Fig. 2: The crystal structure of PET46 resembles the crystal structure of the IsPETase and LCC - with unique features.
From: An archaeal lid-containing feruloyl esterase degrades polyethylene terephthalate
All three proteins have the α/β-hydrolase fold and the same catalytic triad, but PET46 (coral orange; PDB 8B4U) contains a lid domain (bright green) that is not present in the IsPETase (sky blue; PDB 6EQE and 5XH3 in complex with HEMT - cyan) nor LCC (olive green, PDB 4EB0 and 7VVE in complex with MHET). Other structural differences are present in Loop 1 (deep blue) and Loop 2 (magenta), containing the active site’s His a. The bacterial and the archaeal enzymes present the typical residues of Ser-hydrolases at the catalytically active positions (Ser, His and Asp), but PET46 lacks a Trp associated with PET binding and formation of the aromatic clamp in the IsPETase and LCC. IsPETase is the only enzyme containing a disulfide bridge close to the active site b. Due to high similarity between IsPETase and LCC, and for clarity, only PET46 and IsPETase are shown in “a”. *5XH3 and 7VVE are inactive mutants.
