Fojan, P. | Search bioRxiv

bioRxiv2023

De novo Design of a Polycarbonate Hydrolase

Enzymatic degradation of plastics is currently limited to the use of engineered natural enzymes. As of yet, all engineering approaches applied to plastic degrading enzymes retain the natural /{beta} -fold. While mutations can be used to increase thermostability, an inherent maximum likely exists for the /{beta} -fold. It is thus of interest to introduce catalytic activity toward plastics in a different protein fold to escape the sequence space of plastic degrading enzymes. Here, a method for designing highly thermostable enzymes that can degrade plastics is described. This has been used to design an enzyme that can catalyze the hydrolysis of polycarbonate, which no known natural enzymes can degrade. Rosetta enzyme design is used to introduce a catalytic triad into a set of thermostable scaffolds. Through computational evaluation, a potential PCase was selected and produced recombinantly in E. coli. CD spectroscopy suggests that the design has a melting temperature of >95{degrees}C. Activity towards a commercially used polycarbonate (Makrolon 2808) was confirmed using AFM, which showed that a PCase had been designed successfully. O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=58 SRC="FIGDIR/small/532063v1_ufig1.gif" ALT="Figure 1"> View larger version (15K): org.highwire.dtl.DTLVardef@1369436org.highwire.dtl.DTLVardef@3c87b3org.highwire.dtl.DTLVardef@1f1138forg.highwire.dtl.DTLVardef@3b4bba_HPS_FORMAT_FIGEXP M_FIG C_FIG

synthetic biology↗

bioRxiv2022

Biochemical characterization and NMR study of a PET-hydrolyzing cutinase from Fusarium solani pisi

In recent years, the drawbacks of plastics have become evident, with plastic pollution becoming a major environmental issue. There is an urgent need to find solutions to efficiently manage plastic waste by using novel recycling methods. Biocatalytic recycling of plastics by using enzyme-catalyzed hydrolysis is one such solution that has gained interest, in particular for recycling polyethylene terephthalate (PET). To provide insights into PET hydrolysis by cutinases, we have here characterized the kinetics of a PET-hydrolyzing cutinase from Fusarium solani pisi (FsC) at different pH values, mapped the interaction between FsC and the PET analog BHET by using NMR spectroscopy, and monitored product release directly and in real time by using time-resolved NMR experiments. We found that primarily aliphatic side chains around the active site participate in the interaction with BHET, and that pH conditions and mutation around the active site (L182A) can be used to tune the relative amounts of degradation products. Moreover, we propose that the low catalytic performance of FsC on PET is caused by poor substrate binding combined with slow MHET hydrolysis. Overall, our results provide insights into obstacles that preclude efficient PET hydrolysis by FsC and suggest future approaches for overcoming these obstacles and generating efficient PET-hydrolyzing enzymes. TOC Graphic (For Table of Contents use only) O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=116 SRC="FIGDIR/small/514593v2_ufig1.gif" ALT="Figure 1"> View larger version (30K): org.highwire.dtl.DTLVardef@1f59d35org.highwire.dtl.DTLVardef@242467org.highwire.dtl.DTLVardef@d2198eorg.highwire.dtl.DTLVardef@18bba0d_HPS_FORMAT_FIGEXP M_FIG C_FIG

biochemistry↗