Scientists announced a bold step Thursday in the enduring quest to create
artificial life. They've produced a
living cell
powered by manmade DNA. While such work can evoke images of
Frankenstein-like scientific tinkering, it also is exciting hopes that
it could eventually lead to new fuels, better ways to clean
polluted water, faster vaccine production and more.
Is it really an artificial life form?
The
inventors call it the world's first synthetic cell, although this
initial step is more a re-creation of existing life — changing one
simple type of bacterium into another — than a built-from-scratch kind.
Maryland genome-mapping pioneer J. Craig Venter
said his team's project paves the way for the ultimate, much harder
goal: designing organisms that work differently from the way nature
intended for a wide range of uses. Already he's working with ExxonMobil in hopes of turning algae into fuel.
And
the report, being published Friday in the journal Science, is
triggering excitement in this growing field of synthetic biology.
"It's been a long time coming, and it was worth the wait," said Dr. George Church, a Harvard Medical School genetics professor. "It's a milestone that has potential practical applications."
The project has overcome some hurdles in engineering larger genomes that will help push forward the field, said biological engineer Dr. Ron Weiss, a Massachusetts Institute of Technology leader in synthetic biology.
"It's an important step," said Weiss. Even though the manmade DNA
needed an already living cell to start working, eventually it
reproduced and "all elements in the cells after some amount of time can
be traced to this initial artificial DNA. That's a great
accomplishment."
Scientists for years have
moved single genes and even large chunks of DNA from one species to
another. Venter aimed to go further. A few years ago, his team
transplanted an entire natural genome, all of an organism's genes, one
bacterium into another and watched it take over — turning a goat germ
into a cattle germ.
Next, the researchers built from scratch another, smaller bacterium's genome, using off-the-shelf laboratory-made DNA fragments.
Friday's
report combines those two achievements to test a big question: Could
synthetic DNA really take over and drive a living cell? Somehow, it did.
"This
is transforming life totally from one+ species into another by changing
the software," said Venter, using a computer analogy to explain the
DNA's role.
The researchers picked two species of Mycoplasma, simple germs that contain a single chromosome and lack the cell walls
that form barriers in other bacteria. First, they chemically
synthesized the genome of M. mycoides, that goat germ, twice as large
as the germ genome they'd previously built.
Then they transplanted it into a living cell from a different Mycoplasma species, albeit a fairly close cousin.
At
first, nothing happened. The team scrambled to find out why, creating a
genetic version of a computer proofreading program to spell-check the
DNA fragments they'd pieced together. The result: They found that a
typo in the genetic code,
in one of the synthetic genome's million chemical base pairs, was
rendering the manmade DNA inactive, delaying the project three months
to find and restore that bit.
"It shows you how accurate it has to be, one letter out of a million," Venter said.
That
fixed, the transplant worked. The recipient cell started out with
synthetic DNA and its original cytoplasm, but the new genome "booted
up" that cell to start producing only proteins that normally would be
found in the copied goat germ. It reproduced into a small colony of
germs in a lab dish.
The researchers had tagged the synthetic DNA to be able to tell it
apart, and confirmed that those new ones really looked and behaved like
M. mycoides, not the recipient cell