Unusual base pairing during the decoding of a stop codon by the ribosome.

ABSTRACT: During normal translation, the binding of a release factor to one of the three stop codons (UGA, UAA or UAG) results in the termination of protein synthesis. However, modification of the initial uridine to a pseudouridine (Ψ) allows efficient recognition and read-through of these stop codons by a transfer RNA (tRNA), although it requires the formation of two normally forbidden purine-purine base pairs. Here we determined the crystal structure at 3.1 Å resolution of the 30S ribosomal subunit in complex with the anticodon stem loop of tRNA(Ser) bound to the ΨAG stop codon in the A site. The ΨA base pair at the first position is accompanied by the formation of purine-purine base pairs at the second and third positions of the codon, which show an unusual Watson-Crick/Hoogsteen geometry. The st

SUBMITTER: Fernandez IS 

PROVIDER: S-EPMC3732562 | biostudies-literature | 2013 Aug

REPOSITORIES: biostudies-literature