Conserved Cysteine Residues of GidA Are Essential for Biogenesis of 5-Carboxymethylaminomethyluridine at tRNA Anticodon

Takuo Osawa, Koichi Ito, Hideko Inanaga, Osamu Nureki, Kozo Tomita, Tomoyuki Numata

Research output: Contribution to journalArticle

36 Citations (Scopus)

Abstract

The 5-carboxymethylaminomethyl modification of uridine (cmnm5U) at the anticodon first position occurs in tRNAs that read split codon boxes ending with purine. This modification is crucial for correct translation, by restricting codon-anticodon wobbling. Two conserved enzymes, GidA and MnmE, participate in the cmnm5U modification process. Here we determined the crystal structure of Aquifex aeolicus GidA at 2.3 Å resolution. The structure revealed the tight interaction of GidA with FAD. Structure-based mutation analyses allowed us to identify two conserved Cys residues in the vicinity of the FAD-binding site that are essential for the cmnm5U modification in vivo. Together with mutational analysis of MnmE, we propose a mechanism for the cmnm5U modification process where GidA, but not MnmE, attacks the C6 atom of uridine by a mechanism analogous to that of thymidylate synthase. We also present a tRNA-docking model that provides structural insights into the tRNA recognition mechanism for efficient modification.

Original languageEnglish
Pages (from-to)713-724
Number of pages12
JournalStructure
Volume17
Issue number5
DOIs
Publication statusPublished - May 13 2009
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Structural Biology
  • Molecular Biology

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