Synthetic bacteria would appear after a maximum of four years
American scientists have completely rewritten the genetic code of Escherichia coli, making it a gene more than 62 thousand changes. The resulting micro-organism is completely resistant to all known viruses will not be able to exchange genes with other bacteria and will synthesize previously existing proteins.
Usually, proteins consist of 20 types of amino acids, however, uses modified E. coli for the synthesis of polypeptides, four additional artificial amino acids. Since the latter do not exist in the natural environment, the organism cannot grow and reproduce outside of laboratory conditions.
DNA of any living organism made up of four types of nucleotides: A, T, G and C. Each triplet (three) of nucleotides encodes one of the 20 protein amino acids. Since the total number of possible combinations reaches 64, a set of triplets are redundant.
For example, three combinations — TAG, TAA and TGA are stop codons, i.e., signals the termination of protein synthesis during translation. However, scientists decided to use the extra triples to encode new amino acids.
Previously, researchers were able to edit 314 triplets TAG in E. coli, and now they plan to change seven different codons. Because it requires to make the genome of a bacteria are 62 thousands of changes, biologists first synthesized short DNA segments with a length of about two thousand nucleotides. They were stitched together and then introduced in E. coli.
Researchers have identified a number arising of lethal mutations, but they hope that defects will be quickly corrected. According to estimates of the authors, synthetic bacteria will be born after a maximum of four years.
In the future, the researchers plan to create the immune to viruses, stem cells of human and farm animals. Such cells can be used for the production of vaccines and organs for transplantation.
