Team:KEYSTONE/Contribution
We made an informational contribution to the part PETase (Part:BBa_K2010999) on the usage of a two-enzyme system with MHETase to increase degradation efficiency based on a study by Brandon C. Knott et al. See Part:BBa_K2010999.
The deconstruction of recalcitrant polymers is done in nature by synergistic enzyme cocktails. There is a recent discovery on a type of two-enzyme system for the structure of polyethylene terephthalate（PET). This system used a kind of enzyme to transform the polymer to a soluble intermediate and another kind of enzyme for constituent PET monomer production. This discovery suggests that nature may start to involve with the deconstruction of synthetic plastics. The evolution of microbes is with the ability to use synthetic polymers as sources of carbon and energy. Ideonella sakaiensis was found recently to secrete a two-enzyme system. The sakaiensis PETase depolymerizes PET, and release soluble products, such as 2-hydroxyethy, MHET that was cleaved from the terephthalic acid and ethylene glycol by MHETase. 1.6 Å resolution MHETase structure was recorded, which means MHETase core domain is covered by a lid domain and has similarity with PETase. Simulations of catalytic itinerary predict the MHETase uses the typical two-step serine hydrolase mechanism. The Bioinformatics analysis said the MHETase is a result of the evolution of ferulic acid esterases, and the two homologous enzymes show the exhibit of MHET turnover. The result of two homologous enzymes and MHETase S131G also shows the residue is very important for the accommodation of MHET about the active site. MHETase lid is also important to hydrolysis of MHET, and MHETase does not turnover mono-furanoate of mono-isophalate. Also, all exhibit improved PET and MHET show turnover to free enzymes of the PETase chimeric proteins of linker lengths. These results suggested information for future work on the two-enzyme PET depolymerization, and can contribute to future deconstruction of plastics through biological ways.
References:
Brandon C. Knott (13 Oct. 2020.). Characterization and engineering of a two-enzyme system for plastics depolymerization. PNAS. Retrieved from https://www.pnas.org/content/117/41/25476.
