Objective
The incorporation of unnatural amino acids (more than 50 to date) into proteins in vivo has resulted in the generation of
proteins with novel chemical, biological, and physical properties. However, some unnatural amino acids possess properties,
such as an inability to cross the cell membrane or a level of toxicity dangerous to the organism, that restrict their incorporation
into proteins in vivo. In addition, even when an unnatural amino acid crosses the cell membrane, its transport efficiency
within the cell is very low. We propose to overcome these limitations by exploiting translational components evolved
tRNA-synthetases and their cognate suppressor-tRNA from Archea for the incorporation of an array of unnatural amino acids
into proteins in vitro in a cell-free protein translation system. The expressed recombinant proteins containing the unnatural
amino acids will be purified from the reaction mixture and used for further research. Using the cell free system, first we will
demonstrate our new approach by incorporating novel unnatural amino acids, i.e. thiolysine analogues, into proteins using
the broad substrate specificity of evolved tRNA synthetases. We will then incorporate a thiolysine analogue into PCNA for
the site-specific ubiquitination and SUMOylation of these proteins for in vitro studies of the interactions between PCNA and
interacting proteins and to follow the progress of the replication fork. This unique approach will show for the first time the use
of evolved synthetases in a cell free translation system, with the advantage being that previously un-incorporable unnatural
amino acids can be incorporated using this approach. Our overall aim is to enable the introduction of new functionalities into
proteins.
Fields of science
Call for proposal
ERC-2010-StG_20091118
See other projects for this call
Funding Scheme
ERC-SG - ERC Starting GrantHost institution
84105 Beer Sheva
Israel