4X33: Structure of the Elongator cofactor complex Kti11/Kti13 at 1.45A

UNLABELLED: 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 A 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 beta-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. DATABASE: Structural data have been submitted to the Protein Data Bank under accession number 4X33.
PDB ID: 4X33Download
MMDB ID: 126357
PDB Deposition Date: 2014/11/27
Updated in MMDB: 2018/07
Experimental Method:
x-ray diffraction
Resolution: 1.45  Å
Source Organism:
Similar Structures:
Biological Unit for 4X33: dimeric; determined by software (PISA)
Molecular Components in 4X33
Label Count Molecule
Proteins (2 molecules)
Diphthamide Biosynthesis Protein 3(Gene symbol: KTI11)
Molecule annotation
Protein Ats1(Gene symbol: ATS1)
Molecule annotation
Chemicals (11 molecules)
* Click molecule labels to explore molecular sequence information.

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