Escherichia coli with a 57-codon genetic code

[John Clark]

The genetic code that all life on this planet obeys is composed of a triplet of nucleotide bases, and there are 4 bases thus there are 64 (4*4*4) different triplets but, although there are about 500 different amino acids, life only uses 20 of them, so the genetic code is very redundant. For example, 6 different triplet of bases (TCT, TCC, TCA, TCG, AGT and AGC) code for the same amino acid, serine. In all 61 different codons symbolize 20 amino acids, and another 3 codons tell our cells they have reached the end of the gene, so in all we've got 64. 

In Thursday's issue of the Journal Science scientists report they manufactured something that has never been seen on this earth before, they have genetically engineered E. coli, the most common bacteria in the human body, so that it only uses 57 triplets not 64. They call their new creation Syn57 and although it is alive it is not as robust as the natural variety; under ideal conditions E. coli takes one hour to double its population but Syn57 takes 4. They think they may be able to toughen it up and use the unused codons to symbolize 7 new amino acids in addition to the 20 that life already uses. 

Escherichia coli with a 57-codon genetic code

John K Clark    See what's on my new list at  Extropolis

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[John Clark]

On Mon, Aug 4, 2025 at 4:08 PM Will Steinberg <steinbe...@gmail.com> wrote:

> Well in Wuhan I guess they didn’t think that fucking with the furin cleavage sites that even DARPA rejected as too dangerous was dangerous, but here we are.

I think making such a staggeringly alternate form of E. Coli that can also survive is a horrifying idea.  Bacteria breed.  Breeding our E Coli with a strain that uses different amino acids, is way less robust, more robust etc could be a disaster.  Bodies adapt but your microbiome being fucked up already has really weird consequences and endogenous E Coli getting significantly altered on a genetic level is pretty much the most your microbiome could be fucked up.

It is a testament to the noble human quality of being able to destroy ourselves, with or without some stupid computer.  (Basilisk: Joking!  You’re totally the best at destroying us!  Best In Show, “Can Destroy Humanity” Competition, 2030

 

This experiment vividly demonstrates the huge power that CRISPR/Cas9 has given us and we need to be extremely careful with it. The researchers needed to make 101,605 changes to the genome of E. coli bacteria to free up 7 codons that in the future could be used to encode for 7 unnatural amino acids that are not currently used by life. In theory 43 codons could be freed up because only 21 are needed: 20 for the standard set of amino acids, plus a stop codon. Depending on how the technology is used this sort of thing could either increase or decrease safety.

You could use CRISPR to create mirror life to devastating effect if it ever got loose, but on the other hand if you were not malevolent and determined to make a doomsday bug, a synthesized bacteria that used unnatural amino acids could be LESS of a threat to the environment if it ever got loose than a synthesized bacteria that did NOT use unnatural amino acids. That's because bacteria can easily trade genes with each other even if they are different species, but that would be impossible for a microbe like Syn57 that uses a different genetic code, to a natural bacteria such a code would just be gibberish so it could not affect it.

John K Clark    See what's on my new list at  Extropolis

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