Engineering of a peptide α-N-methyltransferase to methylate non-proteinogenic amino acids

Funding: This work was supported by grants to M.K. (CTI/Innosuisse 25951.2) and J.H.N. (BBSRC BB/R018189/1 and ERC 339367). A.J.B. isa Damon Runyon Fellow of the Damon Runyon Cancer Research Foundation (DRG-2283-17).Introduction of α-N-methylated non-proteinogenic amino acids into peptides can improve their biological activities, membrane permeability and proteolytic stability. This is commonly achieved, in nature and in the lab, by assembling pre-methylated amino acids. The more appealing route of methylating amide bonds is challenging. Biology has evolved an α-N-automethylating enzyme, OphMA, which acts on the amide bonds of peptides fused to its C-terminus. Due to the ribosomal biosynthesis of its substrate, the activity of this enzyme towards peptides with non-proteinogenic amino acids has not been addressed. An engineered OphMA, intein-mediated protein ligation and solid-phase peptide synthesis have allowed us to demonstrate the methylation of amide bonds in the context of non-natural amides. This approach may have application in the biotechnological production of therapeutic peptides.Publisher PDFPeer reviewe