Protein Fusion Improves Synthesis

Scientists have engineered mammalian cells to produce resveratrol, an antioxidant found in grapes and peanuts. Resveratrol previously has been shown to have antiaging properties and is one of the compounds thought to provide the possible health benefits of red wine.

Oliver Yu and coworkers at the Donald Danforth Plant Science Center and Washington University School of Medicine, both in St. Louis, increased the amount of resveratrol produced by tweaking the natural resveratrol pathway so that two of the enzymes are linked as a fusion protein (J. Am. Chem. Soc., DOI: 10.1021/ja0622094). The connection keeps the enzymes close together and increases the efficiency of the synthetic pathway.

In plants, the pathway requires four enzymes, but Yu and coworkers use a bacterial enzyme as a shortcut that enters the pathway midway, thereby reducing the total number of enzymes to three. Two of these three enzymes are part of the fusion protein.

When the researchers expressed this version of the pathway in yeast cells, the cells produced 15 times as much resveratrol as did engineered yeast cells expressing the enzymes separately. After 20 hours, yeast cells with the fusion protein had produced 3,500 times as much resveratrol as a yeast system previously reported by another group.

Yu and his coworkers engineered this resveratrol pathway into human kidney cells. Depending on what the cells were fed, they produced either 0.34 µg/mL or 85 ng/mL resveratrol, compared with 5.25 µg/mL in the yeast system. "To my knowledge, nobody has ever put an entire plant pathway with multiple enzymes into mammalian cells," Yu says. He and his collaborators hope that in the future the engineered cells could be used for medical applications, such as increasing the life span of neurons or other cells such as transplanted insulin-producing cells.