"When we started this work several years ago, we knew it was going to be difficult because we were treading into unknown territory," said Hamilton Smith, M.D., senior author on the publication. "Through dedicated teamwork we have shown that building large genomes is now feasible and scalable so that important applications such as biofuels can be developed."
Methods for Creating the Synthetic M. genitalium
The process to synthesize and assemble the synthetic version of the M. genitalium chromosome began first by resequencing the native M. genitalium genome to ensure that the team was starting with an error free sequence. After obtaining this correct version of the native genome, the team specially designed fragments of chemically synthesized DNA to build 101 "cassettes" of 5,000 to 7,000 base pairs of genetic code. As a measure to differentiate the synthetic genome versus the native genome, the team created "watermarks" in the synthetic genome. These are short inserted or substituted sequences that encode information not typically found in nature. Other changes the team made to the synthetic genome included disrupting a gene to block infectivity. To obtain the cassettes the JCVI team worked primarily with the DNA synthesis company Blue Heron Technology, as well as DNA 2.0 and GENEART.
From here, the team devised a five stage assembly process where the
cassettes were joined together in subassemblies to make larger and larger
pieces that would eventually be combined to build the whole synthetic M.
genitalium genome. In the first step, sets of four cassettes were joined to
|SOURCE J. Craig Venter Institute|
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