Research reveals new tools to regenerate plants in various applications, including the carbon-neutral use of plant biomass for agro-industrial applications.
Plant biologists at the US Department of Energy’s Brookhaven National Laboratory have discovered a new level of regulation in the biochemical “machinery” that plants use to convert organic carbon from photosynthesis into organic forms, variety of spices. The research, published in the journal Science Advances, provides new strategies for controlling plant biochemistry for agricultural and industrial applications.
“Our study reveals the long-neglected complexity of a group of enzymes known as cytochrome P450 monooxygenases,” said lead author Chang-Jun Liu of Brookhaven’s Department of Biology. Lab. “These pigs work as synthetic machines that produce many aromatic compounds in plants, including compounds that build the bones and vasculature of plants, and others that provide protection against insect attacks and radiation ultraviolet (UV).
Unraveling the complexities of how these enzymes are regulated provides a new set of genes that scientists can use to precisely control the compounds produced in different parts of the plant. The project can help to ensure long-term carbon storage and the neutral use of biomass plants for energy applications, improve the nutrition of plants or make them resistant to diseases and harsh environmental conditions.
A molecular machine
Scientists have long known that P450 enzymes do not work alone to determine the structural and biological properties of aromatic compounds.
“To make the P450 machine work, they need complementary molecules to release electrons. These electrons act as a source of energy to power the machine,” Liu explained.
In the past, scientists thought that P450s interacted with a general electron donor called cytochrome P450 reductase to produce various aromatic compounds. But the new study shows that different P450s interact with different electron donors (in the electron transport chain) to carry out their activities. In addition, the researchers found that the same P450 enzyme can use different electron donors and electron transport chains in different parts of the plant (trees, leaves and seeds) to produce different types of aromatics.
Scientists made these findings by analyzing the aromatic compounds that accumulate in different plants that have been selectively deleted from the genes of different electron donors.
“By knocking out these genes, we can identify the contribution of different electron donors, identifying those that lead to the production of different aromatics in different parts of the plant ,” said Liu. “Then, in yeast cells, we assembled different electron transport chains together with plant P450 enzymes to mimic the reaction of plants. These studies helped us to identify the contribution of electron donors to the chain Transportation supports P450 service.”
The experimental work is led by postdoctoral researcher Xianhai Zhao under Liu’s guidance. Zhao explained:
Plants have developed many genes that are responsible for electron donors, so we need to create plants with the deletion of one gene and a combination of genes. We then looked at the evolution of aromatic products during plant development.
“We also carried out a detailed analysis of the electron-donating genes and electron abundance in different parts of the plant and measured the electron transfer rates of different transport chains,” Zhao added.
These experiments helped scientists to understand why some P450 enzymes are associated with different electron transport chains in different parts of the plant.
Next step
This knowledge provides scientists with new mechanisms by which genes can be manipulated to control the production of aromatic substances.
“We can use electron donors – instead of P450s – to remove different types of aromatics and get the desired results,” Liu said.
For example, reducing the aromatic substance known as lignin and you will make the plant easier to break down and turn into fuel. Reducing the level of certain aromatics in the fruit can improve their nutritional value.
“The detailed knowledge presented in this study allows us to make selective changes in one part of the plant without affecting another, such as the collection of aromatic compounds that provide UV sunscreen to the leaves,” Liu said.
The Brookhaven team plans to test these genetic techniques to improve bioenergy crops. They will also conduct further studies using cryo-electron microscopes at Brookhaven’s Biomolecular Structure Laboratory to understand the atomic-level details that govern selective interactions between P450 enzymes and electron donors.
“Exploring the molecular basis of the P450 electron donor group will help us better understand how the P450 system works,” Liu said. “This, in turn, will allow us to create a more efficient enzyme system to produce the desired bioproducts and improve the conversion and storage of the carbon involved in photosynthesis.”
