New enzyme discovery is another leap towards beating plastic waste


Date:
March 21, 2022
Source:
University of Portsmouth
Summary:
Scientists who helped to pioneer the use of enzymes to eat plastic
have taken an important next step in developing nature-based
solutions to the global plastics crisis. They have characterized
an enzyme that has the remarkable capacity to help break down
terephthalate (TPA), one of the chemical building blocks of
polyethylene terephthalate (PET) plastic, which is used to make
single-use drinks bottles, clothing and carpets.



FULL STORY ========================================================================== Scientists who helped to pioneer the use of enzymes to eat plastic have
taken an important next step in developing nature-based solutions to
the global plastics crisis.


==========================================================================
They have characterised an enzyme that has the remarkable capacity
to help break down terephthalate (TPA), one of the chemical building
blocks of polyethylene terephthalate (PET) plastic, which is used to
make single-use drinks bottles, clothing and carpets.

The research, which is published inThe Proceedings of the National Academy
of Sciences (PNAS), was co-led by Professor Jen DuBois, Montana State University, and Professor John McGeehan from the University of Portsmouth,
who in 2018 led the international team that engineered a natural enzyme
that could break down PET plastic. The enzymes (PETase and MHETase)
break the PET polymer into the chemical building blocks ethylene glycol
(EG) and TPA. This new research describes the next steps, specifically
for managing TPA.

Professor DuBois said: "While EG is a chemical with many uses -- it's
part of the antifreeze you put into your car, for example -- TPA does
not have many uses outside of PET, nor is it something that most bacteria
can even digest.

However, the Portsmouth team revealed that an enzyme from PET-consuming bacteria recognises TPA like a hand in a glove. Our group at MSU then demonstrated that this enzyme, called TPADO, breaks down TPA and pretty
much only TPA, with amazing efficiency." With more than 400 million
tons of plastic waste produced each year, the overwhelming majority of
which ends up in landfills, it is hoped this work will open the door
to improve bacterial enzymes, such as TPADO. This will help tackle the challenge of plastic pollution and develop biological systems that can
convert waste plastic into valuable products.

Professor McGeehan, who is the Director of the University's Centre
for Enzyme Innovation, said: "The last few years have seen incredible
advances in the engineering of enzymes to break down PET plastic into its building blocks. This work goes a stage further and looks at the first
enzyme in a cascade that can deconstruct those building blocks into
simpler molecules. These can then be utilised by bacteria to generate sustainable chemicals and materials, essential making valuable products
out of plastic waste.

"Using powerful X-ray at the Diamond Light Source, we were able to
generate a detailed 3D structure of the TPADO enzyme, revealing how
it performs this crucial reaction. This provides researchers with a
blueprint for engineering faster and more efficient versions of this
complex enzyme." The study was undertaken as part of the BOTTLE
Consortium, an international collaboration between the US and UK,
bringing together researchers from across a wide range of scientific
areas to tackle plastic recycling and upcycling.


========================================================================== Story Source: Materials provided by University_of_Portsmouth. Note:
Content may be edited for style and length.


========================================================================== Journal Reference:
1. William M. Kincannon, Michael Zahn, Rita Clare, Jessica Lusty
Beech, Ari
Romberg, James Larson, Brian Bothner, Gregg T. Beckham, John
E. McGeehan, Jennifer L. DuBois. Biochemical and structural
characterization of an aromatic ring-hydroxylating dioxygenase
for terephthalic acid catabolism.

Proceedings of the National Academy of Sciences, 2022; 119 (13)
DOI: 10.1073/pnas.2121426119 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2022/03/220321150409.htm

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