title: Accurate translation of the genetic code depends on tRNA modified nucleosides.
abstract: Transfer RNA molecules translate the genetic code by recognizing cognate mRNA codons during protein synthesis. The anticodon wobble at position 34 and the nucleotide immediately 3' to the anticodon triplet at position 37 display a large diversity of modified nucleosides in the tRNAs of all organisms. We show that tRNA species translating 2-fold degenerate codons require a modified U(34) to enable recognition of their cognate codons ending in A or G but restrict reading of noncognate or near-cognate codons ending in U and C that specify a different amino acid. In particular, the nucleoside modifications 2-thiouridine at position 34 (s(2)U(34)), 5-methylaminomethyluridine at position 34 (mnm(5)U(34)), and 6-threonylcarbamoyladenosine at position 37 (t(6)A(37)) were essential for Watson-Crick (AAA) and wobble (AAG) cognate codon recognition by tRNA(UUU)(Lys) at the ribosomal aminoacyl and peptidyl sites but did not enable the recognition of the asparagine codons (AAU and AAC). We conclude that modified nucleosides evolved to modulate an anticodon domain structure necessary for many tRNA species to accurately translate the genetic code.
authors.affiliation: Department of Biochemistry, North Carolina State University, Raleigh, North Carolina 27695-7622, USA.
authors.forename: Connie
authors.initials: C
authors.lastname: Yarian
authors.forename: Hannah
authors.initials: H
authors.lastname: Townsend
authors.forename: Wojciech
authors.initials: W
authors.lastname: Czestkowski
authors.forename: Elzbieta
authors.initials: E
authors.lastname: Sochacka
authors.forename: Andrzej J
authors.initials: AJ
authors.lastname: Malkiewicz
authors.forename: Richard
authors.initials: R
authors.lastname: Guenther
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Miskiewicz
authors.forename: Paul F
authors.initials: PF
authors.lastname: Agris
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000737:chemistry; D001216:Asparagine / Q000737:chemistry; D020029:Base Pairing; D001483:Base Sequence; D003062:Codon; D005815:Genetic Code; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D009705:Nucleosides / Q000378:metabolism*; D014176:Protein Biosynthesis; D017434:Protein Structure, Tertiary; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D012336:RNA, Ribosomal, 16S / Q000378:metabolism; D012343:RNA, Transfer / Q000378:metabolism*; D012270:Ribosomes / Q000378:metabolism; D013891:Thiouridine / Q000031:analogs & derivatives* / Q000737:chemistry; D014529:Uridine / Q000031:analogs & derivatives* / Q000737:chemistry
chemical_list: C105273:2-thiouridine; C099620:5-methylaminomethyluridine; D003062:Codon; C111429:N6-methyl-N6-threonylcarbamoyladenosine; D009705:Nucleosides; D012333:RNA, Messenger; D012336:RNA, Ribosomal, 16S; D013891:Thiouridine; D012313:RNA; D001216:Asparagine; D012343:RNA, Transfer; D000241:Adenosine; D014529:Uridine