Total synthesis of Escherichia coli with a recoded genome.
Level 5 - mechanism / opinion, no new human data
Bench research / in vitro organism engineering (Level 5 by design analogy)
PubMed 31092918 · doi:10.1038/s41586-019-1192-5
What was done
Researchers engineered a variant of Escherichia coli with a four-megabase synthetic genome using high-fidelity convergent total synthesis. The genome was recoded and refactored to replace every occurrence of two sense codons and one stop codon with synonymous alternatives across the entire genome, with sequence corrections implemented at seven positions.
What was found
The synthetic genome replaced 18,214 codons in total, producing a viable E. coli strain operating on a 61-codon genome (59 codons for the 20 amino acids plus stop codons). This reduction enabled the deletion of a transfer RNA gene that was previously essential in wild-type E. coli. The abstract reports no numerical growth rates or physiological parameters.
Why it matters
This study demonstrates that the canonical genetic code can be compressed through de novo whole-genome synthesis without loss of viability. Freeing up codons and associated tRNAs creates dedicated channels for engineering synthetic biology systems with non-canonical amino acids.
Limits
As an in vitro laboratory study in a single bacterial species (E. coli), generalizability to other organisms is unknown. The abstract does not report comparative growth rates, fitness costs, translational accuracy, or long-term evolutionary stability of the recoded strain.
Cited by
- supports In the standard genetic code, there are 64 triplet codons, and AAA codes for the amino acid lysine.