Overview
of
PET-Degrading
Enzymes
POLYETHYLENE terephthalate (PET) is a widely used
plastic with an extremely slow degradation process,
causing severe environmental pollution. In recent years, researchers found that certain
microorganisms can secrete specific enzymes (e.g., PETase, MHETase) to degrade PET.PET-degrading
enzymes mainly belong to the cutinase family and also include some esterases with
similar structures and functions. These enzymes can hydrolyze the ester bonds in PET, breaking it
into more easily metabolizable small molecules like terephthalic acid (TPA) and ethylene glycol
(EG).
HOWEVER, most known wild-type PET-degrading enzymes
and engineered high-activity variants like IsPETase and ICCG are mainly from terrestrial sources and
work best under low-salinity conditions. Thus, their applicability is greatly limited in high-salt
environments.Our main objective is to mine PET-degrading enzymes from marine microbial
metagenomes
and modify them to enhance enzymatic activity. This approach aims to solve the problem of
PET
microplastic pollution in high-salinity water bodies and expand the practical application scope of
these enzymes in marine environmental remediation.
MarineDerived
PET-Degrading
Enzymes
THE
marine environment is one of the richest in
biodiversity on Earth. In recent years, through
metagenomic technology, scientists have identified multiple potential PET-degrading enzyme sequences
from marine samples
PET05 is widely regarded as one of the most
representative and valuable candidate enzymes among
marine-derived PET-degrading enzymes, due to its well-characterized structure and function,
moderate
sequence conservation, and verified capabilities such as PET degradation and thermal stability.
PET05 —
Engineering
Modification
THE
ThermoMPNN – A deep learning-based tool used to
design thermostable enzyme variants by
predicting
mutations that enhance thermal properties. AlphaFold – A structural prediction algorithm that
provides high-resolution 3D structures of the enzyme, facilitating rational design of mutations.
FoldX – A computational tool employed to evaluate the effects of mutations on protein stability
and folding.
Determination of enzyme activity
Data measurement and comparison
FROM these predicted and
designed mutations, mutants
are constructed, followed by enzyme activity
assays to evaluate their performance. Experimental data are then fed back into the computational
pipeline, guiding the design of combinatorial mutations for further optimization.
This iterative
process enables the systematic enhancement of PET05's catalytic efficiency and stability under
various environmental conditions.
PET05 —
Discovery Pipeline,
Seed Sequence
PSI-BLAST — A
bioinformatics tool for protein
sequence
alignment. It improves the detection of
evolutionarily related, distantly homologous proteins by iteratively searching sequence
databases
and building a Position-Specific Scoring Matrix (PSSM). GOMC — A search database that integrates
resources from the NCBI, Ocean Microbiomics Database (OMD), and publicly available marine
bacterial
and archaeal genomeses from OceanDNA4 and OceanDNA6.
In
bioinformatics-based discovery, selecting an
appropriate "seed" sequence is critical for
effective
BLAST analysis. PET05 serves as a well-characterized seed sequence, enabling the identification
of
related sequences in marine environmentsswith high specificity and sensitivity.
How can we save our oceans and our planet from plastic
pollution？
We will utilize the plastic-degrading enzymes derived
from the ocean, continuously exploring, optimizing and modifying them.
What mysteries have we discovered from the marine
metagenome?
We have discovered the future of synthetic biology and
enzyme engineering, just like a gold mine.
