A Designed, Highly Efficient Pyrrolysyl-tRNA Synthetase Mutant Binds o-Chlorophenylalanine Using Two Halogen Bonds.
Vatansever, E.C., Yang, K.S., Geng, Z.Z., Qiao, Y., Li, P., Xu, S., Liu, W.R.(2022) J Mol Biol 434: 167534-167534
- PubMed: 35278475 
- DOI: https://doi.org/10.1016/j.jmb.2022.167534
- Primary Citation of Related Structures:  
7RSM - PubMed Abstract: 
As one of the most valuable tools for genetic code expansion, pyrrolysyl-tRNA synthetase (PylRS) is structurally related to phenylalanyl-tRNA synthetase (PheRS). By introducing mutations that mimic ligand interactions in PheRS into PylRS, we designed a PylRS mutant. This mutant, designated as oClFRS, recognizes a number of o-substituted phenylalanines for their genetic incorporation at amber codon. Its efficiency in catalyzing genetic incorporation of o-chlorophenylalanine (o-ClF) is better than that for N ε -tert-butyloxycarbonyl-lysine catalyzed by PylRS. The crystal structure of oClFRS bound with o-ClF shows that o-ClF binds deeply into a hydrophobic but catalytically inactive pocket in the active site and involves two halogen bonds to achieve strong interactions. The shift of o-ClF to a catalytically active position in the oClFRS active site will be necessary for its activation. This is the first reported aminoacyl-tRNA synthetase that involves two halogen bonds for ligation recognition and might represent an alternative route to develop aminoacyl-tRNA synthetase mutants that are selective for noncanonical amino acids over native amino acids.
Organizational Affiliation: 
The Texas A&M Drug Discovery Laboratory, Department of Chemistry, Texas A&M University, College Station, TX 77843, USA.