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It took geneticist Craig Venter 15 years and US$40 million to synthesize the genome of a bacterial parasite. Today, an academic team made up mostly of undergraduate students reports the next leap in synthetic life: the redesign and production of a fully functional chromosome from the baker’s yeast Saccharomyces cerevisiae.
As a eukaryote, a category that includes humans and other animals, S. cerevisiae has a more complex genome than Venter's parasite. The synthetic yeast chromosome which has been stripped of some DNA sequences and other elements is 272,871 base pairs long, representing about 2.5% of the 12-million-base-pair S. cerevisiae genome. The researchers, who report their accomplishment in Science, have formed an international consortium to create a synthetic version of the full S. cerevisiae genome within 5 years.
“This is a pretty impressive demonstration of not just DNA synthesis, but redesign of an entire eukaryotic chromosome,” says Farren Isaacs, a bioengineer at Yale University in New Haven, Connecticut, who was not involved in the work. “You can see that they are systematically paving the way for a new era of biology based on the redesign of genomes.”
The project began a few years ago, when Jef Boeke, a yeast geneticist at New York University, set out to synthesize the baker’s yeast genome with much more drastic alterations than those demonstrated by Venter and his team in 2010.
The group at the J. Craig Venter Institute in Rockville, Maryland, had chemically synthesized short strands of DNA and stitched them together to create a version of the 1.1-million-base-pair DNA genome of the bacterium Mycoplasma mycoides, which was then inserted into a recipient cell. Venter’s team wrote a few coded 'watermarks' into the genome sequence, which spelled out the names of the team members, as well as several famous quotes. But besides these tweaks and a few other changes, the synthetic M. mycoides genome was identical to its blueprint.
By contrast, Boeke and his team thought that by stripping the genome of certain features to test their importance, they could justify the enormous cost and effort of synthesizing whole yeast chromosomes.
“I wasn’t sceptical about whether it could be done,” Boeke says. The question, he explains, was: “How can we make this different from a normal chromosome and put something into it that’s really going to make it worthwhile?”
Source: www.nature.com
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