World's Most “Recoded” Genome Revealed

The breakthrough in synthetic biology came from England’s Medical Research Council Laboratory.
Jessica Miley

Synthetic Biologists created the world's most “recoded” genome. Jason Chin and his colleagues at England’s Medical Research Council Laboratory of Molecular Biology in Cambridge outlined their breakthrough in Nature journal.


The team has a sample of Escherichia coli growing in their lab that has an entirely different genome to any other strains of the same bacteria. So what did they do? Every organism on earth uses the same system to organize itself.

Make nature more efficient

Codons are the three-letter combinations of DNA’s A’s, T’s, C’s, and G’s that specify the amino acids into proteins. Every organism we have ever encountered uses the same 64 codons available to them.

For example, the codon GCA specifies serine, AAG specifies lysine. But AGT also means serine, as do AGC, TCT, TCC, and TCG. So in some ways, nature can be seen as inefficient as it could actually reduce down and use just 20 codons for 20 amino acids, plus one for “stop.”

Breakthrough for synthetic biology

Recoders like Chin do something like this streaming but removing the redundant codons and assigning them new functions. In an incredibly painstaking process, Chin and his colleagues replaced every occurrence of the serine codon TCG with AGC, every TCA (also serine) with AGT, and every TAG (stop) with TAA, for a total of 18,214 replacements.

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Chin notes there are several ways to do this princess, but in any method, the bacteria must stay alive. He was able to figure a method to keep the E. coli alive despite only using 59 codons rather than the naturally occurring 61 to make all 20 amino acids, and two codons rather than nature’s three to say stop.

The breakthrough will open doors to new kinds of recoding of genomes for use in research as well as possible medical applications. 

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