ON 14 December 1967, Arthur Kornberg at Stanford University and colleagues announced that they had copied the DNA of the Phi X174 virus, producing an entity with the same infectivity as the wild virus. Though the DNA sequence in question was not known, Kornberg hoped the achievement would aid studies of genetics and the search for cures for diseases, and reveal the most basic processes of life itself. President Lyndon B. Johnson cited Kornberg’s claim to have come the “closest yet” to creating life and hailed it as “a very spectacular breakthrough”.
In 2003 we were able to go a step further, using DNA made from a sequence in a computer rather than a copy made by an enzyme. By 2008 we could synthesise a small bacterial chromosome over 20 times as big as that of Phi X174, though we were unable to activate it in a cell. With our publication in Science last week, we have now achieved this step with the 1.08-million-base-pair genome of Mycoplasma mycoides (see “Synthetic life: where next?”).
We did not create life from scratch: we transformed existing life into new life. Nor did we design and build a new chromosome from scratch. Rather, using only digitised information, we synthesised a modified version, a copy of the M. mycoides genome with 14 of its genes deleted and a “watermark” written in another 5000-plus base pairs. The result is not an “artificial” life form; it is a living, self-replicating cell that most microbiologists would find hard to distinguish from the progenitor cell, unless they sequenced its DNA.
It took 15 years to get to this proof-of-concept experiment. And it is just that: proof that it is possible to use a computer and four chemical bases to create a cell with no biological ancestor. Of course, we began by modifying an existing genome. Where else to start? Had we tried a new genome design it wouldn’t have worked. Even so, we had 99 failures for every success. Link…
JCVI-syn1.0, the first self-replicating species whose parent is a computer (Image: Tom Deerinck and Mark Ellisman/National Center for Microscopy and Imaging Research/University of California)