Rutgers’ Markus Hackl working in the laboratory. Photo: Markus Hackl.
Rutgers’ Markus Hackl working in the laboratory. Photo: Markus Hackl.

Scientists at Rutgers University have developed an analytical toolkit to measure the binding forces of single proteins when they are pulled away from their substrate. According to the scientists, this toolkit will help to develop new nanomaterials, improve biofuel production and global carbon cycling, and identify new and better drug targets.

The scientists used the toolkit to examine the molecular interactions between a carbohydrate binding module (CBM) protein and cellulose. They report their findings in a paper in the Proceedings of the National Academy of Sciences.

Cellulose, a type of plant-fiber polymer made of repeating glucose sugars, can be used to make textiles, cellophane, paperboard and paper, in addition to serving as a renewable feedstock for the production of biofuels and biochemicals. It is the most abundant organic compound on Earth that is naturally decomposed by microorganisms and hence plays a central role in the global carbon cycle.

Scientists still have a limited understanding of how microorganisms like bacteria break down cellulose by first anchoring or ‘sticking’ to its surface using carbohydrate binding proteins and enzymes. To engineer more efficient enzymes for breaking down cellulose into the sugars that can be used to produce biofuels such as ethanol, biodiesel, green diesel or biogas, scientists need to better understand how carbohydrate binding proteins anchor to cellulose. This should allow them to engineer enzymes with optimum ‘stickiness’.

“The binding of proteins and enzymes to complex carbohydrates at the solid-liquid interface is a fundamentally important biological phenomena relevant to plant growth, pathogen-host cell infections and biofuels production,” said Shishir Chundawat, senior author of the paper and an associate professor in the Department of Chemical and Biochemical Engineering at Rutgers. “But such interfacial binding processes are not well understood because of the lack of analytical tools to observe these subtle and short-lived molecular interactions between proteins and carbohydrates like cellulose.”

According to Chundawat, the toolkit developed at Rutgers can measure single protein-carbohydrate molecule contacts and associated forces with a precision of one trillionth of a newton. One newton is equivalent to the minimum force required to unstick a gecko lizard anchored to a wall or surface.

The research team studied a CBM protein that allows bacterial cells to anchor tightly to cellulose surfaces and then engineered the protein’s surface ‘stickiness’, as measured using this new toolkit, to enhance the break down of cellulose. The toolkit produced findings that were in agreement with other experiments and simulations conducted to further explain the underlying molecular rules that are responsible for CBM protein stickiness towards cellulose surfaces.

“If particular CBMs can stick to the carbohydrates in specific structural orientations that enhances enzymatic function, traditional methods are not able to differentiate one specific binding orientation from the other necessary to fine-tune protein stickiness for surfaces,” said Markus Hackl, a doctoral candidate in the Department of Chemical and Biochemical Engineering at Rutgers and first author of the paper, who led the development of the toolkit. “Our method, however, can pick up on those subtle differences in protein stickiness by detecting and measuring the signal from a single protein molecule interaction with cellulose.”

Such a toolkit can help scientists’ study and fine-tune the sticky molecular interactions between proteins and carbohydrates. This could ultimately aid in the development of better-targeting protein-based drugs for improved healthcare or efficient industrial-grade enzymes for low-cost biofuels production.

This story is adapted from material from Rutgers University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.