thiouridine and 5-methylaminomethyluridine

Colicin D is a plasmid-encoded bacteriocin that specifically cleaves tRNA

Topics: Anticodon; Bacteriocins; Base Pairing; Binding Sites; Colicins; Escherichia coli; Gene Expression Regulation, Bacterial; Molecular Docking Simulation; Nucleic Acid Conformation; Peptide Elongation Factor Tu; Plasmids; Protein Binding; Protein Biosynthesis; Protein Conformation, alpha-Helical; Protein Conformation, beta-Strand; Protein Interaction Domains and Motifs; Ribosomes; RNA, Bacterial; RNA, Transfer, Arg; Substrate Specificity; Thiouridine; Uridine

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.

Topics: Adenosine; Asparagine; Base Pairing; Base Sequence; Codon; Genetic Code; Molecular Sequence Data; Nucleic Acid Conformation; Nucleosides; Protein Biosynthesis; Protein Structure, Tertiary; Ribosomes; RNA; RNA, Messenger; RNA, Ribosomal, 16S; RNA, Transfer; Thiouridine; Uridine