The genetic code can be expanded to include unnatural amino acids by using orthogonal tRNA/aminoacyl-tRNA synthetase pairs. New chemical and physical properties can be site-specifically introduced into proteins in vivo using such novel amino acids, and can be exploited to investigate various biological processes in their native settings. We are expanding this methodology to various cell types and organisms to study challenging questions in signal transduction, stem cell differentiation and neurobiology.
The genetic code is universally preserved in life forms on earth with few exceptions. The establishment of the genetic code is a critical transition in the evolution of all modern organisms. Why is a specific amino acid assigned to a particular codon? Why are only 20 common amino acids used in the code? We are developing synthetic biological methods to address these and other questions related to the origin and evolution of the genetic code.