Rachelle Lemke

“The chemistry of FuFAs helps the bacterial cell fight off damage in the membrane. The oxygen atom in FuFAs is also what makes it interesting to the biofuel and other industries,” says Rachelle Lemke, a GLBRC senior research specialist who led a study of FuFA production published recently in the Journal of Biological Chemistry. “Think of oxygen as the lighter that helps ignite all the other molecules in a fuel to burn. The chain length of FuFAs also make it a potential lubricant for engines and other devices.”

Lemke previously identified FuFAs while exploring why a bacterium, Rhodobacter spheroides, dies when exposed to a hyperreactive oxygen molecule called singlet oxygen. As a graduate student studying with Tim Donohue, UW–Madison bacteriology professor and GLBRC director, Lemke originally found that singlet oxygen kills R. spheroides unless FuFAs are present. Still, they lacked information on how these important class of fatty acids were made.

In their new study, Lemke and a team of GLBRC researchers identified the steps this and other bacteria use to produce FuFAs. The team’s findings reveal previously unidentified intermediate molecules that ultimately get converted into FuFA. They also found enzymes that add oxygen to the FuFA chain while decorating the ring with methyl groups that serve as the chemical makeup for the genesis of fuels.

Tim Donohue

The team also used genome sequences and genetics to identify enzymes that perform chemical reactions that have never been observed until now. With these genetic GPS signals, the team was able to identify proteins that catalyze the same reactions in one other bacterium and predict the presence of this newly described pathway for FuFA production in both microbes and plants.

The next steps for GLBRC scientists are to understand the molecular basis of these newly discovered enzymes and to train cells to make more FuFAs so researchers can test the fatty acids in a variety of applications.

“With more tests, it’s possible we will understand how the new classes of enzymes work, and design cells to crank up FuFA production in bacteria and other cells,” Lemke says.

What began more than a decade ago with a simple question: “why do some bacteria die when there’s oxygen around?” has added another layer to the production line of fuels and bioproducts from plants, now patented and available for licensing through the Wisconsin Alumni Research Foundation.

“This discovery is another great example about how interdisciplinary GLBRC teams can mine genomes to reveal previously unknown biochemical pathways,” says Donohue. “In addition, we have received interest in evaluating furan fatty acids as lubricants, as compounds with antimicrobial activity and as food additives from groups around the globe.”