Canadian Scientists Find Potent Antifreeze Protein That Equips Insects To Brave Winter

In two studies published in the July issue of Nature magazine, Queen's biochemist Dr. Peter Davies and his colleagues describe the unusual beta helix structure of the antifreeze proteins, the secret to some insects' ability to survive winters in temperatures as low as minus 30 degrees Celsius.

The new findings build on earlier research by Drs. Davies and Zongchao Jia and their students that explained how ocean fish survive Arctic waters as a result of the antifreeze proteins in their blood. Four years ago, the Queen's biochemists revealed the structural basis for how the fish proteins bind irreversibly to ice crystals and stop them from growing.

A secondary benefit of the research may be a powerful weapon in the fight against the spruce budworm, the scourge of the boreal forests of eastern Canada, and the mealworm beetle, commonly found where grains and animal feeds are stored. The Queen's researchers have isolated and documented the molecular structures of two "hyperactive" antifreeze proteins in these two insects.

"This is very exciting. These proteins are far more potent than those found in fish," says Dr. Davies. "With this information, we can go on to modify other molecules to produce new antifreeze proteins that mimic these or are even more effective."

The findings hold promise for agriculture in the event that antifreeze proteins can be used to make plants frost resistant and extend both the growing season and the geographic areas in which crops can be grown. They may also represent a breakthrough for the frozen food industry. "By controlling the size of ice crystals in frozen foods, you can extend the shelf life of these products," Dr. Davies says.

Other members of the research team include Dr. Virginia Walker, an expert in the molecular biology of insect development, and Dr. Brian Sykes from the University of Alberta, an expert in structural biology and nuclear magnetic resonance.

Antifreeze proteins are found in some fish, insects and plants. They bind to ice crystals and prevent them from growing to a size where they would damage the host. The Queen's research involves the isolation and characterization of antifreeze proteins from different sources, and the cloning and expression of their genes to produce recombinant proteins for three-dimensional structural analysis by nuclear magnetic resonance spectroscopy and X-ray crystallography.

The rather unusual beta helix structure of the antifreeze proteins of the spruce budworm and the mealworm beetle -- coil-like with a flat surface -- is highly efficient for binding to ice surfaces.

This collaborative research in the four labs has been funded by grants from the Medical Research Council, the Natural Sciences and Engineering Research Council, and the Killam Foundation.

Editor's Note: The original news release can be found http://advancement.queensu.ca/qnews_html/docsvr?v=adv_html/qnews.qnews&t=htmp&h=article&key=964008000&id=964037386951>here.