title: Gcn4 misregulation reveals a direct role for the evolutionary conserved EKC/KEOPS in the t6A modification of tRNAs.
abstract: The EKC/KEOPS complex is universally conserved in Archaea and Eukarya and has been implicated in several cellular processes, including transcription, telomere homeostasis and genomic instability. However, the molecular function of the complex has remained elusive so far. We analyzed the transcriptome of EKC/KEOPS mutants and observed a specific profile that is highly enriched in targets of the Gcn4p transcriptional activator. GCN4 expression was found to be activated at the translational level in mutants via the defective recognition of the inhibitory upstream ORFs (uORFs) present in its leader. We show that EKC/KEOPS mutants are defective for the N6-threonylcarbamoyl adenosine modification at position 37 (t(6)A(37)) of tRNAs decoding ANN codons, which affects initiation at the inhibitory uORFs and provokes Gcn4 de-repression. Structural modeling reveals similarities between Kae1 and bacterial enzymes involved in carbamoylation reactions analogous to t(6)A(37) formation, supporting a direct role for the EKC in tRNA modification. These findings are further supported by strong genetic interactions of EKC mutants with a translation initiation factor and with threonine biosynthesis genes. Overall, our data provide a novel twist to understanding the primary function of the EKC/KEOPS and its impact on several essential cellular functions like transcription and telomere homeostasis.
authors: LEA Laboratory of Nuclear RNA metabolism, Centre de Génétique Moléculaire, CNRS-FRE3144, 1 av de la Terrasse, 91190 Gif sur Yvette, France.
authors: Marie-Claire
authors: MC
authors: Daugeron
authors: Tineke L
authors: TL
authors: Lenstra
authors: Martina
authors: M
authors: Frizzarin
authors: Basma
authors: B
authors: El Yacoubi
authors: Xipeng
authors: X
authors: Liu
authors: Agnès
authors: A
authors: Baudin-Baillieu
authors: Philip
authors: P
authors: Lijnzaad
authors: Laurence
authors: L
authors: Decourty
authors: Cosmin
authors: C
authors: Saveanu
authors: Alain
authors: A
authors: Jacquier
authors: Frank C P
authors: FC
authors: Holstege
authors: Valérie
authors: V
authors: de Crécy-Lagard
authors: Herman
authors: H
authors: van Tilbeurgh
authors: Domenico
authors: D
authors: Libri
mesh_terms: D000241:Adenosine / Q000031:analogs & derivatives* / Q000378:metabolism; D050976:Basic-Leucine Zipper Transcription Factors / Q000096:biosynthesis / Q000235:genetics*; D018387:Codon, Initiator; D040061:Eukaryotic Initiation Factor-5 / Q000235:genetics; D019143:Evolution, Molecular; D020869:Gene Expression Profiling; D015966:Gene Expression Regulation, Fungal; D008666:Metalloendopeptidases / Q000737:chemistry / Q000235:genetics; D009154:Mutation; D010802:Phylogeny; D014176:Protein Biosynthesis; D012343:RNA, Transfer / Q000737:chemistry / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics* / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics
chemical_list: D050976:Basic-Leucine Zipper Transcription Factors; D018387:Codon, Initiator; D040061:Eukaryotic Initiation Factor-5; C501391:GCN4 protein, S cerevisiae; C509947:KEOPS complex, S cerevisiae; C111429:N6-methyl-N6-threonylcarbamoyladenosine; C513653:PCC1 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D012343:RNA, Transfer; C480738:Kae1 protein, S cerevisiae; D008666:Metalloendopeptidases; D000241:Adenosine