Figure 2
Active site of TpCSH6 subunit A bound to the C-terminus of subunit D (blue bonds). All illustrated residues also contact OAA (His262 and Arg271) or AcCoA (the remainder). His222 and Asp317 are responsible for deprotonating the AcCoA acetyl group, stabilizing the resulting enolate/carbanion and promoting the condensation reaction that produces CitCoA. An intra-residue hydrogen bond that stabilizes the neutral π tautomer of His222 is shown in black. A similar analysis of the TpCS active site bound to the CitCoA analogue CitMX (Supplementary Fig. S8) shows that many of the same residues are involved in substrate contacts. All polar contacts presumed to result in hydrogen-bonding interactions are shown, with distances in Å. |