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Crystal structure of a translation termination complex formed with release factor RF2.

Authors
  • Korostelev, Andrei
  • Asahara, Haruichi
  • Lancaster, Laura
  • Laurberg, Martin
  • Hirschi, Alexander
  • Zhu, Jianyu
  • Trakhanov, Sergei
  • Scott, William G
  • Noller, Harry F
Type
Published Article
Journal
Proceedings of the National Academy of Sciences
Publisher
Proceedings of the National Academy of Sciences
Publication Date
Dec 16, 2008
Volume
105
Issue
50
Pages
19684–19689
Identifiers
DOI: 10.1073/pnas.0810953105
PMID: 19064930
Source
Medline
License
Unknown

Abstract

We report the crystal structure of a translation termination complex formed by the Thermus thermophilus 70S ribosome bound with release factor RF2, in response to a UAA stop codon, solved at 3 A resolution. The backbone of helix alpha5 and the side chain of serine of the conserved SPF motif of RF2 recognize U1 and A2 of the stop codon, respectively. A3 is unstacked from the first 2 bases, contacting Thr-216 and Val-203 of RF2 and stacking on G530 of 16S rRNA. The structure of the RF2 complex supports our previous proposal that conformational changes in the ribosome in response to recognition of the stop codon stabilize rearrangement of the switch loop of the release factor, resulting in docking of the universally conserved GGQ motif in the PTC of the 50S subunit. As seen for the RF1 complex, the main-chain amide nitrogen of glutamine in the GGQ motif is positioned to contribute directly to catalysis of peptidyl-tRNA hydrolysis, consistent with mutational studies, which show that most side-chain substitutions of the conserved glutamine have little effect. We show that when the H-bonding capability of the main-chain N-H of the conserved glutamine is eliminated by substitution with proline, peptidyl-tRNA esterase activity is abolished, consistent with its proposed role in catalysis.

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