This Bare-Bones Synthetic Cell Has World's Smallest Genetic Code

Syn 3.0 has what it needs to survive and replicate, and absolutely nothing else.

C. Bickel

Today a team of synthetic engineers has unveiled an entirely new life-form. It's a bacterium called Syn 3.0. No, the new organism won't dazzle you with any new or special tricks. In fact, just the opposite. It's the most stripped-down form of life ever created.

"Our hope here is to understand the minimal basis of life."

Scientists led by J. Craig Venter at his namesake nonprofit institute in La Jolla, California, genetically trimmed, clipped and pared down to only the barest essentials for independent, self-sustaining life on a Petri dish. Like a survivalist's bare-bones knapsack, any DNA not absolutely necessary for this living cell's survival has been junked. With a mere 473 genes, the new synthetically engineered bacteria has the smallest genetic code on Earth for a self-sufficient creature. The new cell is outlined today in the journal Science

"Our hope here is to understand the minimal basis of life," says Venter, whose team of researchers has been working on this effort for more than 20 years.

The Cliff's Notes of Life

To put Syn 3.0's tiny genome into context, the bacteria has 40 times fewer genes than you do. If written out by hand, the bacteria's genetic code of A,C, G, and T base-pair letters would be 12 times shorter than your own, editing the book of life down to a mere pamphlet.

J. Craig Venter
The Washington PostGetty Images

As you might've deduced already, Syn 3.0 isn't the first such attempt. In 2010, Venter and his colleagues created 3.0's forebear: Syn 1.0, the first synthetic cell. That was a (relatively) simple creation made by swapping out the DNA of a banal bacteria called Mycoplasma mycoides with an identical, but synthetic, lab-written genetic code. This specific species of bacteria was picked for really one reason—its genetic code is the smallest yet found in nature.

For Syn 3.0, Venter's team slimmed down the genome via the oldest and simplest method in he scientist's toolkit: trial and error. Using a genetic technique that let the researchers silence genes one by one, the researchers over thousands of trials figured out what could be removed without killing the cell and whittled it away. (In case you're wondering, Syn 2.0 was a slimmed-down cell created in the middle of this trimming process.)

Today's stripped-down cell basically does just one thing. It exists and multiplies every three hours on a Petri dish.

A Programmable Chassis

Syn 3.0 is an amazing achievement, but what exactly do we hope to do with this bare-bones cell?

"Well, our long term vision has been to design and build synthetic organisms on demand," starting with a "blank" organism like Syn 3.0, "and set in specific functions," says Daniel Gibson, a synthetic biologist at the  J. Craig Venter Institute. "These cells would be a very useful chassis for many industrial applications such as biochemicals, agriculture, nutrition, or creating medicines, and biofuels."

There are other more immediate uses, too. Venter is optimistic that Syn 3.0 could be used as "a very important experimental tool." Scientists could add genes to Syn 3.0 one by one (perhaps the very genes trimmed away in its creation) and study the exact effect of each gene. To be sure, this type of gene-by-gene research is already being done on various other microbes today. But with Syn 3.0, scientists wouldn't need to worry about misreading weird crossover effects from thousands of extra genes in the messy, complex genetic codes found in all natural creatures.

And studying Syn 3.0 on its own may uncover important facts about the genetic machinery of life. Right now, a full 32 percent of Syn 3.0's 473 genes are a mystery to biologists. While they're all-important for self-sustaining life, no one yet knows what their exact biological functions are. 

"Just knowing that we're missing a third of our fundamental knowledge [for what genes are required for life] is a very key finding, even if there's no other uses for this organism," says Venter.

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