Scientists create living bacteria with largest 'recoded' synthetic genome

Researchers Created New Bacteria Strain From An Artificial Genome

Researchers Created New Bacteria Strain From An Artificial Genome

"It was completely unclear whether it was possible to make a genome this large and whether it was possible to change it so much", study co-author Jason Chin, a biologist at the University of Cambridge, tells the Guardian's Ian Sample. The output from the DNA still needed tweaking, however, which meant the team had to stitch together smaller pieces into longer ones before it could be put into a living E. coli bacterium-they named it Syn61 because only 61 of the 64 possible codes were used.

The bacteria are alive but are slow in reproducing themselves and have unusual shapes. Cultivating living bacteria is an often expensive and time consuming process, if researchers can produce synthetic bacteria that can be custom fit to goal, it could bring costs down and enable more research. Genetic code is written in four letters: A, T, C, and G, which represent the molecules adenine, thymine, cytosine, and guanine. These combinations, in turn, correspond with specific amino acids, or organic compounds that build the proteins necessary for life.

Researchers have been, up till now, able to make artificial DNA of about one million base pairs or letters, "notably a set of chromosomes from the yeast Saccharomyces cerevisiae and several versions of the genome of the bacterium Mycoplasma mycoides".

In the new study, DNA was computationally designed, chemically synthesised and assembled to recode 18,214 DNA letters to create an organism that required only 61 codon genomes to produce all of the amino acids the organism needs.

The construction of every amino acid in the cell is guided by three bases fixed in the DNA thread. "No one's done anything like it in terms of size or in terms of number of changes before". Sixty-one codons, and not 20 encrypt amino acids. The manufacturing of serine, for instance, is conducted by six separate codons.

Chin was intrigued by all this duplication and asks: "Were all these chunks of DNA essential to life?" He explained that because life usually utilizes six codons, they still didn't know what the answer is, so Dr. Chin and his team thought of creating an organism that could help in understanding life better and also answer his question. Despite this seeming disparity, the synthetic bacteria appear to function much like normal E. coli. Rather than demanding six codons to produce serine, the DNA utilized only four. Specifically, the team replaced two of the codons that encode the amino acid serine with a synonym and did the same for a stop codon, freeing up three codons for future alternative uses.

Scientists have created a living organism whose DNA is entirely human-made - perhaps a new form of life, experts said, and a milestone in the field of synthetic biology. The DNA was way too long and too complicated to pressure it into a cell from the first try. Luckily, the scientists didn't have to complete this work by hand. But many of them do the same job. Modifying DNA could also enable researchers to scheme contrived cells so that their genes won't function if they get into other species. "Beyond the 20 amino acids used by all living things, there are hundreds of other kinds".

Chin hopes to build on this experiment by removing more codons and compressing the genetic code even further.

James Kuo, a postdoctoral researcher at Harvard Medical School, is somehow cautious regarding this as stapling bases side by side to create genomes is significantly costly. If the request for artificial genomes will rise, prices could go lower.

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