title: Ribosomal synthesis of dehydroalanine-containing peptides.
abstract: Dehydroalanine is a nonproteinogenic amino acid, but it is a component of a wide variety of natural products with therapeutic activities. Indeed, this alpha,beta-unsaturated residue is a highly versatile building block due to its rigidifying effect on peptide backbones and its electrophilicity which allows site-specific thiol ligations of peptides with small molecules or proteins. To harness such versatility in genetically encoded, combinatorial peptide libraries, we report a simple and robust method for the ribosomal synthesis of dehydroalanine-containing peptides. Selenalysine, a selenium-containing lysine analogue, was recruited as a masked dehydroalanine equivalent. This residue is efficiently incorporated by a reconstituted Escherichia coli translation system at high fidelity and efficiency despite the presence of low levels of lysine. Mild oxidative conditions were used to convert selenalysine into dehydroalanine post-translationally. Using this method, we demonstrate the preparation of polyunsaturated and highly decorated peptides. This report is an important step toward the preparation and selection of large libraries of protein-reactive compounds with potential use as novel drugs or as analytical tools.
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: Florian P
authors.initials: FP
authors.lastname: Seebeck
authors.forename: Jack W
authors.initials: JW
authors.lastname: Szostak
mesh_terms: D000409:Alanine / Q000031:analogs & derivatives* / Q000737:chemistry; D004926:Escherichia coli / Q000235:genetics; D008239:Lysine / Q000031:analogs & derivatives / Q000737:chemistry; D016566:Organoselenium Compounds / Q000737:chemistry; D010456:Peptides, Cyclic / Q000138:chemical synthesis* / Q000737:chemistry; D014176:Protein Biosynthesis; D011487:Protein Conformation; D012333:RNA, Messenger / Q000235:genetics; D012270:Ribosomes / Q000737:chemistry / Q000378:metabolism*
chemical_list: D016566:Organoselenium Compounds; D010456:Peptides, Cyclic; D012333:RNA, Messenger; C011351:selenalysine; C015102:dehydroalanine; D008239:Lysine; D000409:Alanine