Monohydroxyethyl terephthalate (MHET) hydrolase (MHETase) is an enzyme known to be involved in the final degradation step of poly(ethylene terephthalate) (PET) by hydrolyzing MHET into terephthalic acid and ethylene glycol in Ideonella sakaiensis. Here, we report the extracellular production of MHETase in an active form with a proper folding. Based on the structural observations and biochemical experiments, we reveal that MHETase also functions as exo-PETase by hydrolyzing the synthesized PET pentamer. We further present that MHETase has a hydrolysis activity against the termini-generated PET film, demonstrating the exo-PETase function of the enzyme. We also develop a MHETaseR411K/S416A/F424I variant with a higher BHET activity, and the variant exhibits an enhanced degradation activity against the PET film. Based on these results, we propose that MHETase plays several roles in the biodegradation of PET using the BHETase and exo-PETase activities as well as the MHET hydrolysis function.
Bibliographical noteFunding Information:
This work was supported by the Cooperative Research Program for Agricultural Science & Technology Development (project no. PJ01492602), Rural Development Administration, Republic of Korea. H.-Y.S. and H.S. were supported by the Global Ph.D. Fellowship Program of the Korean Government (2017H1A2A1042052 and 2018H1A2A1061751, respectively).
© 2020 American Chemical Society.
Copyright 2020 Elsevier B.V., All rights reserved.
- Ideonella sakaiensis
- extracellular production
- polyethylene terephthalate (PET)
ASJC Scopus subject areas
- General Chemistry