Fig. 2: The structures of SxtT and GxtA with their native hydroxylated substrates bound reveal the essential active site interactions.
From: Design principles for site-selective hydroxylation by a Rieske oxygenase
a The quaternary trimeric architectures of each determined structure are shown as ribbon diagrams and overlaid with each other (SxtT with β-STOH bound is shown in gray, GxtA with β-STOH bound is shown in pink, and GxtA with STX bound is shown in teal). The metallocenters that bridge two subunits are highlighted in purple and the substrate-binding site of one subunit is highlighted in teal. b The structure of SxtT with β-STOH bound reveals the myriad of interactions that this molecule forms in the active site. Tyr198 (gray font) interacts with the β-hydroxyl group of β-STOH via a water molecule. c STX binds in the active site of GxtA. The α-hydroxyl group interacts with active site residues Ser159 and Tyr255 (cyan font). d Despite the similar makeup of the GxtA active site relative to SxtT, β-STOH binds in a remarkably different orientation and interacts with conserved residues Gln226 and Asp239. In all panels, the position of hydroxylation is marked with a red asterisk.
