title: Ribosomal synthesis of N-methyl peptides.
abstract: N-methyl amino acids (N-Me AAs) are a common component of nonribosomal peptides (NRPs), a class of natural products from which many clinically important therapeutics are obtained. N-Me AAs confer peptides with increased conformational rigidity, membrane permeability, and protease resistance. Hence, these analogues are highly desirable building blocks in the ribosomal synthesis of unnatural peptide libraries, from which functional, NRP-like molecules may be identified. By supplementing a reconstituted Escherichia coli translation system with specifically aminoacylated total tRNA that has been chemically methylated, we have identified three N-Me AAs (N-Me Leu, N-Me Thr, and N-Me Val) that are efficiently incorporated into peptides by the ribosome. Moreover, we have demonstrated the synthesis of peptides containing up to three N-Me AAs, a number comparable to that found in many NRP drugs. With improved incorporation efficiency and translational fidelity, it may be possible to synthesize combinatorial libraries of peptides that contain multiple N-Me AAs. Such libraries could be subjected to in vitro selection methods to identify drug-like, high-affinity ligands for protein targets of interest.
authors.affiliation: Howard Hughes Medical Institute and Center for Computational and Integrative Biology, Massachusetts General Hospital, 185 Cambridge Street, Boston, Massachusetts 02114, USA.
authors.forename: Alexander O
authors.initials: AO
authors.lastname: Subtelny
authors.forename: Matthew C T
authors.initials: MC
authors.lastname: Hartman
authors.forename: Jack W
authors.initials: JW
authors.lastname: Szostak
mesh_terms: D000596:Amino Acids / Q000737:chemistry* / Q000378:metabolism; D020650:Combinatorial Chemistry Techniques; D010455:Peptides / Q000138:chemical synthesis*; D014176:Protein Biosynthesis; D012333:RNA, Messenger / Q000737:chemistry* / Q000378:metabolism; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; D046249:Transfer RNA Aminoacylation
chemical_list: D000596:Amino Acids; D010455:Peptides; D012333:RNA, Messenger