J. Craig Venter Institute Researchers Publish Significant Advance in Genome Assembly Technology
Advance Allows for More Efficient Construction of Synthetic Genomes
Today’s publication represents major improvements in the methods that the team developed and described in their
While this was a big advance, it took several years to come to fruition and in the end was a tedious, multi-stage process in which the team had to build the genome a quarter at a time using the bacterium Escherichia coli to clone and produce the DNA segments. During this building process the team found that E. coli had difficulty reproducing the large DNA segments, so they turned to the yeast Saccharomyces cerevisiae. They were then able to finish creating the synthetic bacterial genome using a method called homologous recombination (a process that cells naturally use to repair chromosome damage).
Realizing how robustly yeast performed, the team wondered if it could be used to build the entire M. genitalium genome from multiple, smaller, overlapping segments of DNA. For this study the team used DNA fragments that ranged in size from about 17,000 base pairs to 35,000 base pairs. These relatively short segments were inserted into yeast cells in one step and through the mechanism of homologous recombination were assembled into the synthetic M. genitalium genome. Several experiments were then done to confirm that all 25 pieces of the synthetic DNA had been correctly assembled in the yeast cells, and to show that the experiment could be successfully reproduced.
The JCVI team continues to explore the capacity for DNA assembly in yeast, and the various applications of this particular method. They conjecture that a variety of combinations of DNA molecules and genetic pathways could be manufactured in yeast, in essence turning yeast into a genetic factory for specifically designed and optimized processes. This advance is being used by scientists at the company SGI in making next generation biofuels and biochemicals more efficiently.
“We continue to be amazed by the capacity of yeast to simultaneously take up so many DNA pieces and assemble them into genome-size molecules,” said lead author Dr. Gibson. “This capacity begs to be further explored and extended and will help accelerate progress in applications of synthetic genomics.”
Key Milestones/Ethical Background of JCVI’s Synthetic Genomics Research
Mid-1990′s: After sequencing the M. genitalium genome, Dr. Venter and colleagues begin work on the minimal genome project. This area of research, trying to understand the minimal genetic components necessary to sustain life, started with M. genitalium because it is a bacterium with the smallest genome known that can be grown in pure culture. This work was published in the journal Science in 1995.
2003: Drs. Venter, Smith and Hutchison (along with JCVI’s
2007: JCVI researchers led by
Since the beginning of the quest to understand and build a synthetic genome, Dr. Venter and his team have been concerned with the societal issues surrounding the work. In 1995, while the team was doing the research on the minimal genome, the work underwent significant ethical review by a panel of experts at the
Dr. Venter and the team at JCVI continue to work with bioethicists, outside policy groups, legislative members and staff, and the public to encourage discussion and understanding about the societal implications of their work and the field of synthetic genomics generally. As such, the JCVI’s policy team, along with the Center for Strategic & International Studies (CSIS), and the
About the J. Craig Venter Institute
The JCVI is a not-for-profit research institute in
SOURCE J. Craig Venter Institute