Figure 1
From: A single mutation in the core domain of the lac repressor reduces leakiness
Binding promiscuity in the inducer binding pocket of LacI. A. Superposition of LacI PDB structures [PDB:2P9H] (dark red), [PDB:1LBH] (orange), [PDB:2PAF] (light blue) and [PDB:1EFA] (dark blue) showing the three-domain architecture of the protein. The second monomer of each structure is coloured in grey. IPTG (from structure 2P9H) is shown in black sticks. B. LacI binding pocket with the small molecule effectors IPTG (2P9H and 1LBH) and ONPF (2PAF and 1EFA). Interacting side chains as calculated by the DistancesRH pymol script (see Additional file1: Table S1 for details) are shown. Structures follow the same colour-code and order as in panel A. The side chain of tryptophan 220 is depicted in black. Note how 1LBH and 1EFA show IPTG and ONPF, respectively, bound in opposite orientations to those seen in 2P9H and 2PAF.