title: Converting nonsense codons into sense codons by targeted pseudouridylation.
abstract: All three translation termination codons, or nonsense codons, contain a uridine residue at the first position of the codon. Here, we demonstrate that pseudouridylation (conversion of uridine into pseudouridine (Ψ), ref. 4) of nonsense codons suppresses translation termination both in vitro and in vivo. In vivo targeting of nonsense codons is accomplished by the expression of an H/ACA RNA capable of directing the isomerization of uridine to Ψ within the nonsense codon. Thus, targeted pseudouridylation represents a novel approach for promoting nonsense suppression in vivo. Remarkably, we also show that pseudouridylated nonsense codons code for amino acids with similar properties. Specifically, ΨAA and ΨAG code for serine and threonine, whereas ΨGA codes for tyrosine and phenylalanine, thus suggesting a new mode of decoding. Our results also suggest that RNA modification, as a naturally occurring mechanism, may offer a new way to expand the genetic code.
authors.affiliation: Department of Biochemistry and Biophysics, University of Rochester Medical Center, 601 Elmwood Avenue, Rochester, New York 14642, USA.
authors.forename: John
authors.initials: J
authors.lastname: Karijolich
authors.forename: Yi-Tao
authors.initials: YT
authors.lastname: Yu
mesh_terms: D000595:Amino Acid Sequence; D000596:Amino Acids / Q000235:genetics / Q000378:metabolism; D001483:Base Sequence; D003062:Codon / Q000235:genetics*; D018389:Codon, Nonsense / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal; D005815:Genetic Code / Q000235:genetics; D008668:Metallothionein / Q000235:genetics / Q000378:metabolism; D008969:Molecular Sequence Data; D010443:Peptide Chain Termination, Translational; D014176:Protein Biosynthesis / Q000235:genetics*; D011560:Pseudouridine / Q000378:metabolism*; D012331:RNA, Fungal / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000235:genetics*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics; D012359:tRNA Methyltransferases / Q000235:genetics
chemical_list: D000596:Amino Acids; C500769:CUP1-1 protein, S cerevisiae; D003062:Codon; D018389:Codon, Nonsense; D012331:RNA, Fungal; D012333:RNA, Messenger; D029701:Saccharomyces cerevisiae Proteins; D011560:Pseudouridine; D008668:Metallothionein; D012359:tRNA Methyltransferases; C024845:NCL1 protein, S cerevisiae