Insights into the hyperthermostability and unusual region-specificity of archaeal Pyrococcus abyssi tRNA m1A57/58 methyltransferase. - Archive ouverte HAL Accéder directement au contenu
Article Dans Une Revue Nucleic Acids Research Année : 2010

Insights into the hyperthermostability and unusual region-specificity of archaeal Pyrococcus abyssi tRNA m1A57/58 methyltransferase.

Amandine Guelorget
  • Fonction : Auteur
Martine Roovers
  • Fonction : Auteur
Carole Barbey
  • Fonction : Auteur
Xuan Li
  • Fonction : Auteur
Béatrice Golinelli-Pimpaneau

Résumé

The S-adenosyl-L-methionine dependent methylation of adenine 58 in the T-loop of tRNAs is essential for cell growth in yeast or for adaptation to high temperatures in thermophilic organisms. In contrast to bacterial and eukaryotic tRNA m(1)A58 methyltransferases that are site-specific, the homologous archaeal enzyme from Pyrococcus abyssi catalyzes the formation of m(1)A also at the adjacent position 57, m(1)A57 being a precursor of 1-methylinosine. We report here the crystal structure of P. abyssi tRNA m(1)A57/58 methyltransferase ((Pab)TrmI), in complex with S-adenosyl-L-methionine or S-adenosyl-L-homocysteine in three different space groups. The fold of the monomer and the tetrameric architecture are similar to those of the bacterial enzymes. However, the inter-monomer contacts exhibit unique features. In particular, four disulfide bonds contribute to the hyperthermostability of the archaeal enzyme since their mutation lowers the melting temperature by 16.5°C. His78 in conserved motif X, which is present only in TrmIs from the Thermococcocales order, lies near the active site and displays two alternative conformations. Mutagenesis indicates His78 is important for catalytic efficiency of (Pab)TrmI. When A59 is absent in tRNA(Asp), only A57 is modified. Identification of the methylated positions in tRNAAsp by mass spectrometry confirms that (Pab)TrmI methylates the first adenine of an AA sequence.

Domaines

Chimie organique

Dates et versions

hal-00534231 , version 1 (09-11-2010)

Identifiants

Citer

Amandine Guelorget, Martine Roovers, Vincent Guérineau, Carole Barbey, Xuan Li, et al.. Insights into the hyperthermostability and unusual region-specificity of archaeal Pyrococcus abyssi tRNA m1A57/58 methyltransferase.. Nucleic Acids Research, 2010, 38 (18), pp.6206-18. ⟨10.1093/nar/gkq381⟩. ⟨hal-00534231⟩
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