Two University researchers have made a discovery that could pave the way to expanded sources of renewable energy.

Debra Mohnen, a faculty member in the University’s Complex Carbohydrate Research Center, and Melani Atmodjo, a postgraduate scholar in the Center, have broken new ground in research on how plant cell walls are formed.

The researchers have discovered that two proteins, GAUT1 and GAUT7, come together to form pectin in the cell walls of plants. Pectin is a set of polysaccharides that is essential to the growth development of plants and that is also used as a gelling agent in jams and jellies.

Mohnen said this discovery provides new knowledge about how pectin is formed and how scientists can use it.

“If you understand how something is synthesized, you can manipulate it and you can modify plants for the pectin they produce, whether you want to use it as a product or whether you want to change plant growth development,” she said.

This discovery could lay the groundwork for further research into using plant cell walls as a form of renewable biomass energy. Plant cell wall materials can be used as a hydrocarbon source to produce ethanol, but right now, it’s difficult to break down the complex plant cell walls enough to produce this form of energy. Mohnen said the U.S. government has put out a call to produce more ethanol from the cell walls of all plants — right now, the majority of ethanol used in the U.S. is made from cornstarch, but the government is looking for other renewable sources that won’t compete with the country’s food supply.

Mohnen said this new knowledge about how pectin is formed in cell walls could make it easier for scientists to engineer the plants to produce ethanol.

“If you understand how the wall is made, you can figure out how you want to change those biosynthetic enzymes so you can make walls that are easier to break down,” she said. “When you make those walls that are easier to break down, then it’s going to be more cost effective to divert them into ethanol or other biofuels.”

The researchers found that GAUT7 acts to anchor GAUT1 in the Golgi body within the plant cell. Mohnen said this is the first example she’s seen of this type of anchoring mechanism in the Golgi body of a protein.

“It’s an important step forward, and we actually think it might represent a paradigm whereby one protein can act as an anchor for catalytic subunits,” she said. “Maybe additional complexes can be discovered that use this same mechanism.”

Atmodjo, who was a Ph.D. student when the discovery was made, said this discovery is important because scientists typically focus more on other components of plant cell walls, such as cellulose, when doing research. She said pectin’s structure is much more complicated than cellulose, which makes research on it difficult — and makes researchers shy away from it.

“People didn’t really pay attention much to pectin. It was thought to be just a minor component,” she said. “Well it’s actually not a minor component — it’s actually a pretty big chunk of the cell wall.”

Mohnen said going forward, she and Admodjo want to understand the pectin-forming process in more detail — what other proteins associate with the complex, the order in which they interact, and what specific parts of the GAUT7 protein are important for bonding. They also want to better understand the ways scientists can modify plant cell wall synthesis to produce renewable energy sources.