title: A bacterial strain with a unique quadruplet codon specifying non-native amino acids.
abstract: The addition of noncanonical amino acids to the genetic code requires unique codons not assigned to the 20 canonical amino acids. Among the 64 triplet codons, only the three nonsense "stop" codons have been used to encode non-native amino acids. Use of quadruplet "frame-shift" suppressor codons provides an abundant alternative but suffers from low suppression efficiency as a result of competing recognition of their first three bases by endogenous host tRNAs or release factors. Deletion of release factor 1 in a genomically recoded strain of E. coli (E. coli C321), in which all endogenous amber stop codons (UAG) are replaced with UAA, abolished UAG mediated translation termination. Here we show that a Methanocaldococcus jannaschii-derived frame-shift suppressor tRNA/aminoacyl-tRNA synthetase pair enhanced UAGN suppression efficiency in this recoded bacterial strain. These results demonstrate that efficient quadruplet codons for encoding non-native amino acids can be generated by eliminating competing triplet codon recognition at the ribosome.
authors.affiliation: Department of Chemistry and the Skaggs Institute for Chemical Biology, The Scripps Research Institute, 10550 North Torrey Pines Road, La Jolla, CA 92037 (USA); Department of Chemistry, Boston College, 2609 Beacon Street, Chestnut Hill, MA 02467 (USA).
authors.forename: Abhishek
authors.initials: A
authors.lastname: Chatterjee
authors.forename: Marc J
authors.initials: MJ
authors.lastname: Lajoie
authors.forename: Han
authors.initials: H
authors.lastname: Xiao
authors.forename: George M
authors.initials: GM
authors.lastname: Church
authors.forename: Peter G
authors.initials: PG
authors.lastname: Schultz
mesh_terms: D000596:Amino Acids / Q000235:genetics* / Q000378:metabolism; D000604:Amino Acyl-tRNA Synthetases / Q000235:genetics / Q000378:metabolism; D018388:Codon, Terminator / Q000235:genetics*; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D063747:Methanocaldococcus / Q000145:classification* / Q000235:genetics* / Q000378:metabolism; D012343:RNA, Transfer / Q000235:genetics / Q000378:metabolism; D013489:Suppression, Genetic / Q000235:genetics
chemical_list: D000596:Amino Acids; D018388:Codon, Terminator; D012343:RNA, Transfer; D000604:Amino Acyl-tRNA Synthetases
keywords: frame-shift suppression; genomically recoded E. coli; quadruplet codons; release factor 1; unnatural amino acids