By Kyle Hoffman

In the most recent issue of Organic and Biomolecular Chemistry, a paper from Matthew Hartman’s lab highlights the use of an editing-deficient valine-tRNA synthetase (ValRS T222P) to incorporate 11 non-canonical amino acids (ncAAs) into peptides synthesized in vitro [1].

The eleven ncAAs are comprised of L-amino acids with side chain modifications, α, α-disubstituted amino acids containing an α-methyl group, and β-amino acids. To prepare ncAA-tRNA, total tRNA was extracted from E. coli then charged by ValRS T222P. PURE in vitro translation reactions were supplemented with ncAA-tRNA for incorporation at a valine codon in an mRNA template. Interestingly, the efficiency of dual incorporation of α-methyl alanine and α-methyl serine was comparable to that of valine using an in vitro transcribed valine tRNA variant. This study demonstrates the value of ValRS T222P for production of novel ncAA-tRNAs and the synthesis of peptides with new structures and properties.

1. Iqbal, Emil S., Kara K. Dods, and Matthew C. T. Hartman. 2018. “Ribosomal Incorporation of Backbone Modified Amino Acids via an Editing-Deficient Aminoacyl-tRNA Synthetase.” Organic & Biomolecular Chemistry. doi:10.1039/c7ob02931d.