Imagine the most sophisticated engineering feat you can think of, and you might not consider a living cell. And yet cells are fabulously sophisticated, able to produce all the proteins, tissues, and biological circuits that give rise to life. Scientists have spent hundreds of years just trying to understand cells and to work with them as they were created by nature. Now it's becoming possible to "rewire" cells using genetic circuits, protein pathways, and other biomolecular machinery created in the laboratory. By swapping out natural genetic circuitry for synthesized components made of DNA, scientists are putting cells to work as sensors and as miniature factories that make pharmaceuticals, fuels, and industrial chemicals.
These possibilities not only blur the lines between engineering and biology but also are transforming how scientists approach challenges in energy, human health, and the environment. Robert Kitney, a professor of biomedical systems engineering at Imperial College of Science, Technology, and Medicine in London, England, believes the field's influence could rival or exceed that of synthetic chemistry, which made modern pharmaceuticals, detergents, plastics, and computer semiconductors possible. "We're talking about harnessing cells--which I describe as the ultimate manufacturing units--to carry out human-controlled processes," says Kitney. "And that's a completely new world with many up sides."
David Rejeski, who directs the Science and Technology Innovation Program at the Woodrow Wilson International Center for Scholars in Washington, DC, predicts a steady convergence of nanotechnology and synthetic biology will redefine manufacturing over the next 100 years. "It's a profound change--the next Industrial Revolution," he says. "Precision control of matter at the nanoscale will change the way we produce just about everything, from electronics to drugs, fuels, materials, and food."
Defining the Field
Despite that potential--or perhaps because of it--this new field of synthetic biology suffers from an identity crisis. Ask 10 experts to define "synthetic biology," and you're liable to get 10 different answers. The field overlaps with genetic engineering, which involves adding or deleting single genes, and also with metabolic engineering, which allows scientists to optimize cellular processes to produce desired substances, such as hormones. Pamela Silver, a professor of systems biology at Harvard Medical School and a core faculty member with Harvard University's Wyss Institute for Biologically Inspired Engineering, says synthetic biology embraces metabolic engineering but also diverges from it by relying on modular components made from DNA. Scientists can now synthesize genes from DNA subunits arranged to user specifications. Those genes are then strung together into components and devices that cells, under laboratory conditions, can absorb into their chromosomes.
In what's seen as a major proof of concept for the field, scientists at Amyris Biotechnologies in Emeryville, California, rewired 12 genes in yeast so the organism would produce artemisinin, an antimalarial drug. On the environmental front, scientists are also rewiring algae and other organisms to make biofuels for the transportation sector. Eric Toone, a professor of chemistry and of biochemistry at Duke University, says that without synthetic biology it's unlikely biofuels could ever be produced at the volumes and prices needed to compete economically with gasoline, diesel, or jet fuel.
But if synthetic biology is exciting, it's also unsettling to those concerned about its risks. Engineered microbes might escape and propagate in the wild with unforeseen consequences, some say. Others caution that synthetic biology has high potential for abuse. Customized DNA sequences delivered through the mail can now be bought for just 40[cents] per base pair. Gene synthesis companies aren't legally …