title: Consecutive Elongation of D-Amino Acids in Translation.
abstract: Recent progress in the field of genetic code reprogramming using a reconstituted cell-free translation system has made it possible to incorporate a wide array of non-proteinogenic amino acids, including N-methyl-amino acids and D-amino acids. Despite the fact that up to ten N-methyl-amino acid residues can be continuously elongated, the successive incorporation of even two D-amino acids into a nascent peptide chain remains a formidable challenge, thus far being nearly impossible. Here we report achievement of continuous D-amino acid elongation by the use of engineered tRNAs and optimized concentrations of translation factors, enabling us to incorporate up to ten consecutive D-Ser residues into a nascent peptide chain. We have also expressed macrocyclic peptides consisting of four or five consecutive D-amino acids consisting of D-Phe, D-Ser, D-Ala, or D-Cys closed by either a disulfide bond or a thioether bond.
authors.affiliation: Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; JST, PRESTO, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: katoh@chem.s.u-tokyo.ac.jp.
authors.forename: Takayuki
authors.initials: T
authors.lastname: Katoh
authors.affiliation: Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan.
authors.forename: Kenya
authors.initials: K
authors.lastname: Tajima
authors.affiliation: Department of Chemistry, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan; JST, CREST, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan. Electronic address: hsuga@chem.s.u-tokyo.ac.jp.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Suga
mesh_terms: D000596:Amino Acids / Q000378:metabolism*; D010452:Peptide Biosynthesis; D010441:Peptide Chain Elongation, Translational; D012343:RNA, Transfer / Q000378:metabolism
chemical_list: D000596:Amino Acids; D012343:RNA, Transfer
keywords: D-amino acid; cyclic peptide; genetic code reprogramming; peptide; ribosome; tRNA; translation