by John Bohannon
Wired, November 2010
This is the story of life’s creation. Not the first creation—3.5 billion years ago in some pool of organic molecules—but the second. This time, it’s happening at Harvard. Just as before, life will begin as a primitive protocell, a tiny machine that eats certain chemicals, produces others, and makes copies of itself. But these cells will be different from all the rest on Earth: This is life from a universe on the other side of the looking glass. Every part—down to its molecular building blocks—will be a mirror image of our own.
Mirror life can’t eat our food. (And we can’t eat its food.) It can’t infect us. (And we have no predators to check its growth.) Its creation may help us solve a baffling riddle about our own origin. And if it can be controlled, mirror life might make some people very, very rich.
All our proteins are “left-handed” (L-amino acids)—so named because they rotate polarized light counterclockwise. And all of our DNA is “right-handed” (D-deoxyribose). Those handed ingredients force the rest of our molecules to be in only one mirror form. Bio-molecules work together like locks and keys—a mirror image of one doesn’t work with the other. So only cells and molecules with the same handedness can play. But the primordial soup on the early Earth had an even mixture of both. So here’s a mystery: How did we end up stuck on one side of the mirror?
Five years ago, a trio of Harvard scientists started to wonder if they could find out—by rebooting the system. If a primitive mirror image of the kind of cells we are made of could be created in a lab, would it survive? If it did, it would encounter no predators or competitors, “so we are making sure that it’s handicapped, needing our constant help to keep it alive,” says Dimitar Saselov. He’s the physicist on the team, one of the directors of the Kepler mission to look for other Earth-like planets. The geneticist is George Church, whom Wired wrote about two years ago, and he’s already built a mirror ribosome. The third team member is Jack Szostak, who won a Nobel last year for his work on cell membranes. He’s already custom-built membranes, and he’s waiting to inject them with Church’s mirror guts.
And if it works? Insulin manufacture without fear of viral contamination. Cells that convert sugar to biofuel without consuming any of it. Maybe even cheap materials that biodegrade when mirror cells get a bite. The down side? These bugs will express mirror- image versions of thousands of molecules, any of which could turn out to be toxic. And if some later generation gained the ability to eat food from the other side of the mirror—either through engineering or evolution—there’s not much that could stop it. Worst case: the biological equivalent of grey goo. Unless, of course, there’s a “shadow biosphere” out there, some elder-god version of life that’s still here, on the margins.
Saselov thinks there might be—and thinks he can use mirror cells as a honey pot to attract naturally-occurring mirror viruses and bacteria that have been hiding here on Earth all along.