Expanding the Genetic Code of Lactococcus lactis and Escherichia coli to Incorporate Non-canonical Amino Acids for Production of Modified Lantibiotics

Front Microbiol. 2018 Apr 6:9:657. doi: 10.3389/fmicb.2018.00657. eCollection 2018.


The incorporation of non-canonical amino acids (ncAAs) into ribosomally synthesized and post-translationally modified peptides, e.g., nisin from the Gram-positive bacterium Lactococcus lactis, bears great potential to expand the chemical space of various antimicrobials. The ncAA Nε-Boc-L-lysine (BocK) was chosen for incorporation into nisin using the archaeal pyrrolysyl-tRNA synthetase-tRNAPyl pair to establish orthogonal translation in L. lactis for read-through of in-frame amber stop codons. In parallel, recombinant nisin production and orthogonal translation were combined in Escherichia coli cells. Both organisms synthesized bioactive nisin(BocK) variants. Screening of a nisin amber codon library revealed suitable sites for ncAA incorporation and two variants displayed high antimicrobial activity. Orthogonal translation in E. coli and L. lactis presents a promising tool to create new-to-nature nisin derivatives.

Keywords: antimicrobial peptides; bacteriocin; nisin; non-canonical amino acids; orthogonal translation system; pyrrolysyl-tRNA synthetase; stop codon suppression.