E. coli TdcF. Ribbon representation of the E. coli TdcF structure. Shown is the 2-ketobutyrate-bound form with the individual subunits coloured green, blue and grey; the 2-ketobutyrate ligands are shown in space-filling representation in yellow. Part of the loop between β1 and β2 that moves depending on the status of the ligand-binding pocket is shown in red for each subunit. The inset shows the extent of this movement in the various states, where: grey = empty site; blue = ethylene glycol-bound; yellow = serine-bound; green = propionate-bound; red = 2-ketobutyrate-bound. The small spheres indicate the variation in the position of the Cα atom of Ile-14, being the residue that is displaced the most (maximum displacement 4.2Å). It is notable that the loop is poorly ordered in the empty site and best resolved in the in the 2-ketobutyrate-bound site, where Ile-14 makes non-bonding interactions with the ligand. Figure generated using PyMOL [31].