DNA Transplant Transforms Bacteria

Two colonies of the transformed mycoplasma mycoides bacterium. i

Bacterial colonies of the transformed mycoplasma mycoides bacterium. J. Craig Venter Institute hide caption

itoggle caption J. Craig Venter Institute
Two colonies of the transformed mycoplasma mycoides bacterium.

Bacterial colonies of the transformed mycoplasma mycoides bacterium.

J. Craig Venter Institute

Scientists have completed another step on the road to creating synthetic life.

Researchers at the J. Craig Venter Institute in Rockville, Md., have taken the entire genome out of one bacterium, altered it, and reinserted it into a different bacterium.

Such genome transplants should soon allow scientists to create life from scratch.

In the form of bacteria, this synthetic life could clean up pollution or create new forms of biofuel.

The basic blueprint for life is written in long, stranded molecules known as DNA. Scientists can decode an existing genome by looking at the DNA one segment at a time. It's a bit like taking beads off a string.

John Glass, a researcher at the Venter Institute, wants to reverse the process. "We're adding new beads onto a string to make what we want," he says. What Glass's group would like to do is build a small genome of the type found in simple bacteria and set it to work. He says it could reveal a lot about what makes life alive.

"We're trying to understand how life works," Glass says. "What is in these organisms that makes this bag of chemicals be more than a bag of chemicals?"

The group already has shown how to make an artificial genome. They use a yeast cell as a kind of factory. The yeast's natural enzymes assemble the artificial genome from pieces of synthetic DNA. But an artificial genome in yeast doesn't do anything. To make it spring to life they need to get it into a bacterial cell.

That's not so easy. Yeast is a fungus, and bacterial immune systems attack foreign genetic material. Reporting this week in the journal Science, the group says it has solved that problem by shutting down the bacterial defenses.

They tested their technique using a nonsynthetic genome from one bacterial species common to goats. They put the genome in yeast, made a few small genetic modifications, and then implanted it in a different species of bacteria, whose immune system was suppressed. The surrogate accepted the new genetic material.

They still have to try it with an artificial genome. But the paper proves the last step needed to build synthetic life, says Drew Endy of Stanford University.

"All the steps of the process have been demonstrated," Endy says. "Anybody in the world could begin the good work of trying to figure out how living organisms work."

Endy hopes that this technology could eventually lead to cheap ways to produce pharmaceuticals or biofuels. It could be used for ill as well, he adds.

He thinks that the public and scientists should engage in a healthy public debate about how synthetic life can benefit society. "A lot has to do with who we are as human beings and how we choose to respect one another," Endy says.

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