Fig. 3: The protein structure of archaeal PETase PET46 and ferulic acid esterases (FAEs) is closely related to bacterial PETases.

A heatmap represents structure similarity (Z-Score⁸⁷) and reveals structural clusters. The FAE cluster, to which PET46 (coral orange) belongs, shows the highest similarity to the cluster of bacterial PETases. PET 46 is the FAE with the highest structural similarity to the bacterial PETases. Enzymes for which no activity on PET has been proven (e.g., FAEs) are shown in gray a. PET46 shares most of its structure with FAEs b. The structure of the archaeal PETase (coral orange) is overlaid to the crystal structure of the cinnamoyl esterase LJ0536 S106A mutant from Lactobacillus johnsonii (dark gray, PDB 3QM1) in complex with ethylferulate (EF, cyan). Loop 1 (deep blue) and Loop 2 (magenta) are highly conserved, but there are some variations in the lid domain (bright green). A Tyr in the loop of LJ0536 involved in substrate binding has a homologous Phe in PET46 (bright green). For structural alignments with other two FAEs and the tannase IsMHETase, see Supplementary Fig. 4. *No obvious phylogenetic affiliation. Data supporting panel “a” can be found in Supplementary Data 2.