University of Veterinary Medicine Vienna tRNA binding to Kti12 is crucial for wobble uridine modification by Elongator In yeast, tRNA modifications that are introduced by the Elongator complex are recognized by zymocin, a fungal tRNase killer toxin that cleaves the anticodon. Based on zymocin resistance conferred by mutations in KTI12, a gene coding for an Elongator interactor, we further examined the yet vaguely defined cellular role of Kti12. Guided by structural similarities between Kti12 and PSTK, a tRNA kinase involved in selenocysteine synthesis, we identified conserved basic residues in the C-terminus of Kti12, which upon site-directed mutagenesis caused progressive loss of tRNA binding in vitro. The inability of Kti12 to bind tRNA led to similar phenotypes caused by Elongator inactivation in vivo. Consistently, tRNA binding deficient kti12 mutants drastically suppressed Elongator dependent tRNA anticodon modifications and reduced the capacity of Kti12 to interact with Elongator. We further could distinguish Elongator unbound pools of Kti12 in a tRNA dependent manner from bound ones. In summary, the C-terminal domain of Kti12 is crucial for tRNA binding and Kti12 recruitment to Elongator, which are both requirements for Elongator function suggesting Kti12 is a tRNA carrier that interacts with Elongator for modification of the tRNA anticodon. en TEXT journal article Wissenschaftlicher Artikel Articolo di rivista Text Wissenschaftlicher Artikel Text journal article Testo Articolo di rivista RNA, Transfer Metabolism RNA, Transfer Chemistry Uridine Metabolism Saccharomyces Cerevisiae Proteins Metabolism Saccharomyces Cerevisiae Proteins Chemistry Saccharomyces Cerevisiae Proteins Genetics Saccharomyces Cerevisiae Genetics Saccharomyces cerevisia Metabolism Protein Binding Anticodon Metabolism Mutation Killer Factors, Yeast Metabolism Amino Acid Sequence 2025 2025 David Scherf Alexander Hammermeister Pauline Böhnert Alicia Burkard Mark Helm Sebastian Glatt Raffael Schaffrath Oxford University Press