Technical University of Munich
Expanding the Genetic Code — Protein Chemistry in Living Systems
The desire to study and manipulate biological processes in their native environment has fuelled the development of approaches to endow proteins with new chemical functionalities in vivo. Genetic code expansion allows the site-specific incorporation of artificial amino acids into virtually any protein in living cells and animals. Together with significant developments in designing and re-discovering chemical reactions that are amenable to physiological conditions and applicable in living systems these methods have begun to have a direct impact on studying biological processes.
By site-specifically incorporating unnatural designer amino acids into proteins, we have developed tools to visualize proteins and modulate their enzymatic activity in living cells and to study protein-protein interactions as well as posttranslational modifications. [1-3]
In this talk I will present a novel approach that utilizes site-specifically incorporated designer amino acids as a platform for chemoenzymatic reactions. Combining genetic code expansion, Staudinger reduction and sortase-mediated transpeptidation we have developed a novel and generally applicable tool to ubiquitylate/SUMOylate target proteins in an inducible fashion. 
Our approach allows the site-specific attachment of ubiquitin and ubiquitin-like modifiers - via a native isopeptide bond – to non-refoldable, multi-domain proteins under native conditions. It further enables for the first time the site-specific, inducible and E1/E2/E3-independent ubiquitylation of proteins in living mammalian cells, providing a powerful tool to dissect the biological functions of ubiquitylation with temporal control.
AffiliationsTechnical University of Munich and Institute for Advanced Study, TUM IAS, Department of Chemistry, Lichtenbergstr. 4, 85748 Garching, Germany
1. K. Lang et al.; Chem Rev. 2014, 114, 4764
2. M. Cigler et al.; Angew. Chem. Int. Ed. 2017,, 56, 15737
3. T.A. Nguyen et al.; Angew. Chem. Int. Ed. 2018,, 57, 14350
4. M. Fottner et al., Nat. Chem. Biol. 2019,, 15, 276