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A genetically encoded picolyl azide for improved live cell copper click labeling

Provisionally accepted
The final, formatted version of the article will be published soon
 Simon Elsässer1, 2*,  Lindon W. Moodie3, 4*, Birthe Meineke1, 2,  Johannes Heimgärtner1, 2, Alexander Craig4 and Michael Landreh5
  • 1Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Science for Life Laboratory (SciLifeLab), Sweden
  • 2Ming Wai Lau Centre for Reparative Medicine, Stockholm node, Karolinska Institute, Sweden
  • 3Uppsala Antibiotic Centre, Uppsala University, Sweden
  • 4Drug Design and Discovery, Department of Medicinal Chemistry, Biomedical Centre, Sweden
  • 5Department of Microbiology, Tumor and Cell Biology, Karolinska Institutet (KI), Sweden

Bioorthogonal chemistry allows rapid and highly selective reactivity in biological environments. The copper-catalyzed azide–alkyne cycloaddition (CuAAC) is a classic bioorthogonal reaction routinely used to modify azides or alkynes that have been introduced into biomolecules. Amber suppression is an efficient method for incorporating such chemical handles into proteins on the ribosome, in which noncanonical amino acids (ncAAs) are site-specifically introduced into the polypeptide in response to an amber (UAG) stop codon. A variety of ncAA structures containing azides or alkynes have been proven useful for performing CuAAC chemistry on proteins. To improve CuAAC efficiency, biologically incorporated alkyne groups can be reacted with azide substrates that contain copper-chelating groups. However, the direct incorporation of copper-chelating azides into proteins has not been explored. To remedy this, we prepared the ncAA paz-lysine (PazK), which contains a picolyl azide motif. We show that PazK is efficiently incorporated into proteins by amber suppression in mammalian cells. Furthermore, PazK-labeled proteins show improved reactivity with alkyne reagents in CuAAC.

Keywords: Genetic Code Expansion, Amber suppression, Non canonical amino acid, bioorthogonal chemistry, Click Chemistry, copper catalysed azide–alkyne cycloaddition (CuAAC)

Received: 31 Aug 2021; Accepted: 13 Oct 2021.

Copyright: © 2021 Elsässer, Moodie, Meineke, Heimgärtner, Craig and Landreh. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence:
Prof. Simon Elsässer, Science for Life Laboratory (SciLifeLab), Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Solna, Sweden
Prof. Lindon W. Moodie, Uppsala Antibiotic Centre, Uppsala University, Uppsala, Sweden