Improving Yield and Thermostability of PETase as a Maltose Binding Protein Fusion in the Periplasm of Escherichia coli

초록

Polyethylene terephthalate (PET) waste accumulation requires sustainable recycling alternatives. While Ideonella sakaiensis PETase offers a green solution, its industrial application is hindered by low solubility and poor thermostability. In this study, we systematically evaluated the synergistic effects of maltose-binding protein (MBP) fusion and periplasmic translocation strategies to optimize PETase production in Escherichia coli. Our results demonstrate that MBP acts as a potent solubilizing partner for PETase, with the cytosolic MBP-PETase variant achieving a high purification yield of 8.4 mg per gram of wet cell weight-a significant improvement over the PelB-PETase control (1.1 mg per gram of wet cell weight). Furthermore, the periplasmic MalE-MBP-PETase construct provided an optimal intermediate compromise between the yield, thermal stability, and catalytic activity by leveraging the oxidative environment of the periplasm for critical disulfide bond formation. Although PelB-PETase exhibited higher specific activity, its low yield limits industrial scalability. This study establishes a robust plug-and-play platform for high-throughput PET depolymerization, providing a foundational step toward a circular plastic economy.

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