Enhancement of N-Methyl Amino Acid Incorporation into Proteins and Peptides Using Modified Bacterial Ribosomes and Elongation Factor P

ACS Chem Biol. 2024 Jun 21;19(6):1330-1338. doi: 10.1021/acschembio.4c00165. Epub 2024 May 20.

Abstract

N-Methylated amino acids are constituents of natural bioactive peptides and proteins. Nα-methylated amino acids appear abundantly in natural cyclic peptides, likely due to their constraint of peptide conformation and contribution to peptide stability. Peptides containing Nα-methylated amino acids have long been prepared by chemical synthesis. While such natural peptides are not produced ribosomally, recent ribosomal strategies have afforded Nα-methylated peptides. Presently, we define new strategies for the ribosomal incorporation of Nα-methylated amino acids into peptides and proteins. First, we identify modified ribosomes capable of facilitating the incorporation of six N-methylated amino acids into antibacterial scorpion peptide IsCT. Also synthesized analogously was a protein domain (RRM1) from hnRNP LL; improved yields were observed for nearly all tested N-methylated amino acids. Computational modeling of the ribosomal assembly illustrated how the distortion imposed by N-methylation could be compensated by altering the nucleotides in key 23S rRNA positions. Finally, it is known that incorporation of multiple prolines (an N-alkylated amino acid) ribosomally can be facilitated by bacterial elongation factor P. We report that supplementing endogenous EF-P during IsCT peptide and RRM1 protein synthesis gave improved yields for most of the N-methylated amino acids studied.

MeSH terms

  • Amino Acids* / chemistry
  • Amino Acids* / metabolism
  • Methylation
  • Peptide Elongation Factors* / chemistry
  • Peptide Elongation Factors* / metabolism
  • Peptides / chemistry
  • Peptides / metabolism
  • Ribosomes* / metabolism

Substances

  • Amino Acids
  • factor EF-P
  • Peptide Elongation Factors
  • Peptides