Enzyme could protect plants against cold

jbrehm2, September 12, 2014 | View original publication

Enzyme could protect plants against cold

A UNL scientist’s in-depth molecular study of a protein that helps plants survive freezing temperatures will be featured on the Sept. 19 cover of JBC the Journal of Biological Chemistry.

Rebecca Roston, assistant professor of biochemistry at UNL's Beadle Center, is the study’s lead author. She and her colleagues analyzed the molecular structure of the protein, called Sensitive to Freezing 2 or SFR2, in an effort to better understand how it confers frost tolerance.

The answers they found could help other scientists develop agricultural crops that can better withstand the cold. There also could be industrial or pharmaceutical uses, by providing a better understanding of nature’s catalytic processes.

“It’s unclear at this point why some plants are protected from freezing damage and others are not,” Roston said. “That is something that relies upon multiple genes. We’re still focusing on the role of SFR2 as far as how big a player it is.”

Though SFR2 is believed to be found in all plants, Roston used Arabidopsis thaliana, commonly known as thale cress, in her study. A member of the Brassicaceae family that includes cabbage, kale and cauliflower, thale cress is often used in research because it has a quick life cycle and was one of the first plants to be genotyped.

SFR2 provides a mechanism for plants to survive at temperatures of up to 8 degrees Celsius below zero. It does this despite its structural similarity to a family of enzymes that do not confer freezing tolerance.

“It is a surprise that it has the activity it does,” Roston said. “This paper looked at the molecular determinants of that activity.”

The paper’s most interesting finding, she said, is that the unique areas she found in the structure of SFR2 were not in the active catalytic sites of the enzyme.

“The unique areas of SFR2, which allows it to have changed activity, weren’t where we thought they would be,” she said. “All the changes we found were external to active sites.”

The magazine cover features her model of the enzyme’s structure, constructed of purple plastic and resembling a surreal flower, photographed in the snow next to a bunch of flat-leaf parsley. The image was taken by Uthman Shabazz, a friend who is a professional photographer.