麻豆淫院

Despite their fundamental differences, plants, animals, and fungi share certain metabolic processes. Biologists at the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have discovered that a unique protein plays a key role in one such process鈥攜et the protein is found only in plants.

As described in a just published in Science Advances, a deeper understanding of this plant-specific protein could lead to more robust bioenergy crop plants鈥攁nd potentially a new way to eliminate weeds.

Chang-Jun Liu, a senior scientist in Brookhaven's Biology Department, studies the role of cytochrome b₅ proteins in Arabidopsis plants, which are commonly used for understanding basic plant biology. These proteins, classified as electron carriers, help drive metabolic processes in plants, animals, and fungi by transferring electrons between molecules.

In earlier work, Liu and his team discovered a cytochrome b₅-like protein (CB5LP) in Arabidopsis plants. Its genetic sequence is similar to that of conventional cytochrome b₅ proteins, but its major functional pieces, or domains, are arranged differently.

"CB5LP is clearly a special protein," said Liu. "But we did not know what it did. We were curious to know if it functions like conventional cytochrome b₅ proteins."

Xianhai Zhao, a postdoctoral researcher in Liu's group, began the investigation by engineering Arabidopsis plants that did not produce CB5LP. The outcome was striking: The plants could not survive without CB5LP.

"We routinely edit plants by deleting specific genes to study the roles of various proteins or compounds," said Zhao. "There are usually several effects, but it's rare that removing just one protein kills them."

This drastic consequence suggested that CB5LP is involved in synthesizing an important compound鈥攁nd that other cytochrome b₅ proteins could not act as a substitute.

Protein partners

Cytochrome b₅ proteins often partner up with cytochrome P450 enzymes to carry out metabolic processes. So, the scientists thought that CB5LP may also work with a molecular partner whose function could help reveal its role.

With collaborators at the Carnegie Institution for Science, they used proximity labeling analysis to identify proteins in the vicinity of CB5LP that could be potential partners.

"We uncovered a set of candidate proteins," said Zhao. "Then we examined, one by one, the metabolic processes each one likely participates in and the compounds they help produce."

One of the potential partners was a cytochrome P450 enzyme involved in the synthesis of sterols鈥攃ompounds that are essential for the integrity and function of cell membranes in plants, animals, and fungi.

Sterols are so critical for survival that they are typically the target of antifungal drugs, which disrupt sterol synthesis to prevent fungal growth or reproduction. Sterols in plants and animals鈥攌nown as phytosterols and cholesterols, respectively鈥攁re also precursors to hormones and vitamins vital for growth and overall health.

Using genetic and biochemical analyses, the researchers revealed that CB5LP, like cytochrome b₅ proteins, functions as an electron carrier, specifically in the sterol synthesis pathway.

They also discovered that CB5LP is found only in plants and not in animals or fungi. This was especially surprising because many aspects of sterol synthesis, including key cytochrome P450 proteins, are shared across all three groups.

This unique distinction could help inform the development of novel herbicides, or "weed killers" that interfere with essential plant processes, like sterol synthesis. In particular, the findings suggest that targeting plant-specific CB5LP鈥攁nd disrupting sterol synthesis鈥攃ould offer a new strategy for eliminating weeds while avoiding potential adverse effects for animals or fungi.

Liu said, "This work also contributes to our knowledge of plant metabolism, which will ultimately help us engineer stronger and more productive bioenergy crops."