Poly(ethylene terephthalate) (PET)
is one of the most commonly
used plastics worldwide and its accumulation in the environment is
a global problem. PETase from Ideonella sakaiensis 201-F6 was reported to exhibit higher hydrolytic activity and specificity
for PET than other enzymes at ambient temperature. Enzymatic degradation
of PET using PETase provides an attractive approach for plastic degradation
and recycling. In this work, extracellular PETase was achieved by Escherichia coli BL21 using a Sec-dependent translocation
signal peptide, pelB, for secretion. Furthermore, engineering of the
pelB through random mutagenesis and screening was performed to improve
the secretion efficiency of PETase. Evolved pelB enabled higher PETase
secretion by up to 1.7-fold. The improved secretion of PETase led
to more efficient hydrolysis of the PET model compound, bis (2-hydroxyethyl)
terephthalic acid (BHET), PET powder, and PET film. Our study presents
the first example of the increasing secretion of PETase by an engineered
signal peptide, providing a promising approach to obtain extracellular
PETase for efficient enzymatic degradation of PET.
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