title: Codon reassignment in the Escherichia coli genetic code.
abstract: Most organisms, from Escherichia coli to humans, use the 'universal' genetic code, which have been unchanged or 'frozen' for billions of years. It has been argued that codon reassignment causes mistranslation of genetic information, and must be lethal. In this study, we successfully reassigned the UAG triplet from a stop to a sense codon in the E. coli genome, by eliminating the UAG-recognizing release factor, an essential cellular component, from the bacterium. Only a few genetic modifications of E. coli were needed to circumvent the lethality of codon reassignment; erasing all UAG triplets from the genome was unnecessary. Thus, UAG was assigned unambiguously to a natural or non-natural amino acid, according to the specificity of the UAG-decoding tRNA. The result reveals the unexpected flexibility of the genetic code.
authors: RIKEN Systems and Structural Biology Center, 1-7-22 Suehiro-cho, Tsurumi, Yokohama 230-0045, Japan.
authors: Takahito
authors: T
authors: Mukai
authors: Akiko
authors: A
authors: Hayashi
authors: Fumie
authors: F
authors: Iraha
authors: Aya
authors: A
authors: Sato
authors: Kazumasa
authors: K
authors: Ohtake
authors: Shigeyuki
authors: S
authors: Yokoyama
authors: Kensaku
authors: K
authors: Sakamoto
mesh_terms: D000596:Amino Acids / Q000378:metabolism; D003062:Codon; D018388:Codon, Terminator; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins / Q000235:genetics; D017353:Gene Deletion; D010454:Peptide Termination Factors / Q000235:genetics
chemical_list: D000596:Amino Acids; D003062:Codon; D018388:Codon, Terminator; D029968:Escherichia coli Proteins; D010454:Peptide Termination Factors; C489005:prfA protein, E coli