Plastic Degrading Enzyme Enhanced

Researchers in South Korea have used genetic engineering to improve the ability of a bacterial enzyme to degrade plastic waste.

AsianScientist (Feb. 7, 2018) – A research group at the Korea Advanced Institute of Science and Technology (KAIST) in South Korea has identified the mechanism of plastic-degrading enzymes in bacteria. They also modified the enzyme to enhance its activity. Their findings are published in Nature Communications.

Poly (ethylene terephthalate) (PET), the main compound in plastics, is an important material in our daily lives. However, PET after use causes tremendous contamination issues to our environment due to its non-biodegradability. Conventionally, PET is disposed of in landfills, incinerated, or recycled using chemical methods, which further contribute to environmental pollution. This highlights a need for highly-efficient PET degrading enzymes to break down PET in an ecologically friendly manner.

In 2016, a new bacterial species, Ideonella sakaiensis, which can use PET as a carbon source, was isolated. The PETase of I. sakaiensis (IsPETase) can degrade PET with relatively higher success than other PET-degrading enzymes. However, the detailed enzyme mechanism has not been elucidated, hindering further studies.

In this study, a team of scientists led by Professor Lee Sang Yup at KAIST and Professor Kim Kyung-Jin at the Kyungpook National University obtained the three-dimensional (3D) crystal structure of IsPETase and uncovered the mechanism by which it degrades PET.

Based on the 3D structure and related biochemical studies, they successfully predicted the reasons for extraordinary PET degrading activity of IsPETase and suggested other enzymes that can degrade PET with a newly-classified phylogenetic tree. Furthermore, they succeeded in developing a new variant of IsPETase with much higher PET-degrading activity, showing that the altered structure of the variant better accommodates PET substrates than wild type PETase.

“Environmental pollution from plastics remains one of the greatest challenges worldwide with the increasing consumption of plastics. We successfully constructed a superior PET-degrading variant with the determination of a crystal structure of PETase and its degrading molecular mechanism,” said Lee.

“This novel technology will help further studies to engineer other superior enzymes with high efficiency in degrading plastics. This will be the subject of our team’s ongoing research projects to address the global environmental pollution problem for next generation,” said Lee.

The article can be found at: Joo et al. (2018) Structural Insight into Molecular Mechanism of Poly(ethylene terephthalate) Degradation.


Source: Korea Advanced Institute of Science and Technology; Photo: Pixabay.
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