Scientists have created the world's first living organism that has fully synthetic synthetic DNA changed radically.
The cultivated bacterium, a strain of bacteria found in human soil and intestines, is similar to its natural cousins, but it survives on a smaller set of genetic instructions.
The existence of the bug proves that life can exist with limited genetic code and pave the way for organisms whose biological machines are licentious to produce drugs and useful substances, or to add new features such as resistance to the virus.
In a two-year effort, researchers at the Molecular Biology Laboratory, University of Cambridge, have read and redesigned the bacteria's DNA E. Coley (E – voice), Prior to cell formation with a synthetic version of the altered genome.
The artificial genome contains base pairs of 4m, the genetic code units listed in letters G, A, T and C. Printed in full on A4 pages, they run to 970 pages, making the largest genome up to science ever built.
"It was not clear whether a large genome could be made, and if it could be changed so much," says Jason Chen, a specialist in synthetic biology who led the project.
When the cell needs more protein to grow, for example, it reads the DNA that encodes the right protein, and the DNA letters are called triads, such as TCG and TCA.
Almost all life, from jellyfish to humans, uses 64 codons. But many of them do the same job. In total, 61 codons make 20 natural amino acids, which can be stretched together as beads on any white build protein wire. The other three codons are actually stopping the signs: they say to the cell when the protein is done, as to stop the whole end of this sentence.
The Cambridge team went out to redesign the God coli By removing some of her superfluous codes. When working on a computer, the scientists passed the DNA of the bug.Every time they encountered TCG, a codon that makes an amino acid called serine, they rewrote it as AGC, which does the same job.
More than 18,000 edits later, the scientists removed every occurrence of the three codes from the bug magnum. The newly designed genetic code was then chemically synthesized, and a piece of piece was added God coli Where he replaced the natural genome of the organism. The result, reported in nature, is that the bacterium with fully synthetic DNA code has changed radically. Known as Association 61, the bug is a bit longer than normal, and grows slower, but survives anyway.
"It's pretty amazing," said Chen. When a bug was created, shortly before Christmas, the research team had a photo taken in the laboratory with a plate of bacteria as the central figure in the recreation of the birth.
Such life forms a designer can come in handy, Chen believes. Because their DNA is different, invading viruses will struggle to spread within them, making them virtually virus resistant. God coli Has been used by the biopharmaceutical industry to produce insulin for diabetes and other medical compounds for cancer, multiple sclerosis, heart attacks and eye diseases, but complete production runs can be broken when bacterial cultures are contaminated with viruses or other bacteria. But that's not all: in future work, loose genetic code can be repurposed to make cells churn the designer enzymes, proteins and drugs.
In 2010, American scientists announced the creation of the world's first organism in the synthetic genome. Bug, Mycoplasma, There is a smaller genome than God coli – about 1m pair pairs – and was not radically redone. Commenting on the latest work, Clyde Hutchison of the American research group said: "The scale of the genome replacement is greater than any complete genome replacement reported so far."
"They took the synthetic genome field to a new level, not only having managed to build the largest synthetic genome yet, but also making the most subtle changes to the genome so far," said Tom Ellis, a synthetic biology researcher at Imperial College London.
But the records may not last very long. Alice and others are building a synthetic genome for bakers' yeast, while Harvard scientists are making bacterial genomes with more coding changes. That re God coli Not grown as well as natural varieties not surprising, added Alice. "If anything, it's surprising that it grew at all after so many changes," he says.