Building on the plastic-eating enzyme success:
Following the success of the discovery of a plastic eating enzyme, The University of Portsmouth’s Professor John McGeehan and his team have done it again, this time with the discovery of a family of plant eating enzymes. The enzymes discovered digest lignin, one of the main components of plants, and could have similar potential in the application of recycling as their plastic-eating cousin by converting plant waste in to sustainable and high-value products, such as nylon, plastics, chemicals, and fuels. It is believed that there is potential for industrial application of both of these enzymes.
Lignin provides plants with a type of scaffolding and plays a key role in water delivery, providing strength and protection from pathogens. For many decades, scientists have attempted to find ways to break down lignins and, more over, it appears that the family of enzymes discovered are promiscuous in that they are able to break down a variety of lignin based products.
Professor John McGeehan explained that:
“To protect their sugar-containing cellulose, plants have evolved a fascinatingly complicated material called lignin that only a small selection of fungi and bacteria can tackle. However, lignin represents a vast potential source of sustainable chemicals, so if we can find a way to extract and use those building blocks, we can create great things.”
Publication in Nature Communications
The study in Nature Communications is is published today and builds on current work engineering enzymes. The plastic eating enzyme PETase was accidently improved through trying to understand how it works in the lab. Similar techniques at the Diamond Light Source were used to determine the crystalline structure of the enzymes. Professor McGeehan’s team have discovered that microbial anabolic catabolism is a promising approach to convert lignin in to useful products and that demethylation of lignin monomers is a new tool for a critical step in biological lignin conversion.
Professor McGeehan said:
“It’s an amazing material, cellulose and lignin are among the most abundant biopolymers on earth. The success of plants is largely due to the clever mixture of these polymers to create lignocellulose, a material that is challenging to digest.”
A collaborative approach
Professor McGeehan and his team worked in collaboration with Dr Greg Beckham at the US Department of Energy’s National Renewable Energy Laboratory (NREL), Professor Jen Dubois at Montana State University, and Professor Ken Houk at the University of California, Los Angeles. Lead author of the paper is University of Portsmouth PhD student Sam Mallinson, who said:
“There is a long-standing phrase – you can make anything out of lignin except money – but by harnessing the power of enzymes, this is set to change. Using advanced techniques, from X-ray crystallography at the Diamond Light Source synchrotron, to advanced computer modelling, we have been able to understand the detailed workings of a brand new enzyme system.”
The enzyme discovered is a new class of Cytochrome P450. Dr Beckham explained:
“This new cytochrome P450 enzyme can degrade a lot of different lignin-based substrates. That’s good because it means it can then be engineered to be a specialist for a specific molecule and we can evolve it further to push it in a certain direction.
“We now have one of the most well-known, versatile, engineerable and evolvable classes of enzymes ready to go as a foothold for biotechnology to move forward and make the enzyme better.”
Another study published in the journal PNAS, led by Professor Ellen Neidle at the University of Georgia together with members of this team, which found a way of speeding up the evolution of this enzyme, will now work together to discover and evolve even faster enzymes to enable the development of lignin-based high-value sustainable products.
It is exciting news that Professor John McGeehan plays such a key role in the development of biological catalysts that could be responsible for the eradication of what are two of society’s most problematic waste products. This could help discover a whole new approach to how we manufacture and dispose of these products.
The research has been jointly funded by the Biotechnology and Biological Sciences Research Council (BBSRC), National Science Foundation (NSF), and the DOE EERE Bioenergy Technologies Office.
You can find out more information about Professor John McGeehan as a researcher in our previous blog post Behind the research: Professor John McGeehan and unlocking a solution for the problem of plastic on our planet.