Structure of the Elongator cofactor complex Kti11/Kti13 provides insight into the role of Kti13 in Elongator-dependent tRNA modification.
Fiche publication
Date publication
mars 2015
Journal
The FEBS journal
Auteurs
Membres identifiés du Cancéropôle Est :
Pr CAVARELLI Jean, Dr SERAPHIN Bertrand
Tous les auteurs :
Kolaj-Robin O, McEwen AG, Cavarelli J, Séraphin B
Lien Pubmed
Résumé
Modification of wobble uridines of many eukaryotic tRNAs requires the Elongator complex, a highly conserved six-subunit eukaryotic protein assembly, as well as the Killer toxin-insensitive (Kti) proteins 11-14. Kti11 was additionally shown to be implicated in the biosynthesis of diphthamide, a post-translationally modified histidine of translation elongation factor 2. Recent data indicate that iron-bearing Kti11 functions as an electron donor to the [4Fe-4S] cluster of radical S-Adenosylmethionine enzymes, triggering the subsequent radical reaction. We show here that recombinant yeast Kti11 forms a stable 1 : 1 complex with Kti13. To obtain insights into the function of this heterodimer, the Kti11/Kti13 complex was purified to homogeneity, crystallized, and its structure determined at 1.45 Å resolution. The importance of several residues mediating complex formation was confirmed by mutagenesis. Kti13 adopts a fold characteristic of RCC1-like proteins. The seven-bladed β-propeller consists of a unique mixture of four- and three-stranded blades. In the complex, Kti13 orients Kti11 and restricts access to its electron-carrying iron atom, constraining the electron transfer capacity of Kti11. Based on these findings, we propose a role for Kti13, and discuss the possible functional implications of complex formation.
Mots clés
Binding Sites, Crystallography, X-Ray, Electron Transport, Iron, chemistry, Models, Molecular, Mutagenesis, Site-Directed, Protein Conformation, RNA, Transfer, chemistry, Repressor Proteins, chemistry, Saccharomyces cerevisiae Proteins, chemistry, Static Electricity
Référence
FEBS J.. 2015 Mar;282(5):819-33