The Pyrrolysyl-tRNA synthetase (PylRS) and its cognate tRNAPyl are extensively used to add non-canonical amino acids (ncAAs) to the genetic code of bacterial and eukaryotic cells. However, new ncAAs often require a cumbersome de novo engineering process to generate an appropriate PylRS/tRNAPyl pair. We here report a strategy to predict a PylRS variant with novel properties. The designed polyspecific PylRS variant HpRS catalyzes the aminoacylation of 31 structurally diverse ncAAs bearing clickable, fluorinated, fluorescent, and for the first time biotinylated entities. Moreover, we demonstrated a site-specific and copper-free conjugation strategy of a nanobody by the incorporation of biotin. The design of polyspecific PylRS variants offers an attractive alternative to existing screening approaches and provides insights into the complex PylRS-substrate interactions.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledgements: Te research reported in this publication was supported by funding from King Abdullah University of Science and Technology (KAUST). We thank the SFB749/A10 (M.G.) for fnancial support. We are grateful to Prof. Peter G. Schultz (Te Scripps Research Institute, La Jolla, CA) for kindly providing the original pEVOL-PylRS plasmid.