Scientists create 'designer' genetic code

Scientists have created a new way of using the human genetic code, by adding 'designer' amino acids to the proteins in DNA to alter its biochemical behaviour. The research could pave the way to the development of what lead researcher Jason Chin is calling 'a parallel genetic code'.

Chin and team, from the UK Medical Research Council's laboratory of molecular biology in Cambridge, developed a new ribosome which is able to read four nucleotide codons (the 'words' of the genetic code) rather than the usual three. The ribosome targets the part of the RNA which programs new properties into proteins, altering how our DNA behaves. The research was published in the journal Nature and shows that it is possible to add unnatural amino acids into proteins and create new biochemical reactions, or more stable bonds, for enzymes which are less resistant to harsh environments. Normal kinds of bonds, called disulphide bonds, can be broken in extreme environments such as heat and acidity, much like egg whites in boiling water. Chin and team are now studying how many of the potential 256 quadruplet codons it is possible to add to new amino acids.

'Using different chemical building blocks has the potential to create totally new chemistries with fascinating implications for how we understand and use living systems', comments Christina Agapakis on the science blog Oscillator, in reference to the findings. 'The technology seems to work very well, offering a marked improvement in the yields of bis-modified proteins', observes Tom Muir, professor at the Selma and Lawrence Ruben Laboratory of Synthetic Protein Chemistry at Rockefeller University.

The strengthening of the chemical bonds which hold proteins in cells together could lead to practical applications such as helping to create drugs which can be taken orally, without being destroyed by the acids in the digestive tract, reports the New Scientist. 'This work provides foundational technologies for the encoded synthesis and synthetic evolution of unnatural polymers in cells,' conclude Chin and co-authors.