2. Academic Validation
  3. An extended dsRBD is required for post-transcriptional modification in human tRNAs

An extended dsRBD is required for post-transcriptional modification in human tRNAs

  • Nucleic Acids Res. 2015 Oct 30;43(19):9446-56. doi: 10.1093/nar/gkv989.
Charles Bou-Nader 1,  Ludovic Pecqueur 1,  Damien Bregeon 2,  Amina Kamah 3,  Vincent Guérineau 4,  Béatrice Golinelli-Pimpaneau 1,  Beatriz G Guimarães 5,  Marc Fontecave 1,  Djemel Hamdane 6
Affiliations

Affiliations

  • 1 Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France.
  • 2 Sorbonne Universités, UPMC Univ. Paris 06, IBPS, UMR8256, Biology of Aging and Adaptation, F-75005 Paris, France.
  • 3 Université de Lille-Nord de France, CNRS UMR 8576, Institut Fédératif de Recherches 147, Villeneuve d'Ascq, France.
  • 4 Institut de Chimie des Substances Naturelles, Centre de Recherche de Gif, CNRS, 1 avenue de la Terrasse, 91198 Gif-sur-Yvette, France.
  • 5 Synchrotron SOLEIL, L'Orme des Merisiers, Saint-Aubin, 91190 Gif-sur-Yvette, France.
  • 6 Laboratoire de Chimie des Processus Biologiques, CNRS-UMR 8229, Collège De France, France, 11 place Marcelin Berthelot, 75231 Paris Cedex 05, France djemel.hamdane@college-de-france.fr.
PMID: 26429968 DOI: 10.1093/nar/gkv989
Abstract

In tRNA, dihydrouridine is a conserved modified base generated by the post-transcriptional reduction of uridine. Formation of dihydrouridine 20, located in the D-loop, is catalyzed by dihydrouridine synthase 2 (Dus2). Human Dus2 (HsDus2) expression is upregulated in lung cancers, offering a growth advantage throughout its ability to interact with components of the translation apparatus and inhibit Apoptosis. Here, we report the crystal structure of the individual domains of HsDus2 and their functional characterization. HsDus2 is organized into three major modules. The N-terminal catalytic domain contains the flavin cofactor involved in the reduction of uridine. The second module is the conserved α-helical domain known as the tRNA binding domain in HsDus2 homologues. It is connected via a flexible linker to an unusual extended version of a dsRNA binding domain (dsRBD). Enzymatic assays and yeast complementation showed that the catalytic domain binds selectively NADPH but cannot reduce uridine in the absence of the dsRBD. While in Dus Enzymes from bacteria, Plants and fungi, tRNA binding is essentially achieved by the α-helical domain, we showed that in HsDus2 this function is carried out by the dsRBD. This is the first reported case of a tRNA-modifying Enzyme carrying a dsRBD used to bind tRNAs.

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