Rewriting E. coli’s genetic code
SynBERC researchers at Harvard are a step closer to engineering new "words" in the DNA language of bacteria by co-opting one of the codons in its genetic code to give it new meaning. In the July 15 2011 edition of Science, George Church's group describes its genome engineering technologies that are capable of fundamentally reengineering genomes by expanding the number of DNA codons it can read. The researchers plan to teach bacteria a new language by co-opting one of the words in the genetic code and giving it a new meaning.
In the workhorse bacteria E. coli, the codons TAA and TAG both signal the DNA machinery to stop copying DNA. The Church group replaced all instances of TAG with TAA, such that the bacteria’s genes all still code for all the same things but a word has been freed up so it can be given a new meaning.
The next step in the research is to redefine the replaced word. This could be done by mutating the cell’s reading machinery using well established genetic techniques. For example, they might change the definition of the TAG so that it codes for an exisiting amino acid such as Met or Lys. Done correctly, this could make bacteria immune to viral infection, which would be a boon for the biotech industry as it loses millions of dollars every year because of infected bacterial strains. Later, the newly available TAG codon could be redefined to encode an amino acid that that isn’t already in the genetic code. Then we’ll be able to easily create different proteins with properties useful as medicines, industrial enzymes, or novel biomaterials.
