Fig. 5
From: Catalytic mechanism and molecular engineering of quinolone biosynthesis in dioxygenase AsqJ
Crystal structure of the AsqJ_V72I mutant. a) Close-up of the active site in complex with 1d (shown in green). The amino acids engaged in ligand binding are depicted as sticks and labeled by the one letter code, α-ketoglutarate (αKG) shown in orange, and NiII is shown as a black sphere. The electron density depicts a 2Fo–Fc map with I72, H134, and 1d omitted for phasing. I72 contains two alternative conformations with an occupancy of ~50% (PDB ID: 5OA8). An extra lobe of electron density around the phenyl ring of 1d indicates increased mobility of the phenyl ring. b Structure of the active site superposition of AsqJ_V72I:1d with the wt AsqJ:1d (shown in gray; PDB ID: 5DAX). π-stacking and coordination of the metal atom are indicated by black-dotted lines. Note that the surrogate 1d adopts identical positions in both crystal structures, while there are only marginal shifts in the distances of I72 coordinating the aromatic moiety of the ligand
