Saturday, March 26, 2016

the minimal cell



theatlantic |  In 2010, a team of scientists announced that they had created a synthetic living cell. The team, led by Nobel laureate Ham Smith, microbiologist Clyde Hutchison III, and genomics pioneer Craig Venter, fashioned the full genome of a tiny bacterium called Mycoplasma mycoides in their lab, and implanted the DNA into the empty cell of another related microbe. They nicknamed it Synthia. Some news sources claimed that the team had, for the first time, created artificial life.Others noted that they had merely photocopied life, putting an existing genome into a new chassis, like a “hermit crab taking up residence in an abandoned shell.”

But amid the hyperbole and skepticism, the team continued working. “The 2010 paper was basically the control experiment,” says Venter. Their true mission was to create a cell with a minimal genome.

All living things evolved from a common ancestor, so despite our grand variety, we all share genes that are essential for our survival. They’re at the core of our operating systems: the fundamental software without which we would die. Smith, Hutchinson, Venter, and their colleagues wanted to create an organism with just these essential genes—only those it needed to survive, and nothing more. A minimalist microbe. Kondococcus, perhaps.

Why bother? Because they ultimately want to intelligently design new life-forms from scratch—say, bacteria that can manufacture medical drugs, or algae that churn out biofuels. And creation requires understanding. “We had to start with a system where we knew and understood all the components, so that when we added specific ones to it, we could do so in a logical design way,” Venter says. They needed a minimal genome—a vanilla model that they could later kit out with deluxe accessories.

And they’ve done it. Six years after Synthia, they’ve finally unveiled their bare-bones bacterium. And in piecing together its components, they realized that they’re nowhere close to understanding them all. Of the 473 genes in their pared-down cell, 149 are completely unknown. They seem to be essential (and more on what that means later). Many of them have counterparts that are at work in your body right now, probably keeping you alive.
And they’re a total mystery.

“We’ve discovered that we don’t know a third of the basic knowledge of life,” says Venter. “We expected that maybe 5 percent of the genes would be of unknown function. We weren’t ready for 30 percent. I would have lost a very big bet.”