Structure of the Kti11/Kti13 Heterodimer and Its Double Role in Modifications of tRNA and Eukaryotic Elongation Factor 2

• Published in: Structure (London) 2015-01, Vol.23 (1), p.149-160
• Main Authors: Glatt, Sebastian, Zabel, Rene, Vonkova, Ivana, Kumar, Amit, Netz, Daili J., Pierik, Antonio J., Rybin, Vladimir, Lill, Roland, Gavin, Anne-Claude, Balbach, Jochen, Breunig, Karin D., Müller, Christoph W.
• Format: Article
• Language: English
• Subjects: Models, Molecular; Organisms, Genetically Modified; Peptide Elongation Factor 2 - chemistry; Peptide Elongation Factor 2 - metabolism; Protein Biosynthesis - genetics; Protein Multimerization; Protein Structure, Quaternary; Repressor Proteins - chemistry; Repressor Proteins - metabolism; Repressor Proteins - physiology; RNA Processing, Post-Transcriptional - genetics; RNA, Transfer - chemistry; RNA, Transfer - metabolism; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Saccharomyces cerevisiae Proteins - chemistry; Saccharomyces cerevisiae Proteins - metabolism; Saccharomyces cerevisiae Proteins - physiology
• ISSN: 0969-2126; 1878-4186
• DOI: 10.1016/j.str.2014.11.008

The small, highly conserved Kti11 alias Dph3 protein encoded by the Kluyveromyces lactis killer toxin insensitive gene KTI11/DPH3 is involved in the diphthamide modification of eukaryotic elongation factor 2 and, together with Kti13, in Elongator-dependent tRNA wobble base modifications, thereby affecting the speed and accuracy of protein biosynthesis through two distinct mechanisms. We have solved the crystal structures of Saccharomyces cerevisiae Kti13 and the Kti11/Kti13 heterodimer at 2.4 and 2.9 Å resolution, respectively, and validated interacting residues through mutational analysis in vitro and in vivo. We show that metal coordination by Kti11 and its heterodimerization with Kti13 are essential for both translational control mechanisms. Our structural and functional analyses identify Kti13 as an additional component of the diphthamide modification pathway and provide insight into the molecular mechanisms that allow the Kti11/Kti13 heterodimer to coregulate two consecutive steps in ribosomal protein synthesis. [Display omitted] •Kti11 binds Kti13 through conserved residues at the top of the β-propeller•Kti11/Kti13 heterodimerization is required for modifications of tRNA and eEF2•Metal coordination by Kti11 is equally required for both modification reactions•Kti1/Kti13 coregulates two consecutive steps in ribosomal protein synthesis Glatt et al. report the crystal structures of the WD40 protein Kti13 and the Kti11/Kti13 heterodimer. Mutational analyses demonstrate the importance of Kti11/Kti13 heterodimerization and Kti11 metal binding in regulating two consecutive steps in ribosomal protein synthesis.