Researchers rebuilt the genome of E. coli using fewer genetic instructions, demonstrating how extensively biology’s code can be rewritten.
Scientists at the Medical Research Council Laboratory of Molecular Biology achieved a major synthetic-biology milestone by constructing a redesigned version of the Escherichia coli genome. Published in Nature in May 2019, the research produced a living bacterium called Syn61, whose synthetic genome contained approximately four million DNA base pairs.
The achievement centred on simplifying the genetic code. Cells read genetic information in three-letter units called codons, which specify amino acids or signal when protein production should stop. The standard code contains 64 codons, with several providing alternative instructions for the same amino acid.
Researchers replaced 18,214 occurrences of selected codons, allowing Syn61 to operate with 61 codons while still producing proteins containing the usual 20 amino acids. The result demonstrated that some redundancy in the genetic code could be removed across an entire bacterial genome.
This was extensive genome redesign, rather than the creation of a wholly new biological system. Syn61 remained based on E. coli, retaining the underlying machinery and biological functions of its bacterial ancestor. The experiment changed how familiar biological instructions were encoded.
The work also created opportunities for expanding what engineered cells can manufacture. In subsequent research reported in 2021, the team reassigned freed-up codons to support the production of polymers containing nonstandard building blocks and demonstrated resistance to tested viruses. Such capabilities could contribute to future medicines and materials, although those applications require further development.
The lasting significance is a clearer understanding of how flexible the genetic code can be—and a foundation for designing cells with capabilities beyond those found in their natural ancestors.
Sources:
