Exploring the Determinants of PETase Activity through Protein Engineering and Structural Bioinformatics

Abstract

Enzymatic plastic recycling has been proposed as a sustainable alternative to the traditional open-loop recycling methods, allowing for the de-coupling of plastic use and production from fossil-fuels. However, the feasibility of the process is highly dependent on enzymes achieving high depolymerisation extents in short periods of time. Engineering for thermostability has taken us so far, however the lack of understanding regarding how exactly the proteins interact with each other and with the plastic increases the complexity of the challenge. In this thesis, through question- driven approaches we take a deeper dive into factors that affect the viability of using enzymes to recycle plastic at scale. By investigating how thermostability of accessory domains affect the activity of PETases, studying the mechanism underlying concentration-dependent inhibition, and engineering electrostatics to control substrate morphology preference and enzymatic synergy, the work in this thesis clarifies some of the interactions happening at the polymer surface and defines the rules necessary to engineer them.

Date of Award	31 Mar 2025
Original language	English
Awarding Institution	University of Portsmouth
Supervisor	Bruce Lichtenstein (Supervisor), Birte Hocker (Supervisor) & Sam Robson (Supervisor)