Structure of the plastic-degrading Ideonella sakaiensis MHETase bound to a substrate.
Palm, G.J., Reisky, L., Bottcher, D., Muller, H., Michels, E.A.P., Walczak, M.C., Berndt, L., Weiss, M.S., Bornscheuer, U.T., Weber, G.(2019) Nat Commun 10: 1717-1717
- PubMed: 30979881 
- DOI: https://doi.org/10.1038/s41467-019-09326-3
- Primary Citation of Related Structures:  
6QG9, 6QGA, 6QGB, 6QGC - PubMed Abstract: 
The extreme durability of polyethylene terephthalate (PET) debris has rendered it a long-term environmental burden. At the same time, current recycling efforts still lack sustainability. Two recently discovered bacterial enzymes that specifically degrade PET represent a promising solution. First, Ideonella sakaiensis PETase, a structurally well-characterized consensus α/β-hydrolase fold enzyme, converts PET to mono-(2-hydroxyethyl) terephthalate (MHET). MHETase, the second key enzyme, hydrolyzes MHET to the PET educts terephthalate and ethylene glycol. Here, we report the crystal structures of active ligand-free MHETase and MHETase bound to a nonhydrolyzable MHET analog. MHETase, which is reminiscent of feruloyl esterases, possesses a classic α/β-hydrolase domain and a lid domain conferring substrate specificity. In the light of structure-based mapping of the active site, activity assays, mutagenesis studies and a first structure-guided alteration of substrate specificity towards bis-(2-hydroxyethyl) terephthalate (BHET) reported here, we anticipate MHETase to be a valuable resource to further advance enzymatic plastic degradation.
Organizational Affiliation: 
Molecular Structural Biology, University of Greifswald, Felix-Hausdorff-Str. 4, 17487, Greifswald, Germany.